NOAATRNMFSCIRC-388

A UNITED STATES
DEPARTMENT OF
COMMERCE
PUBLICATION

/.v \

NOAA Technical Report NMFS CIRC-388

S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Marine Fisheries Service

Proceedings of the First U.S.-Japan
Meeting on Aquaculture at Tokyo, Japan
October 18-19, 1971

Under fhe Aquaculture Panel, U.S.-Japan
Cooperafive Program in Natural Resources (UJNR)

Panel Chairmen:

WILLIAM N. SHAW - United States

ATSUCHI FURUKAWA - Japan

SEATTLE. WA
February 1974

J

NOAA TECHNICAL REPORTS

National Marine Fisheries Service, Circulars

The ma^r rMponsibilities of the National Manne Fisheries Service iNMFS) are to monitor and assess the abundance and K^oKraphic distribution of fisherv resources, to
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the indu8tr>'

The NOAA Technical Report NMFS CIRC senes continues a series that has been in existence since 1941, The Circulars are technical publications of general mteresi in-
tended to aid conservation and management. Publications that review in considerable detail and at a high technical level certain broad areas of research appear in this aeries.
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scientific and technical publications in the marine sciences. Individual copies may be obtained (unless otherwise noted) from D83. Technical Information Division. Environ-
mental Science Information Center. NOAA. Washington. D.C. 20235. Recent Circulars are:

315. Synopsis of biological data on the chum salmon, Oncorhynchus keta (Walbaum)
1792. By Richard G. Bakkala March 1970. iii + 89 pp.. 15 figs., 51 tables.

347. Synopsis of biological data on Pacific ocean perch, Setxutodes alutus By Richard
L. Major and Herbert H Shippen December 1970. iii -f 38 pp., 31 figs., 11 tables.

319. Bureau of Commercial Fisheries Great Lakes Fishery Laboratory, Ann Arbor.
Michigan. By Bureau of Commercial Fisheries. March 1970, 8 pp., 7 figs.

349. Use of abstracts and summaries as communication devices in technical articles. By
F. Bruce Sanford. February 1971, iii + 11 pp., 1 fig.

330. EASTROPAC Atlas: Vols. 1-7. CaUlog No. I 49.4:330/(vol.> 11 vols. Available from
the Superintendent of Documents. U.S. Government Printing Office, Washington, D.C.
20402.

350. Research in fiscal year 1969 at the Bureau of Commercial Fisheries Bioloincal
Laborator.-. Beaufort, N.C. By the Laborator>- staff November 1970. ii + 49 pp.. 21 figs..

17 tables.

331. Guidelines for the processing of hot-smoked chub. By H. L. Seagran. J. T.
Graikoski. and J. A. Emerson. January 1970, iv + 23 pp., 8 figs., 2 tables.

332. Pacific hake. (12 articles by 20 authors.) March 1970. iii + 152 pp.. 72 figs.. 47
ubies.

333, Recommended practices for vessel sanitation and fish handling. By Edgar W. Bow-
man and Alfred Larsen. March 1970. iv + 27 pp., 6 figs.

335. Progress report of the Bureau of Commercial Fisheries Center for Estuarine and
Menhaden Research, Pesticide Field Station. Gulf Breeze. Fla.. fiscal year 1969, By the
Laboratory staff. August 1970. iii + 33 pp.. 29 figs., 12 tables.

336. The northern fur seal. By Ralph C. Baker. Ford Wilke. and C Howard Baltzo. April
1970. iii + 19 pp.. 13 figs.

351. Bureau of Commercial Fisheries Exploratory Fishing and Gear Research Base.
Pascagoula. Mississippi. July 1, 1967 to June 30, 1969. By Harvey R. Bullis. Jr.. and John
R. Thompson, November 1970. iv + 29 pp.. 29 figs.. 1 ubie

352. Upstream passage of anadromous fish through navigation locks and use of the
stream for spawning and nurser>- habitat. Cape Fear River. N.C. 1962-66. By Paul R.
Nichols and Darrell E. Louder. October 1970. iv + 12 pp.. 9 figs.. 4 tables.

356. Floating laboratory for study of aquatic organisms and their environment. By
George R. Snyder, Theodore H. Blahm. and Robert J. McConnell. May 1971, iii -t- 16 pp..
11 figs.

361. Regional and other related aspects of shellfish consumption — some preliminary
findings from the 1969 Consumer Panel Survey. By Morton M. Miller and Darrel A. Nash.
June 1971, iv -f 18 pp., 19 figs., 3 UbIes. 10 apps.

337, Program of Division of Economic Research. Bureau of Commercial Fisheries, fiscal
year 1969 By Division of Economic Research. April 1970. iii + 29 pp,. 12 figs.. 7 tables.

338, Bureau of Commercial Fisheries Biological Laboratory, Auke Bay, Alaska. By
Bureau of Commercial Fisheries. June 1970. 8 pp., 6 figs.

339, Salmon research at Ice Harbor Dam. By Wesley J. Ebel. April 1970. 6 pp.. 4 figs.

340, Bureau of Commercial Fisheries Technological Laboratory, Gloucester,
Massachusetts. By Bureau of Commercial Fisheries. June 1970, 8 pp., 8 figs.

341, Report of the Bureau of Commercial Fisheries Biological Laboratory. Beaufort,
N.C. for the fiscal year ending June 30. 1968. By the Laboratory staff. August 1970, iii +
24 pp.. 11 figs,. 16 tables,

342, Report of the Bureau of Commercial Fisheries Biological Laborabory, St.
Petersburg Beach. Florida, fiscal year 1969. By the Laboratory staff. August 1970, iii + 22
pp.. 20 figs., 8 tables.

343, Report of the Bureau of Commercial Fisheries Biological Laboratory. Galveston,
Texas, fiscal year 1969. By the Laboratory sUff. August 1970, iii + 39 pp., 28 figs., 9
tables.

344- Bureau of Commercial Fisheries Tropical Atlantic Biological Laboratory progress in
research 1965-69, Miami. Florida By Ann Weeks October 1970. iv + 65 pp., 53 figs.

362. Research vessels of the National Marine Fisheries Ser%ice By Robert S. Wolf
August 1971. iii + 46 pp., 25 figs.. 3 tables. For sale by the Superintendent of Documents.
U.S. Government Printing Office, Washington, DC. 20402.

364. History and development of surf clam harvesting gear. By Phillip S. Parker. Oc-
tober 1971. iv + 15 pp.. 16 figs, Ffor sale by the Superintendent of Documents. U.S.
Government Printing Office, Washington. DC, 20402.

365. Processing EASTROPAC STD data and the construction of vertical temperature
and salinity .actions by computer. By Forrest R. Miller and Kenneth A. Bliss. February
1972. iv + 17 pp.. 8 figs.. 3 appendix figs For sale by the Superintendent of Documents,
U.S. Government Printing Office. Washington. DC. 20402.

366. Key to field identification of anadromous juvenile salmonids in the Pacific
Northwest. By Robert J. McConnell and George R. Snyder. January 1972, iv + 6 pp., 4
figs. For sale by the Superintendent of Documents, U.S. Government Printing OfTice.
Washington. DC. 20402

367. Engineering economic model for fish protein concentration processes. By K, K.
Almenas. L. C Durilla. R.C Ernst. J W Gentry. M. B. Hale, and J M Marchello. Oc-
tober 1972, iii + 175 pp.. 6 figs.. 6 ubIes. For sale by the Superintendent of Documents,
US. Government Printing Office. Washington, DC. 20402,

368. Cooperative Gulf of Mexico estuarine inventory and study. Florida: Phase 1. area
description. By J Kneeland McNulty. William N, Lindall. Jr.. and James E. Sykes.
November 1972. vii + 126 pp., 46 figs., 62 tables. For sale by the Superintendent of
Documents, US. Government Printing Office, Washington. DC, 20402.

346. Sportsman's guide to handling, smoking, and preserving Great Lakes coho salmon.
By Shearon Dudley, J. T. Graikoski, H. L. Seagran. and Paul M. Earl, September 1970. iii
4- 28 pp., 15 figs.

369. Field guide to the anglefishes (Pomacanthidae) in the western Atlantic, By Henry
A. Feddem. November 1972, iii + 10 pp., 17 figs. For sale by the Superintendent of
Documents. U.S. Government Printing Office, Washington, D.C. 20402.

Continued on inside back cover.

^O ftTMOSp^,

''Mew of

U.S. DEPARTMENT OF COMMERCE
Frederick B. Dent, Secretary

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
Robert M. White, Administrator

NATIONAL MARINE FISHERIES SERVICE
Robert W. Schoning, Directot— — —

i mm Bioiotiual Laijti^cttiD
j LIBRARY

JUL 29 197^

NOAA Technical Report NMFS CIRC-388

Proceedings of the First U.S.-Japan
Meeting on Aquaculture at Tokyo, Japan,
October 18-19, 1971

WILLIAM N. SHAW (Editor)

Under fhe U.S.-Japan Cooperative Program
in Natural Resources (UJNR)

•OV-^TIO/^

''6-1

SEATTLE, WA
February 1974

Kor sHle h\ ihe Superintendent of Documents. VS. Government Printini! Oftice
Wiishinnton. DC 10W2

PREFACE

The United States and Japanese counterpart panels on aquaculture were formed in 1969 under the
United States-Japan Cooperative Program in Natural Resources (UJNR). The panels currently in-
clude specialists drawn from the federal departments most concerned with aquaculture. Charged with
exploring and developing bilateral cooperation, the panels have focused their efforts on exchanging
information related to aquaculture w hich could be of benefit to both countries.

The UJNR was started by a proposal made during the Third Cabinet-Level Meeting of the Joint
United States-Japan Committee on Trade and Economic Affairs in January 1964. In addition to
aquaculture, current subjects included in the program are desalination of seawater, toxic microor-
ganism, air pollution, water pollution, energy, forage crops, national park management, mycoplas-
mosis, wind and seismic effects, protein resources, forestry, and several joint panels and committees
in marine resources research, development, and utilization.

Accomplishments include: Increased communications and cooperation among technical
specialists: exchanges of information, data, and research findings: some 30 missions involving over 300
scientists and engineers; seven meetings of the Conference, a policy coordinative body: administration
staff meetings: exchanges of equipment, materials, and samples; several major technical conferences:
and beneficial effects on international relations. Because of the importance of natural resources in this
cooperation, the Secretary of State asked the Secretary of the Interior to serve as U.S, Coordinator of
the UJNR,

William N, Shavs - United States
Atsushi Furukawa - Japan

CONTENTS

Page

Opening remarks

HIATT. ROBERT W. Remarks at first meeting, UJNR panel on aquaculture. 18-19 I

October 1971

Papers presented by Japanese panel members

HASEGAWA. YOSHIO, and YUKIMASA KUWATANl. Present status of major marine

cultivation and propagation in Hokkaido and some problems of the research activities 3

SUTO, SHUNZO. Mariculture of seaweeds and its problems in Japan 7

KAWATSU. HIROSHI. Some technical problems in freshwater fish culture in Japan 17

KAN-NO. HiSASHl, and TOMOO HAYASHl. The present status of shellfish culture in

Japan 23

FUJIYA, MASARU. Fish farming and the constraints in Japan 27

Papers presented by U.S. panel members

MOCK. CORNELIUS R. Larval culture of penaeid shrimp at the Galveston Biological

Laboratory 33

WILDMAN. ROBERT D. Aquaculture in the National Sea Grant Program 41

SHAW. WILLIAM N. Aquaculture of molluscs along the United States Atlantic and Gulf

coasts 57

WILLOUGHBY. HARVEY. Freshwater fish culture in the United States 67

LONGWELL. A. CROSBY. Genetics of the American oyster, Crassostrea virginica

Gmelin 75

GLUDE. JOHN B. Recent developments in shellfish culture on the U.S. Pacific coast ... 89

Overview papers based on U.S. panel members" tleld trips

WILDM.'\N. ROBERT D. Seaweed culture in Japan 97

WILLOUGHBY. HARVEY. Freshwater fish culture in Japan 103

SHAW. WILLIAM N. Shellfish culture in Japan 107

MOCK. CORNELIUS R. Crustacean culture Ill

GLUDE. JOHN B. Marine fish culture in Japan 115

LONGWELL. A. CROSBY. Some impressions regarding genetics and the fisheries

of Japan 1 23

The National Marine Fisheries Service (NMFS) does not approve, rec-
ommend or endorse any proprietary product or proprietary material
mentioned in this publication. No reference shall be made to NMFS, or
to this publication furnished by NMFS, in any advertising or sales pro-
motion which would indicate or imply that NMFS approves, recommends
or endorses any proprietary product or proprietary material mentioned
herein, or which has as its purpose an intent to cause directly or indirectly
the advertised product to be used or purchased because of this NMFS
publication.

REMARKS AT FIRST MEETING

UJNR PANEL ON AQUACULTURE,

18-19 OCTOBER 1971

ROBERT W. HIATT'

The initial meeting of the UJNR (United States-
Japan Natural Resources) Aquaculture Panel is a
significant event in the most comprehensive bilateral
cooperative program between our two countries.
This meeting brings together technical representa-
tives of an ancient but still far from scientifically
mature endeavor m any country, and it is especial-
ly significant that this initial meeting takes place in
the country acknowledged to be in the vanguard of
the "'art" of aquaculture.

My personal interest in this field is great, as my
professional background in marine ecology has in-
volved studies of Hawaiian fish ponds as well as
attempts at rearing zoeal stages of crabs. My feeling
for the field thus enables me to sympathize with
those who have labored long and hard at aquacul-
tural problems, and my interest has led me to visit
many of the aquacultural activities of Japan during
my brief period of residence in this country.

Japanese panel members have spent much time
and effort on the conference program which should
not only give each delegation a summary review of
aquacultural activities in each country, but will sift
through the problems of the field and thus establish
principal points for the agenda of the next panel
meeting to be held in the United States. Field trip
organization has been both elaborate and detailed so
that special interests of the U.S. participants can be
fulfilled.

Aquaculture in the Western world most likely
dates from the early Roman period when oysters
were brought under cultivation. Whether or not
.-Xsian aquacultural activities antedate those of the
West I do not know, but there is little doubt that
Japan's mariculture is the most varied and success-
ful in any country today. Unlike aquaculture in
Southeastern Asia which deals with few species in

Scientific Attache. U.S. Embassy. Tokyo. Japan.

mass production systems, Japan's objective has
been to produce variety and to sustain a large group
of seashore residents in gainful economic activity.
In the last few decades the mass production of export-
able products such as oyster spat has sustained not
only a host of Japan's mariculturists but those of the
western United States and other areas of the world
as well. Recently, a news item indicated that 15
planeloads of seed oysters from Sendai will be
shipped to Bordeaux, France, via New York to re-
plenish the declining oyster breeding farms there.
Each plane will carry approximately 243 million seed
oysters.

Mariculture, like most other industries, makes
major surges when breakthroughs in technology
occur. Most of these breakthroughs have occurred
in Japan, indicating that the world renowned
"green thumb" of the Japanese is based on substan-
tial scientific observation, experimentation, and de-
duction.

Everyone is well aware of the great strides in
mariculture being made in Japan, both with plant and
animal species. Special mention should be made of
very promising success in marine cultivation of rain-
bow trout, which ultimately may replace our di-
minishing salmon supply on the world's tables. One
need only to let his mind wander a bit to realize what
potential lies in the selection of rainbow trout for
rapid growth, a la Lauren R. Donaldson of the Uni-
versity of Washington, combined with the greatly
accelerated growth rate of trout reared in seawa-
ter.

During the field trips the impact of Japan's indus-
trialization and urbanization on mariculture will be
most apparent. Many of these problems are also
being experienced in the United States. 1 hope that
during the course of these and future joint panel
meetings an assessment can be made of this threaten-
ing environmental circumstance so that agencies in

each country, recently established for environmen- ically these are viable concepts and should receive

tal affairs, can bring proper action to bear on preserv- attention very soon.

ing the basic environment for aquaculture. We all We all look forward to an outstanding series of

realize that pollution ofinshore waters may not be all meetings and field trips. I should like to take this

bad. We have not really attempted to utilize con- opportunity, on behalf of the U.S. Government, to

trolled eutrophication or warmed water from power thank the Japanese panelists for an outstanding job

plants to increase maricultural production. Theoret- of organization.

PRESENT STATUS OF MAJOR MARINE CULTIVATION AND

PROPAGATION IN HOKKAIDO AND

SOME PROBLEMS OF THE RESEARCH ACTIVITIES

YOSHIO HASEGAWA and YUKIMASA KUWATANI'

GENERAL FEATURES OF THE
WATERS AROUND HOKKAIDO

Hokkaido is the northernmost island of Japanese
archipelago. It has a long shoreline extending about
2.700 km, which corresponds to about 10% of the
Japanese coastline. The island is surrounded by
three different seas— the Japan Sea, the Pacific
Ocean, and the Okhotsk Sea. The coastline of Hok-
kaido is influenced by two warm currents, the
Tsushima and the Kuroshio, and one cold current,
the Oyashio (Fig. 1). The seasonal fluctuations of
these warm and cold currents considerably influence
the oceanographic conditions in each local region.
Therefore, Hokkaido has many specific ecological
features as a result of these oceanographic, as well as
topographic, conditions.

Japan Sea Region

The Japan Sea coast of Hokkaido can be divided
into two regions by the Shakotan Peninsula: The
northern region is characterized by simple sandy
beaches, while the southern region, including the
Shakotan Peninsula, is characterized by a rough,
rocky shoreline. Along this coast, the warm
Tsushima Current Hows northward. In addition,
some upweliing of cold water-masses from the lower
layers of the Japan Sea occurs both in the offshore
waters and the inshore area of the Tsushima Cur-
rent. This intermingling of warm and cold water-
masses complicates the oceanographic conditions of
the area. Moreover, strong northwest winds bring
stormy weather conditions to this region during the
winter. Therefore, because of the oceanographic
conditions, stormy winters, and open topography, it

is very difficult to establish and maintain artificial
equipment (rafts, longlines, etc.) for marine cultiva-
tion.

Pacific Region

The Pacific coast can also be divided into two
regions by Cape Erimo. In the eastern region, there
are many small bays or inlets in the Akkeshi area,
but the largest embayment, Uchiura Bay, is found in

' Hokkaido Regional Fisheries Research Laboratory. Yoichi.
Hokkaido. Japan.

Figure I . — Sea currents and isothermal lines in Japanese waters
during .August.

the western region. The whole coastline of the
Pacific region, except in the area of Tsugaru Strait,
where wide, rocky shores are found, is made up of
simple, sandy beaches. The fundamental water sys-
tem of this region consists of two warm currents, the
Kuroshio and the Tsugaru, and one cold current, the
Oyashio. In the western region, the warm Tsugaru
Current and the cold Oyashio Current interchange
alternatively by seasons; therefore, the oceano-
graphic conditions of this region are quite variable.
On the other hand, in the eastern region, the coastal
area is affected entirely by the cold Oyashio Current
throughout the entire year. Dense sea fogs often
occur during the summer (June to August), espe-
cially in the eastern part. There are. on the average,
58 foggy days per year.

between Hokkaido and Kunashiri Island is called
the Nemuro Strait. This region is characterized by
many large and small brackish lakes along the coast.
The warm Soya Current (a branch of the Tsushima
Current) flows southward along the Okhotsk Sea
coast and a cold East Sakhalin Current runs along
the outside and parallel with the Soya Current. Con-
siderable freezing of seawater, especially in lakes
and inlets, and drifting ice occur from December to
April in this region. Because of these icy conditions,
fishing activities as well as maintaining artificial
equipment for marine cultivation are greatly re-
stricted during this period.

PRESENT STATUS OF THE PRODUCTIVITY
OF IMPORTANT MARINE ORGANISMS

Okhotsk Sea Region

The Okhotsk Sea coast can be divided into two
regions by the Shiretoko Peninsula: The northern
region is characterized by a flat sandy beach; in the
southern region, a big embayment is formed between
the Shiretoko Peninsula and the Nemuro Peninsula.
In addition, some of the Kurile Islands are located in
the entrance of this embayment. The channel lying

The major species which are artificially cultivated
and propagated in Hokkaido are restricted in num-
bers because of environmental conditions of this
region. Almost all are northern forms which have
their major distributional range in Hokkaido (Table
1). Recently, the cultivation of fishes and other
marine organisms has become of major interest in
Hokkaido, and it has become necessary to establish
seed production systems for some of the most impor-

Table 1. — Catch statistics for main fishing species as the subject of the cultivation and propagation in
Hokkaido in 1969, and show it related percent to the total Japanese landings.

Species

Japan (A)

Hokkaido (B)

(^ X 100)

Fish

Oncorhynchiis spp.

l(X).799 tons

78.870 tons

(78.24)

Clitpea paltasi

3 1 .644 tons

20.664 tons

(65.30)

Flounders

168,296 tons

58.389 tons

(34.69)

Pteurogrammus

azonus

107,085 tons

101.898 tons

(95.15)

Crab

Punilitluiiles

camtschatka

4,794 tons

4.761 tons

(99.31)

Chionoecetes opilio

elongatus

26,291 tons

13.515 Ions

(51.40)

ShelUibh

Palinopeclen

yessoensis

14,642 tons

8.618 Ions

(58.85)

Macira

sachalinensis

3,980 tons

3.689 tons

(92.68)

Haliolis discus

6.574 tons

634 tons

( 9.64)

Sea urchin

26.873 tons

12.204 tons

(45.41)

Marine algae

Lamiiiiiriti spp.
Uiidciria

145.696 tons

129.114 tons

(88.61)

piniuitifida

91,885 tons

8.005 Ions

( 8.71)

PiirpliMci spp.

5.522,918.000 sheets

11,575.0(K) sheets

( 0.21)

tant northern forms. The species listed in this article
are presently being cultivated in Hokkaido.

The present status of some important inverte-
brates and seaweeds is as follows:

Scallop (Patinopecten yesoenssis)

Sea scallops are distributed along the whole coast
of Hokkaido. However, in recent years, the major
areas of production have been limited to the Okhotsk
Sea region, especially in the southern half of the
northern region and the Nemuro Strait area in the
southern region. Scallop production in Hokkaido
reached its peak in 1934, when 78,674 tons were
harvested. Since then, production has been declin-
ing, with accompanying wide annual fluctuations. A
low of 3,843 tons was recorded in 1968. However, in
1969, production rose to 8,618 tons. This increase
may be due to the gradual development of the artifi-
cial cultivation and the use of underwater off-bottom
techniques in Lake Saloma and Uchiura Bay, and
the stocking of seed scallops along the Okhotsk Sea
coast. It is not clear whether the remarkable reduc-
tion in production was caused by overfishing or by a
decrease in the amount of scallop setting as a result
of some adverse oceanographic conditions.

Japanese surf clam (Mactra sachaHensis)

This clam is found along the entire Hokkaido
coast. Major areas of production are the Pacific
coast region and the Nemuro Strait. In Hokkaido,
the annual production of surf clams is nearly 5.000
tons. Commercial-sized clams range in age composi-
tion from 4 to 10 yr old, and it is doubtful that the
resource would recover if overfished. At present,
the clam resource is being carefully managed by
regulating the size of the catch, fishing seasons, fish-
ing grounds, and minimum shell size. Transplanting
of juvenile clams has been attempted for the purpose
of preserving this resource.

Abalone (Haliotis discus)

Abaione are limited to the Japan Sea coast, the
Tsugaru Strait, and Uchiura Bay: it has never been
found in other areas. This restriction in its geo-
graphical range may be attributed mainly to the low
seawater temperatures during the winter season.
The number of abalone per unit of area is considera-
ble in Hokkaido. Because of cold waters, the growth
rate is slower than in the southern part of Japan.

Accordingly, Hokkaido has played an important
role as a source of seed abalone for southern Japan.
Growth rates vary considerably along the Hokkaido
coast and successful transplants have been made
from poor growing grounds to good growing
grounds.

Sea urchin (Strongylocentrotus intermedius and
S. nudus)

Hokkaido's species of the sea urchins differ from
those of the southern part of Japan. They are of
commercial importance in Hokkaido and are found
along all coasts. Recently, effective management of
sea urchin populations has been carried out and. as a
result, the annual catch has shown a rising tendency.
In managing the populations, severe regulations
have been established on the fishing grounds, desig-
nated fishing seasons, and minimum carapace size.
Also, young individuals (those with immature
ovaries) have been transplanted to productive
grounds rich in seaweeds.

Kelp (Laminaria spp.)

Laminaria growing along the coast of Hokkaido
are classified into several species, namely L.
japonica, L. religiosa, L. ochotensis, L. diaboUca,
L. angustata, andL. angustata var. longissima. The
classification is based on their morphological
characters. However, from the taxonomical as well
as distributional viewpoints, it is appropriate to di-
vide the above-mentioned Luminaiia into two major
groups — Laminaria japonica group (including L.
japonica. L. ochotensis, and L. diaboUca) and
Laminaria angustata group (including L. angustata
andL. angustata var. longissinui)- The former group
is found in Uchiura Bay, the Tsugaru Strait, the
Japan Sea, the northern part of Okhotsk Sea region,
and along the coast of Shiretoko Peninsula. The
latter group grows along the coast of the Pacific
Ocean. Since 1955, the annual production of
Laminaria in Hokkaido has fluctuated between
100,000 and 150,000 tons in fresh weight. The most
abundant harvests were recorded, based on a 5-yr
cycle, in 1957, 1962, and 1967. Since the 19th cen-
tury, various attempts have been made to increase
Laminaria production. These include the planting of
stones and rocks and the blasting of rocky reefs. In
the recent years, cultivation of Laminaria,
especially forced cultivation, by a longline type or

rope-curtain type, was popularized, as in Uiuhiria in
southern Hokkaido.

Brown algae (Undaria pinnatifida)

The distributional range of Undaria in Hokkaido
is generally the same as that of abalone. In recent
times, the annual production of Undaria in Hok-
kaido has been constant at about 10.000 tons in fresh
weight.

Red algae (Porphyra spp., mainly Porphyra yezoensis)

Hokkaido is still an underdeveloped area for the
cultivation of Porphyra because there are many ob-
stacles hindering its growth, such as heavy wind-
storms along the Japan Sea coast, freezing of sea
waters, and floating drift ice in the inlets along the
eastern part of the Pacific coast and the Okhotsk
coast. However, since 1953. the cultivation oi Por-
phyra has increased gradually in Uchiura Bay, Ak-
keshi Bay. and the northern part of the Japan Sea
coast. In the former two places, the algae are not
damaged by the above obstacles, while in the latter
place, they are protected by special breakwater
fences.

IMPORTANT PROBLEMS
OF THE RESEARCH ACTIVITIES

As in many agencies, organization, staff, budgets,
and facilities are problems affecting research ac-
tivities. However, these are omitted from this dis-
cussion for want of space. The problems to be solved
in future studies are as follows:

All species being artificially propagated

1) Identification of food organisms and develop-
ing best methods for their mass production.

2) Determination of an adaptive environmental
condition for each species.

3) Determination of the size and the quality of

seed to be stocked and places where stocking \\ ill be
done.

4) Explanation of an annexing effect to the natural
stocks as an important problem in the future.

Scallop

1) Clarification of the major factors causing the
decline in populations on both the Japan Sea coast
and the northern part of the Okhotsk Sea coast.

2) Establishment of a large-scale, dependable sys-
tem for the mass production of seed (target is 800
million individuals).

Japanese surf clam

Establishment of a large-scale, dependable system
for producing seed both naturally and artificially.

Abalone and sea urchin

Establishment of a technique for artificially plant-
ing seaweeds and clarification on the ability of
abalone and sea urchin to propagate following plant-
ing.

Laminaria

1) Investigation of methods of growing high qual-
ity Laminaria {2-yr old plants).

2) Improvement of methods forthe forced cultiva-
tion of Laminaria (1-yrold plants).

3) Study how to protect the cultured Laminaria
from the noxious bryozoan. Memhranipora ser-
rilamella.

Porphyra

1) Identification of the new local species and the
breeding of Porphyra.

2) Study the adaptation of each local species to its
environmental conditions.

3) Establishment of a suitable culture technique
for each local condition.

MARICULTURE OF SEAWEEDS AND ITS PROBLEMS IN JAPAN

SHUNZO SUTO'

D>4TRODUCTION

The change in annual production of seaweeds in
Japan is shown by species in Tatile 1, where the
production from cultivation and harvest of wild
populations are mentioned separately.

Japanese and people in East Asia consume most of
the seaweed harvested for human food, and its use in
industrial materials is comparatively less. The situa-
tion differs clearly from that in the other areas of the
world. Japanese taste for "norV (Undaria.
Lam'maria. Monostroma, etc.) is quite developed,
and the shortage of its supply and resulting rise of its
price have encouraged efforts to increase its produc-
tion from the natural beds and also the development
of its cultivation on the surface of the sea.

Of course, the progress of cultivation depends on
social economic factors and the techniques to make
it profitable. Nori cultivation, it is said, started about
300 yr ago and harvested quantities are increasing
every year. The cultivation of [//z^/ana (a member of
Laminariaceae) has recently grown to an industry and
the one for Laininaria has just begun. Monostroma
has been cultivated for 30 yr, and in the past 10 yr,
the amount of its harvest has kept a constant level,
satisfying the consumers" demands.

The amounts of Laminaria, Undaria, Gelidium,
etc. harvested from their natural beds have not in-
creased much from year to year. Little increase in
Undaria production seems to come from overhar-
vesting. Many efforts have been made to increase its
production, but so far none has proved to be effec-
tive on the whole: though in some local grounds
successful attempts have been reported — by setting
stones to enlarge seaweed bed substrate, by blowing
up shallow beds with dynamite to lower their level.

' Mariculture Division. Tokai Regional Fisheries Research
Laboratory. .-Vrasaki. Nagai. ^okosuka. Kanagawa-ken, Japan.

or by removing useless weeds which will otherwise
occupy the substrate of the species being cultivated.
Another problem is found in the natural produc-
tion. Sometimes, a local decay of seaweeds, often
lasting more than several years, causes not only the
decrease in the algal production, but also the de-
crease in the abalone catch, which feed on seaweeds,
and also affect the catch of coastal fish, owing to the
lack of production of juvenile fishes that grow
around the seaweed beds. The reasons why the
decay of seaweeds occur and why seaweeds cannot
recover soon are being studied at the present.

NORI (PORPHYRA)
Cultivation of Nori
Historical Reviews

The cultivation of nori started about 300 yr ago
around the coast of Tokyo Bay and developed
gradually in many localities on the bays facing the
Pacific coast of Japan, where this culture can find
protection from strong surf and an adequate tidal
range necessary for growth.

Nori grounds were limited in those days to the
shallow waters around the mouth of rivers, on the
basin of which cities and rice farms developed, sup-
plying rich nutrients to nori grounds.

Bundles of twigs of trees such as oaks, cherry, etc.
were set in rows on the ground in the fall as the
collectors, to which nori spores attach themselves
and grow. In the winter, grown nori plants are har-
vested, made into dried products similar to sheets of
paper, and are sold to consumers, mostly city
dwellers.

The cultivators were mainly farmers in the coastal
regions. Gradually product dealers controlled and
exploited the cultivators, whose income was very
low, which in turn held back the industry from rapid
progress.

Table 1. — Change in annual amount of seaweed production.
[Wet basis: 1,000 tons.]

Seaweed Harvested
from

1936-40

1941-45

1946-50

1951-55

1956-60

l%l-65

1966-70

Consumed
in

Nori Cultivation 27

tPorphyra) Natural bed

Wakame Cultivation

(Undaria) Natural bed 37

Monostroma Cultivation

Laminuria Natural bed 305

Gelidiiim Natural bed 12

Gracilaria Natural bed

Iridaea and

Chondnis Natural bed

Cloiopellis Natural bed 5

Ecklonia and

Eisenia Natural bed

33

31

132

36

139

18
48

148

17
12

45

51
12

142

15
12

61
7

4

57

14

144

13

169

7

66
57

15

167

18

118

Food
Food

Food
Food

Food

Food.
A part,
alginate
material

Agar
material

Agar
material

Mostly-
plastering

Starch
for silk
clothes

A part,
alginate
material

The nori harvest increased only gradually,
amounting to 1 billion sheets — a sheet is a paperlike

product of nori, of about 20 x 20 cm in size and about
3 g in weight — just before World War 11.

Advances in the culture techniques were also
poor. Old collectors (twigs from trees of oak, cherry,
etc.) were replaced by bamboo twigs, promising
more harvest than the old ones. Modern net collec-
tors were found more effective to increase the har-
vest, but they were adopted only in limited localities
because of the higher cost than the old collectors.

It should he mentioned here, that the nori cultiva-
tion in Korea had a rapid growth 10 years prior to
World War it by introducing new techniques which
produced about the same amount of nori as in
Japan.

After World War 11, nori cultivation in Japan
made rapid progress. The amount of the harvest

doubled in 1945, became four times in 1955, and is
now six times that of the prewar level.
Social economic reasons for this abrupt rise are:

1) Increase in the demand by consumers. The
food rationing system during and after World War
11 supplied nori to all of the people in Japan, mak-
ing many new consumers. The increase of con-
sumers and the halt of the import of nori from
Korea brought about a severe shortage of nori and
the rise of market price.

2) Innovation of fisheries systems after the War.
Nori cultivators organized themselves in cooper-
ative unions, which shut out the capital control of
dealers and established a cooperative selling sys-
tem that raised the rate of net income from about
30% in the prewar times to an income of 60-70%.

Rise of the market price of nori and increase

of the net income made the nori cultivation the
most profitable fishery. This was followed also by
the rapid expansion of the industry throughout
Japan, making strong demands on the advances of
culture techniques.

3) Expansion of the nori grounds. Increase of
population, fertilization of rice fields, and the
progress of industry made the coastal waters
richer in nutrients, making cultivation possible to
spread away from areas adjacent to river mouths
where nori often suffers from declining salinity
during rainy weather.

Under these circumstances, the following culture
techniques were pushed forward at a rapid advance:

1) Techniques to find new grounds suitable for
nori culture. Conditions required are a) sufficient
exchange of water by currents and waves, b) suffi-
cient supply of nutrients, and c) protection from
freshwater inflows and strong surf.

2) Improvement of collectors. Old collectors
were replaced by a net made of palm fiber string
and then of synthetic fiber string of 2-3 mm in
diameter. The strings are netted in a mesh of about
20 cm, and the standard size of a net is 18.2 x 1.3
m-. The nets are set stretched horizontally into the
sea and are tied to bamboo poles set in two rows on
the shallow sea. The net collector has many ad-
vantages over the old ones in rearing nori. It is far
easierto deal with, surf resistant and more produc-
tive. The replacement made possible a wider cul-
ture, spreading from the limited waters near the
mouth of rivers to deeper waters of rougher wave
action, as the waters became more nutritious.

The net collector made possible the
cultivator's control on the growth of nori. Elevat-
ing the net a little from its standard level slows the
growth of nori but controls the growth of weeds,
such as Enteroinorpha and diatoms which may
overcome the nori and decrease the harvest. Low-
ering the net accelerates the nori growth, but the
nori often becomes weak by disease; Enter-
oinorpha and diatoms grow vigorously on
the net, displacing the cultured nori, if the weather
in winter is calm and not too cold. Nori cultivators
can then control the net level height as well as the
nori growth, protecting against diseases and in-
jurious ueeds.

3) Seed control. Soon after the findings of K. M.
Drew on the ■"Conchocelis phase" in the life his-
tory of Porphyra. its whole history was made clear

in Japan, being followed by the artificial control of
nori spores. In 19.S.*i-60, nori producers cultured a
necessary amount of Conchocelis for themselves
through the summer and produced nori spores to
start its culture. The technique removed the short-
age of natural spores which had limited the
growth of the cultivation especially in the western
Japan.

It can be said, that the replacement of old collec-
tors by net doubled the production of pre- World War
II time, also doubling the seed control.

It should be mentioned that a change of species in
nori occurred with the change of culture techniques.
P. yezoensis became dominate in place of P. tenerci,
the former seems to adapt more readily to higher
salinities and to easier cultivation of spores. The
change increased the harvest but produced a low-
grade product with decreased odor and hardening
when tasted.

General View of Actual Nori Cultivation

At present, nori is cultivated in most bays and
inland seas along the Pacific coast of Japan. Nori
grounds are about 60,000 hectares in area, produc-
ing about 5-6 billion sheets of nori a year worth 70-80
billion yen. Fishermen's cooperative unions obtain
prefectural government sanction to set nori grounds
and manage them. About 60,000 fishermen set their
own collectors, harvest grown nori on them, and
produce dried paperlike products. The products are
sold through the cooperative unions to the dealers.

Coastal waters of 0-5 m in depth are available for
nori grounds of classic net systems, setting the nets
by spreading them between two rows of bamboo
poles. By the actual development of the new floating
net system, cultivators have been able to turn waters
20-m deep into profitable grounds.

Usually a net, in a cultivating set, has a spread of
18.2 m X 1.3 m. Now 5 million sets are prepared for
all the grounds. About 10 million nets are used per
year, i.e., in a set two nets are spread one after
another during a harvesting season, from November
to next March or April.

Every fisherman has equipment for harvesting
nori plants and also for manufacturing them into
paperlike products. Generally the cooperative un-
ions prepare cold storage for preserving nets with
young buds in living condition. These unions some-
times have equipment for culturing Conchocelis and
also for manufacturing nori products.

Paperlike products are gathered by unions and

sold to the dealers, who preserve the products and
sell them to consumers. Each Japanese eats an aver-
age of 50-60 sheets of nori per year. Nori is rich in
vitamins, and two sheets of nori can supply one
daily dose of them.

Processing in Actual Nori Cultivation

Seed. — Present cultivation depends completely on
the spores from cultured Conchocelis. The culture is
done by each fisherman or by his cooperative union.
The culture begins at the end of the last season.
Many cleaned oyster shells are spread on the bottom
of shallow tanks filled with seawater. Cut pieces of
mature nori plants are put on the water, so that the
carpospores released from the plant will attach
themselves to the shells and develop to the Con-
chocelis phase on them. Shells with Conchocelis are
hung down in other tanks 0.5- 1 .0 m in depth, where
they are kept throughout the summer. The water in
the tanks is changed if it becomes dirty. Light in the
tanks is controlled so that Conchocelis grows well
without getting ill. At the end of summer, the Con-
chocelis matures and produces many spores which
develop into nori buds.

In the fall, when the seawater temperature goes
dow n below 24°C, fishermen prepare the cultivation.
Twenty to forty nets are set in a layer in the sea.
Shells with fertile Conchocelis are put into many
vinyl bags, and these are hung just under the nets in
order to have the spore find the collector as they
come out of the bag. Sometimes the net layer is put
into a large polyethylene bag with Conchocelis and
left floating on the surface of the sea. This method
prevents the cultivator from wasting spores and can
also be done in deeper waters. After several days,
when the spores have fixed themselves to the nets,
these nets are taken out from the bag and are tied to
the poles for spore development.

Biiiii;inii up ofyoiiiii; hints. -A set of 20-40 layered
nets is separated into sets of 5-6 layered nets, which
are then separated into single nets, as the buds grow.
In the process of separation, when the buds are 5-50
mm in length, the necessary amount of nets with
buds are taken out of the water, dried and stored in
refrigerators set at -20°C. Here the buds are kept
alive, preparing for the recovery of crops when the
planted nori suffers from a prevailing disease or a
heavy storm. Fishermen always control the level of
nets as the climate and the tide changes, so that the
buds do not suffer from severe drying out in low tide
and alsi) from mowth of weeds and diatoms.

Reiirini; of nori pUiiils iiiiil their luirvesl. -.\boul
50 days after budding, nori plants grow to 15-20 cm in
length and then are harvested. After the first harvest
many buds remain on the nets, promising another
harvest in 15-20 days. In this way harvesting can be
repeated several times from a net throughout the nori
season. But generally the crop decreases in repeat-
ing harvests; sometimes the crop may die from the
diseases of nori or by some accident. Then, the cul-
tivators replace these nets with the refrigerated ones
that can replace the crop in 15-30 days.

Harvesting is done by using machines which make
the labor at sea more comfortable and etTicii-nt.

Manufactitrinii paperlike dried prodiicls from
cropped nori. — Cropped nori plants are cleaned by
washing with seawater. Then they are chopped and
spread on screens made of fine twigs of bamboo orot
fine plastic rods and finally dried in a dryer with an
old burner. Drying has to be done quickly at low
temperatures, commonly in 2-3 hrwith the tempera-
ture lower than 50°C. In these conditions nori is kept
alive until the end of the drying procedure. This
makes the product glossy, tasty, and sweet smelling,
and retains all vitamins.

Recent Advances in Culture Techniques

Recent yearly changes of nori production is shown
in Figure I, with changes of numbers of cultivating
sets, of nets used, and of nets stored in refrigerators.
The overall nori production has increased year by
year but show sharp fluctuations. In these days
progress in culture techniques has tended towards I )
new methods on how to expand the nori grounds. 2)
how to prevent sharp declines in the yearly produc-
tion, and 3) how to reduce labor in culti\ation and to
make laborers more comfortable.

Techniques to prevent sharp declines in the yearly
production. -O^ course, nori growth is affected by
certain conditions, especially by the climate in the
growing season. But the sharp drops in production
were caused by severe outbreaks of diseases which
occur successively in important grounds. It was
found that the disease occurs in connection with
overpopulation of the plants on the grounds — setting
of too many nets for greater harvest. This finding led
to the development of the techniques to get a far
more stable cropb\ controlling the amount of nets to
be set on a ground.

The technique to store live nori buds in cold stor-
age was first applied in 196.^, making it possible for

10

crops to recover when the planted nori become se-
verely damaged by disease or by some accident.
Nets with young buds are dried until the water con-
tent of the nori comes down to about 20-309f , are
packed in polyethylene bags, and are stored in re-
frigerators at about -20°C, in which buds can be
kept alive for more than 6 mo and capable of recover-
ing normal growth whenever they are returned to
sea. Even wet buds can endure the cold storage for a
short period, while many of the weeds and diatoms
are killed. Also a parasitic fungus, which often
causes disease on nori. loses its ability to reproduce
by this treatment.

The number of nets with young buds stored in
refrigerators has increased in the past 5 yr. as shown
in Figure 1. This brought about new difficulties in
bud rearing, because cultivators have to rear the
buds with doubled amount of nets. In 1966-70, when
too many nets are set during bud rearing, these nets
often caused severe damage to the buds, resulting in
a sharp decline in harvest. This problem is now
solved by reducing the nets to a reasonable and
manageable amount on each ground.

Techniques to expand nori grounds. -By using the
net collectors, nori culture has developed the

c

>- 2

o =

c Z

O Q

= 2
iQ <

"" tn

Z I-
O LlI

F ^

O u.

-I

10

9

8
7
6
5
4
3
2

NETS USED

TOTAL SET
PRODUCTION

C3/f^

1

NETS
REFRIGERATED

— FLOATING
SYSTEM

— CLASSIC
SYSTEM

I960

1965

1970

Figure I. — Change inannualamount of "nori" production and in
the amount of cultivating sets and nets used. Generally a net is
spread in a set.

grounds in the new areas after the old grounds were
destroyed by polluted waters and so on until 1965:
after that the development and loss came into bal-
ance. However, nori grounds are still showing an
overall increase by using a new rearing system, i.e..
a floating-net system, which can make profitable
grounds out of waters of about 20 m deep and with
strong wave action.

Generally a square frame of synthetic rope is set
floating on the surface of the sea with the help of
buoys and anchors, and 20 nets with small buoys can
be set in it. Waters with currents faster than 30
cm/sec or with somewhat strong wave action are
convenient for rearing nori by this system. The
frame systems can resist the impact of a wave 4 m in
height without any damage to nori.

Mechanization of processes in nori culti-
vation.— Labor shortages and culture enlarge-
ment demanded the mechanization of each process
of production. It turns culture labor into a comfort-
able and profitable one. keeping the young labor force
from tlowing out into land industries. This is an
exception to the labor shortage situation for all
fisheries. For instance, oyster culture appears more
profitable in some localities than nori cultivation, but
labor in oyster culture is far more severe and dirty,
causing an outflow of young labor from the culture
industry. This loss of labor is making the culture fall
behind the nori cultivation.

Introducing engineering principles to nuike or to
improve nori grounds. -From about 1965 engineering
principles have been introduced in nori cultivation.
For example, concrete or iron piles were set to de-
crease wave action in order to have nori culture
possible behind them. On the grounds in shallow
waters, water ways were dug to better the exchange
of water and to increase the harvest, and now in
several old grounds digging works are planned. Here
the connection between the biological and engineer-
ing techniques have to collaborate closely to make
the effort effective for production increment.

Problems in Nori Cultivation

The demand for nori by consumers, which is sup-
posed to increase year by year, was estimated at
about 5-6 billion sheets a year in 1970. The import of
nori from Korea is now politicallv limited to 200
million sheets a year, but it may increase to I billion
sheets in the future. Cultivation in Japan produced 6
billion sheets in 1970. satisfying the amount of con-

11

sumers" demand, and Japan is capable of increasing
its supply with the increase of the consumers" de-
mand, ifthe following technical problems are solved:
1 ) How to prevent a bad crop, and 2) how to improve
the quality of the products.

There is another problem which has arisen, the
spreading of industrial pollution. Coastal waters be-
came polluted and nori products became contami-
nated with cadmium, mercury, etc. We are afraid we
may need hygienic control in the future if pollution
increases.

The most important problem in nori culture is
found in its administration, income of the cultivators
increased more quickly than that of city laborers, but
in recent years this is not so. The increase came from
the rise in nori prices and also from the increase in
the harvests. In the future the rise in the prices can
be expected, but the increase in the harvest will
cause oversupply. The mechanization of the culture
processes is raising the cost of nori. especially in the
case of small-scale operations.

The technique to store live nori buds in cold stor-
age is also used for cropped nori plants. This will
inevitably stimulate the development of factories
which store cropped nori and make it into products
far more efficiently than each fisherman can. Until
now, the income of a cultivator was the sum of
harvest plus manufacturing, and if the latter is re-
moved, he must recover his loss by production in-
crease.

In the near future nori cultivators will be divided
into two groups, the majority going into mass pro-
duction using the floating system and the minority
going into small-scale operations producing nori of
special quality.

The number of cultivators has been kept at a level
of 60.000 in the past 20 yr. but this level will decrease
with the scale-up of each operation. Substitution of
cultivators will occur, and cultivators who combine
farming will decrease and ones who combine fishery
will increase.

Under these changes of circumstances, the tech-
nical problems will be:

1 ) How to prevent cultivation from a bad crop?
A bad crop is generally caused by outbreaks of
diseases, and techniques to forecast and prevent
the outbreak of diseases are expected.

2) How to simplify each culture process? The
present processes were developed for small-scale
operations. They have to be modified to fit the
need of a large-scale operation.

3) How to improve the qualities of the products?
Development of an effective fertilizing technique
will be expected.

4) Breeding of nori and introducing foreign
Porpliyrci will be helpful for items 1-3 — nori with
more resistance to diseases, nori of higher produc-
tivity, perhaps of not maturing under winter's
short-day conditions, and nori of higher quality,
making the product more glossy, w ith more odor
and better taste. A variety off. teneni is highly
productive and resistant to diseases but of lower
quality.

5) Techniques for mass manufacturing of crop
products.

WAKAME (UNDARIA)

Biology

"Wakame" is a seaweed peculiar to Japan and
Korea, and 60.000 tons of this raw seaweed are
landed annually. 10.000 tons in dry weight. Cur-
rently cultivation extends the seaweed industry to
the northern areas, now including many districts all
over Japan. The output from cultivation was over
60,000 tons in 1970.

The seaweed grows from beginning of winter to
spring, then dies out after liberating zoospores.
Within 20-40 days several hundred million spores
come out from one plant. The spores germinate im-
mediately to a microscopic filamentous alga, which
lies dormant during the summer, in the fall, when the
water temperature goes below 20°C. egg and sper-
matium are produced, germinate, and grow into the
wakame plant. This seaweed grows to several mil-
limeters long in 1 mo. 10 cm in 2 mo. and 1-2 m long in
3-4 mo. The temperature at the northern limit of
distribution is 2°C in the winter and at the southern
limit. 14°C.

Cultivation

Historical Reviews

in 193.*^ Kanda found that the life history of
wakame was almost the same as that o\' hiiiiiiuirin.
its cultivation started in the 1940"s along the coast of
southern Manchuria, together uith that of
luiiiiliuiriii, where their natural growth is almost
zero.

.•\fter World War ii. the industry was introduced
into China w hich produced 30,000 tons of raw prod-
uct a year, most of which isLaminaria. Meanwhile
in Japan, the cultivation did not develop because of
sufficient supply of natural products.

12

However, with increase in population, shortages
in the supply of wiki wakame occurred in the 1960's,
stimulating the development of its cultivation. A
new product, salted wakame, was developed and
welcomed by consumers for convenience in cook-
ing, and this product did a great deal for increasing
consumption.

Under these circumstances wakame cultivation
had an abrupt growth mainly in northern districts of
Japan. The annual production was almost zero in
1963 and was over 60,000 tons in 1970, which ex-
ceeds the harvest from natural beds.

Processes in Cultivation

At the end of the season, wakame becomes mature
and develops zoospores, at the time fishermen start
to prepare the "seed strings"" for the next season.

For collecting spores, strings of 2-3 mm in diame-
ter made of synthetic fiber are used. The 100-m long
strings are reeled over a frame made of vinyl plastic
tube of 2-3 cm in diameter. A tank is filled with fresh
seawater. Mature sporophylls of wakame are put
into the tank after half drying. Enormous numbers of
spores are released into waters, when the vinyl
frames with strings are set in the tank so as to catch
the spores. Several sporophylls are necessary for
seeding a 100-m string. After 1-2 hr the frames are
taken out and are put into culture tanks of about 1 m
deep, where they are kept through the summer under
controlled light intensity. It is desirable to keep the
water temperature lower than 25°C. Favorable light
intensity over them is 500 lux at 25°C and 1 ,000 lux at
20°C.

Germlings of wakame develop in the fall when the
water temperature goes below 20°C. When young
buds grow to about 1 mm in length, the frames with
strings are put into the sea hanging from a raft, so as
to accelerate their growth.

In northern waters, where invasion of fouling
seaweeds and animals is less, the seeded strings are
often cultured in the sea.

Management and Harvesting

The cultivation starts when the seawater tempera-
ture becomes 15°C and fouling organisms become
scarce. A synthetic rope of 100 m long and of 8-10
mm in diameter is floated into the sea with the help of
buoys and anchors. Often many branch ropes are
hung from the rope. Seed strings with young buds of
wakame are rolled up to the rope. Sometimes seed
strings are attached to the ropes at 10-cm intervals
after being cut into pieces of about 10 cm long.

In waters which are too rough or with many float-
ing 5«/\i,'flii///?( plants, the rope is set at a depth of 1
m, where the buds can escape being damaged by
wave action or by rubbing off by Sciif^a^siiiu.

Wakame grows quickly in winter. The optimum
temperature for its growth may be about IO°C. The
longer the period of lower than 15°C, the greater the
harvest. However, temperatures lower than 5°C
may injure the plant and may decrease the crop. Fast
current and strong wave action are favorable for
growth of the alga, if they do not damage the cultiva-
tion set.

Harvest is done by cutting the weed which has
grown to about 1 m in length. Most of it is dried under
the sun or in a drier. Some of it is sold raw to meet
local demands. The yield from 1 m of cultivating
rope in a season is about 10 kg in wet weight in the
northern areas and about 5 kg in warmer districts.

The amount of labor work in wakame cultivation
is far less than that in nori cultivation. The set of the
former is more resistant against rough waves than
that of the latter. For these conditions the former is
more profitable in northern open coast than the lat-
ter. However, the amount of consumption is now
limiting progress of the industry.

With the spreading of the cultivation, new prob-
lems are occurring, i.e. , damages caused by bacterial
diseases and by the eating of young buds by isopods
and gastropods.

Harvest of Wild Wakame

The amount of production changes every year
primarily because of the variations in water tempera-
ture. The low temperature in the growing season,
winter to spring, brings about a good crop except at
the north limit.

Elimination of harmful seaweeds in wakame beds
is found to be effective in increasing production dur-
ing the season. The bed is likely to be taken over by
other perennial weeds, Phyllospadix in the north and
Sargassiim and Ecklonia in the south. The best time
to control the weeds may be during the germinating
season of wakame buds.

We have never produced a favorite culture area by
throwing stones into the sea. which is effective in the
case of Laminaria and Gelidium. Limiting the
amount of the harvest and transplanting mature
plants were found ineffective for producing a better
crop the following year.

Wakame is an annual plant and there is an enorm-
ous mortality in the microscopic phase in the sum-
mer. These conditions may cause the ineffectiveness

13

of the foregoing techniques. However, after germi-
nation the plant grows to maturity with a little mor-
tality. If some devices are used to plant young hiids
in large quantities, the efficiency will he quite reli-
able. Trials of this method are now underway.

LA\fI\ARIA

Biology

Important species are Laminaria japonica and L.

ani;iisuita. L.japonicd is the best quality though not
much is produced. HalfofallZ.£(/;;//;^//7« harvested is
L. a ng us tat a var. longissima.

Laminaria mature in the fall. Some hundred mil-
lion zoospores, each having two cilia, come out from
a frond. A germling is a microscopic filiment. When
the water temperature goes to 10°C or below in
winter, the germling gives rise to spermatia and eggs.
A fertilized egg germinates and grows into a
Laminaria plant. The filaments do not fruit at water
temperature over 10°C and for this reason Laminaria
grows only in northern Japan.

Young plants are seen in early spring, then grow
rapidly, but start to decay from the top of the frond in
the autumn. In the second year, a growth at the top
of the stipe develops and becomes a second year's
blade. The growth in the spring is good at 5°-I5°C,
but never takes place at over 20°C in the summer.
The second year's blades are the main parts of the
plant harvested because the firsi year's blades are of
unsuitable quality for consumption in Japan.

Harvesting

The harvesting season is from July to August. A
drying process after harvesting is important to get an
excellent product. Hokkaido is subjected to foggy
days frequently: therefore, the drying by a drier is
useful for increasing production and for improving
quality.

Culture Techniques

Shinran-shonin. an old famous Buddhist priest, is
said to have been the first to propagate Laminaria in
1718. At present a large amount of the national ex-
penditure is invested in Hokkaido.

Throwing stones into the sea for propagation im-
provement has been practiced for many years with
good results. The yield rate in the area where stones
are thrown is roughly the same as the one in natural
growing districts. The area in which this technique is

used should not be one in which the bottom is altered
by the movement of sands. Use of a short cylinder of
concrete which was thrown into the sea was prac-
ticed on a large-scale basis at Nemuro, Hokkaido.
The expense is supposed to be recovered in 7-8 yr.
The reefs which are too high to drain the even
surface are dynamited so that Laminaria plants are
able to grow. To eliminate harmful weeds such as
Phyllospadix from the bed bottom explosives are
also useful. An explosive equivalent to 150-31)0 g of
dynamite has an effective area of about 4 m-.

Cultivation

China is said to produce .30,000 tons oi Laminaria
annually due to the recent progress in cultivation to
produce a dietary balance.

In Japan the emphasis has been on increasing the
production of Laminaria plants which grow nat-
urally in the sea, because it supplied sufficient
amounts for the demand of consumers. With in-
crease of consumption and rise of market price,
cultivation has been attempted.

There are some obstacles preventing a break-
through in Laminaria cultivation, especially the fact
that the plant takes 2 yr to grow into a desirable
market product for Japanese consumers, i.e., 2 yr
plants. Research is now going on to reduce this
period.

GELIDIUM (AND OTHER AGAR WEEDS)

Introduction

The production of raw seaweeds for agar-agar in
recent years has been 6,500 tons dry weight and
5,500 tons are imported. The latter, sold at a cheap
price though not of good quality, replaced the ones
raised in Japan. Agar output was 5,500 pounds in
1963. Korea which exported raw materials in prewar
days is now producing more agar-agar every year
and soon is going to exceed Japan's production.

Biology

Raw seaweeds for producing agar belong to the
families of Gelidiaceae and Gracilariaceae. Of
these. Geliclium amansii is the most important
species. It grows between low tide level and 20- to
30-m depth. They are found in areas which are influ-
enced by warm currents. More than 609?^ of the total
production comes from Izu Peninsula and Izu Is-
lands, where the rock of the andesite, clear water.

14

and warm current are located and where the trans-
parency of the water is high which enables G. ainan-
sii to grow. In the Izu Islands, plants do not appear
in large amounts in the region directly washed by
the warm current, but grow in good amounts in the
waters with an upweiling of bottom water. They al-
so do not grow in muddy water, or on rocks covered
with fouling organisms, but grow well on rocks on
sandy bottom.

G. (iiminsii reach 10 cm high in 1 yrand 20 cm in 2
yr. The span of the lifetime of a plant seems to be 2
yr. but a holdfast remains several years and pro-
duces new plants. The crop largely depends upon the
plants that developed from these holdfasts.

The plants are able to grow in densities up to 1
kg/m- at Izu Peninsula, the most favorable bed. At
harvesting, plants up to 0.2 kg/m^ are usually left to
grow because these plants grow back to 1 kg/m-
within 2 mo after harvesting. Harvesting is done
three times in a season, the yield per square meter is
well over 2 kg.

Sometimes in vast areas most algae except
Surgassum disappear and calcareous algae take
over. The cause of this phenomenon, "Isoyake" in
Japanese, is still obscure. All trials, such as adding
stones and transferring plants, to bring about recov-
ery of the vegetation have been unsuccessful.

Harvest

Harvest is done under the control of a
Fishermen's Cooperative Association that manages
the ground. A rest period is required during the
harvesting season to save labor and increase yield in
the fruitful years. Plants remaining at the end of the
fishing season do not thrive the next year. There-
fore, the plants should be cropped as many times as
possible.

Culture Techniques

Gcliiliiini is a perennial with a slow rate of growth.
The most reliable technique for propagation is to
produce more places in favorable areas by throwing
stones into the sea. The elimination of harmful
weeds, such as Eckloiiki and Eisenia that grou in
Gi'liJinni beds, is effective for 1 or 2 yr.

Cultivation is not an efficient way for increasing
production because the spores take 2 yr to grow and
reach harvesting size. Branchesof plants attached to
a rope, which is hung into the sea. grow well. How-
ever, the costs of plants for seed are high, and the

cost of the large labor force, which is needed for
setting seed plants on the rope, leaves little for profit.

In order to expand the growing area, stones should
be placed on the sandy bottom in and around the
growing areas. Stones weighing 20-100 kg are used
since they are not moved by wave action and do not
embed into the sand. Soon after calcareous algae
such as Lithotluimnion appear on the stones and
spores of Gelidium grow on them.

It does not make much difference if the stones are
set at the best time so far as production is concerned,
but does make a big difference whether it is a suitable
place or not. Production on new substrate provided
along the Izu Peninsula is almost the same as that of
natural populations, i.e., 1-2 kg/m-. The expendi-
tures for setting stones is recovered in 4 yr. In re-
gions where production is less than 0.3-0.4 kg/m^ it
is not recommended that stones be added because
the costs cannot be recovered.

Introduction of a gradually dissolving lump of fer-
tilizer into the bed is said to be effective in restoring
both color and growth during the summer. It has not
been clear whether it is profitable or not.

CONCLUSION AND PROBLEMS

There are two different ways to increase seaweed
production: 1) to increase harvest from its natural
ground and 2) to cultivate in or near the surface
being completely independent from its rocky natural
ground.

Problems in Propagation Protection

Many attempts to increase natural crops by in-
creasing the size of the seaweed bed by setting
stones or concrete blocks on sandy bottoms around
the seaweed ground have proved to be quite effec-
tive. Annual growth on these stones was the same as
the ones grown nearby on natural substrate.

Expenditures for setting stones is recovered
within 4-5 yr with Gelidiiim and in 5-8 yr with
Liiniinaria on the most favorable grounds. Regions
of low production cannot be recommended for set-
ting stones in the sea. Fov IriJaea andClionclnis. the
period of cost recovery would be 20 yr: therefore,
this attempt for habitat improvement is not a profita-
ble one.

In Porphyra. a concrete cover on rugged rocks
increased their harvest. This investment is recov-
ered in 3-4 yr on profitable beds.

15

However, even in a good ground, a project of
setting stones or a concrete cover could not be an
object of investment from a private enterprise. In
Japan, the privilege to harvest seaweeds is reserved
for Fishermen's Cooperative Association, who in
return is responsible to manage and protect this
resource by means of propagating seaweeds and
enlarging their substrate. This association has
worked on substrate enlargement by stone setting
v\ith government aid of 100 million yen per year, an
amount too small to improve their total production.

Other attempts to improve the production from
natural beds are found to be not so effective. Elimi-
nation of injurious weeds may sometimes improve
production in 1 to 2 yr. Also, trials to recover from
decreased production in "Isoyake"" waters by stone
setting proved to be ineffective.

On the seaweed grounds, the fauna and tlora have
interrelations with each other depending on en-
vironmental conditions. Due to the difficulties in
changing the environment with a limited budget, the
way to increase production or recover from produc-
tion declines is to change the succession
mechanisms of flora and fauna.

For instance, in waters where seaweed population
has decreased by some accident, starved abalones,
top shells, and other gastropods may eat up and
consume the young seaweed buds, decreasing the
flora recovery. Therefore, to protect these buds, it is
necessary to put a large amount of transplanted sea-
weeds sufficient enough to feed gastropods and
other grazers, preventing the ingestion of buds
needed for the vegetation to recover.

Problems in Seaweed Cultivation

In cultivation, seaweeds grow on a net, a rope, era
raft set or floating at or near the surface of the sea.
This means the cultivation is done free from the
bottom conditions, on which natural growth of sea-
weeds largely depends. The cultivation can be done
anywhere on any species, if techniques and water
conditions make it profitable. The problems are:

I ) Whether demand of consumers and tech-

niques make the cultivation of a seaweed to be
profitable or not.

2) How many water areas can be made into
profitable grounds.

When these terms are met, the amount of production
can increase enormously, as it has in the cultivation
of Porpliyra. Monostroma, and UnJtirici. and that of
Luiniinaiia will follow them in the near future. This is
in contrast to the difficulties in increasing production
from natural beds, being limited by bottom condi-
tions.

However, the cultivation ofGelitliiiin. Gnu iliirici.
Irichu'd. and Chondnis has yet not developed, be-
cause it is not profitable. This stems from the fact
that these crops are too small or that their cultivation
requires too much labor. Here an epochal improve-
ment in techniques is expected in making their culti-
vation practical.

In the already industrialized cultivation of
Forpliyni and so on, the problems are:

1 ) How to save labor in its cultivation and make
it more comfortable. Mechanization of the work is
being done. However, it will result in a reorganiza-
tion of the management, from fishermen's private
ones to their cooperative operation.

2) How to change water areas of rough waves
into profitable grounds: that is to say, how to
improve the culture apparatus to make it more
resistant to waves and how to reduce wave action
by some engineering techniques.

3) How to protect cultivated plants from dis-
eases, which cause large fluctuations in yearly
production.

4) Hou to improve the quality of products,
especially in Porpliyra. to meet better the con-
sumers' demands. An effective fertilizing tech-
nique is expected to develop.

5) Breeding is expected to be useful to answer
some of these problems. Looking for more favor-
able species abroad will be of consequence in the
breeding.

16

SOME TECHNICAL PROBLEMS IN FRESHWATER
FISH CULTURE IN JAPAN

HIROSHI KAWATSU'

INTRODUCTION

During the past 10 yr. considerable attention has
been paid to fish culture in various countries, espe-
cially in the United States and Japan. Inour country,
freshwater fish culture has a long history, but the
recent remarkable improvement of culture tech-
niques has brought on a great change in production
methods.

PRESENT STATUS OF FRESHWATER FISH
PRODUCTION

Four major species of freshwater fishes are cul-
tured in Japan: 1( rainbow trout, Salmo gairdneri.
2) common carp, Cyprinus carpio, 3) eel, Anguilla
japonica, and ayu. Plecoglossus altivelis . From 1959
to 1969, production of cultured fish for food in-
creased from 15,000 to 52,000 tons, for a percent

' Freshwater Fisheries Research Laboratory. Hino-shi.
Tokyo. Japan.

increase of 236. This can be compared to an increase
of only 26% for wild fish from inland waters in this
same period (Table !).

Government statistics on fish culture in Japan
classify the culture methods into four categories,
namely, 1) standing-water pond, 2) running-water
pond, 3) irrigation pond, and 4) net culture in lakes.
Running-water ponds give the highest production
per unit area for all species; net culture is second.
Harvest from irrigation ponds is slightly higher than
from standing-water ponds, because the larger water
area of the former is more favorable to the growth of
fish.

In 1968, the number of ponds utilized in various
types offish culture was 35,239 in number and 8,500
hectares in area. A total of 7,5 18 of these ponds were
used to produce food fish. The number offish farms
classified by water area are listed in Table 2. Almost
all the rainbow trout and ayu are cultured in
running-water ponds, and eel in standing-water
ponds. In the case of carp, both standing- and
running-water ponds are used. Number and area of
ponds per fish farm are shown in Table 3. These

Table I. — Annual catch and crop in inland waters, 1959-69.

Natural
waters

Cultured fish for food

Year

Total

Carp

Eel

Trout

ig.-ig

43.658

15.481

4,562

5,663

2,643

1960

43.916

15.940

4,629

6,136

2.670

1961

47,188

18.990

5.142

8,105

3,023

1962

49.194

20.230

6,344

7,572

3.507

1963

48,349

23,371

6,592

9.918

3.936

1964

50.781

29,780

7,557

13.418

5,412

1%.-;

53.423

33.096

7.971

16.017

5,745

1966

49.294

36.375

9.827

17.015

6.231

1967

50.683

41.852

10.886

19.605

7.882

1968

52.110

51.932

14.460

23.640

9.454

1969

54.918

52,044

13.971

23.276

10.254

Source: Bureau of Statistics ( 19691.

17

Table 2. — Number of management units by size of water area in freshwater fish culture. 1%8.

Water

Carp

Eel

Rainbow trout

Ay

u

Stand-

Run-

Irriga-

Net

Stand-

Run-

Irriga-

Net

Run-

Irriga-

Net

Run-

Net

area

ing

ning

tion

cul-

ing

ning

tion

cul-

ning

tion

cul-

ning

cul-

(m-l

water

water

pond

ture

water

water

pond

ture

water

water

ture

water

ture

<100

157

648

59

16

18

1

1

281

5

20

1

100-

200

121

241

48

8

21

—

3

—

156

4

—

30

1

200-

300

106

117

38

3

26

2

1

—

102

T

—

32

—

300-

500

124

157

75

8

36

—

4

—

128

2

—

68

—

-

1.000

198

170

115

6

60

—

4

—

183

2

—

98

—

-

3.0(K)

204

125

227

1

183

1

4

—

214

—

1

88

—

-

5.000

71

31

108

3

337

1

1

—

39

—

—

15

—

-

lO.tKK)

37

12

194

1

449

—

1

—

21

—

—

5

—

-

30,()(K)

22

7

251

—

390

—

3

1

12

—

—

—

—

-

50.()()()

5

1

76

—

79

—

—

—

1

—

—

—

—

-

100.000

7

1

62

—

43

—

—

—

1

—

—

—

—

>

100.000

3

->

52

—

12

—

—

—

—

—

—

—

—

Total

1 ,055

1.512

1.305

46

1.654

5

T>

1

1.138

17

1

356

T

Source: Bureau of Statistics (l%9).

Table 3. — Number and area of pond per fish farm, and average area of pond in each of the types.

Average

area of pond

Number
of

Number
of pond

Total
water

Standing

Runing

Irriga-

Fish

fish

per fish

area per

water

water

tion

Net

species

farm

farm

fish farm

pond

pond

pond

culture

m-

in-

m'-

m-

m-

Carp

3,918

2,8

8.957

718

280

12,939

143

Eel

1,682

4.3

12.247

3,061

91

7,410

367

Rainbow

trout

1 , 1 56

8.3

1.100

328

127

589

200

Ayu

358

7.2

1.777

461

461

15,062

28

Source: Bureau of Statistics (1969).

tables indicate that the fish farms in Japan are run on
a small scale.

As shown in Table 4, private farms predominate in
fish culture in Japan. Most of them produce vegeta-
bles and crops as well as fish. The proportion of
farms engaging in monoculture is only 3% in carp
culture. 28% in eel culture, 109f in ayu culture, and
6% in rainbow trout culture. The increase of
monocultural fish farms will be desirable in the fu-
ture. On the other hand, the reduced demand for rice
may increase the culture offish as a sideline in the
rice producing area.

As shown in Figure 1, carp culture farms are dis-
tributed from Hokkaido to Kyushu regions. Most eel
farms are centered in four prefectures: Shizuoka,

Table 4.

^"lassification of fish farms.

lolal

Fish

number

species

of farms

Private

Company

Others

Carp

3.918

3.431

76

411

Eel

1.682

1.371

217

94

Rainbow

trout

1. 1 56

918

75

163

Ayu

358

249

30

79

Source: Bureau of Statistics (1969).

Aichi. Mie. and Tokushima. They account for
78.6% of all eel culture farms. Ayu culture farms are
distributed in the southern part along the Pacific

18

Rainbow Trout

Figure I. — Di'^lribution offish farms.

19

coast. Rainbow trout farms are distributed in all
parts of the country. However, fish farms which
produce fish for export are centered in Shizuoi<a and
Nagano Prefectures.

SOME TECHNICAL PROBLEMS IN
FRESHWATER FISH PRODUCTION

Many technical problems have arisen in freshwa-
ter fish production. While many of the same prob-
lems occur with all species, their relative order of
importance differs by species as follows:

Carp: I- Improvement of breed.
Eel: 1. Stabilization of elver supply.

2. Prevention of epidemic diseases.
Rainbow trout:

1. Prevention of epidemic diseases.

2. Improvement of breed.
Ayu: 1. Mass production of fry.

2. Prevention of epidemic diseases.
Other fish species:

1. Culture of native trout fingerlings for

stocking in natural waters.

2. Transplantation of foreign species

suitable to the tastes of Japanese.

Carp

No urgent problems are found in carp culture at
present, but in the future, improvement of the breed
will be desirable. The selective breeding of strains
considered to have desirable characteristics has
been started by several institutions.

Eel

In eel culture, elvers are collected along the
Pacific coast from December to April. Eel culturists
are often troubled with scarcity of young eels be-
cause of fluctuations in abundance from year to year.
The demand for elvers has rapidly increased in re-
cent years proportionally with the increase of culture
ponds. Three counterplans have been adopted to
solve the problem: I) improvement of survival
rate of elvers, 2) imporlation of elvers from foreign
countries, and 3) establishment of spawning tech-
niques.

Heating apparatus to increase winter tempera-
tures in ponds is proving to be effective for improv-
ing the survival of eels. This apparatus includes two
main systems, heating and a circulating filter system.

In the latter, the water is filtered and recirculated
back to the culture ponds. In the process of circula-
tion, the water is heated to a constant temperature.
Although this apparatus entails high costs, survival
rates often reach 939^.

Recently, elvers of other eel species have been
imported from various countries such as France,
Philippines, and New Zealand. In 1969, 25.2 tons of
elvers were stocked in Shizuoka Prefecture, of
which 9 tons were imported from various countries.
Foreign species have different habitat needs than
native species: therefore, satisfactory results are not
always obtained. Culture methods suitable for them
are being developed.

Establishment of spawning techniques is an ex-
tremely difficult problem because the physiology
and spawning behavior of adults and the life history
of hatchery fry are not well understood. Several
public institutions are wrestling with this problem,
under the guidance of T. Hibiya, Professor of Fa-
culty of Agriculture, University of Tokyo.

The prevention of epidemic disease is another im-
portant problem in eel culture. It is difficult to keep
accurate records of mortalities in eel culture, be-
cause turbidity of the pond water inhibits finding or
seeing dead fish. Attempts at estimating losses in
Shizuoka Prefecture have revealed a seasonal pat-
tern. That is, the mortality begins to increase in
March and reaches its peak in April or May. Figure 2
shows these seasonal changes of mortality in
Shizuoka Prefecture in 1968. In that year, most of
the loss in the spring was due to fungus disease,
while in summer bacterial gill disease caused the
most mortalities.

In 1970, eel production suffered heavy losses.
During the first half of the year, crop mortality to-
taled 2,600 tons in Shizuoka Prefecture (Table 5).
This was due to a new epidemic disease, bran-
chionephritis, named by S. Egusa. Professor of Fa-
culty of Agriculture, University of Tokyo. Fortu-

Tahle .^. — Loss of eel in Shizuoka Prefecture.

Year

Amount of loss

1964
1965
1966
1967
l%8
1%9
1970

Ions

492
200
522
199
449
20.'>
1,639

20

« Marketable eel

O O Fingerling

Apr May Jun Jul Aug. Sep.Oct. Nov. Dec. Jan. Feb. Mar
Month
Figure 2. — Seasonal change of loss in eel culture ponds [n
Shizuoka Prefecture, in 1968.

nately, this epidemic did not return last winter
(1971).

Rainbow trout

Prevention of epidemic disease is also the most
important problem in trout production. Infectious
pancreatic necrosis (IPN). Vibrio infection, bacter-
ial gill disease, and Hexainita infection are the prin-
cipal diseases in Japan. Among them. IPN is most
harmful. Fortunately, viral hemonhagic septicemia
( VHS) and whirling disease, Myxosomci cerehralis.
have not yet been discovered in Japan. However,
preventive systems against these two epidemics
have been in effect since 1967. These preventive
systems display the power in epidemiological sur-
veys in other epidemic diseases. For example, they
estimated the critical temperature as 12°C for out-
break of IPN.

Recently, the net culture of rainbow trout in shal-
low seavvater has begun in the northern part of
Japan. .\\\ attempts resulted in failure in southern
Japan, because the water temperature is too high for
rainhou trout to survive in seawater. The upper limit
for survival in seawater is estimated to be 22°-23°C
(72°-73°F). Water temperatures above 23°C lead to
bacterial infections. An analogous phenomenon is
observed in ayu reared in seawater.

Ayu

Ayu is familiar to the taste of Japanese and is also
the most impoilant game fish in inland waters. Most
fingerlings for culture are caught in Lake Biwa and
along the seashore. Fingerlings from Lake Biwa are
of good quality: however, the supply is limited by the
natural standing crop. The catch from the seashore is
also limited for the same reason. .Attempts at artifi-
cial production of ayu fry have been started in sev-
eral prefectures. At present, two systems of fry pro-
duction are used, one type uses salt water and the
other fresh water. At present, saltwater culture gives
better results. In both types of culture, Rotifem are
used as the starting feed. Bnicliioniis plicatilis is
used for seawater culture and B. calyciflorns for
freshwater culture.

Vibrio and Gliii>ea infections are the principal dis-
eases of ayu culture. Vibrio infections annually
occur in Shiga and Tokushima Prefectures. This dis-
ease also is observed in wild populations in Shiga
Prefecture. Disinfection of fingerlings is widely
practiced in many culture farms.

PRODUCTION OF

NATIVE TROUT FINGERLINGS FOR

STOCKING IN NATURAL WATERS

With the development of game fishing, it has been
requested to propagate the populations of cold-water
game fishes in natural streams. Rainbow trout are
not suitable for this purpose, because these fish do
not remain in the stocking area. The native trouts on
the other hand appear to be very suitable for this
purpose. Prompted by this information, many pre-
fectural trout hatcheries have carried out the ex-
perimental production of native trout fingerlings.
Large-scale production will be realized in various
parts of the country.

TRANSPLANTATION OF

FOREIGN SPECIES SUITABLE TO THE

JAPANESE TASTES

Concurrent with the reduction of rice production,
part of the fields will be changed to fish ponds. As
this occurs, demand for a variety of cultured fish will
increase. In anticipation of this situation, various
foreign species have been experimentally introduced
into our country. Examples are bluegill sunfish.
whitefish. German carp, and channel catfish. Chan-
nel catfish attracts much attention because of the
ease of production: its taste is also suitable to the
Japanese people.

21

REFERENCES

BROWN. E. E.

1969. The freshwater cultured fish industry of
Japan. Univ. Georgia. Coll. Agric. Exp. Stn. Res. Rep.
41, p. 57.

EGUSA. S.

1970. Branchionephritis prevailed among eel populations in
farm ponds in the winter of 1969-1970. Fish Pathol.
5(1 );5 1-66.

BUREAU OF STATISTICS. OFFICE OF THE PRIME
MINISTER. JAPAN.

1969. Fisheries. [In Japanese and English] //( Bureau of
Statistics. Japan statistical yearbook, p. 145-166.

1971. Inland fisheries. [In Japanese and English.) In
Bureau of Statistics. Japan statistical yearbook, p. 160.
SHIZUOKA PREFECTURAL FISHERIES EXPERIMENT
STATION. HAMANAKO BRANCH.
1%9. Hamana. Shizuoka Prefectural Fisheries Experi-
ment Station. Hamanako Branch. No. 98.

1970. Studies on the disease of eel culture. Shizuoka Pre-
fectural Fisheries Experiment Station. Hamanako Branch,
No. 152. p. 26.

22

THE PRESENT STATUS OF SHELLFISH CULTURE IN JAPAN

HISASHI KAN-NO' and TOMOO HAYASHl-

INTRODUCTION

In 1969, shellfish production (including pearl oys-
ters) in Japan was 561,132 tons worth 58,444 million
yen (Table 1). Types of shellfish products landed
during the past decade have changed because of
certain effects on the environment and changes in
commercial demands. Shellfish, like Meretiix.
which live along the coastal area, have decreased
remarkably in production because of the loss of their
habitat from industrialization. In 1969, the oyster
industry in the Seto Inland Sea area was seriously
affected because the oysters were heavily fouled by
the calcareous tube worm. Hydioides nonegica.
For the past several years, production in the pearl
industry has declined because of reduced demand
for pearls. On the other hand, landings of scallops,
abalone, and top shell, so-called high grade prod-
ucts, have been increasing yearly both in tonnage
and value because of the demand by the consumer
for fresh marine products. Production through
aquaculture has remained commercially stable in
Japan.

In the past, shellfish aquaculture in Japan was
limited, strictly speaking, to oysters and pearls. Re-
cently, both scallops and abalone are being grown
using aquaculture techniques. In general, aquacul-
ture requires three important techniques: 1 ) to catch
the juveniles in desirable places with collectors, 2) to
produce seed for culture using hatchery (artificial)
techniques, and 3) to cultivate the seed to market
size in the field. .Aquaculture techniques are being
utilized to grow oysters, pearls, and scallops, and it
is expected that abalone will also be produced in the
near future through aquaculture.

In my presentation at the first UJNR (United
States-Japan Natural Resources) Aquaculture Panel
meeting. I would like to explain briefly about the

Table 1. — Shellfish production in Japan, 1969.

' Tohoku Regional Fisheries Research Laboratory. Shiogama.
Mi\agi-ken. Japan.

- National Pearl Research Laboratory. Kashikojima. Mie-ken.
Japan.

Shellfish

Landings
in tons

Value in
million

of yen

.Abalone iHaliotis discus luinai.

H. discus, H. gijiantiea. H.

sicholdi) 6.463

Top shell ( Turhu corneliis) 8.459

Hard clam (Merelrix meretrix.

M. liisoriu) 7,081

Short-necked clam (Venerupis

semidccussala) 1 16,572

Common scallop (Palinopeclen

yessoensis) 14,644

Surf clam (Spisula sachalinensis) . . . 4,050
Ark shell (Anadara suhcrenata) .... 38.289

Other molluscs 114.281

Oyster (Cnissosrrea gigas) 245,458

Pearl 97

Pearl molber sheW (PicUula fucalu) . 5,738

Total 561.132

5,692

1,7L5

966

3.025

1.833
948
1.918
9.920
8.149
22,600
1.678

58.444

present status of shellfish aquaculture in Japan and
its prospects for the future.

OYSTER CULTURE

Production of oysters (Crassostrea gii^cis) has
rapidly increased since the 1950"s because of the
development of hanging culture. Strings of oysters
are hung from racks, rafts, or longlines, depending
on water depth. Hanging culture makes good use of
the water column and is not limited by depth or
nature of bottom. In 1969, production was 245,458
tons (including shell) valued at 8.149 million
yen (Table 1).

The first operation in oyster culture is to catch the
juveniles (seed). Strings of shells are suspended dur-
ing the summer spawning season from racks placed
in coastal areas such as bays and inlets. After set-
ting, the seed is hardened, a process of draping the
strings over racks so that they are out of water for a

23

considerable period of time during each tidal cycle.
Hardening results in an increased percentage of
survival, better growth rates, and less fouling. In
northern Japan, almost all commercial oyster seed
production takes place in Miyagi Prefecture. At
present, oyster seed production supplies not only
domestic uses, but also supplies some 30,000 to
50.000 cases of seed per year to the Pacific coast
of the United States and to parts of Europe, prin-
cipally France.

Two met hods of hanging oysterculture are usually
practiced in southern Japan. In the first method,
seed oysters are transplanted to the rafts about 1 mo
after setting to grow: no hardening is done. These
oysters are harvested at the end of I yr. This method
is characterized by a short growing period and low
labor costs. In the second method, seed oysters are
hardened until autumn orearly winter. They are then
transferred to the rafts to grow and are not harvested
until the following year (known as 2-yr culture).

The best oyster producing area in Japan is in the
Seto Inland Sea where calm conditions exist. Here
there are wide areas which enable the growers to use
large size rafts, 20 m long by 10 m wide. The Tohoku
region of northern Japan is also favorable for oyster
culture and longlines are used in some of the rough
water areas. It takes 2 yr for the oysters to grow to
market size.

Oyster production is expected to remain stable
over the next few years. New species of oysters such
as the European flat oyster, Ostrea editlis. and the
Portuguese oyster, Crassostrea aniiiilata. may enter
commercial production in the future if the problem
of pollution along the coastal areas can be over-
come.

SCALLOP CULTURE

The aquaculture of scallops. Patinopecten yes-
soensis. has recently been developed in Japan. The
production of scallops on natural grounds has re-
mained poor during the past decade with annual
landings fluctuating between 5.000 and 15,000 tons.
Since the development of the hanging method for
catching seed and culturing scallops, production has
increased rapidly during the past few years and will
continue to do so. Because considerable quantities
of seed are being caught in Aomori and Hokkaido
areas of northern Japan, the scallop fishery is cur-
rently expanding. Ihe seed is not only beingcultured
in nets to market size but also released on the bottom
where good returns are being obtained 2 to 3 yr later.

In 1969, 14.644 tons worth 1,833 million yen were
harvested from natural grounds and approximately
5,0(X) tons were produced from hanging culture.

Seed scallops are caught in the spring. Several
kinds of cultch materials are used: vinyl fibre (used
gill net), vinyl film, branches of trees, etc. These are
suspended from rafts or longlines. Three months
after setting, the young scallops are transferred to
nets where they grow to 3-4 cm by autumn. The
culture of scallops can then go one of two ways:
Either the seed can continue to grow in nets for l'/2yr
to market size or they can be released on the natural
grounds. As high as an 809? return has been obtained
from released seed on the coastal area of Hokkaido.

In the near future, a large-scale bottom farming of
scallops can be expected along the coast of Okhotsk
Sea, Hokkaido. This project will be made possible
because large amounts of scallop seed are available.
The site once produced 60,000 tons of scallops annu-
ally. To make the program successful, systematic
engineering and newly developed harvesting
machines such as suction dredges and underwater
bulldozers will be utilized.

ABALONE CULTURE

Considerable interest has developed in the cultur-
ing of abalone (Haliotis discus luinai in cold waters
and //. discus in warmer waters). These are very
important commercial species along the rocky sea
bottom both in quantity and quality. Production has
remained relatively stable over the past years as a
result of good management practices such as the
transplanting of natural sets to areas of poor setting.
In 1969, abalone landings totaled 6,463 tons valued
at 5,692 million yen (Table 1).

Two approaches are planned in the aquaculture of
abalone — mass production of seeds in hatcheries
and the artificial production of food in the field by
seaweed afforestation. Artificial seed production
was developed in the 1960"s. Seed production is
expected to expand as studies are compjeted on the
conditioning of abalone for spawning and as com-
mercial hatcheries are developed. Good returns can
be expected from released seeds, 2-3 cm in shell
length, when they are harvested 3-4 yr later.

There is a lack of knowledge about the food condi-
tions in the abalone's natural habitat. For this
reason, research was initiated in afforestation in the
field. .Afforestation could produce about 40 tons of
food that could feed up to 4 tons of abalone. The
seeds for this program will come from hatcheries.

24

PEARL INDUSTRY

The pearl industry first began in 1906. The indus-
try has developed rapidly after World War II and
reached its peak of production in 1967 when 130 tons
of pearls were produced by 4,701 culturist (called
management units). The increase was related to
techniques in artificially collecting seeds and rearing
the mothershells (Piiutada sp.). The mother shell
industry has grown rapidly since 1952. In 1965.
1 1 .000 tons of mother shells were harvested from
69,000 rafts operated by 7,859 management units.

A rapid increase in the number of management
units occurred from the postwar era to 1964. These
were mostly small-scale units using less than 30
rafts. In recent years, the number of units has not
been increasing and many units are using more rafts,
indicating an enlargement of the individual industry
units.

The everlasting aim of the industry is to improve
the quality of the cultured pearl. In the 1920's, pearls
were small but, after developing successful tech-
niques of transplanting mantle pieces in the gonad,
bigger pearls were produced. Between 1952 and
1969, the production of small pearls (less than 6 mm)
decreased from 67% of the total production to 24%;
those in the medium size range (6.0-7.6 mm) and
large pearls (7.6 mm) increased in total production
from 24 to 58% and from 9 to 18%, respectively.

As the industry developed, culture grounds
spread rapidly over the middle and southeastern
parts of Japan. These areas were used mainly for the
production of mother shells. In 1956, 82% of all
pearls produced in Japan came from the middle
Pacific region; 73% of these came from rafts. Re-
cently, however, production in this area has declined
because of overcrowding and deterioration of cul-
ture grounds. In 1964, 20% of the total pearl produc-
tion came from the Seto Inland region but, recently,
production dropped to 10%. On the other hand, pro-
duction in the southern Pacific and East China re-
gions has been on the increase, and over half of the
total Japanese pearl landings now comes from these
two areas.

Until 1963, yields from pearl rafts were stable but,
thereafter, production per raft has gone down.
Reasons for this decline have been related to
crowded conditions and to the use of unsuitable cul-
ture grounds. In the Seto Inland region, the deterio-
ration of the waters caused by man-made pollution
has caused a drop in yields from certain culture
grounds. Special provincial laws have been under-
taken to regulate production, recover the balance of
supply and demand, and effectively utilize suitable
culture grounds. The success of these regulations
will insure the steady foundation of the industry and
the production of better quality pearls.

25

FISH FARMING AND THE CONSTRAINTS

IN JAPAN

MASARU FUJIYA'

INTRODUCTION

Geographically and historically, utilization of
marine products, which has been quite significant to
the Japanese people and fisheries, is one of the most
important industries of the Nation.

Before the World War II, Japan expanded her
fishing area and Japanese fishermen worked all over
the world to obtain their foods. The catch was
mainly consumed as the protein source for nutrition
of the people, and the expansion of production was
most important. This situation continued until about
a decade ago.

During recent years the situation has changed re-
markably. The Japanese people have demanded
greater variety of fishery products of high quality
with improvement of their living standard. However,
high-quality species occur along the coast of our
homeland, and these stocks had decreased because
of overfishing and/or water pollution. Under these
circumstances, fish farming has become necessary.

ESSENCE AND SIGNIFICANCE OF
FISH FARMING

In 1962, the Seto Inland Sea Farming Fisheries
Association was established, and by 1966 five opera-
tion centers were completed and began operation.
At present, the tasks of tlsh farming are expanding as
scheduled, but some problems remain. Through
cooperative research, biologists and fish farming
specialists are searching for solutions to these prob-
lems in order to advance the operations. Fish farm-
ing is somewhat different from ordinary aquaculture.
The differences are explained briefly and some con-
straints are discussed in this paper.

When the Seto fish farming operation was started,
it was planned to release the larvae following the

procedures used with salmon and trout. At that time
the Inland Sea was regarded as a fish culture pond,
and early stages of larvae were released directly
from the operation centers without any care because
no effective technique had been developed for rear-
ing marine fish through their larval stages in captiv-
ity.

Subsequently, it became apparent that more effec-
tive utilization of artificially produced larvae was
require!^, and some new techniques were developed
for larval culture and for acclimation to natural wa-
ters. Also, procedures were developed for maintain-
ing a brood stock in captivity for earlier production
of seedlings and production of more healthy seed-
lings. As a new idea, some civil engineering techni-
ques were proposed to rehabilitate growing and re-
leasing grounds.

Thus, the present farming fisheries are really
equivalent to agriculture in water areas. Artificially
produced seedlings are held or planted in shallow
coastal regions, and these seedlings utilize natural
productivity of these waters for their growth. Recap-
ture or harvest occurs within a certain period (Fig. 1)
when the products are ready for market.

SMdIing

Accltmalion

Reformation
of
Growing Growing Areas

or
Rearing

Recapture

or
Harvest

Utilization

of

Natural Productivity

' Nansei Regional Fisheries Research l,ahorator\'. Maruishi.
Ohno-cho. Saeki-gun. Horoshima-ken. Japan.

Figure I, — Fundamental conception of Ush tarming.

27

In this process, the utilization of natural produc-
tivity is an indispensable condition for farming
fisheries which is different from ordinary aquacul-
ture in which the growth of species, such as trout and
eels, depends almost entirely upon introduced
foods.

The following items are considered in selecting
suitable organisms for farming:

1 ) They should adapt easily to farming operation.

2) Their growth rate should be high.

3) They should have a reasonably high market
value as a product.

4) The seedlings can be supplied easily from a
hatchery or from natural reproduction.

5) The feeding habits of larvae and/or young
should be clearly known ecologically and physiolog-
ically.

6) Foods for the organisms should be readily
available and cheap.

7) They should be resistant to diseases, or
disease-control methods should be available.

The satisfaction of these requirements is espe-
cially significant for a successful operation. How-
ever, if demand for a species is great and the market
value is high, greater efforts to develop farming
techniques for the species will be justified, even
though that species would be difficult to farm. The
most important consideration in planning of fish
farming may not be the technical problems, but the
development of an economical system. Composite
planning will be required from both technical and
economical points of view.

As a special case, geographical transplantation of
organisms is ideal for some species. Rapid growth
and greater production can be expected when north-
ern species are transplanted to southern regions.
Some places isolated from a source of organisms
sometimes have few native species, but have food
and space capacity for additional species. So, when
the investigation for farming is carried out. the idea
of introducing a new species should be considered.

TWO TYPES OF FISH FARMING

Present and/or proposed farming fisheries could
be classified into two types: 1 ) stock recruitment and
2) artificial control, as shown in Figure 2.

Stock Recruitment Type

In stock recruitment type of farming, the seedlings

are transferred from the operation centers or hatch-
eries to a temporarily constructed acclimation facil-
ity. This procedure allows the seedlings to adapt to
the environmental conditions of the recei\ing waters
and to naturalize their behavior while protected from
predators. After certain periods, they are released
into natural waters forgrowth. In this case, the plant-
ing sites are determined from the results of scientific
investigation of the environments and distribution
and behavior of natural stocks.

For example, when a shrimp release program is
planned, investigations are carried out in advance to
determine the suitability of various places for shrimp
growth and the best place is selected for the planting.
Places where natural shrimps thrive are likely to be
satisfactory release sites.

When environmental conditions in an area are ac-
ceptable for the planned species and when results of
scientific investigations show that the adaptation
and the naturalization are unnecessary, seedlings are
released directly into the waters. Otherwise, accli-
mation techniques are applied. In the case of shrimp,
the seedlings are acclimated in net enclosures for 1 -3
wk depending upon the situation.

The stock recruitment type of farming is practiced
at present with prawn, blue crab, and several species
of fin fish.

Artificial Control Type

The artificial control type of farming is usually
smaller in scale than the stock recruitment type, and
frequently some facilities or mechanical equipment

Fish Forming

ArTif iciol
Control Typ*

Stock

Recruitment

Type

Seedling
Production

Acclimotion

Nursing

Seedling
Production

Ulilliotion

of

Noturol Productivity

^ Acclimotion Releasing

i

Releosing
^ Growing

Horveat Recapture

Figure 2. — Brief diagram of fish r;irniing in Japan.

28

are involved. The farming of oyster, abalone, clam,
algae in Japan, and of milkfish in South Asian coun-
tries are of this type.

A new experiment in the culture of red sea bream
is based on conditioning the fish to respond to
sounds. The seedlings, 20-50 mm in total length, are
kept in floating cages and trained with sound and
feeding of pellets. Within 2-8 wk, they are adapted to
sound of certain frequency (100-600 Hz) and develop
the habit of gathering around a feeding place every
time the sound discharges. After they obtain this
habit, the fish are liberated into natural waters, and
most of them retain the habit and do not scatter.
Although a small amount of pellets is necessary to
feed them, they can eat more natural foods for their
growth. Therefore, this idea could be categorized as
a tlsh farming.

SEEDLING PRODUCTION

The first step and one of the key points of fish
farming process is the seedling production. At the
incipient period, zygotes, larvae, and young fish col-
lected from natural waters are mainly used as seed-
lings, but artificial seedling production techniques
have been developed for important species and these
techniques are applied for the actual farming opera-
tions. The process is briefly shown in Figure 3.

Matured adults from wild stocks are still used to
obtain eggs and sperm in most cases, but research to
develop techniques for obtaining eggs from adults
reared to maturity in captivity are in progress.

In order to obtain zygotes, stripping and artifi-
cial spawning methods are sometimes used, but most
species can be induced to spawn naturally in artifi-
cially controlled tanks. Matured adults are put in a
tank of water, and the zygotes are collected after
spawning and fertilization occur. Then, the eggs are
transferred into a rearing facility such as a tank or

aquarium. For some species, matured adults are put
directly into the larval rearing tank and removed
after spawning.

The zygotes are reared in tanks of still water, but
slow running water can be used for larvae after they
reach certain sizes. With some species, the larvae
are transferred to floating cages until they reach
seedling size, but with shrimp, the larvae are kept in
the same tank till they reach seedling size. In this
case, control of population density to achieve the
desired numbers of final stage is important. The size
of seedlings varies depending on the purpose and
environmental conditions of receiving waters.

The planned numbers of seedlings to be produced
in five centers in 1971 fiscal year are shown in Table
1. The prefectural centers are also producing some
seedlings, but their main purpose is the development
of culture methods.

Breeder
Collection

Breeder
Reoring

Spowning Stripping

Natural Zygote Collection

Natural Larva Collection

Natural Young Collection

Figure 3. — Seedling production process.

Table 1.— Planned production of seedlings in five centers of Farming Fisheries

Association in 1971 .

Organisms

Season

Number of
production

Size

Prawn

Pendens japoniciis

May-Aug.

140 X

10"

0.01-0.02 g

Blue crab

Poiliiniis irUiiheniilunis

June-Aug.

30 X

10"

Megalopa

Red seabream

Poqriis major

May-July

?00 X

lO-'

0.01-0.1 g

Flounder

Piiialichlhws oliyticeiix

J an. -Mar.

600 X

10'

0.1 g

Rocktlsh

S elm Stic IIS iiuiniioiiiiiis
Sehtistes inerniis

Dec. -Mar.

\^ X

10"

0.07 g

29

CONSTRAINTS AND PROBLEMS

Although fish farming is in progress in Japan,
some problems and constraints remain.

Technical constraints include problems concern-
ing seedling production, nutrition of larvae, disease
and parasite control, and feeding. Among these,
seedling production techniques are being developed
rapidly, and experience with the successful culture
of several species should be applicable in the future
to other species. Among other problems, however,
fundamental research for the advancement of tech-
niques for nutrition of larvae and control of disease
and parasites are the most important. Aquatic or-
ganisms go through several larval stages with selec-
tive food habits, and the most suitable food has to be
found for each stage. At present, phytoplankton and
zooplankton cultured and/or collected from natural
waters are fed to the larvae, but the supply fre-
quently becomes the limiting factor for seedling pro-
duction. Thus, the development of a stable supply of
foods for larval stages is necessary for the advance-
ment of seedling production. The development of
artificial foods is especially needed.

As the history of aquaculture has shown us, dis-
ease and parasite control is also significant. In fish
farming, disease control for larva! stage will have to
be developed. Usually, larvae are weaker than
adults, and contagious diseases are most serious. It
is not unusual to have several millions of larvae
killed during a short-time period in actual farming.

In aquaculture, practical methods for treatment of
diseases and parasites have been developed. For
instance, chemotherapy has assisted the treatment
and prevention offish diseases. These kinds of ad-
vanced techniques should be applicable to fish farm-
ing, but some fundamental problems such as resis-
tant strains and human public health considerations
remain.

As an effective method for preventing disease
mortality, it may be possible to breed resistant
strains but little research has been done for this
purpose.

The most significant constraint concerning the
utilization of seedlings is the hypothesis that artifi-
cially reared seedlings are equal to those from
natural reproduction. As mentioned before, the re-
lease of seedlings is based on the results of prelimi-
nary investigations on the environmental conditions
of planting area and the behavior of natural or-
ganisms. In most cases, the suitability is estimated
from the presence of natural larvae indicating a fun-

damental hypothesis that artificially produced seed-
lings are equivalent to natural larvae. However, the
results of farming trials along the coast of the Inland
Sea and surrounding districts have been variable.
Successful results have not always been obtained in
spite of the determination, based on preliminary in-
vestigations, that these places were suitable for
farming. These circumstances raise doubts concern-
ing the validity of this hypothesis.

The larvae reared under the ailificial conditions
are pampered. They are kept in optimal environmen-
tal conditions as far as possible, with adequate food
supply, and protected from competitors and pred-
ators.

On the other hand, larvae in natural vsaters must
survive the fluctuation of environmental conditions,
effects of competitors and predators, and. in addi-
tion, they must find food for themselves. Thus, they
are hardened in nature. Therefore, it is likely that
there are some differences in the biological charac-
teristics of natural larvae and artificially produced
seedlings as diagrammed in Figure 4.

In order to obtain more successful results of farm-
ing, evaluation of suitability of the receiving waters
should include consideration of biological charac-
teristics of seedlings.

There have been suggestions that comparative re-
search should be carried out to define the difference
in biological characteristics between natural and ar-
tificially produced larvae. However, this is some-
times impractical because of the difficulty in collect-
ing samples of natural larvae. In some species, the
natural larvae have not been observed and. with the
present state of knowledge, could not be identified
even if some larvae could be found. The best method
is to experimentally establish expected environmen-
tal conditions and to observe the effect of these
conditions on biological characteristics, such as, re-
sistance to the fluctuation of environments,
physiological activity, avoidance reaction from
predators, and ability of shrimp and crab to bury
themselves in the bottom sediments.

Techniques for acclimating artificially produced
seedlings should be varied with the species and the
results desired. At present, almost standardized
facilities and methods are used for acclimation of
seedlings without adequate consideration of objec-
tives. These include net enclosures and net cages for
shrimp and crab and floating cages for fish, in which
seedlings are kept with feed for several weeks. Al-
though this procedure is helpful for adaptation to
natural water conditions, it does not train the seed-

30

Usage Route for Seedlings
Characteristics of Naturol
Larvae and Seedlings

Acclimation
including
Noturalizotion
Adaptation
C onditioning

and or
Hardening

Biological
Characteristics
of
Natural Larvae

\

Optimal Conditions
for Natural Larvae

Optimal Conditions
for Artificial
Seedlings

Biological
Charocteristics

of
Artif iciol
Seedlings

J

Figure 4. — Some differences in the biological
characteristics between natural larvae and seed-
lings and artificial seedlings.

lings to find natural foods orto avoid predators. Con-
ditioning and training, based on biological require-
ments to achieve the intended purpose, should be
tried in the acclimation facility; otherwise, success-
ful acclimation cannot be expected.

The greatest problem connected with the future of
fish farming is the pollution of natural waters. Al-
though water pollution is a matter of concern among
the people and plans for pollution control are being
developed, the adverse effect on fish farming is not
fully recognized.

Some aspects of this biological problem have been
investigated to find ways to reduce the effects of
pollutants on fisheries, and water quality criteria and
water quality standards have been described for
some aquatic organisms. However, most of the re-
search data are on adult organisms.

In fish farming, the situation is more severe. For
example, the period of larval development is the
weakest stage of the life history of organisms, and
even seedlings have lower resistance to pollution
than adults. Brood stocks require a high quality of
water to maintain healthy adults v\hich will produce
active larvae.

As the mass production of seedlings is possible, a
limited number of hatcheries can supply the demand
for seedlings. Places chosen for hatching facilities
should have the best environmental conditions in
unpolluted regions. Farming, especially of the stock
recruitment type, requires extensive areas of unpol-
luted water for the production of large amounts of
fish or shellfish. Complete water pollution control
will be needed to keep released organisms safe. For
this purpose, the cooperative research will have to
be carried out by fishery biologists and specialists on
pollution control. Without this cooperation the ad-
vancement and expansion of fish farming will be
hopeless.

CONCLUSION

The history of aquaculture in Japan is quite long.
Mariculture of oysters and algae was started some-
time before the beginning of science. Procedures
were established by fishermen, and the techniques
have been developed and reformed year by year
based on their experiences.

Since the beginning of fisheries science about a

31

century ago. the scientists have verified the suitabil-
ity of techniques developed by fishermen, though
some technical contributions have been offered.
Therefore, it cannot be said that scientists have de-
veloped the fundamental concepts for the advance-
ment of aquaculture.

Considering the period in which it was developed.
the idea offish farming should be esteemed highly as
an epochal accomplishment. At the present time,
however, ancient and new ideas of aquaculture in
Japan are mixed together. These ideas should be
reorganized systematically to establish efficient op-
eration plans and research projects.

Among the old aquaculture techniques, there are
some helpful ideas and methods for the development
of new farming fisheries. For example, an artificial
fish shelter of concrete blocks is an effective method
to build a new fishing ground. A larger scale shelter
would form an "artificial bank." If the technology of

artificial shelter or bank and fish farming could be
combined, greater fish production may be expected.
Therefore, the combination of differently
categorized ideas or techniques v\ili accelerate the
advancement of practical fish farming.

Fish farming is becoming of global interest and
Japan is considered as the most advanced country in
this field. People concerned with fish farming and
aquaculture expect to obtain the information from
Japan, and sometimes they are apt to apply the
Japanese methods and techniques directly. Biologi-
cal techniques are so complicated, however, that
direct application in other environments may be un-
successful and some modifications will be required.
Certainly fish farming should be encouraged on a
universal basis, but many problems remain to be
solved. Greater advancement can be expected with
the international cooperation of experts in this
specialized field.

32

LARVAL CULTURE OF PENAEID SHRIMP AT THE GALVESTON

BIOLOGICAL LABORATORY'

CORNELIUS R. MOCK'

PRELIMINARY EXPERIMENTATION

The first larval culture experiments at the Na-
tional Marine Fisheries Service Galveston Labora-
tory were conducted to aid the identification and
description of the larval stages of penaeids found in
the Gulf of Mexico. By 1966 the three commercially
important penaeid shrimp (white shrimp. Peiiaciis
setiferus; brown shrimp, P. aztecus; and pink
shrimp, P. dtiorariim) had been reared to the post-
larval stage. The basic techniques used to culture
larval shrimp were similar to those described by
Hudinaga (1942) and Hudinaga and Miyamura
(1962).

During this period the following organisms were
tested individually as foods for the larval shrimp:
Skclctoiieina costatiim, Eiicampi sp., Gym-
nodinhim splendcns. Tetraselmis sp., Tliiilassiosira
sp., a euglenoid protozoan, and Artemia sp. As a
result of this work, two suitable food organisms were
selected for use in subsequent experiments. These
were Skelctonemu costatiim, because it could be
cultured easily, and Artemia sp., because it was
readily available (Cook and Murphy, 1966; Cook,
1967).

Following the initial phase of this work, research
was directed toward developing methods of rearing
penaeid larvae en masse in order to supply shrimp
grown under known conditions for physiological
studies and forexperimental pond culture. A variety
of specialized equipment was designed and tested in
an attempt to perfect larval culture techniques.

PROGRESS BETWEEN 1966-1969

From 1966 to 1969, considerable effort was di-

rected toward growing mass cultures of algal foods in
natural seawater. Although samples of seawater
were tested prior to each experiment with several
types of fertilizers to determine which combinations
of nutrients should be used with that batch of seawa-
ter for best algal growth, satisfactory growth did not
always occur. It soon became apparent that a more
reliable medium than seawater was needed. A
number of media made with synthetic sea salts and
tap water were tested. "'Instant Ocean"^ was cho-
sen from those tested for use at the Galveston
Laboratory along with a complement of nutrients,
trace elements, and vitamins (Mock and Murphy,
1971). With this medium dense unialgal cultures can
be grown and maintained. For example, 300 liters of
Skeletonema costatiim can be cultured from an
8-liter starter culture to a density of 4-5 x 10" cells
per milliliter in 4 days.

Additional algal foods fed experimentally in-
cluded Cyclotella nana. Isochiysis galbana, and
Cerataiilina sp.

Based on observations made during this ex-
perimentation the following conclusions were made:
1 ) the responses of Penaeiis aztecus larvae to differ-
ent light intensities were inconsistent; 2) a tempera-
ture range of 28°-30°C (82°-86°F) and a salinity range
of 27-35"/i]o were most satisfactory for penaeid larval
culture; 3) addition of several algal foods gave better
survival than additions of only a single species when
comparable concentrations were used; 4) the omis-
sion of antibiotics from the larval culture media was
possible when the chelator EDTA (ethylene-
diaminetetraacetic acid) was substituted at
concentrations of 0.01 g per liter of seawater; and 5)
postlarvae could be shipped successfully either by
motor vehicle or air when placed in plastic bags filled
with oxygen and seawater (Cook, 1965, 1966, 1968,
1969).

' Contribution No. .144 from the National Marine Fisheries
,Ser\ice. Galveston Laboratory. Galveston. Texas.

- Gulf Coastal Fisheries Center. National Marine Fisheries
Service. NOAA. Fon Crockett. Galveston. TX 77550.

' Reference to trade names does not imply endorsement hy the
National Marine Fisheries Service. NOAA.

33

RECENT EXPERIMENTATION

Beginning in 1969, the major objective of the re-
search at Galveston was to develop methods
whereby larval shrimp could be cultured more effi-
ciently and economically. It was realized that the
economic success of shrimp culture was largely de-
pendent upon the costs of producing larval shrimp in
quantity. Two key problems contributing to the
costs were: I ) costs of food production and 2) costs
of labor. Research was initiated that was designed to
reduce the investment required for the construction
of a shrimp hatchery, to increase the efficiency of
algal and larval culture procedures, and to reduce the
amount of labor required in the hatchery.

The approach used has been to grow unialgal cul-
tures separately from the larval shrimp and to add
only that number of algal cells needed to maintain the
shrimp population. However, when algal densities
were low, large volumes of the culture had to be
transferred to the shrimp rearing tanks. This resulted
in changes in the temperature of the larval culture
media which frequently caused mortalities. In addi-
tion, the medium in which the diatoms were grown
was slightly toxic to the larval shrimp. For these
reasons, it was decided to separate the cells from
their culture medium.

Separation with a centrifuge has been successful
with several types such as a table model, a continu-
ous centrifuge, or a large cream separator. When a
continuous centrifuge or cream separator is used,
the algal concentrate accumulates within the cen-
trifuge and is removed by disassembling the
machine. If the speed of the centrifuge is adjusted so
that the cells are not damaged, the resulting concen-
trate is a satisfactory food. The cells are then sus-
pended in a known volume of water and a series of
counts made to determine cell density. The concen-
trate is then measured into a number of suitable
containers in volumes predetermined to provide
appropriate feeding levels in the larval rearing tanks.

Experimentation with methods of preserving algal
concentrates was initiated in an effort to increase the
reliability of the larval culture procedure.

In the past it had been necessary to begin algal
cultures several days before the gravid female
shrimp were captured to insure adequate volumes of
the culture for feeding. Often cultures were ready,
but gravid shrimp could not be captured, or if gravid
shrimp were captured, the algal cultures failed.

Refrigeration has been used successfully to hold
the concentrates for periods of 96 hr. For storage

under refrigeration the concentrate is placed in a
plastic container and diluted to a volume of 6 to 8
liters, then held at 5C and aerated gently.

Freezing in a deep freeze at -19° to -22°C has
also been a suitable method of holding algae. Frozen
algal concentrates have been held 7 mo without
apparent damage to the cells. Research has also been
done on algal foods which are freeze-dried alone or
in the presence of protectants. Brown (1972) re-
ported that freeze-dried diatoms are suitable foods
for larval shrimp, although they are inferior to live
diatoms.

The final modification in procedures made possi-
ble by the concentration of algae is the use of a
continuous feeding device consisting of a small
peristaltic pump. Either freeze-dried, frozen, or
fresh concentrated algae is suspended and diluted
slightly so that it can be pumped into a larval culture
at rates as slow as a few milliliters per hour. Larval
densities of 100-500 per liter have been maintained in
tanks up to l,80()-liter capacity using this technique
(Mock and Murphy, 1971).

The entire procedure of centrifuging, freezing,
and feeding automatically has been performed with
cultu-res of Skeletonemu, Tetruselmis. Tha-
lassiosira, -and Cyclotella. Single species and mixed
species of algal concentrations have been tested. In
every case the algae used were reared in unialgal
cultures. Each step in this procedure contributes to a
more efficient hatchery operation, and the freezing
and automatic feeding reduce the labor requirements
of the operation significantly.

TYPICAL EXPERIMENTAL RESULTS

For purposes of demonstrating the value of re-
search conducted in small tanks, the results of two
experiments conducted in 1971 are presented below.
The results of these experiments were not particu-
larly outstanding, but they can be used to illustrate
the type of information which can be obtained using
this procedure.

Experiment I

Data are presented for a single tank from Experi-
ment I conducted March 31, 1971 (Table I). This
was the first use of frozen algae as food during the
protozoeal stages at the Galveston Laboratory. The
spawn from two brown shrimp were placed in a
1 , 520-liter fiber glass tank ( 1 .8 m in diameter, 0.9 m
high. v\ilh a flat bottom) in a greenhouse. Twelve

34

Table 1 . — Experiment I. Use of frozen Skclelonema costatiim (S). Cyclotella nana (C), and freshly hatched and frozen
Anemia by larval and postlarval brown shrimp, Penaeus aztectis.

1971

Month

Day

Hour

Larval
stage

Larval
count

Algae

Residual

Feed

Anemia

Residual

Feed

No. cells/ml

No. cells
fed/ml

No. /ml

March
April

April
April

April

2145

Spawn

0900

Egg nauplii

1120

Hatching

0830

Nauplii lll-lV

1500

Nauplii IV-V

2400

Nauplii V

0900

Protozoea 1

1000

1500

0900

Protozoea I

April

April

April

1700

0800

2000

0800

1130
1630

2100

0800

1415
1545

Protozoea II

304.000

307,290

304.000

297.061

Protozoea II

301.244

Protozoea III

Protozoea 111

Protozoea III
Protozoea 111

304.000

27,0(M) S
210.000 C
' 10,000 N

48.000 S
19,000 C

145.000 S

220,000 C

10,000 N

231,000 5
845,000 C

5,000 N

30.000 S

217.500 C

15.000 N

62.500 S

195.000 C

12.000 N

92,500 S

275,000 C

30,000 N

22.500 S
232.500 C

32. .500 N

37,500 S
197.500 C
47.500 N

70.000 S

277.500 C

15,000 N

65,000 S

322.0(X) C

10.000 N

124,600 S

152.100 S
272.300 C

187.000 S
876,000 C

200,000 S
500,000 C

250,000 S

250.000 S
500.000 C

217.100 S

147.100 S

349.000 S
353.250 C

194.0(K) S
194.000 S

35

Table 1. — Continued.

1971

Month Day

Algae

Hour

Larval
stage

Larval
count

Residual

Feed

Artemiu

Residual Feed

April 7 — continued

April 8

April
April

April
April

10

2045

Mysis I

0800

1 1 30

1600

2115

0800

1700

IKK)

1900

0900

1700

0800

Postlarvae 1

289,000

No. cells/ml

187,500 S

445,000 C

45.000 S

507.500 C

No. cells
fed/ml

300.000 S
312.000 S

231.000 S

131,000

No./ml

3.0

0.2
3.5

3.4
1.4

3.8

3.4

5.2

18.6
K 14.9

4.0
5.0

5.0

5.0

- 8.0

^20.0

' N = Nitzschia sp.

- Frozen Anemia (Anemia did nol hatch).

airstones along the side and one in the middle of the
tank aerated the water.

The food used initially was the diatom
Skc'letonema costaiiim; however, live Nitzschki sp.
and Cyclotella nana were also present. Because this
e.xperiment was conducted in a greenhouse, the ad-
ditional species, which were introduced inadver-
tently, grew in the tank. Since C. nana had also been
frozen and was present in the tank, it was added to
the experiment. Frozen cultures of Nitzschia sp.
were not available, so it was decided to only monitor
its presence.

Examination of Table I will reveal that at times the
uneaten cells remaining in the tank were at a higher
level than that fed. These discrepancies are due to
counting error.

.Aliquot counts of the population on 8 .April
showed that 95^r of the larvae had advanced to mysis
I stage. Unfortunately, because two successive
days — 10 and 1 1 .April — of poor hatches ot'Arteniia
occurred, frozen Artemia were used as food. The
frozen Artemia sank to the bottom, deteriorated

rapidly, and caused apparent decline in water qual-
ity. Before fresh seawater could be exchanged and
before freshly hatched Artemia could be added, a
number of the larval shrimp perished. Only 429f of
the population survived to the postlarval stage.

A second rearing experiment was performed in
May 1971 using two 1,893-liter (500-gal) fiber glass
tanks with conical bottoms. Average length of the
shrimp that spawned was 191 mm. and the average
number of eggs spawned was 2.^ I. ()()() per shrimp
(range 71,000-380,000) with an individual hatching
success of about 12.8% (range of 0.5-35.7). The
spawn from each shrimp was divided into equal parts
and each part v\as poured into one of the rearing
tanks.

Experiment II

In E.xperiment II. Tank I (Table 2). two species of
concentrated frozen algae, Skeletonema costatiim
and Tetraselmis sp., were used, the latter being in-
troduced during the advanced protozoeal II stage.

36

Table 2. — Experiment II. Tank 1. V'ae of fvozenSkclcloiwina coslutKni {S).Ti'rrciscliiiix sp. {T).andAi!ciiii<i by larvaland

postlarval brown shrimp. Pendens azteciis.

1971

Day

Hour

Larval

stage

Larval
count

Algae

Residual

Feed

Anemia

Residual Feed

No. cells

No. cellslml fedlinl

May

20

Spawn

■

•

May

21

0730
1300

Egg nauplii
Nauplii I

May

->->

0700
1800
2000

Nauplii III
Nauplii IV
Nauplii V

84,000

250.000 S

May

23

0800

Protozoea 1

84,000

230,000 S

2000

Protozoea I

144,000 S

346.000 S

May

24

0800
1615

Protozoea I
Protozoea I

82,300

132,000 S
250,000 S

350.000 S

2130

Protozoea 1

170.000 S

270,000 S

May

25

0800
1000
1545
1630
2130
2300

Protozoea II
Protozoea 11
Protozoea II
Protozoea II
Protozoea 11

77,800

1 10.000 S
147.500 S
149.800 S

210,000 S
297,500 S
449,800 S

May

26

0800
0930
1530

Protozoea II
Protozoea II
Protozoea II

70,800

137.000 S

132.000 S
6.250 T

15,000 T
14,050 T

2200

Protozoea III

100,000 S
13,750 T

250.000 T
21.550 T

May

27

0730
1630

Protozoea III
Protozoea III

217.500 S

23.700 T

225.000 S

1700

Protozoea III

7.500 T

27.500 T

2130

Protozoea III

36.250 S

136.250 S

May

28

0800
0900

Protozoea III

57.500 S
25.500 T

35.000 T

1330

Protozoea III

60,000

67.500 S

16.30

16,250 T

36.250 T

2130

Mysis I

66.250 S

16.875 T

2245

Mysis 1

47.875 T

May

29

0800
1045

2215
2320

Mysis I
Mysis 1

Mysis 1
Mysis 1

48.750 S
13,750 T

21.250 S

17.500 T

321.250 S

148.750 S
63.750 T

87.500 T

May

30

0800

1115
1130

:(x)()

22(K)

Mysis 11
Mysis 11

Mysis 11
Mysis 11

57.500 S
55.000 T

37.500 S
30.000 T

157.500 S
85.000 T

137,500 5
90.()()() T

No. /ml

0.9

2.9

6.0

7.3

3.0

3.0

6.0

9.0

37

Table 2. — Continued.

1971

Month

Day

Hour

Larval
stage

Algae

Larval
count

Residual

Feed

Anemia

Residual Feed

May

31

0800

June

Mysis III

1030
1045

Mysis III
Mysis 111

2000

Mysis 111

2100

Mysis 111

0800

Postlarvae 1

4().()()()

No. cellslml

35,000 S
33.750 T

27,500 S
38,750 T

37.500 S
21.250 T

No. cells
fedlml

135,000 S
89.750 T

127,500 S
86,750 T

No. /ml
5.0

6.8
8.0

8.0

8.8

Of the 84,000 nauplii which hatched, 71% reached
the mysis stage. Once again, owing to a buildup of
algal food on the bottom, water fouling caused high
mortalities. From mysis 1 to mysis II, thoseArtemia
fed to the shrimp were eaten; however, from mysis
II to postlarvae I, Xhe Artemia begin to graze quite
heavily on phytoplankton and some grew so rapidly
that the larval shrimp could not eat them. It was then
necessary to build the Artemia level higher in order
to have enough available to feed the young
shrimp.

Not only was fouling on the bottom a problem, but
from the mysis stage on, the shrimp tended to ac-
cumulate at the bottom of the tank where the fouling
was occurring, thus increasing the stress upon the
population. Only 48*^ of the initial population
reached the postlarval stage.

The second of the two tanks was used to test a
small peristaltic pump set up for feeding continu-
ously the algal concentrate into the larval culture
tank (Table 3). Unfortunately, enough Skeletonema
had not been concentrated and frozen for this tank,
so concentrated frozen Skeletonema was used in the
continuous feeder and concentrated fresh
Skeletonema was used for the initial feeding and for
supplemental feedings needed to raise the standing
cell level. At times the automatic feeder was pump-
ing too fast, so it was shut off or the food concentra-
tion was reduced.

On 28 May. it was necessary to transfer about half
of the population from this lank for an additional
experiment, leaving 42.750 mysis Is in the tank.

Survival was good from mysis I to postlarvae II.
However, when this tank was harvested, an accumu-
lation of debris had built up on the bottom of the
tank, with dark areas of decomposition, indicating
hydrogen sulfide production. In more recent work
using airlift pumps to keep the debris suspended, the
problems related to the accumulation of debris on
the bottom have been solved.

By careful measurement of the abundance of the
larval shrimp populations as well as the densities of
food organisms at regular intervals, biologists have
been able to learn much concerning the survival,
behavior, and environmental requirements of larval
shrimp. While these methods may or may not have
commercial applications, they are a useful research
tool.

LITERATURE CITED

BROWN, A, JR.

1972. Experimental techniques for preserving diatoms
used as food for larval Pciiiieiis uzleciis. Proc. Natl.
Shellfisheries Assoc. 1971. 62:21-25.
COOK. H. I..

1965. Rearing and identif\ing shrimp larvae. In M. J.
Lindner and J. H. Kutkuhn (editors). Biological Labora-
tory, Galveston. Tex., fishery research lor the year ending
June 30, 1964, p. 11-13. U.S. Fish Wildl. Serv.. Circ.
230.

1966. Identification and culture of shrimp larvae. //iM.J.
Lindner and J. H. Kutkuhn (editors!. .Annual Report of
the Bureau of Commercial Fisheries Biological Labora-
tory. Galveston. Texas. Fiscal Near 1965. p. 12-13. U.S.
Fish Wildl. Serv . C irc. 246.

38

Table 3. — Experiment II, Tank II. Use of fresh concentrated and tVozen concentrdtedSkclc'i(}n('mti coslutiim and A rteniia

by larval and postiarval brown shrimp. Fciuwiis aztcciis.

1971

Month

Day

Hour

Larval
stage

Larval
count

Residual

Algae

Fresh

A rteinia

Frozen Residual Feed

Cell/ml

Cells /ml Cells Imllhr

No. /ml

May

May
May
May

May

20

23

24

May

May

May

May

May

May

June
June

26

27

29

30

31

Spawn

0730

Egg nauplii

1300

Nauplii 1

0700

Nauplii III

1800

Nauplii IV-V

2000

Nauplii V

171.000

250,000

10,000

0800

Protozoea 1

167.500

280.000

.

1000

. ,

2000

Protozoea 1

205.000

20,000

0800

Protozoea I

127,000

347.500

10,000

1130

Protozoea 1

5,000

1650

Protozoea 1

360,000

Turned off

2130

Protozoea II

177,000

202,000

1 0.000

0800

Protozoea II

142.500

107,500

\

1000

Protozoea 11

157,000

1415

Protozoea II

217.500

1545

Protozoea II

195,000

4

1630

Protozoea II

20,000

2130

Protozoea II

113.000

288,000

t

0830

Protozoea II

119.000

208.750

1010

Protozoea II-II

4

1030

Protozoea II-II

30.000

1530

Protozoea II-II

232,000

' ;

2200

Protozoea II-II

235,000

33.300

0730

Protozoea II-II

344,500

t i

1230

Protozoea II-II

1 14,800

1630

Protozoea II-II

251,500

"

21.30

Mysis I

178,750

20.000

0800

Mysis 1

302,500

10.000

1300

Mysis 1

93,500

('/2 population transferred for another

1645

Mysis I

42,750

300,250

1715

Mysis I

200,250

2130

Mysis I

220,000

0800

Mysis I

93.750

'

0930

Mysis II

193,750

20,000

1120

Mysis II

. .

2215

Mysis II

125.500

' '

2300

Mysis II

30.000

0800

Mysis III

128.750

■

I

1130

Mysis III

2000

Mysis III

240.000

.

2200

Mysis III

32.000
35.000

0800

Postlarvae 1

117.500

1100

Postlarvae 1

21X)0

Postlarvae 1

197.500

i

2 UK)

Postlarvae 1

30.000

0800

Postlarvae 1

146,250

1630

Postlarvae 1

81,250

0800

Postlarvae 1 1

42.400

1.1

rimei
0.5

3.3
3.1

5.7
5.3
8.8
8.9
4.8
7.2

2.0

3.5

6.2

8.0

39

I%7. Identification and culture of shrimp larvae. /fiM.J.
Lindner and R. E. Stevenson (editors). Report of the
Bureau of Commercial Fisheries Biological Laboratory.
Galveston, Texas, Fiscal Year 1%6, p. 6-7. U.S. Fish
Wildl. Serv., Circ. 268.

I%8. Taxonomy and culture of shrimp larvae. In M. J.
Lindner and R. E. Stevenson (editors), Report of the
Bureau of Commercial Fisheries Biological Laboratory.
Galveston, Texas, Fiscal Year 1967, p. 7-8. U.S. Fish
Wildl. Serv., Circ. 295.

1969. Larval culture, //i M. J. Lindner and R. E. Steven-
son (editors). Report of the Bureau of Commercial
Fisheries Biological Laboratory, Galveston, Texas,
Fiscal Year 1%8, p. 5-6. U.S. Fish Wildl. Serv., Circ.
325,

COOK. H. L.. and M. A. MURPHY

1966. Rearing penaeid shrimp from eggs to post-
larvae. Proc. Conf. Southeast Assoc. Game Comm.
19:283-288.
HUDINAGA [FUJINAGA], M.

1942. Reproduction, development and rearing ofPenaeiis
japonuiis Bate. Jap. J. Zool. I0:.1()5:.19.3.
HUDINAGA. M.. and M. MIYAMURA.

1962. Breeding of the "Kuruma" prawn {Penaeiis
juponUiis Bate). (In Japanese. English abstract.)
J. Oceanogr. Soc. Jap.. 20th Vol.. p. 694-706.
MOCK, C. R., and M. A. MURPHY.

1970. Technique for raising penaeid shrimp from egg to
postlarvae. Proc. Annu. Workship World Mari. Soc.
1970. p. 143-156,

40

AQUACULTURE IN THE NATIONAL SEA GRANT PROGRAM

ROBERT D. WILDMAN'

INTRODUCTION

The National Sea Grant Program was created by
an Act of the Congress of the United States to accel-
erate the development and optimum utilization of
our marine resources. This was to be accomplished
through the support of research and development,
education and training, and advisory service ac-
tivities. Major emphasis was to be placed on the
conduct of these programs through the establish-
ment and operation of Sea Grant Colleges, the ocean
equivalent of our Land Grant Colleges which were
instrumental in making the United States one of the
greatest agricultural nations of the world.

The Sea Grant Program, originally a part of the
National Science Foundation, is now in the National
Oceanic and Atmospheric Administration of the
U.S. Department of Commerce. Several require-
ments, restrictions, and methods of operation affect
the Program in important ways. Sea Grant funds
may not be used for construction or maintenance
purposes, or for vessel rental. Any recipient of Sea
Grant support must provide at least one-third of the
total cost of the project from non-Federal sources.
All grantees are encouraged to develop cooperative
programs with other scientists from universities,
government agencies, and/or private industry. Many
of our programs have, in fact, operated in this way.
When the National Sea Grant Program was created
by the Congress, aquaculture was one of the few
fields of research specifically identified for em-
phasis. In carrying out this mandate, the Sea Grant
Program has provided more support to this one area
of research than to any other. At the present time
over 209? of our research funds go into aquacultural
efforts. Asof 30June 1971, we were supporting over
50 projects directly related to aquaculture. The total
cost of these projects was nearly S5 million with over
S3 million coming from our Program. The remainder

' Program Director. Office of Sea Grant. NOAA. Washington.

D.c. :o:.\'!.

of the funding is being provided by the universities,
state agencies, and private industrial organizations
participating in these Sea Grant Programs.

Due to the low level of past activity in the aquacul-
ture field in the United States, very few research
groups had any capability or experience on which to
base an expanded effort. As a result, much of the
early work under Sea Grant support has been de-
voted to the establishment of trained, experienced
groups who are equipped and capable of conducting
the type of research necessary to solve the many and
varied problems encountered by anyone in aquacul-
ture as a business venture. This includes studies on
economics and law, environmental quality, en-
gineering, and seafood technology as they relate to
aquaculture. Such studies are not described in this
paper even though they may ultimately provide the
solution to the most critical problem faced by one or
more aquaculture ventures.

For the purpose of this paper, the Sea Grant
aquaculture projects will be described by type of
organism being studied, except for a few projects of a
general type.

CRUSTACEANS

Shrimp

The first aquaculture project to be supported by
Sea Grant, the University of Miami program contin-
ues to be one of the most advanced in experimental
shrimp culture. Begun in cooperation with Armour
and Company, the United ( Fruit) Brands Company,
and Florida Power and Light Company, the main
objectives have been 1) to rear large numbers of
shrimp from eggs to postlarvae (about 1 cm long) and
2) to grow these postlarvae to marketable size
quickly and at low cost. Since the first objective has
been achieved for the most part, emphasis is now
given to the problems associated with the second.
Specifically, the work is now devoted to the further
development of satisfactory foods and feeding
methods which w ill provide rapid growth, high sur-

41

vival and yields in ponds, tanks, and cages, and to
further develop techniques for pond management,
including procedures for assuring adequate oxygen
supply and optimization of other pond conditions
such as bottom material, depth of water, and fer-
tilizer regimen. Other efforts are underway on rapid
and efficient harvesting techniques, cage culture,
and testing of the important variables in the culture
system such as food types, stocking density, and
feeding methods.

A new rotatable cage for high density culture has
been designed. It is intended to solve the problem of
fouling of the mesh. Every portion of the cage is out
of the water for about half the time where it is ex-
posed to sunlight and drying and can be easily
cleaned. It is not necessary to handle the animals in
order to clean the cage. Harvesting w ill also be great-
ly simplified by this design.

In a related project at Miami, attempts are being
made to induce maturation of ovaries and oocytes m
pink shrimp. Penaeus duororuin . This is a necessary
step in the control of the life cycle of the animals in
captivity w hich will relieve the commercial culturist
from his dependency on wild populations for gravid
females as the source of fertilized eggs. The research
to date has included efforts to develop various mea-
sures of maturation and investigation of factors (light,
temperature, salinity, and hormones) which enhance
maturation by inhibiting molting.

Another project at Miami, aimed at the general
objective of life cycle control of shrimp, involves the
development of techniques to attain in vitro fertiliza-
tion of ova and sperm removed from ripe animals.
Included in this investigation are in vitro studies of
maturation of oocytes and ovaries, effects of hor-
mones and ovarian extracts on maturation of ovarian
cells, and development of cryogenic techniques to
preserve viabilit\ of ova and sperm, fertilized eggs,
and cultured ovarian colls. Biochemical studies of
gonad maturation are underway using electrophore-
tic profiles to assess maturity.

Aquacultural research at Texas A&M University
is aimed at shrimp farming as a commerically feasi-
ble operation. Twenty '/2-acre ponds (0.2 hectares)
are used for study of artificial feeds, shrimp stocking
rates, mortality, and growth rates. Some ponds are
stocked with hatchery-reared postlarval brown
shrimp. P. (iztcciis. supplied by the Dou Chemical
Company. Yields from 1970 harvests averaged 2.'>0
pounds of shrimp per acre (2S0 kg/ha), with some
ponds exceeding 450 pounds per acre (.'^04 kg/ha).
The wholesale market price of the shrimp at harvest

ranged from SO. 65 to 50.85 per pound, heads on
(465-608 yen/kg). In cooperation with Ralston
Purina, new feed rations have been developed. Har-
vesting of the 1971 crop, now in progress, should
also reveal effects of pond fertilization on growth
rates and survival.

Other shrimp research at Texas A&M includes
studies on temperature and salinity etTects on post-
larvae and feeding behavior, and diet preference of
postlarvae. To date one phase of this research has
provided information regarding upper incipient
lethal temperature, acclimation rate to temperature
change, and the influence of environmental salinity
on heat tolerance of postlarval brown shrimp. Pres-
ent work will extend results to include white shrimp
P. setifents. postlarvae. Differences have been
demonstrated between the responses to diets of
postlarval brown and white shrimp. It was shown
that shrimp responses to foods, including initial diet
preference, survival, growth, and resistance to
high temperature may vary independently.

The 4.700 square miles (12. 17.^ km-) of brackish to
marine marshlands and 1.600 square miles (4.144
km-) of bays, estuaries, bayous, and canals in south-
ern Louisiana are potential sites for impoundments
for mass culture of brown and white shrimp without
supplemental feeding. A research program being
conducted by biologists from Francis T. Nicholls
State University has been attempting to solve the
many problems involved in demonstrating that such
a system is feasible. Two shallow. 10-20 acre (4-8 ha)
impoundments containing water and Spartina
patens marsh are being used to determine the basic
productivity (shrimp production) and for measure-
ments of the effect of fish and crab predator control
on shrimp production. Natural stocking of ingress-
ing postlarval shrimp occurs on nighttime flood
tides across weirs in the impoundments. Large
shrimp and predators are prevented from entering by
hardware cloth screening.

Predator control is exercised in the larger, test
impoundment by rotenone application for fish and
baited wire traps for blue crabs. Efficient harvesting
of the ponds consists of draining surface water at
night across the weir into a net. Shrimp of commer-
cial size rise to the surface and migrate out o^ the
cstuarine areas and into the Gulf at night during ebb
tides. With predator control the brown shrimp grew
to .^4 count (heads on) in 75 days and to 12 count in
200 days; the white shrimp grew to .^4 count in 60
days. The total harvest of both species for one sea-
son was 125 pounds (57 kg) of .''4 count shrimp per

42

acre. In the pond with no predator control, the total
harvest was 44 pounds (20 kg) of 70 count shrimp per
acre, which is probably about the natural productiv-
ity of unmanaged marshes.

In a study of the penaeid shrimp, Pemieiis
ifiaifiinatus, aimed at developing techniques for in-
tensive cultivation under manipulated environmen-
tal conditions, investigators at the University of
Hawaii have successfully spawned females and
reared the larvae through all stages. A new,
intensive-culture enclosure is being built that will
boost production by vertically arranging the shrimp
in small cages on frames, so as to allow the use of the
entire water column. Also, a shrimp nutrition study
is underway. This project is to provide the technical
information needed for a commercial-scale opera-
tion to be established and operated by a community
group in Hawaii.

Biologists and food scientists at Louisiana State
University are developing new rations (foods) for
crustaceans in culture. Emphasis has been on the
utilization of products such as crustacean meals,
single-cell protein (torula yeast), food processing
"waste" fiber and cellulosic products, and other
products of the fishery processing industries. Spe-
cial attention is being given to the evaluation of
the nutritional value of sun-dried shrimp meal and
other shrimp meal prepared by various processing
procedures. These rations will be tested for feeding
efficiency rates, durability and acceptability, and the
effect of various attractants to stimulate shrimp feed-
ing will be identified. A suitable ration which uses
alginates as a pellet binder has been developed and is
being evaluated under a range of environmental con-
ditions. Other hydrocolloids and modified starches
are also being evaluated as pellet binders. Experi-
mental samples are being made available to inves-
tigators for testing on a range of economically valu-
able crustacean species, i.e., penaeid shrimp,
freshwater shrimp, and crawfish.

A part of this project includes work to prepare the

feeds developed as microcapsules in varying sizes
and densities according to the stage of development
of the animal. Forexample. the feed forthe nauplius,
zoea, mysis, and early postlarval stages will be small
and have near-neutral buoyancy, whereas that for
the late postlarval and juvenile stages would be
larger, would sink, and exhibit good water stability.
Although the microcapsules are expensive initially.
they should result in healthier animals and greater
survival through provision of all nutritional require-
ments and controlled amounts of expensive sophis-

ticated chemicals (hormones, antibiotics, stimu-
lants, etc.). Use of the microcapsules will also re-
lieve the culturist from the tedious and expensive
algal cultural systems now employed in most aqua-
culture operations.

Another study into the environmental and nutri-
tional requirements of shrimp in culture is being
carried out at the Skidaway Institute of Oceanog-
raphy in Georgia. Following a series of experiments
which established a suitable water flow rate, type of
substrate, oxygen level, stocking density, and light
intensity, preliminary nutritional studies using
purified pelleted diets were conducted. Eighteen dif-
ferent diets which varied in level and quality of pro-
tein, carbohydrate, lipid, vitamins, and minerals
were evaluated by growth rate and percent survival.
Rates of ingestion under given environmental condi-
tions, rates of assimilation of specific biochemical
entities and calorie-protein relationships are now
being investigated. To date, a semipurified diet, con-
taining about 70% shrimp meal and 8% anchovy
meal, fed at a rate of 15% of the total biomass daily
has produced the best results (164% increase in
weight with 95-100% survival during a 3-mo period).

Crabs

Mass culture techniques to produce large numbers
of larval stone crabs, Meiiippe mercenaria. and blue
crabs, Calliiiectes sapiclus, have been achieved in a
project at the University of Miami. However, tech-
niques must be improved to reduce and control the
problem of cannibalism among larval stone crabs.
The stone crab matures, copulates, and spawns via-
ble eggs under conditions of captivity. P., offspring
of blue crabs have also been attained in captivity.
Investigations are now underway to improve techni-
ques of larval culture and to test feasibility of rearing
crabs to marketable size in cages placed in natural
waters.

A Samoan or mangrove crab, Syclla seirata. has
been studied at the Hawaii Institute of Marine Biol-
ogy. The Samoan crab has been maintained in cages
suspended from rafts and its growth rate measured.
This study indicated this crab could attain market-
able size of 1 - 1 '/2 pounds (0.5 - 0.7 kg) in about 1 Vi
yr at ambient temperatures (24°C). Tests at higher
temperatures (27°C) indicated that the time to reach
market size could be reduced to 1 yr. Also, a diet of
artificial food resulted in faster growth than natural
foods.

In another crab culture project, efforts are under-
way at Humboldt State College in northern Califor-

43

nia to develop methods of growing the Dungeness
crab. Cancer nuii^ister, using locally produced fish
wastes as food. The studies are being conducted in
two different environments in Humboldt Bay, in
pens — one using heated effluents from an electric
power plant and the other in bay ponds at ambient
temperatures. The diet preference, condition, and
growth are determined and evaluated. This project
could provide a cheap source of food for an aqua-
culture operation as well as make use of what is
now a waste disposal problem. Early results indicate
that a food mixture of rockfish, sablefish, Dover
sole, and shrimp offal produced the best results.

Research is underway at Hast Carolina University
on the reproductive cycles and fungal parasites of the
blue crab and will begin shortly on the American
lobster, Honuinis cuncikaniis. Studies to date on
the crab have included observations of the condition
of the ovary as seen through the carapace, condition
of eggs of ovigers, and occasion of spawning by
certain individuals. The crabs which ovulated were
successfully induced to attach their egg mass, some-
thing not previously reported for the blue crab. At-
tempts to date to isolate La^enidiiim callinectes or
other fungal parasites of crab eggs have
been unsuccessful.

In laboratory studies at Texas A&M University
with young blue crabs (5-40 mm), a sand plus oyster
shell substrate supported significantly better survi-
val than did either sand alone or bare glass. The
suitability of various temperatures and salinity levels
were also evaluated.

Lobster

One of the most highly prized seafood organisms
in the world, the American lobster, Homcinis
anii'iicuniis, is being studied by geneticists at the
University of California at Davis. The intent is to
develop the technology necessary to grow large
numbers of edible quality lobsters, to marketable
si/.e, in a short period of time, at less cost than the
market value. The project is being conducted in
cooperation with the State of Massachusetts Lob-
ster Hatchery on Martha's Vineyard Island. The
work includes the improvement of culture facilities;
development of an economically feasible form of
tood; studies of the effect of selected environmental
parameters on growth; application of genetics tech-
niques for the selection of fast growing lobsters:
cvakialion of biochemical methods for controlling
cannibalism, mating, molting, and disease ; and phys-
ical methods to control cannibalism. Research, al-

ready completed has shown that it is possible to
produce a 1 pound (0.45 kg) lobster in 2 yr time
instead of the 7-8 yr it takes in the sea, by growing
them at 20°C and feeding them daily.

Work on the American lobster at the University of
Rhode Island is also directed toward reducing the
time required to grow the animal to market size.
Here the effort has resulted in the development of
methods for accelerating the hatching of eggs and the
mass culture of larvae to juveniles under controlled
conditions. Work is now in progress for maximizing
the growth rate of juveniles to market size under
optimum conditions.

Several parts of a multifaceted program of re-
search at San Diego State College on spiny lobster,
Pdniiliriis iiuerniptiis, and American lobster involve
aquacultural work. Juveniles of spiny lobster have
been studied with respect to the effects of elevated
temperatures (20°. 22°, 26°, and 28°C) on growth and
metabolic energy budget. Studies of American lob-
ster in progress are providing a comprehensive evalu-
ation of the biological and economic feasibility as
well as the potential benefits and dangers of estab-
lishing this species as a fishery resource in California
waters. Part of this work is concerned with develop-
ing and evaluating lobster culturing techniques, with
the primary aim of producing large numbers of young
suitable for stocking.

Crayfish

In a project to develop crayfish culture in the
Pacific Northwest, biologists at Oregon State Uni-
versity are developing husbandry methods in con-
trolling environments. A system for holding and
breeding adult crayfish in captivity has been de-
veloped.

Juveniles are raised singly in small cells to avoid
cannibalism of soft-shelled animals. Several natural
and artificial diets have been tested and research on
nutrition is now centered around a simulated natural
diet versus a high protein vegetable pellet diet. The
role of temperature and salinity on growth and sur-
vival is also under study.

MOLLUSCS

Oysters

In a large multidisciplinary effort, scientists at the
L'niversity of Delaware are working to improve our
techniques in shellfish culture. .\ variety of prob-
lems are being attacked in both open and closed
'ulture systems. Over 500 million oyster larvae were

44

reared at least to the straight hinge stage in 51 sepa-
rate cultures during the past year. These larvae, the
results of 40 spawning attempts, were used in a vari-
ety of rearing and setting experiments. The algal
culture facilities can now provide food on a year-
round basis and are capable of producing 150 liters of
dense algal culture every 24 hr. Research on the
feeding of adult oysters in being conducted to show
how the oyster utilizes available food energy. Pre-
liminary experiements have determined the caloric
content of cultured algae and have shown that an
oyster can assimilate at least 859f of the energy con-
tent in the food that it consumes. Research is also
being conducted on the bacteria associated with
supplemental feeding of oysters in closed systems.
and efforts to produce viable offspring from hybridi-
zation of the Eastern (or American) oyster,
Crassostrea virginica. and the Pacific oyster, C.
gigas. are continuing.

A pilot-scale oyster hatchery at Newport, Oreg. , is
producing seed from Pacific and Kumamoto {C.
gigas). Olympid (Ostrea lurichi). and European fO.
edulis) oysters on a routine basis. Peak production in
the pilot hatchery approaches 1 million juveniles per
month. The seed is being raised by growers in
Oregon and Alaska, and is being used in a variety of
studies by Oregon State University researchers.

Heritability studies have been completed on the
Pacific oyster, and parentage is controlled to selec-
tively breed for rapid growth, high meat production,
and low mortality. The growth of hatchery seed oys-
ters in warmed ocean water from power plant ef-
fluents is under evaluation. Successful cryogenic
preservation of oyster sperm at -196°C has allowed
self-fertilization of the Pacific oyster after natural
sex reversal for genetic studies. Improved larval
feeding schedules and diets have increased the suc-
cess of setting in the hatchery.

In their program to advance the state-of-the-art in
oyster culture, biologists at the Virginia Institute of
Marine Sciences have developed two new methods
for obtaining free oyster spat (cultchless), one for
relatively clear estuarine areas and one for areas
which ha\e heavy siltation problems. In the first
method, the spat must be removed from the sub-
strate before sufficient new shell for permanent at-
tachment has been produced. The set takes place in
fiber glass salmon-egg hatching trays in complete
darkness, using filtered river water. The spat are
removed from the tray bottom, to which they have
temporarily attached, by a strong stream of river
water, yielding cultch-free spat.

The second method delays the removal of the
newly set spat from the substrate for 18-21 days.
Setting is induced on Frosted Mylar- or Herculene.
A new setting tray was designed to hold the mylar
upright. The spat set on the upright mylar sheets,
thus avoiding most of the siltation and organic de-
tritus. The spat is removed from the mylar sheet by
simply shaking it over a container of river water. It is
then dipped up and down in the container, washing
the loose spat off.

A team of researchers at the Darling Center. Uni-
versity of Maine, is investigating the feasibility of
culturing several species of marine organisms in the
colder waters of that region. Although research is
being conducted on the deep sea scallop and blue
mussel, most of the experiments to date in this new
program have been with cultchless European and
American oysters. Trays of the cultchless oysters
have been placed at many different locations in the
Damariscotta estuary (24 km long) and at 14 sites
along the coastline. These were selected to provide
as good a geographic and ecological spread as possi-
ble and are being monitored for growth, survival,
and presence of fouling organisms. In the first year,
growth response of European oysters was excellent
(to 10 cm) in even the most exposed coastal
locations. The data will be utilized to develop a
predictive model allowing assessment of the poten-
tial of the Maine coast for economically competitive
oyster culture. A cooperative pilot hatchery is being
started at Newcastle which may result in the estab-
lishment of a commercial operation.

The Departments of Agricultural and Mechan-
ical Engineering of the University of Maine are
working on oyster rafting systems which will be
adaptable to this environment and compatible with
multiple use concepts. A pilot model of a submers-
ible raft has been constructed and will be field test-
ed in 1972.

Several problems inherent in the culture of oysters
and clams are being investigated at the University of
Washington. The optimal horizontal spacing of oys-
ter cultches suspended from rafts in relation to
growth, mortality, and condition is being determined
and the local variation in the degree and type of
fouling organisms evaluated. The investigators are
also attempting to determine if bacteria are responsi-
ble for some of the summer oyster mortalities. They
are particularly interested in Vibrio and other types

-' Reference to irade names does not imply endorsement by the
National Marine Fisheries Service. NO.AA.

45

of pathogenic bacteria which may be associated with
these mortalities. In related work, the gonadal de-
velopment of the Manila clam, Venerupis japonica,
is being studied. Also, seed of this clam species is
being planted in commercial growing areas to deter-
mine the best annual planting density and minimum
length of time seed must be held in the hatchery to
give optimum yields to the clam grower.

In a companion program, a prototype continuous
phytoplankton culture unit is being developed at the
University of Washington to provide nutritious, effi-
ciently grown feeds for the clam and oyster farm.
The prototype can produce at least 14 liters per day
of Mo HOC hr}' sis liitheri with a total yield of 2 x 10"
cells, consisting of 6. 8 gash-free dry weight, which is
22% protein.

Clams

A new hard clam culture method has been de-
veloped at the Virginia Institute of Marine Sciences.
The new method involves spreading shell, gravel, or
other material (aggregates) over the sand or mud
bottoms before planting the seed. This type of bot-
tom protects the young clams from their chief pre-
dator, the blue crab, and other predators, such as
other crabs, boring snails, bottom-dwelling fish, and
waterfowl. Other methods of protection tried in the
past included planting the young clams in screened
trays or boxes, within fenced enclosures, under
sheets of netting or hardware cloth, in saltwater
tanks, and intertidally. These techniques were unre-
liable and expensive, caused silting and slow growth,
and thus are unsuitable for commercial use.

Other work on molluscs at the University of
Hawaii has included efforts to develop pond culture
of the Japanese littleneck clam which was intro-
duced to Hawaii, but whose natural populations are
declining. Research to date has identified proper
substrate as a key parameter with sand substratum
yielding normal growth. Spawning was achieved
through temperature elevation (30°-3I°C) and addi-
tion of sperm.

Scallops

The hatchery technicjues of conditioning, spawn-
ing, and rearing the bay scMop. Acqiiipcclen irrci-
(lidiis. have been developed at the Virginia Institute
of Marine Sciences. The scallop has been raised to
market size (5-6.5 cm) with the final growth phase
taking place in wooden, rectangular floats (2.1 m x
0.6 m X 15 cm) whose tops and bottoms are covered

with fiber glass window screen or plastic netting. In
one experiment, the scallops were grovs n from 1.3 to
5.7 cm in a net enclosure directly on a relatively hard
mud-sand bottom. The total growth time from egg to
market size was 6-7 mo. Work is continuing to de-
termine optimum stocking densities and optimum
depth for holding the scallop floats and to develop
other methods for holding scallops from about 2.2
cm to market size.

.\balone

The culture of four commercially important
species of abalone is under study at the Scripps
Institution of Oceanography. University of Califor-
nia. Studies of spawning phenomena, early de-
velopment, settlement, growth of settled juveniles,
and hybridization are being conducted. Approxi-
mately 200, ()()() young red abalone, Haliot'ts nijes-
cens. were reared by the chief investigator in a com-
mercial venture. This resulted in the identification of
the problems being attacked in this research pro-
gram. Primary attention is being given to the influ-
ence of temperature on larval development and
juvenile growth, and to the behavioral problem of
substrate selection by settling larvae. Other efforts
are being devoted to determine the causes of larval
mortalities and to identify micropredators of newly
settle juveniles.

Octopus and Limpets

Two rather unusual species of molluscs are being
studied by University of Hawaii scientists. Work on
large limpets, which are in great demand for
Hawaiian luaus and which sell for as much as $70 per
gallon (6.000 yenVliter). is concentrating on the de-
velopment of an acceptable food source. Eggs have
been obtained from females and artificially fertilized
successfully with the females producing several
thousand eggs each. However, further ecological
work is necessary to ascertain conditions under
which the early larvae can be reared to acceptable
size.

Research on the Day Octopus, another
specialized food that is highly prized in Hawaii, has
indicated a rapid growth rate with the animal reach-
ing the marketable size of 1 pound (0.45 kg) in about 3
mo and growing to 3-4 pounds (1.36-1.8 kg) in only
4-5 mo. Current efforts are directed toward the de-
velopment of an artificial food. Mating occurs read-
ily in captivity with the females producing an aver-
age of 500,000 eggs. Difficulty has been experienced

4(i

in the rearing of larvae since, while they are active
and feed, they do not grow.

FINFISH
Salmonids

One of the oldest research efforts in the United
States directed toward developing improved strains
of seafood organisms is that at the University of
Washington under Lauren R. Donaldson. Over a
period of 40 yr. through a selective breeding pro-
gram, several species of salmon and hybrids of trout
have been developed, and eggs from this program
have been provided to organizations all over the
world. Currently Donaldson and his co-workers are
working with rainbow trout, rainbow-steelhead hy-
brids, and Chinook and coho salmon. Oncorliynchus
tsfunvyscha andO. kisiitch. Millions of eggs are pro-
duced each year, some being used in the breeding
program, some irradiated for studies of the effects of
radiation exposure, and others used or provided to
other organizations for other types of research or for
aquaculture.

In an associated program, other University of
Washington fisheries biologists are attempting to
demonstrate the practicality of rearing salmonids in
floating pens, in brackish water ponds, and in saltwa-
ter estuaries. In this work, which is being conducted
cooperatively with private industry, the salmon are
being reared for two uses: 1 ) direct marketing and 2)
release at an advanced stage for support of sport and
commercial fisheries. This same project also in-
cludes studies of the effects of environmental
parameters on the success of rearing salmonids in
seawater, the training of salmon to come to an
underwater sound source for effective feeding and
harvesting, and feasibility studies on enhancing pro-
duction of 20 species of flatfishes indigenous to
Puget Sound by improved cultural techniques.

A team of researchers at Oregon State University
is investigating several problems associated with
salmon culture. New hatchery methods which simu-
late natural spawning beds are being developed. The
system involves raising salmon alevins (larvae) in
darkness on a gravel substrate instead of on screened
trays or smooth tank bottoms. Water velocity is
similar to that in good quality natural spawning beds.
Several hundred thousand chum salmon. O. keta,
are being produced annually by this method at an
e.xperimental hatchery located at Netarts Bay. The
fry from the gra\el incubator are considerabh larger
than frv from standard hatcherv incubators and do

not exhibit malformed yolks which are common in
hatchery chum salmon alevins. In the laboratory at
Port Oiford, Chinook salmon are being exposed in
rearing tanks to increasing salinities to determine the
feasibility of releasing juveniles directly to seawater
after only a brief period of adaptation. If successful
this could significantly reduce the mortalities which
now occur in freshwater areas.

Other work at Oregon State University on salmon
includes attempts to: improve certain strains
through hybridization and selective breeding; de-
velop methods for rearing in power plant effluents;
determine the effects of infection by the trematode,
Nanophyetus scilmincoUi; and develop techniques
for cryopreservation of gametes. Sperm frozen for 7
days at -I96°C were thawed and used to fertilize
80% or more of fresh eggs from coho salmon and
steelhead trout, Salnio gtiirdnen.

Seafood scientists at Oregon State University are
working with several salmon diet formulations in
order to develop new rations, as well as to learn more
about the nutritional requirements of the salmon.
Experiments now completed indicate that a pelleted
fish food utilizing 40% dewatered and comminuted
shrimp wastes provide results as good as those ob-
tained with the commonly used Oregon moist pellet.
Thus, a use for large quantities of raw shrimp wastes
has been identified.

Coho and chinook salmon are being reared in net
enclosures in the open waters of Puget Sound in a
project being conducted by a private firm. Ocean
Systems, Inc. This project is an outgrowth of work
by the National Marine Fisheries Service whose
scientists continue working on associated problems.
Assistance has also been received from the
Washington State Department of Fisheries and the
University of Washington. The eggs were hatched
and the fingerlings placed in a freshwater pond.
When they reached the desired size, the fish were
transferred by truck to small net enclosures (7.5 x
7.5 X 4.5 m) in the Sound and later transferred to four
larger (15 x 15 x 7.5 m) growing pens which are
attached to an anchored raft. The enclosures are
covered by a net to protect the fish from bird pred-
ators and surrounded on four sides and the bottom
by a 6.4-cm stretch mesh gill net to protect the fish
from dogfish and other predators.

At the present time, approximately 230.000 coho
and 270,000 chinook salmon are growing in the pens.
They are fed a dry salmon pellet ration which is
hand-cast over the enclosure. .Although some of the
salmon have reached potential market size in 8 mo.

47

the average weight was 0.06 kg. The com-
pany, working with the National Marine Fisheries
Service, will begin test marketing the 0.2-0.34 kg fish
shortly after the beginning of the year. Current ef-
forts also include an evaluation of the potential en-
vironmental effects of a large-scale operation of this
type.

In northern California, at Humboldt State College,
fisheries biologists are in the early stages of testing
the efficacy of enriching brackish water and saltwa-
ter rearing ponds with sewage etTluents for the rear-
ing of salmon and trout. The fish are released as fry
and fingerlings into two ponds, one a control sea-
water pond and the other contains a seawater and
sewage effluent mixture. The scientists hope to deter-
mine if it is possible to rear fish to migrant size more
cheaply by this method than with standard fish cul-
ture techniques. Harvest for human use would occur
after the fish had been released and continued their
growth in the natural environment.

At the present time there are 40,000 coho salmon
(10,000 of them marked) and 2,500 steelhead trout
divided between the two ponds. Growth and mortal-
ity studies are being conducted to evaluate the suc-
cess of this technique.

Scientists at the University of Rhode Island are
attempting to develop a new form of aquaculture,
based on a closed cycle, controlled environment
system, which will have almost no environmental
impact and be compatible with other demands on
coastal resources. Salmonids; Atlantic salmon,
Salmo scihir: pink salmon, Uncorhynclus goibiischa;
rainbow trout, bluefish, Pomatomus saltatrix; and
striped bass, Moronc suxcililis. are being grown in
the project. The work is intended to provide infor-
mation which will increase the operating efficiency
and capacity of present day salmon hatchery and
smolt production facilities as well as improve diets
for fish in culture. Nutritional and physiological
studies are underway, with one study the effect of the
level of dietary protein and different lipids on the
nutrition of rainbow trout adapted to an intermediary
salinity (16"/(mi) just completed.

Studies are being conducted to determine the re-
quirements for rapid activation of biological filters in
both marine and freshwater systems. Also, alterna-
tives to biological filters for water purification in the
closed circuit system are being evaluated.

One key part of this work is aimed at solving the
problems resulting from the accumulation of ni-
trogen waste products in the closed system. Another
part of this program is an analysis of the economic

feasibility of commercial salmonid culture for food
fish markets. A projection of production costs for a
model salmonid aquaculture facility has Just been
completed.

Striped Mullet

In an effort to develop a controlled culture system
for striped mullet, Miigil cephaliis. scientists at the
Oceanic Institute in Hawaii have devoted consider-
able effort, with success, to the induction of spawn-
ing. Successful breeding of wild, adult fish has been
accomplished with injections of salmon pituitary in
conjuction with Synahorin. or with low doses of a
partially purified Pacific salmon gonadotrophin.
Spawning was also induced in captive animals using
a controlled photoperiod regime followed by injec-
tions. Larval rearing studies are also underway using
copepod adults and nauplii and gastropod veliger
larvae as food. The veliger larvae appear to be pre-
ferred by the striped mullet larvae and are produced
in the laboratory.

In a companion project, the problems associated
with rearing the striped mullet in coastal ponds are
being studied. Artificial seaweeds ("X" sheets of
plastic) are anchored in the ponds. Algae grow on
this plastic "grass" and are eaten by the fish, thus
providing a cheap source of food for the fish in cul-
ture.

Young striped mullet have been studied at Texas
A&M University to determine high temperature re-
sistance and acclimation rates in laboratory tests.
Salinities of 1 and lO'Von were more suitable than 20
and 30"/oo for temperature acclimation and heat resis-
tance of young mullet. These findings may be useful
in the development of pond stocking guidelines. A
two-factor laboratory study on the effects of salinity
and temperature on survival and growth of striped
mullet has recently been completed. Statistical
analysis of the results has not been completed, but
the data suggest that striped mullet are tolerant to
broad ranges of both factors.

Dolphin

Work is underway by North Carolina State Uni-
versity biologists to determine the feasibility of
commercial propagation of the do\ph\n. C orypluicna
hippiinis. Successful efforts, being conducted at
Hatteras. N.C., and Bimini, Bahamas, have been
directed toward developing artificial spaw ning tech-
niques by use of sex hormones. Capturing and trans-
porting techniques have been developed, and growth

48

studies have yielded an average weight increase of I
pound (0.5 kg) per week with a maximum growth of
7'4 pounds (3.5 kg) in 6 wk. Larval rearing techni-
ques will be developed as dependable spawning is
realized.

valuable bait fish in Texas has been studied at Texas
A&M University to determine the effect of salinity
on high temperature resistance and acclimation rates
in the laboratory. At 10 and 20"/oo these fish fared
better than at 1 or SO^/oo.

Miscellaneous

Several species of finfish (see appendix for names
of species) have been studied at the Hawaii Institute
of Marine Biology on Coconut Island to determine
their potential for aquaculture. They were selected
on the basis of their acceptability as food or bait and
their ability to grow in captivity. Eggs, larvae, juve-
niles, or adults were collected according to their
availability, and attempts were made to ascertain
their environmental requirements in a variety of
situations including small tanks, floating rafts,
ponds, etc. Investigations were made on nutrition,
growth, reproduction, and diseases of the various
species.

Research at Louisiana State University has been
directed toward determining the various parameters
controlling growth of several species of finfish in
culture. The effects of salinity and other water qual-
ity parameters on channel, blue, and white catfish
(htiiliinis piinctatiis, I. furcatiis, and/, cuius) and
on Florida pompano (Trachinolus carolinits) have
been identified. One notable effect of brackish water
on the catfish is that it prevented outbreaks of the
protozoan parasites, Ichtyophthirius multifilis,
which is frequently a serious problem in freshwater
catfish culture. Other studies have examined
growth, development, and survival of the pompano
and the Atlantic croaker, Micropogon undidatus, in
culture.

For the past 6 yr, Louisiana State University
(LSU), in cooperation with the Louisiana Wild Life
and Fisheries Commission, has screened a number
of species for suitability for culture including: three
species of freshwater catfish (blue, channel, and
white), pompano, mullet, croaker, crawfish, and
redfish. These species are also being stocked in vari-
ous combinations, polyculture. In one study, the
mullet-channel catfish combination showed prom-
ise. Total production in ponds was increased. The
mullet, acting as a biological filter, helped to clean up
solid wastes produced by catfish, as well as adding to
total production. LSU has consistently produced
over 1 ton of channel catfish per acre in ponds with
salinities up to lO'Vuo total salinity.

The sheepshead minnow. Cv/«7//<)(/(w; vurici^atiis. a

SEAWEEDS
Red Algae

One of the most advanced programs in seaweed
culture in the United States is being conducted by
phycologists at the University of Hawaii. The pro-
gram consists of the development of techniques for
growing the red alga, Eiicheuma (three species), as a
carrageenan source. Small, pilot-scale farm opera-
tions have been established and successfully demon-
strated in the Philippines, the Trust Territory, and
other Pacific areas. Hopefully, this project will lead
to full-scale commercial operations which will pro-
vide a reliable supply of raw material for the U.S.
carrageenan industry.

Other seaweed projects at the University of
Hawaii are investigating the culturing of other red
and green algae (Gnicilciria, Hypiieu, Cladopliora.
and Ulva) and their potentially useful extracts.

Two projects aimed at expanding the source of
commercially valuable seaweeds in the United
States are underway at the University of South
Florida. One is a field and laboratory study of the
carrageenan source, Eiicheuma isiforme. which in-
volves studies of growth, reproduction, morphol-
ogy, and carrageenan content of tagged plants grow-
ing naturally in the ocean, plants suspended from
lines 2 ft above the bottom, and plants under labora-
tory culture. Results to date suggest that in the ocean,
growth rates are highest in the cooler months,
whereas carrageenan content is highest in the warm-
est months. Morphology does not appear to be
easily influenced by environmental changes, such as
would occur in transplantation, but may be greatly
influenced by nutrient levels. Reproduction appears
to be limited to very brief times and may not even
occur yearly.

The other project consists of experimental cultiva-
tion of about a dozen species of south Florida red
marine algae in various habitats, during different
seasons of the year, using three procedures: 1) veg-
etative growth in net-covered frames or in, or upon,
other forms of substrata: 2) the "seeding"" of
selected substrata with a given species, and obtain-
ing either gametophyte or sporophyte plants as de-
sired: and 3) the placing of solid substrata in areas

49

suitable for algal growth but lacking the necessary
substrata.

The most promising results with a potential for
direct application in the production of quantities of
taw material for industry have come from the first
procedure. Growth of Hypnea musciformis and
GraciUiriafolifera in net-covered cages, floatingjust
15 cm under the surface, during the warmer months
of the year was very rapid, often doubling their
weight in 1 day. These plants, growing in a very
favorable environment and protected from grazers,
increased their weight from lOto lOOgin 10-14days.
The culture of Eialwnma isifonne and E. acantho-
chuliiiu. using some of these techniques, will be
emphasized during the next year.

Methods to culture both benthic and planktonic
marine algae are being developed at the University
of Washington. The phycologists have demon-
strated that Iridaea cordalct, Gigartino exasperata.
dndAi^'dnlliii'lla teiu'ia vav. pacijka can be success-
fully transplanted to habitats in which they have not
previously grown, and have grown these three
species, plus Sarcodiotheca fitnaici, in laboratory
cultures. In a related effort, the investigators have
completed a study on extracellular, water-soluble
polysaccharides produced by various marine
diatoms and isolated in axenic culture the unicellular
red alga, Rhodosonis nuiriniis for subsequent
growth experiments.

A multidisciplinary team at the University of
California at Santa Barbara is studying some of the
varied problems encountered by the seaweed indus-
try in the United States. Biologists and engineers are
studying the settlement and growth of spores, includ-
ing the effects of water motion on spore settlement
and on reproductive stages. Transplants of
Gelidiiim. Gnicilaria, and Maciocysiis are being
made for studies of growth and colloid production.

As part of this program, economists are surveying
the present and future status of the U.S. seaweed
industry. An economic model is being developed for
the agar weed Gelidiiim. which considers growth,
loss, and reproduction rates; production problems:
and agar content.

Future work will include an evaluation of harvest-
ing methods and packaging operations and the de-
\elopment of a '"breeding stock"" of rapidly growing
forms.

Brown Algae

One of the oldest programs in the United States in
seaweed management is the kelp research now being

conducted at the Marine Laboratory of the Califor-
nia Institute of Technology. During their early at-
tempts of restoring the kelp beds off southern
California, the researchers simply transplanted adult
plants from an existing bed to an area where a new
bed was to be established or a disappearing bed
strengthened. The adult plant then released spores
\\ hich produced new plants. At the same time quick-
lime was spread over the bottom to kill the heavy
grazing sea urchins. Attempts were also made to
protect the young plants from grazing fish with net
covers.

Recent work has been devoted to the development
of techniques for raising Macrocystis plants in mass
culture from liberated zoospores, through the
gametophyte to the embryonic sporophyte. The em-
bryonic sporophytes which develop on an artificial
substrate are scraped free and dispersed close to the
bottom in areas suitable for kelp growth. Preliminary
estimates indicate that about lO'* embryos must be
dispersed to yield one attached Macrocystis ']U\Qm\t
about 15 cm tall.

The culture system now in use can produce 10^ to
10" embryos per cm- of culture substrate. Thus, the
low survival rates following dispersal do not prohibit
the use of this system for developing new kelp
stands. Out of five areas in which this technique
was attempted, youngM curacy stis developed in
three of them with hundreds to thousands of plants
resulting in two of the areas.

MARINE PATHOLOGY

Several institutions have directed research efforts
toward the diseases and parasites of seafood or-
ganisms, usually looking at several different kinds of
animals. Most of the animals examined are being
cultured, at least experimentally, in the United
States. Texas A&M University has established an
Aquatic Animal Medicine laboratory on its campus
and is working with a wide variety of finfish and
shellfish, looking for many types of bacteria, vi-
ruses, and other infectious agents. They have iden-
tified the microbial fiora of Gulf of Mexico and
pond-grown shrimp and developed new techniques
for detecting certain agents and diseases in finfish
and shellfish.

Microbiologists at Georgetown University have
been examining several Chesapeake Bay organisms
for the bacterium, I'ihrio pciraliacituilyticiis.
responsible for many cases of food poisoning in
Japan and some recent cases in the United States.

50

This bacterium has been isolated from dead anu
dying blue crabs from Chesapeake Bay and was
isolated from dead and dying cultured shrimp taken
from Texas A&M University's ponds.

Several other universities, including Oregon
State. Miami. Rhode Island, and Washington, have
programs in marine pathology in which both w ild and
cultured animals are being studied. While it will be
difficult, if not impossible, to solve disease and
parasitic problems in wild populations, this work
could lead to solutions of problems with pathogens
encountered in aquaculture.

NEW AQUACULTURE SITES

Two projects are underway at the University of
California to explore the potential of selected envi-
ronments for aquaculture. The first, at the Santa
Barbara campus, involves the study of a California
coastal lagoon to determine its usefulness as a man-
ageable ecosystem for aquaculture. The inves-
tigators believe that it may be possible to increase
productivity by shortening the normal food chains,
reducing predation and/or artificially fertilizing this
ecosystem. Initial efforts are devoted to a study of
the basic ecology of the lagoon, including
meteorological measurements, physicochemical de-
terminations, and biological sampling.

The second, at the Scripps Institution of
Oceanography, is examining the feasibility of a
large-scale seafood production unit utilizing the nu-
trients contained in deep oceanic waters to enrich a
marine food chain. The pilot study is being carried
out on Eniwetok Atoll in the Marshall Islands,
where the deep water may be brought up by drilling
into the coral reef rather than by using a submerged

pipe. Work is in progress toward establishingecolog-
ical and productivity baselines on the trophic sys-
tems in two nuclear craters that are washed over by
the tides and have become invaded with marine or-
ganisms. In preparation, moreover, are efforts to
assess the water yield capacity of the reef and what
changes the nutrients undergo during the seawater"s
passage through the coral formation.

In a somewhat related program, a team of scien-
tists from the Lamont-Doherty Geological Obser-
vatory of Columbia University is working on St.
Croix in the U.S. Virgin Islands to demonstrate the
feasibility of using deep, cold ocean water for
aquaculture and. later, for other uses. The total sys-
tem could involve multi-usage of the water: sea
thermal power production by the Claude process, air
conditioning, ice-making, cooling of electric power
and desalination plants to avoid thermal and brine
pollution, and condensation of atmospheric mois-
ture for freshwater production. The experimental
work to date, however, has been restricted to the
aquaculture portion of the total system.

A pilot-plant operation was established in which
water was pumped into small ponds from a depth of
830 m through an 1 .800-m long polyethylene pipeline
of 7.5-cm internal diameter. The ponds are used to
grow diatoms (mainly Cyclotella nana ) which are fed
into tanks containing trays of Eastern oysters, Cras-
sostrea virginica, and hard shell clams. Mercenaria
mercenaria. Results to date have shown the system
to produce unusually fast growth rates for both types
of shellfish. However, some oyster mortalities have
been experienced. The culture of other types of sea-
food organisms utilizing this technique will be ex-
amined later and an expanded experimental system
is planned.

51

APPENDIX

National Sea Grant Aquaculture Programs
(B> organization)

California institute of Technology

Pasadena, C A 91109
Project:

Restoration, propagation and management
of marine algae (Macrocystis pyrifera).
Wheeler J. North. Department of Engi-
neering and Applied Science.

University of California at Davis
Davis. CA 95616
Projects:

1 . The culture, selective breeding and gene-
tics of the lobster, hotnanis anierlcti-
nus. Robert Shleser, Department of
Genetics.

2. Habitats for rearing of lobsters (//o/?;«/z/.v
ctnu'ikanus). Robert Shleser, Depart-
ment of Genetics.

University of California at San Diego, and
Institute of Marine Resources
La Jolla, CA 92037

Sea Grant Program Director, Dr. George Shor;

telephone (714) 453-2000, ext. 1094.
Projects:

1. Abalone culture methodology and larval
ecology. (Halioiis nifescens (red). H.
conuiidta (corrugated), H. fiilgens
(green), and H. soiensensi (Sorensen).)
David L. Leighton. National Marine
Fisheries Service Laboratory. La Jolla.

2. Enhancement of natural marine produc-
tivity by artificial upwelling. Walter R.
Schmitt, Scripps Institution of Oceanog-
raphy, l,a Jolla.

University of California at Santa Barbara

Santa Barbara, CA 93106
Project:

1. Continued studies of seaweed resource
management (cultivation). (Gclidiiim.
Grciciliirid. and Miicrocystis.) Michael
Neushul and .Alexander Charters,
Department of Biological Sciences;
and Walter J. Mead. Department of
Economics.

2. Ecosystem studies and mariculture
potentialities of a coastal lagoon.
Robert W. Holmes. Department of
Biological Sciences.

Columbia University

Lamont-Doherty Geological Observatory

I'alisades. NY 10964
Project:

Artificial upwelling. Oswald A. Roels,
Chairman, Biological Oceanography.

University of Delaware

Newark. DE 19711

Sea Grant Program Director. Dr. William
Gaither. Dean. College of Marine Studies: tele-
phone (302) 738-2841.
Projects:

1. System engineering and development of
commerically valuable marine shellfish.
(Crassostrea virginica and C. gigas.)
Donald Maurer, Department of Biologi-
cal Sciences.

2. Closed environmentally controlled sys-
tems for aquacultural production.
Oscar R. Harmon. Department of
Agricultural Engineering.

3. System engineering for shellfish
production. Frederick A. Costello.
Department of Mechanical and Aero-
space Engineering.

4. Investigation of new shellfish species for
closed cycle mariculture. (Mercenaria
mercenaria, Cullincctes spaiJii.s.
etc.) Charles Epifanio, College of
Marine Studies.

East Carolina University

Greenville. NC 27834
Project:

Studies on reproduction and fimgal para-
sites affecting reproduction in the lobster.
Honuinis anwricdniis. and the blue crab.
Callinccles sapidits. in North C arolina
waters. Edward P. Ryan and Charles E.
Bland. Department of Biologv .

Georgetown University

Washington. DC 20007
Project:

Vibrio parahaemolyticus in Chesapeake
Bay - isolation, incidence and pathogenicity.
Rita R. Colwell, Department of Biology.

University of Hawaii

Honolulu. HI 96822. and

Hawaii Institute of Marine Biology

Coconut Island

Sea Grant Program Director, Dr. Jack Davidson,
Director of Sea Grant Program; telephone (808)
944-7331.
Projects:

1 . Production of food colloids from tropical
marine algae. Maxwell S. Doty, De-
partment of Botany. Honolulu.

2. Seaweed agronomy. Ma.xwell S. Doty,
Department of Botany.

3. Algal food for aquatic organisms.
Maxwell S. Doty, Department of
Botany.

4. Tropical animal aquaculture: Finfish -
omaka {Caranx mate), yellow ulua
(Gnathanodon speciosus), moiiPoiydac-
lyliis sexifilis), Japanese yellowtail
(Seriola quinquiradiata), Nehu or Ha-
waiian anchovy (Stalephonis piir-
piireus). iao (Pranesiis insulanim),
freshwater threadfm shad (Dorosoma
pelenense). Molluscs - opihi or limpets
(Cellana exarata and C sandwicensis),
Japanese littleneck clam (Tapes philip-
pinariuin). Day Octopus (Octopus
cyanea). Crustacea - Samoan or man-
grove crab (Scylla serrata). white or
haole crab (Portiimis saiiguinolentus),
opae lolo (Penaeus inarginatiisj.

Humboldt State College
.Areata. CA 95521

Sea Grant Program Director. Richard Riden-
hour. Academic Vice President: telephone (707)
826-3632.
Projects:

I. Sewage fertilization of brackish and
saltwater fish ponds for rearing salmon
and trout. iOncorhyncluis kisHlch and
Salmo gairdneii.} George H. Allen. De-
partment of Natural Resources.

2. The utilization offish wastes for rearing
of crabs in salt and brackish water
(Cancermagister). James P. Welch. De-
partment of Natural Resources.

Louisiana State University

Baton Rouge, LA 70803

Sea Grant Program Director, Jack Van Lopik,
Office of Sea Grant Development; telephone
(504) 388-1558.
Projects:

1 . Culture of fish and crustaceans (Penaeus
sp. and Trachinotus carolinus). James
W. Avault, School of Forestry and Wild-
life Management.

2. Nutritionofpenaeid shrimp. Samuel P.
Meyers, Department of Food Science
and Microbiology.

University of Maine

Orono. ME 04401, and

Ira C. Darling Center

Walpole, ME 04573

Sea Grant Program Director, David Dean; tele-
phone (207)563-3146.
Projects:

1. Laboratory spawning and rearing of deep
sea scallops (Placopecten magellan-
icus). Herbert Hidu, Darling Center,
Walpole.

2. Adaptation of known cultural techniques
for the european oy^iev (Ostiea edulis) to
the Maine environment. Herbert Hidu,
Darling Center, Walpole.

3. Engineering assessment of hatchery
mechanization; design and testing of
submersible rafts for oyster culture.
Richard Rowe. Department of Agricul-
tural Engineering; and Walter Schneider,
Department of Mechanical Engineer-
ing, Orono.

University of Miani
Miami, FL 33124

Sea Grant Program Director, Wendell Mordy,
P.O. Box 9178. Coral Gables. FL 33124: tele-
phone (305) 350-7468.
Projects:

1. Commerical culture of brachyuran crabs
(Menippe inercenuria and Ccdliiwctes
sapidiis). W. T. Yang. School of
Marine and Atmospheric Sciences.

53

2. Cryobiological preservation of shrimp
sperm and ova. (Pciuieiis diiontniin.} J.
L. Runnels, School of Marine and Atmos-
pheric Sciences.

3. Commercial culture of penaeid
shrimp. (Penaeus diionirutn and
others.) Charles W. Caillouet, School of
Marine and Atmospheric Sciences.

4. Induced maturation of ovaries and oo-
cytes in Pcnaciis diioraniiii in
vivo. Charles W. Caillouet, School o\'
Marine and Atmospheric Sciences.

5. Virology and protective factors. M. M.
Siegel. Department of Microbiology.

Francis T. Nicholls State University

Thibodaux, LA 70301
Project:

Effects of water exchange and blue crabs
control on shrimp production on Louisiana
salt-marsh impoundments, (Brown
shrimp, Penaeus uztecus, and white shrimp,
P. setifenis.) Alva H. Harris, Department
of Biological Sciences.

North Carolina State University

Raleigh, NC 27607
Project:

Abundance, exploitation, migration and
propagation of the dolphin, Corypluiena
liippiiici.s. William W, Hasler, Depart-
ment of Zoology.

Oceanic Institute
Waimanalo, H 1 96795
Projects:

!. Food resources studies of mullet (Miii^il
cephaliis). Ziad H. Shehadeh, Food
from the Sea Division.
2. Feasibility pilot project for a method of
open water fish farming. Ziad H.
Shehadeh, Food from the Sea Division.

Ocean Systems, Inc.

Reston, VA 22070
Project:

Pacific salmon aquaculture program.
tOiicoilnnilnis lslitn\\r.\c lui and O. ki-
siiicli.i Jon M. Lindbergh, Route #8, Box
848.V Bainbridge Island, \V.\ 98110: tele-
phone (206) 842-5098.

Oregon State University

Corvallis. OR 97331. and

Marine Sciences Center

Newport. OR 97365

Sea Grant Program Director, Herbert Frolander,
Department of Oceanography: telephone (503)
754-2714.
Projects:

1. Physiology of developmental pro-
cesses. Ronald H. Alvarado, Depart-
ment of Zoology, Corvallis.

2. Culture of Pacific salmon. William J.

McNeil, Department of Fisheries and
Wildlife, Newport.

3. Cultureof bivalve molluscs. Wilbur P.

Breese, Department of Fisheries and
Wildlife. Newport.

4. Culture of crayfish, shrimp, and
prawns. John R. Donaldson, De-
partment of Fisheries and Wildlife.
Corvallis.

5. Control of pests on oyster
grounds. Raymond E. Millemann.
Department of Fisheries and Wildlife,
Newport.

6. Field culture of bivalve molluscs.
Howard F. Horton, Department
of Fisheries and Wildlife, Corvallis.

7. Heritability in oysters. Raymond C.
Simon, Department of Fisheries and
Wildlife, Corvallis.

8. Cryogenic preservation of salmonid and

molluscan gametes. Howard Horton,
Department of Fisheries and Wildlife,
Corvallis.

9. Hybridization of salmon. William J.
McNeil, Department of Wildlife and
Fisheries. Nev\port.

10. Culture of algae for mollusks. Harry
K. Phinney, Department of Botany and
Plant Pathology. Corvallis.
II. Nutrition and waste utilization,
Russell O, Sinnhuber, Department
of Food Science and Technology,
Corvallis.

University of Rhode Island
Kingston. Rl 02881

Sea Grant Program Director, Niels Rorholm;
telephone (401) 792-2550.
Projects:

1 . Nutrition of salmonids and other selected

54

species. (Chinook salmon. Onrorliyn-
cluis tshawyisclui: coho or silver salm-
on, O. kisutcli: striped bass, Morone
sa.xatilis; and American lobster. Honuuiis
iimericiuiiis.) Thomas Meade, Marine
Experiment Station.

2. Commerical aquaculture of American
lobster. Akella Sastry, Graduate
School of Oceanography.

3. Chemistry and microbiology of recir-
culating aquaculture systems. John
Sieburth, Graduate School of Oceanog-
raphy.

4. Marine pathology. (Protozoal infection
of ocean pout, Macrozoarces america-
nus; fin rot in salmonids: epithelio-
cystis disease of striped bass, Morone
sa.xatilis, and white perch, Morone
americana; effects of nitrosamines
on marine fish tissue.) Richard
Wolke, Graduate School of Ocean-
ography and Department of Animal
Pathology.

5. Economic analysis of salmonid aqua-
culture. John M. Gates, Department
of Food and Resource Economics.

San Diego State College

San Diego, CA 92115

Sea Grant Program Director, Glenn A. Flittner,
Bureau of Marine Science: telephone (714)
286-6523.
Projects:

1. Studies of recruitment and growth of
puerulus and juveniles of the California
spiny lobster. (Panulirus interruptus.)
Deborah M. Dexter. Division of Life
Sciences.

2. Investigation and development of an
American \ohsXeT{Homariis americaniis)
fishery in California. Richard F. Ford,
Division of Life Sciences.

Skidaway Institute of Oceanography
Savannah, GA 31406
Projects:

1. A study of the nutritional, environmental
and economical requirements for the in-
tensive aquaculture of penaeid
shrimp. iPcnaeiis setifenis. P. azieciis.
and P. cliiorantni.) James W. Andrews,
Life Sciences Division.

2. Experimental rearing of flounder to mar-
ketable size in tidal flushed
ponds. James W. Andrews, Life Sci-
ences Division.

University of South Florida
Tampa, FL 33620
Projects:

1. Experimental cultivation of red algae of
economic value in Florida marine
waters. (12 species of red algae.)
Harold J. Humm, Director, Marine Sci-
ence Institute, St. Petersburg, FL 33701.

2. Ecological and culture studies on the red
alga, Eiicheitma isiforme. Clinton J.
Dawes, Department of Botany and Bac-
teriology.

Texas A&M University
College Station, Texas 77843

Sea Grant Program Director, John C. Calhoun,
Vice President: telephone (713) 845-3854.
Projects:

1. Mariculture of commerical crustaceans
and fishes on the upper Texas
coast. (Panaeus aztecus, P. setifenis,
Callinectes sapid us. and Miigil
cepluilus.) Kirk Strawn, Department of
Wildlife Science, College Station.

2. Mariculture pond demonstration.
(Panaeus aztecus and P. setifenis.)
John E. Hutchison, Director, Cooper-
ative Extension Service, College Sta-
tion.

3. Shrimp culture research. (Panaeus az-
tecus and P. setiferas.) William F.
Mcllhenny, The Dow Chemical Com-
pany. Freeport, TX 77541.

4. Bacterial and viral diseases and cell cul-
tures of marine fish and shellfish.
George W. Klontz, Department of
Veterinary Medicine, College Station.

Virginia Institute of Marine Sciences
Gloucester Point, VA 23062

Sea Grant Program Director, William J. Hargis,
Jr., Director: telephone (703) 642-2111.
Projects:

1. Develop and demonstrate improved
methods of producing hard clams and
investigate the possibility of reviving
the bay scallop industry, i Mercenaria

mercenaria and Aequipecten irra-
dians.) Michael Castagna, Eastern
Shore Laboratory. Wachapreague: and
William T. Duggan. Gloucester Point.
2. Management of larvae, supply of
food. John L. Dupuy, Gloucester
Point.
University of Washington
Seattle. WA 98105

Sea Grant Program Director. Stanley R. Mur-
phy, Division of Marine Resources: telephone
(206) 543-6600.
Projects:

1. Expanded program in salmonoid
aquaculture. (Oncorhynchus ki.siilch,
etc.) Lauren R. Donaldson. College of
Fisheries.

2. Aquaculture of Puget Sound fishes.
lOiicorhyncliKs iscluiwylsclui . etc.)
Ernest O. Salo, College of Fisheries.

3. Development of a clam and oyster farm at
Big Beef Harbor. (Venerupisjaponica
and Crassostrea f;igas.) Kenneth K.
Chew. College of Fisheries.

4. Algal culture as aquaculture feed.
Frieda B. Taub. College of Fisheries.

5. Aquaculture of marine algae. Ilridaea
cordata, Gigartina exasperata, Agar-
dhiella tenera, and Sarcodiotheca
furcata.) Richard E. Norris. Depart-
ment of Botany.

56

AQUACULTURE OF MOLLUSCS ALONG THE UNITED STATES

ATLANTIC AND GULF COASTS

WILLIAM N. SHAW

INTRODUCTION

Today I would like to take you on a tour of the east
and gulf coasts of the United States to review the
past and present status of molluscan aquaculture.
Robert D. Wildman has already reviewed the cur-
rent molluscan aquaculture projects under the Sea
Grant Programs for this area, so I will cover these
projects only briefly in my presentation. Because of
the limited time. I plan to center my discussion
around the culture of three species of molluscs, the
Eastern oyster, Crassostrea virginica; the hard
clam, Mercenaria mercenaria: and the bay scallop,
Aeqiiipecten irradians. Although there are other im-
portant commercial molluscs found along our east
and gulf coasts, such as the surf clam, SpisuUi
solidissima: ocean quahog, Articci ishindka; sea
scallop, Placopecten magellanicus; sunray venus,
Macrocallista nimhosa: calico sc^Wop. Aeqiiipecten
gibhiis: and the soft-shell clam, Mya urenarici. these
species are being hunted. Little or no attempt is
being made to farm these species at the present time.

I will review the fishery for the oyster, hard clam,
and bay scallop and describe past and present at-
tempts to farm each species.

THE EASTERN OYSTER

The Eastern oyster, Crassostrea virginica, (also
called the American or Virginia oyster) ranges along
the entire east and gulf coasts. Peak of production,
near 170 million pounds, was reached in the I890's.
Since then, landings have been on the decline with an
apparent leveling off in the I960"s — around 50-60
million pounds (Engle, 1966). Unlike Japan, oysters
along the east and gulf coasts are grown almost en-
tirely on the bottom. The national average is re-
ported to be only 0.004 tons per acre per year, while

' Middle .Mlantic Coastal Fisheries Center. National Marine
Fisheries Service. NO.A.A. Oxford. MD 21654.

the best yield on the bottom is 2.0 tons per acre per
year (Ryther and Bardach, 1968). These yields are
extremely low when compared to those of Japan
where 23.3 tons per acre per year are being harvested
using off-bottom methods.

Not only are most of the U.S. methods of growing
oysters extremely primitive, but so are our ways of
harvesting. In Maryland, the state that has the
largest annual production of oysters, oystermen
catch oysters with hand tongs and patent tongs and
in dredges pulled along the bottom by sailboats.
Laws in this state prevent the use of more mechani-
cal means such as the hydraulic dredges, except on
private leases.

Realizing that the production of oysters has been
on the decline, many private companies, state and
federal agencies, and universities have in recent
years initiated programs in an attempt to modernize
the oyster industry. I would like to review some of
these programs at this time.

New Hampshire

Under the U.S. Government's Federal Aid Pro-
gram the State of New Hampshire has for 3 yr
(1966-69) investigated the possibility of producing
seed oysters and growing oysters using off-bottom
techniques (Ayer, Smith, and Acheson. 1970). New
Hampshire is at the northern limit of the oyster's
natural range, and because of the cold waters,
growth is slow. Still in certain areas, like Great Bay,
the water warms sufficiently so that the natural oys-
ter populations can spawn and setting does occur. It
appears from their studies that a limited amount of
seed could be produced annually, but intensity
would vary greatly from year to year.

Massachusetts

Production of oysters in Massachusetts is small
and only 72,100 pounds of meats were harvested in

57

1970. Yet. during the 10-yr period from 1910 to
1919. an annual yield of 1.2 million pounds was
realized. Up to recent times, all oysters were grown
on leased bottoms. Because of the cold waters, it
takes up to 5 yr for oysters to reach market size.
Massachusetts oysters are of excellent quality and
are eaten raw on the half shell. The wholesale price is
as high as S22.00 per bushel (7,920 yen. 250 oysters
to the bushel).

in 1956. the Bureau of Commercial Fisheries (now
the National Marine Fisheries Service) initiated
studies on the off-bottom culture of oysters in Mas-
sachusetts. Because of the oyster's high price, it was
felt that this method of culture may be commercially
feasible.

A log raft was constructed and moored in Oyster
Pond River. Chatham. Mass. Oyster and scallop
shells, containing seed oysters, were strung on #14
galvanized wire, each shell separated by a 3-inch
piece of plastic tubing. The strings were suspended
from the log raft for 1 yr, and then the oysters were
removed and planted on the bottom for an additional
year.

The results of the study showed that oysters grew
almost twice as fast as those on the bottom. Survival
of raft oysters was about 6 times greater than for the
bottom grown oysters. Meat quality was excellent.
Finally, the results indicated that raft culture ap-
peared commercially feasible in Massachusetts
(Shaw. 1962).

Similar raft studies were conducted by Matthies-
sen and Toner (1966) on Martha's Vineyard, Duke's
County, Mass. These results showed that suspen-
sion techniques offered a promising method of oys-
terculture in the county. The authors felt that further
refinement of suspended materials was needed and
that rafts which could be conveniently submerged
below the surface should be developed because
many areas were exposed to storms and moving
ice.

It was not until 1970 that off-bottom culture was
attempted commercially in Massachusetts. Aqua
Dynamics Corporation. Wareham. Mass. has begun
to grow oysters suspended from iron-pipe racks (10
ft X 7'/2 ft X 5 ft) that rest on leased bottom. This
year they plan to have 575 racks. Fach rack contains
154 5-ft strings which will yield approximately 60
bushels of oysters. The corporation hopes to market
their oysters, which will measure from 2 to 2' 2 in-
ches, in I '2 \r. In a cooperative study with the
National Marine Fisheries Service. Division of
Marketing, it was learned that these small oysters

have excellent consumer acceptance on the half
shell.

An 8-ft high tower has been constructed adjacent
to the Wareham River for growing oysters (Zahrad-
nik and Johnson. 1970). A series of 4 ft x 4 ft
tray-pallets containing up to 50 bushels of oysters are
in the tower. Water is supplied to the tray-held oys-
ters through a pipe running up the center of the
tower. It is planned to operate the tower for I yr.
including a winter season.

Rhode Island

In 1910 over 15 million pounds of oyster meats
were harvested from Rhode Island. In 1970 only 146
pounds of meats were landed. Although many fac-
tors have contributed to this decline, pollution of
Narragansett Bay is the probable leading factor.

At present, one company is attempting to grow
oysters suspended from rafts (patent pending) in a
small tidal pond. This is a small operation and only
800 bushels were expected to be harvested annual-
ly-

Connecticut-New York

In the late ISOO's. Connecticut was producing
over 10 million pounds of oyster meats annually. In
1970. only a little over 125,000poundsof meats were
landed. Set failures have contributed greatly to the
drop in production. Loosanoff (1966) reported that
during the years 1925-60, a good commercial set has
occurred only 8 times. In addition, factors such as
slow growth, predators, siltation. pollution, and hur-
ricanes have all contributed to the decline of this
once prosperous industry.

In an attempt to help the oyster industry of this
area, a center for shellfish research was established
by the Bureau of Commercial Fisheries at Milford.
Conn. The Milford laboratory has become world
renown for its work in developing shellfish hatchery
techniques (Loosanoff and Davis. 1963). Shellfish
hatcheries are now located throughout the United
States and in many foreign countries. The use of lime
and Polystream- for predator control was also de-
veloped at the Milford laboratory. Unfortunately,
because of the current feelings about dumping chem-

- .'\ polychlorobenzene product produced by Hooker Chemical
Corp . Niagara Falls. New York. Polystream is a registered
trademark. (Reference to trade names does not imply endorse-
ment b\ the National Marine Fisheries Service. NO.'X.A.)

58

icals in the water, the license for using Polystream
has not been renewed.

In 1968, the American Cyanamid Company of
Stamford, Conn., developed a report entitled,
"New Engineering Approaches for the Production
of Connecticut Oysters." They attempted, through
a search of published literature relating to oysters, to
develop an oyster factory. The general conclusion
was that more research was needed (Calbo et al..
1968).

In New York, over 24 million pounds of oyster
meats were landed in 1911. Since then production
has steadily declined and reached an all-time low in
1967 of only 101,000 pounds. From 1968 to 1970,
production has risen slightly to 534,000 pounds in
1970. New York like Connecticut has faced seed
shortages. Three interesting developments have
taken place in recent years in an attempt to alleviate
this problem. At Fisher's Island, N.Y., seed oysters
are being caught on scallop shells suspended from
rafts in a 23-acre brackish water pond (Matthiessen,
1970a). In 1969, 150 rafts were moored in the pond and
roughly 68.000 strings were suspended. This year
approximately 100,000 strings were used. In 7 yrof
operation, only once was there a set failure. A por-
tion of the shells bearing the oyster spat are stripped
from the strings, loaded upon oyster boats, and
planted upon private grounds in Long Island Sound.
The remainder of the shells are transported to Mas-
sachusetts and suspended from the iron-pipe rack
described earlier in the talk.

Second is the development of commercial shell-
fish hatcheries in the Long Island Sound area. One
of the largest is operated by the Long Island Oyster
Farms, Inc., in cooperation with the Long Island
Lighting Company. The hatchery is utilizing a 4-acre
pond which receives warm-water discharge from a
fossil-fuel power plant. The young trayed oysters are
placed in the pond for various periods of time before
being planted on the bottom in the natural waters of
the Sound. Because of the quicker growth rates in
the heated pond, the oysters reach market size in a
year or so sooner. A marine museum adjacent to the
hatchery has been constructed for the viewing pub-
lic.

Third is the New York State Department of En-
vironmental Conservation project supported by fed-
eral funds (PL 88-309) to produce seed oysters in a
natural pond in East Hampton. Long Island. To
date, little success has been obtained in their at-
tempts to catch seed on shells suspended from rafts
or placed on the bottom.

New Jersey-Delaware

The leading area of oyster production in the New
Jersey-Delaware area is Delaware Bay. The once
productive oyster beds in the Bay have been dev-
astated by increasing pollution, freshwater abate-
ment, increased predation problems, and, most re-
cently, by massive mortalities from the disease,
"MSX" (Miiichinia nelsoni). Landings in 1970 to-
talled only 869,000 pounds. In 1950, the two states
produced over 9 million pounds of oyster meats. The
bay can be divided into two areas — the upper seed
beds and the lower leased growing grounds. Shells
are planted on the seed beds and later transplanted
by the private planters to their leased bottoms. Fol-
lowing the heavy mortalities in 1957 and 1958, New
Jersey initiated a large shell planting program to
rehabilitate the oyster industry. Recently, heavy
oyster sets on these shells suggests that the oyster
industry may recover.

Both Rutgers University and the University of
Delaware have been investigating disease resistance
of oysters to MSX. Also, at the University of Del-
aware, extensive studies on the feasibility of semi-
closed and closed systems for culturing oysters are
now underway. This aspect of research is supported
under the Sea Grant Program described earlier by
Robert D. Wildman.

Maryland- Virginia

Chesapeake Bay is one of the leading oyster pro-
ducing areas of the world. In 1880. nearly 125 million
pounds of meats were harvested from the Bay. In
1970. production was just under 35 million pounds or
about one-half of the total U.S. production for that
year. Yet. methods of oyster culture are extremely
primitive with little or no change in either culturing
or harvesting methods since the turn of the century.

In Maryland, for example, the majority of oysters
harvested come from public bars. The tools used to
harvest these oysters include hand tongs, patent
tongs, and dredges pulled by boats under sail. Man-
agement consists mainly of planting up to 5 million
bushels of shells for catching seed oysters and im-
proving or enlarging public oyster bars. Following
setting, the seed is replanted on public oyster bars
where it remains until harvested by oystermen, 3 or 4
yr later.

There have been several attempts in recent years
to demonstrate new methods of oyster culture that
may be applied in Chesapeake Bay. These include

59

hatchery systems, raft production of seed oysters,
and culture of oysters to market size using off-
bottom techniques. Two commercial shellfish
hatcheries have been built, one at Urbanna, Va.,and
the other on West River in Maryland. Both are pro-
ducing cultchless oysters. Unfortunately these
single oysters are very vulnerable to predators and
the handling of the juveniles is a formidable prob-
lem (Matthiessen, 1970b). The former company is
attempting to grow them to market size while the lat-
ter is selling the small spat to private growers. There
are also two research agencies, Virginia Institute of
Marine Science (Andrews and Mason, 1969) and
the Chesapeake Biological Laboratory (Hidu. 1971:
Hidu cl a!., 1969), working on hatchery techniques.

Two agencies, the Maryland Department of
Natural Resources (Otto, 1969) and the National
Marine Fisheries Service (Shaw, 1970), have been
studying raft production of seed oysters. Shells,
either on strings or in chicken-wire bags, are sus-
pended from rafts. E.xcellent sets are being obtained
using the off-bottom techniques, but to date it has
not been adapted commercially in Chesapeake Bay.

The National Marine Fisheries Service has also
been studying the off-bottom culture of oysters
(Shaw, 1969, 1970, 1971). Methods being tested in-
clude raft, longline, and rigid-structure. Strings of
spat-laden shells are suspended from each floating
device and maintained in suspension until the oys-
ters reach market size — about 2'/i yr from time of
set. It is estimated that 1 1 .9 tons of oyster meats per
acre per year could be produced using off-bottom
techniques.

In Virginia the majority of oysters are grown on
private leases. Power dredging is the common
method used for harvesting although hand tonging is
also practiced. The majority of seed for the private
bed cultivation comes from the James River. Unfor-
tunately, in the late 1950"s and early 1960"s, heavy
mortalities from MSX occurred among the oysters in
the high salinity waters which included the spawning
stocks for James River seed. Since then little or no
setting has occurred in the James River.

The Virginia Institute of Marine Science has been
working on developing disease resistant stocks using
hatchery techniques. In addition, spat collecting
shells are being planted in Great Wicomico, Pian-
katank, and other rivers (Bailey and Biggs, 1968). It
is hoped that through the development of disease re-
sistant stocks and managing around the disease,
the oyster industry of Virginia can come back to pro-
ductive levels.

North Carolina, South Carolina, and Georgia

The total production for the three south Atlantic
states — North Carolina. South Carolina, and
Georgia — was estimated to be 1 .4 million pounds in
1970. Methods of culture in these three states are
primitive, harvesting by hand is not uncommon. Lit-
tle attempt has been made, until recently, to investi-
gate new aquaculture techniques. In North Carolina,
a seed collecting project was undertaken under the
federal aid PL 88-309 program. Several varieties of
cultch were tested. Because of heavy fouling, the
cultch was lifted out of the water periodically. Using
the airing technique, good quantities of seed and
commercial size oysters were produced, but because
of the excessive expense involved in the methods
tested, it did not appear commercially feasible (Mar-
shall, 1969).

The Coastal Zone Resources Corporation is at-
tempting to grow oysters caught on passenger car
tire beads (David Adams, pers. comm.). Eighty tons
of eight bead configurations (about 14,000) have
been planted in an area where oysters have the repu-
tation for high quality and rapid growth. Each con-
figuration is anticipated to yield about one-half
bushel of oysters in 30 mo.

Beginning in 1944, extensive studies were con-
ducted in South Carolina on the cultivation of oys-
ters in ponds. Initially (1944-45), excellent results
were obtained and marketable single oysters were
produced in 2 yr. In 1950, drought conditions de-
veloped and salinities in the ponds rose. A sudden
mass mortality among pond held oysters developed
probably by Dennocystidium. It was concluded that
as long as wild oysters are available to the industry,
it is unlikely that pond culture will be economically
practicable (Lunz, 1956).

In Georgia, two members of the Japanese panel.
Atsushi Furukawa and Hisashi Kan-no, assisted in
an attempt to develop off-bottom oyster culture
techniques. Many problems were encountered in-
cluding fouling, heavy siltation, erosion, and retarda-
tion of growth. It was felt that because of the cur-
rent low price of oysters, off-bottom culture did not
appear commercially feasible in Georgia at the pre-
sent time (Linton. 1968).

Florida

In 1970. Florida produced about 3.8 million
pounds of oyster meats. The majority of oysters
comes from the west coast of Florida. Ovsters are

60

harvested from public reefs either by tongs or picked
by hand, with dredging allowed on leased beds. The
future of the Florida oyster industry lies in the culti-
vation of the private leases (Ingle and Whitfield.
1962).

The Florida Department of Natural Resources
has several research projects related to oyster
aquaculture (Florida Department of Natural Re-
sources, 1970) — one is oyster nutrition and the other
is oyster reef modification. Some success has been
obtained in fattening oysters with finely ground
commeal. These studies are continuing in conjunc-
tion with learning optimal conditions (temperature,
salinity, and other parameters) for fattening oysters.

Florida is presently studying the modification of
natural reefs to improve their oyster production.
Artificial gaps are being cut in the reefs. Oysters
planted in these cut-out areas have shown excellent
growth. Florida, through federal aid PL 88-309, is
also constructing artificial oyster reefs using oyster
shells and limestone slag. Some excellent sets have
been obtained on the planted cultch.

One commercial company at Cedar Key, Fla., is
attempting to grow strings of oysters from rigid
structures (Robinson, 1971). Some problems have
occurred resulting from the oysters falling off the
strings. To solve this problem, portable racks have
been built with bottoms to catch the oysters that fall
off

Similar to studies in North Carolina, attempts are
being made to catch and grow oysters on tire beads at
Cedar Keys. Fla. In this case the tire beads and
configuration have been patented. It is not known if
the operation is successful.

Alabama

The oyster industry of Alabama is based upon
natural repopulations of public reefs which include
about 3.064 acres (May. 1971). In addition, there are
approximately 2,000 acres of private bottoms, but
they yield only 12% of Alabama's total oyster
production (annual average from 1948 to 1968 was
1 .2 million pounds of meats). Lack of seed has kept
private production down. All of the oysters from
public reefs are harvested with hand tongs; however,
harvesting from private beds can be accomplished
with dredges.

Very little attempt has been made to try to moder-
nize the .Alabama oyster industry. May ( 1969) inves-
tigated the feasibility of off-bottom oyster culture.
Both rack and raft methods were tested. .Mthough

excellent growth was obtained, he found the off-
bottom culture was not economically feasible be-
cause of high production costs and low market value.
The Alabama Marine Resources Laboratory at
Dauphin Island constructed a '4-acre tidal pond to
study the commercial rearing of oysters. In 1968,
oysters were placed in the pond and after 12 mo the
oysters had increased in height from 18 mm to 101
mm. Ninety-one percent were legal size after SVd
mo of growth. It is not known if studies were con-
tinued.

Mississippi

The entire Mississippi oyster production comes
from public reefs (about 3,000 acres), there are no
private leases (Maghan, 1967). Annual production
fluctuates considerably because of adverse weather
conditions, leveeing of the Mississippi River, pred-
ators, and disease. As an example of these fluctua-
tions, production in 1968 was 3.8 million pounds of
meats while in 1970 only 547,000 pounds were
landed. Except for extensive plantings of shells and
seed oysters, there has been little attempt to moder-
nize the oyster industry of Mississippi.

Louisiana

In 1970, Louisiana produced 8. 1 million pounds of
oyster meats, second in the nation to Maryland.
Roughly 70-80% of the oysters are canned (Matthies-
sen. 1970b). Louisiana has a well-managed industry
based on privately owned or leased bottoms, approx-
imately 83,000 acres, plus state-owned areas
(450,000 acres) set aside as a source of seed oysters
(St. Amant, 1964). Growers are allowed to gather
wild seed for planting on their leased grounds. All
oysters are grown on the bottom and no attempt has
been made to try off-bottom techniques.

The Louisiana Marine Laboratory on Grand
Terre Island has several projects (federal aid PL
88-309) related to oyster culture. These studies in-
clude the reestablishment of historical seed grounds
and control of the Southern oyster drill, Thais
haemostoina. Both projects are still in progress so
final results are not available.

At Grand Terre Island. 16 '4-acre ponds were
constructed on existing marsh floor. The levees
were enclosed by two asbestos bulkheads that were
supported by creosote posts and tied together by
galvanized steel rods. Besides oysters, brown and
white shrimp plus selected fishes are being cultured

61

in these ponds. Preliminary results with oysters
were not promising when high water temperatures
resulted in excessive mortalities (Matthiessen,
1970b).

Texas

In 1970, 4.6 million pounds of oyster meats were
harvested from Texas. The center of production is
Galveston Bay. Harvesting has been confined al-
most entirely to the 22.000 acres of natural reefs
(Hofstetter. 1959). although there are some 3.000
acres of leased bottom. Lack of good bottom for
leasing has been a deterrent to oyster cultivation.

Considerable interest has developed recently in
the pond culture of oysters (More and Elam. 1970).
At Palacios, Texas, the Parks and Wildlife Depart-
ment has built 21 artificial ponds ranging in size from
a quarter of an acre to 4 acres. Studies on disease
resistance to the fungal pardsile Labyrinthomi.xa sp.
are being conducted. Attempts are also being made
to relate water depth and type of pond construction
to oyster growth and survival.

THE HARD CLAM

The hard clam, Mercenaria menenaria, (also
called quahog, quohog, and quahaug) is distributed
along the Atlantic coast and the Gulf of Mexico.
They reached their peak of production in 1950 when
21 million pounds were harvested. Production then
dropped until 1955 when 14.2 million pounds were
landed. Since then, production has remained fairly
stable fluctuating between 13.3 and 15.8 million
pounds, and in 1970 approximately 15.4 million
pounds of meats were produced. New York is the
leading producer (7.9 million pounds) while five
states — Virginia, New Jersey, New York, Mas-
sachusetts, and Rhode Island — accounted for 919^
of the total U.S. landings. The entire fishery comes
from wild stocks although some attempts are being
made to utilize hatchery stocks.

In New York the center of the resource is on the
southern shore of Long Island in the sheltered hays
such as Great South Bay. Many types of gear have
been used to harvest clams. These include tongs,
rakes, dredges, by hand, hoes, and grabs. In 1967,
New York harvesting was divided among three
types of gear — dredges, 2.6 million pounds: tongs,
2.5 million pounds; and rakes, 1.9 million pounds.
Introduced into this industry in recent years was the
hydraulic escalator dredge which harvests clams

with surprisingly little damage (Engle, 1970) to either
the clams or the clam beds. This gear is also used in
Chincoteague Bay, Md.

The hard clam fishery appears to be in excellent
condition although there is some concern over the
increasingthreat of pollution. In New York there are
an estimated 450.000 acres of potential shellfish pro-
ducing bottoms of which 156,892 acres or approxi-
mately 359f of the total are uncertified. Considerable
effort has been devoted by the New York Conserva-
tion Department to develop depuration techniques.
A PL 88-309 project entitled. ""Operation of a depu-
ration plant for hard clams {Merceiuirhi
nwrrcncirid)." was completed in 1969 (MacMilian
and Redman, 1971). Results of the study, using a
""pilot"" scale depuration system, indicated that the
depuration of hard clams is feasible, both economi-
cally and bacteriologically when such shellfish are
harvested from restricted growing areas (Median
Coliform MPN range: 70-700). The successful oper-
ation is greatly enhanced utilizing seawater obtained
from a saltwater well. It was estimated that hard
clams could be depurated at a cost of $1.76 per
bushel.

The most intensive efforts towards propagation on
a commercial scale have been made on Cape Cod
and Long Island (Miller et al.. 1970). Clams are
artificially spawned to setting using methods de-
scribed by Loosanoff and Davis (1963). The seed
clams are held in especially designed hatcheries and
then transplanted to controlled growing areas.
Heavy losses from predation have been a serious
problem following planting on the growing grounds.
To solve this problem the Virginia Institute of
Marine Science has developed the use of aggregates
on the bottom to protect the seed clams from pred-
ators (Castagna, 1970). Three types of aggregates
were found successful: 1) crushed oyster shell. 2)
crushed stone, and 3) stream bed gravel (pea gravel).

An average of more than 809f of the seed clams
planted with aggregates survived compared to
16-30% survival on plots without any aggregates.
Clams should be at least match-head size before
planting and should be scattered over the aggregate
at a rate of about 25-50 per square foot.

One of the largest clam hatcheries is located in
North Carolina (Tyler. 1970). Since early 1970.
Coastal Zone Resources Corporation has been en-
gaged in producing hard clam sets using hatchery
techniques (David A. Adams, pers. comm.). Ap-
proximately 4 million clam larvae are produced each
week. Metamorphosis occurs in about 2 \\k. They

62

are then placed in shallow 2 ft x 4 ft plywood trays
mounted vertically in banks of 10 trays each. Here
the set stays for an additional 8 wk. When the clams
are about 10 wk old, they are transferred into run-
ning seawater concrete raceways. Under ideal con-
ditions, the seed clams measure 1-2 cm at about 14
wk of age. When the clams reach 2.5 cm, they are
either sold as seed clams or planted by the corpora-
tion on nearby mud flats to grow to commercial size.

THE BAY SCALLOP

The bay scallop, Aeqiiipecten irrtulians. ranges
from Maine to the Gulf of Mexico (Belding, 1910).
Principal areas of abundance are the southern New
England states; Peconic Bay, Long Island, N.Y.;
and the bay and inlets of North Carolina (Gutsell,
1931). In 1970, approximately 865,000 pounds, val-
ued at 1.2 million dollars (dockside value $1.39/lb)
were landed in two states. New York and Mas-
sachusetts. The bay scallop rarely lives beyond 2 yr
(Merrill and Tubiash, 1970). Because of its short life
span and high value, this species is highly suitable for
aquaculture. Yet, very little attempt has been made
to farm this animal.

Wells (New York Conservation Commission,
1927) was one of the first to artificially rear bay scal-
lops. Since then others including Loosanoff and
Davis (1963) and Castagna and Duggan (1971) have
successfully spawned and reared the larvae to set-
ting stages.

Several programs are presently underway in an
attempt to farm the bay scallop. Under a federal aid
project PL 88-309, the State of New York has just
begun studies on the growth of scallops during the
fall, winter, and spring in heated waters. Scallops
will be subjected to 40°, 50°, 60°. and 70°F respec-
tively, and periodic growth measurements will be
taken. It is also planned to place scallops in cages
placed in the effluent discharge from LILCO Elec-
tric Power Station at Port Jefferson, N.Y.

Under a Sea Grant Program described earlier by
Robert D. Wildman. the Virginia Institute of Marine
Science is rearing bay scallops to market size
under controlled conditions (Castagna and Duggan,
1971). Scallops collected from Virginia and North
Carolina were conditioned and spawned in the
laboratory. Follow ing setting, juveniles were held in
plastic trays in the laboratory for 1 wk. They were
then moved to outdoor tanks w ith flowing unfiltered
seawater. They remained there until they were 2 mm
in width. The scallops were then moved to natural

waters and placed in plastic coated wooden floats.
They reached an average minimum market size of 50
mm in 12-13 mo. The authors felt that bay scallops
appeared amenable to mariculture.

FUTURE MOLLUSCAN AQUACULTURE

IN THE UNITED STATES

ATLANTIC AND GULF COASTS

I have briefly described the past and present status
of molluscan aquaculture along the Atlantic and
Gulf coasts. The next question is where do we go
from here? In your country (Japan), we realize that
molluscan aquaculture is much further advanced
than in the United States. One reason, of course, is
your basic protein diet consists of aquatic products
while Americans eat basically land-grown products
(beef, chicken, etc.). To supply the Japanese people
with aquatic products, you utilize your inland waters
considerably different than we do in the United
States. For example, almost all of your oysters are
grown off-bottom in order to produce the maximum
numbers per unit of area. You have set priorities on
the use of your waters — first, for food production;
second, for navigation; and third, for recreation. In
the United States the waters are used mainly for
navigation and recreation. The use of our waters for
food production is on a very low scale. For the
United States to develop molluscan aquaculture in
the future, we will have to change our philosophy on
water usage. This is going to be extremely ditTicult
and maybe impossible.

A second point is that the development of mollus-
can aquaculture in the United States will only
succeed if it is done profitably. Already many
companies which entered aquaculture have lost
money and have quickly left the business. For this
reason the development of aquaculture in the United
States must depend initially on animals that have a
high market value. These animals must feed at a low
trophic level. Even using high valued crops, it is a
question whether or not a profit can be made because
of high costs of labor, materials, private leases, etc.

The third problem is that legal rights to conduct
aquaculture must be defined. Only recently laws
were passed in Florida which made mariculture legal
(Davis and Shields. 1971). Similarily. in Maryland,
until this year, it was illegal to grow oysters off-
bottom. These are exceptions — in most states along
the .Atlantic and Gulf coasts, there are no laws w hich
protect the aquaculture investor or even allows
aquaculture to be conducted.

63

The threat of pollution will hinder the develop-
ment of molluscan aquaculture in the United States.
No one wants to invest a great amount of capital,
raise a product to market size, and then find that he
cannot sell his product because it comes from pol-
luted waters. One answer to this problem is to avoid
the use of waterways and to culture the animals in a
closed system similar to methods used to grow chick-
ens. Unfortunately, our technology has not de-
veloped far enough to make this possible. Sea Grant
Programs, like the one at the University of Dela-
ware, are working towards this goal.

It is the hope of all of us at this Symposium, that
aquaculture will develop to the level of agriculture.
Your country has made great strides towards this
goal. Through our state, university, and govermen-
tal agencies, we in the United States are learning
more every day about aquaculture techniques. It is
hopeful that this knowledge can be applied in the
future. It is our goal that someday, through the de-
velopment of aquaculture techniques, we may pro-
duce enough protein to help feed our increasing
world population. IT MAY BE OUR ONLY
SALVATION!!!

LITERATURE CITED

ANDREWS, J. D., and L. W. MASON.

1%9. Exciting new hatchery techniques cultchless seed
oysters. Va. Inst. Mar. Sci. 3. 2 p.
AVER. W. C. B. SMITH, and R. D. ACHESON.

1970. An investigation of the possibility of seed oyster pro-
duction in Great Bay. New Hampshire. N.H. Fish
Game Dep.. Mar. Survey Rep. 2. Ked. Aid PL 88-309.
Proj. 3-.32-R. 106 p.
BAILEY. R. S.. and F. C. BIGGS.

1%8. Lets be oyster farmers. Va. Inst. Mar. Sci.. 59 p.
BELDING. D. L.

1910. A report upon the scallop fishery of Massachusetts
including the habits, life history of PfcWri irradians. its
rate of growth, and other facts of economic value. Mass.
Comm. Fish. Game. 150 p.
CALBO, L. J.. A. PERLUMUTTER. D. R. GOODRICH,
and R. B. WAINRIGHT.
1968. New engineering approaches for the production
of Connecticut oysters. \ problem analysis. .Amertcan
Cyanamid Company. Vol. 1. 140 p.
CASTAGNA. M. A.

1970. Hard clam culture methtKl developed at VIMS. Va.
Inst. Mar. Sci. 4. 4 p.

CASTAGNA. M.. and W. DUGGAN.

1971. Rearing the bay scallop. Aeqiiipeclcii irnulians.
Proc. Natl. Shellfish Assoc. 6l:i«)-«5.

DAVIES. C B.. and H. W. SHIELDS.

1971. Mariculture and the law. Pfoc. 1st .Annu. Work-
shop World Mariculture StK. l970;55-.^9.

ENGLE. J. B.

1966. The molluscan shellfish industry, cuirent status and

trends. Proc. Natl. Shellfish. Assoc. 56:13-21.
1970. Oyster and clam management. In N. G. Benson
(editor), A century of fisheries in North .America. Am.
Fish. Soc. Spec. Publ. 7:263-276.
FLORIDA DEPARTMENT OF NATURAL
RESOURCES.

1970. Current research. Florida Department of Natural
Resources, Marine Research Laboratory, St. Petersburg,
Fla., 19 p.

GUTSELL, J. S.

1930. Natural history of the bay scallop. U.S. Bur. Fish.
46:569-632.
HIDU. H.

1971 . The feasibility of oyster hatcheries in the Delaware-
Chesapeake Bay region. In K. S. Price. Jr.. and D. L.
Maurer (editors). Proceedings on the Conference of the
Artificial Propagation of Commercially Valuable
Shellfish-Oysters-October 22-23. 1969:111-131.

HIDU. H . K. G. DROBECK. E. A. DUNNINGTON,
JR., W. H. ROOSENBURG, and R. L. BECKETT.

1969. Oyster hatcheries for the Chesapeake Bay
region. Univ. Maryland. Nat. Res. Inst.. Contrib. 382,
18 p.
HOFSTETTER. R. P.

1959. The Te.xas oyster fishery. Tex. Game Fish Comm.,
Bull. 40:1-38.
INGLE, R. M.. and W. K. WHITFIELD. JR.

1962. Oyster culture in Florida. Fla. State Board Con-
serv., Educ. Ser. 5 (revised), 25 p.

LINTON, T. L.

1968. Feasibility studies of raft-culturing oysters in
Georgia. Proceedings of the Oyster Culture Workshop
July 11-13, 1967. Ga. Game Fish Comm.. Mar. Fish.
Div.. Contrib. Ser. 6:69-73.

LOOSANOFF. V. L.

1966. Time and intensity of setting of the oyster, Cras-
soslrea virf;inicii. in Long Island Sound. Biol. Bull,
(Woods Hole) 130:211-227.

LOOSANOFF, V. L., and H. C. DAVIS.

1963. Rearing of bivalve mollusks. In F. S. Russell
(editor). Advances in marine biology, vol. 1. p. 1-136.
Academic Press. London and New York.

LUNZ, G. R.

1956. Cultivation of oysters in ponds at Bears Bluff
Laboratories. Proc. Natl. Shellfish. .Assoc. 46:83-87.
MAGHAN. B. W.

1967. The Mississippi oyster industry. U.S. Fish Wildl.
Serv.. Fish. Leafl. 607. 12 p.

MacMlLLAN, R. B.. and J. H. REDMAN.

1971. Hard clam cleansing in New York. Commer. Fish.
Rev. 33(5):25-33.
MARSHALL. H. L.

1969. Development and evaluation of new cultch materials
and techniques lor three-dimensional oyster culture.
N.C. Dep. Conserv. Dev.. Div. Commer. Sports
Fish.. Spec. Sci. Rep. 17, 35 p.

MATTHIESSEN, G. C.

H7()a. Seed oyster production in a salt pond. In H. W.
Youngken. Jr. (editor). Food-Drugs from the Sea Pro-
ceedings |969:87-m.

64

1970b. A review of oyster culture and the oyster industry in
North America. Woods Hole Oceanographic Institu-
tion. Contrib. 2528. 52 p.
MATTHIESSEN. G. C. and R. C. TONER.

1%6. Possible methods in improving the shellfish industry
of Martha's Vineyard Dukes County, Mas-
sachusetts. The Marine Research Foundation. Inc..
138 p.
MAY. E. B.

1969. Feasibility of off-bottom oyster culture in
.Alabama. .Ma. Mar. Res. Bull. 3:1-14.

1 97 1 . A survey of I he oysters and oyster shell resources of
.Mabama. Ala. Mar. Res. Bull. 4:1-53.
MERRILL. A. S. and H. S. TUBIASH.

1970. Molluscan resources of the .Atlantic and Gulf coasts
of the United States. Proc. Symp. Mollusca: Part
in:925-948.

MILLER. W. S., E. M. WALLACE. C. N. SHUSTER.
JR.. and R. E. HILLMAN.

1970. Hard clam. . .the gourmet's delight. Atl. States
Mar. Fish. Comm.. Leafl. 4. 8 p.
MORE. W. R.. and L. L. ELAM.

1970. Salt water pond research 1970. Job 4-Oyster
research. Te,\. Parks Wildl. Dep.. Coastal Fish.. Aus-
tin, Tex., 9 p.
[STATE OF] NEW YORK CONSERVATION COMMIS-
SION.

1927. Report of the experimental shellfish station. In
State of New York Conservation Commission Sixteenth
Annual Report: for the year 1926, p. 113-130. J. B.
Lyon, .Mbany.

OTTO, S. V.

I%9, The Manokin River Project. Commercial Fisheries
News, Chesapeake Bay Affairs 2(2):4.
ROBINSON, P.

1971. String-growing of Florida oysters has promise of
heavy production. Natl. Fisherman, February, p. 4-c.
RYTHER, J. H., and J. E. BARDACH.

1968. The status and potential of aquaculture. Particularly
invertebrate and algae culture. Vol. I., Part I. The status
and potential of aquaculture. American Institution of
Biological Sciences, Washington, D. C, 45 p.

SHAW, W. N.

1962. Raft culture of oysters in Massachusetts. U.S. Fish
Wildl. Serv., Fish. Bull. 61:481-495.

1969. The past and present status of off-bottom oyster cul-
ture in North America. Trans. Am. Fish Soc.
98:755-761.

1 970. Raft production of seed oysters in upper Chesapeake
Bay. Proc. Natl. Shellfish. Assoc. 60:11.

1971. Off-bottom growing techniques. American Fish
Farmer and World Aquaculture News 2(9): 16-21.

ST. AMANT. L. S.

1964. Louisiana leads in oyster production! Louisiana
Wildl. Fish. Comm.. Wildl. Educ. Bull. 84. 11 p.
TYLER, J.

1970. Raising clams for money. N.C. Tar Heel Coast
6(12):l.
ZAHRADNIK, J. W., and C. A. JOHNSON.

1970. Proposed 50 bushel pilot plant for oyster

production.
60:12.

(Abstract.) Proc. Natl. Shellfish. Assoc.

65

FRESHWATER FISH CULTURE IN THE UNITED STATES

HARVEY WILLOUGHBY'

INTRODUCTION

Freshwater fish culture in the United States is a
popular and fast growing business. Fish are reared
for three main purposes: 1) for stocking public and
private waters to support commerciai and sport fish-
ing or to be used as bait to catch sport and commer-
cial species, 2) for marketing directly to the
consumer for food, and 3) for home aquariums or
private tlsh ponds for ornamentation and pleasure.

Rearing fish to augment depleted natural stocks,
or to introduce new species into public waters has
traditionally represented the greatest expenditure of
effort in America. The State of Massachusetts estab-
lished the first government-owned hatchery in the
United States in 1868. It was followed by the States
of Connecticut and New York, and in 1871 the fed-
eral government established a fish commission to
study the decline of native fish stocks and to recom-
mend remedial measures. This commission later be-
came the U.S. Bureau of Fisheries — the predeces-
sor agency of the Bureau of Sport Fisheries and
Wildlife, which I represent, and the National Marine
Fisheries Service, which employs my colleagues,
William N. Shaw. John B. Glude. and Robert D.
Wildman. This yearthen, 1971, marks the centennial
year ofour federal government's involvement in fish
conservation. A series of celebrations and other
special events have been held throughout this year to
commemorate our centennial year.

The activities of the federal government in the
field offish culture, fishery research, and manage-
ment have been expanded greatly during the last one
hundred years, but they have been outpaced by the
indi\ idual state governments. As an indication of the
relative level of effort by the federal and state gov-

ernments, It is noted that the federal government
operates 95 fish hatcheries and funds another 15 that
are operated by states, while hatcheries operated by
the state governments number about 500. To get a
picture of the total U.S. effort in fish culture, one
would add more than 2.000 private fish growers to
the above list.

LEVEL OF FISH PRODUCTION

Fish produced at hatcheries operated by federal
and state agencies are stocked primarily in public
waters to improve or maintain sport and commercial
fishing. The Bureau of Sport Fisheries and Wildlife
and many state agencies also furnish fish, free of
charge, for stocking waters owned or controlled by
individuals. Much emphasis is on stocking sport fish
since fishing is one of the most popular outdoor
sports in the United States. In 1970, over 49 million
sport fishermen fished in fresh and salt waters (U.S.
Bureau of Sport Fisheries and Wildlife, 1971.)

In addition to federal and state hatcheries, there
are well over 2,000 commercial hatcheries in the
United States. These are divided into three general
classes: bait minnow, catfish, and trout hatcheries.

The estimated production of freshwater fish pro-
duced in 1965 by all hatcheries in the United States
was as follows:

Metric Ton

Federal hatcheries

2.565

State hatcheries

12,684

Commercial hatcheries

Bait minnows

22.650

Catfish and other warmwater

fish

13,000

Trout

9,060

' C hiel. DjMsion ot Fish Hatcheries. Bureau of Sport Fisheries
.ind Wildlife. L'.S. Department ofthe Interior. Washinylon. D.C.
20240: present address; Bureau of Sport Fisheries and Wildlife.
L'.S. Dep.irtmeni of the Interior. P.O. Bo\ 25486. Den\er. CO
S0225.

Data from federal fish hatcheries show that pro-
duction costs have been significantly lower in the
past 20 yr (Table I). The total cost of producing a
kilogram of trout has decreased about 4^f
because of better diets, improved feeding practices,
and more efficient operations. Feed costs have been

67

Table I. — Production cost of federal fish and hatcheries in 1947. 1956.

I96X. and 1970.

1947

1956

1%8

1970

Trout:

Production, metric ton

I.S7

466

2.172

1.972

Total cost/kg

$ 3.19

$ 2.24

$ 1.83

$ 1.41

Feed cost/kg

S 0.70

$ 0.57

$ 0.37

$ 0.33

Conversion'

4.8

2.8

1.7

1.5

Salmon:

Production, metric ton

98

58

513

548

Total cost/kg

$ 2.97

$ 2.31

$ 2.60

$ 2.95

Feed costykg

$ 0.42

$ 0.48

$ 0.59

$ 0.55

Conversion

2.9

2.3

1.9

1.8

Pondfish:

Millions offish

93

96

85

83

Production, metric ton

54

57

109

162

Total costykg

$ 7.90

$18.17

$16.24

$ 7.48

Costy 1.000 fish

$ 4.59

$15.41

$26.36

$17.18

Ratio of weight offish feed used to weight offish produced.

Trout 1970:

Average production per man-year 10 metric ton

Average production, liters per second 46 kg

Wanmvuter Fish (1970):

Average production per hectare 170.(KK) fish

Average production per man-year 725.(K)0 fish

reduced sevenfold since the 19th centui^, when in-
flation is considered, and have decreased 25% since
the advent of pelleted diets. However, the cost of
rearing salmon has remained somewhat stable. Cur-
rent cost figures were not available for state and
commercial hatcheries; however, it is believed that
their production costs are somewhat similar to costs
listed for federal hatcheries.

TYPES OF FISH CULTURE

It has long been the custom in the United States to
classify fish hatcheries into two types — extensive,
where large water areas are used to supply both the
nutritional and environmental needs, and intensive,
where the fish are confined in small ponds or tanks,
their nutritional needs met by hand feeding, and their
environmental needs met by rapid exchanges of
water in the pond. By tradition, extensive culture
methods have been used to rear warmwater and
cool-water species (temperatures I5°-27°C), while
intensive culture has been practiced for the cold-
water species (I0°-16°C), in the family Salmonidae.
This distinction is beginning to disappear however,
as improved technology is demonstrating the prac-
ticability of rearing such v\armwater species as

channel catfish, htcilunts piinctalits. and striped
bass, Moronc saxiiilis. by intensive culture
methods.

Extensive Fish Culture

The extensive fish culturist, or pondfish culturist
as he is more commonly called, is basically an
ecologist. His job is to maintain optimum oppor-
tunities for fish to spawn and grow under seminatural
conditions. He hopes to improve upon nature by
increasing the productivity of the pond. High survi-
val rates are achieved by eliminating competition by
other fish and by holding cannibalism to a minimum
through the prevention of a size spread of the fish in
the pond. In order to maintain uniform size, it is
essential that the fish spawn at the same time. This
is achieved with channel catfish and striped bass by
hormone injection. The spawning time of species
such as sunfishes. which are allowed to spawn in the
pond, is controlled by separating the sexes and hold-
ing them in cold water until seasonal water tempera-
tures have reached the desired level.

Attempts are being made to gain greater control
over the spawning and survival of even these
species. Limited success in this direction has been

68

achieved by placing nylon fiber mats in the ponds to
serve as a place for the fish to deposit their eggs.
Experiments conducted at the Fish Culture De-
velopment Center at Marion. Ala., during the past
several seasons, have indicated a promising prefer-
ence for the use of the mats by the largemouth bass,
Micropterus sulmoidcs. After the eggs are depos-
ited, the mats are removed and placed in hatchery
tanks where the required care and protection can be
given them. This is nothing more than a modem
adaptation of the ancient Chinese practice of placing
brush mats in known spawning areas to collect carp
eggs.

A principal limitation to higher yield of warmwa-
ter species in hatcheries has been the problem of
providing natural food. To accomplish this, ponds
are fertilized. Intensive fertilization can produce
enough natural food organisms in static ponds to rear
up to 550 kg offish from a hectare of water in a single
season. Supplementary feeding can increase this up
to about 2,500 kg. O.xygen limitations in lentic envi-
ronments prevent higher yields, but aeration devices
should prove that higher yields are possible.

Efforts to hand feed largemouth bass have often
been discouraging, but work toward this goal con-
tinues, and recent reports from the Development
Center at Marion, Ala., tell of producing largemouth
bass up to 20 cm long by supplemental feeding, with
a conversion ratio of 1.4:1.

Cultural techniques of other species reared at our
warmwater hatcheries are described as follows:

Walleye (Stizostedion vitreum vitreum)

The walleye is one of our most valuable freshwa-
ter sport fish. It also ranks high in the commercial
harvest. In reclaimed lakes, that is lakes in which the
entire fish population has been deliberately poisoned
out, this species has had the greatest success when
stocked as fingerlings 5 cm long.

It has not proved feasible to rear walleyes to
maturit) under hatchery conditions. Consequently,
adult fish must be trapped from the natural environ-
ment during the spring spawning run and hand strip-
ped. The eggs are incubated, usually in ajar battery,
and the sv\im-up fry stocked into fertilized rearing
ponds. Under the best conditions, 5-cm fingerlings
are harvested in about 4 wk.

Muskelliinjje iEsox masquiitongy) and
Northern Pike (E. Lucius)

The muskellunge and northern pike fit a very spe-

cial niche as efficient predators in shallow lakes. The
muskellunge (or muskies for short) is particularly
prized as a trophy fish. Both species are reared in a
somewhat similar fashion as adult spawners are
trapped in the wild and hand stripped. A certain
amoimt of success has been achieved in speeding
maturation of female northern pike by injecting dried
carp pituitary interperitoneally at a rate of 5 mg/kgof
body weight.

Once the eggs have been fertilized and become
turgid, they are incubated in jar batteries until hatch-
ing and swim-up. The fry are then stocked into fer-
tilized ponds and 5-cm fingerlings are harvested 3-5
wk later. In the case of muskies, the fingerlings are
then stocked back into ponds at a reduced rate and
fed forage fish until they reach a length of 25-30 cm.
At that size the fish are ready to be stocked back into
the natural environment and good survival can be
expected.

In recent years, limited success has been achieved
in rearing muskies in concrete tanks on a diet of
forage fish. Indications are that there will be more
tank culture of this species in the future.

Bait Fishes

Bait fishes are raised in farm ponds, natural lakes,
and other still waters devoid of predaceous fish.
Some of the more common species of bait fish reared
in the United States are goldfish, Carassiiis auratiis:
golden shiners, Notemigoniis crysoleiicas: and
fathead minnows. Pimephales proinelas. Once
ponds are prepared, culture in the simplest form may
be undertaken by merely introducing adult breeders.
The prolific nature of these fish generally results in a
rapid increase of the stock by natural reproduction.
Annual yields generally range from 1,300 to 4.500
kg/ha.

Channel Catfish, Ictalurus punctatus

For the past 10 yr channel catfish cultivation has
rapidly increased in the United States. There are
now approximately 24.600 hectares of ponds de-
voted to the growing of catfish. This can be com-
pared to 100 hectares 10 yr ago. The gross annual
value to the farmers in 1971 was approximately $31
million from the 40.800 metric tons produced.

To date, most catfish rearing has been done in
large impoundments, many of them operated in rota-
tion with rice farming. More recent entrepreneurs
into the catfish farming industry are large corpora-

69

tions which employ professional staffs of engineers,
biologists, and business managers. These enter-
prises are beginning to use intensive culture methods
to rear cattish. Production levels of 9 kg/m^ are being
realized in circular tanks.

Raceway culture at the Fish Farming Experimen-
tal Station which the Bureau of Sport Fisheries and
Wildlife operates at Stuttgart, Ark., is producing
about 900 kg of catfish per year in 115 m^ of space
with a total flow of 35 liters/sec. Water temperature
is 28°C. This is far below the potential for this
species in light of experimental data which reveal
that 9 kg/m^ are routinely held in circular tanks
with a diameter of 2 m and with a water flow of
0.3 liters/sec.

Striped Bass, Morone saxalilis

Striped bass culture, like channel catfish, is show-
ing great promise, although the production of this
species is still in the development stage. The geo-
graphical range of striped bass extends from the St.
Lawrence River. Canada, to the large rivers of
South Carolina and Georgia along the Atlantic coast
and along the Gulf coast from western Florida to
Louisiana (Pearson, 1938).

Recent investigations indicate that the only sub-
stantial fishery for this species in Florida is in the
Apalachicola River, which empties into the Gulf of
Mexico.

On the F'acit'ic coast striped bass ranges from
southern California to the Columbia River. Oreg.
Introduction of this species to the Pacific coast was
accomplished with an initial stocking of 133 yearling
fish in San Francisco Bay in 1879 (Mason, 1882).
These fish were seined from the Navesink River,
N.J.. and transported to California by train.

By 1899 the commercial catch of striped bass was
599 metric tons and by 1915 it had risen to 808 metric
tons (Raney et al.. 1952).

The establishment of landlocked striped bass
populations in several inland reservoirs has gener-
ated considerable enthusiasm in regard to the future
potential of this species. Using striped bass on a put.
grow, and take basis could prove to be a desirable
management technique fi>r large freshwater im-
poundments. In addition to its acceptance as a
superb game and table fish, the striped bass also
exhibits the ability to function as a biological control
for gizzard shad. Doii>Si>i)i(i icpcilhiniim.

The ability to produce millions of striped bass fry
through hormone induced spaw ning is nov\ a reality

(Stevens. 1966). This accomplishment has resulted
in major attempts to establish striped bass popula-
tions with large-scale fry plantings. A final evalua-
tion of the success of these programs is not available
at this lime; however, it is the general consensus that
predation will prevent the establishment of desirable
populations with this type of introduction. The al-
ternative is to introduce fingerlings (6-15 cm) instead
of fry. At least six states in the southern United
States have embarked on fingerling rearing pro-
grams.

Production at federal hatcheries increased from
90,000 fingerlings in 1966 to 1.500,000 in 1970.

Intensive Fish Culture

Some of the more common species offish reared
by intensive culture method are; rainbow trout,
Salmo gairdneri; brook trout, Sahelinus fontinoUs;
brown trout, Salmo trutla: lake trout, Sahelinus
nuinayctisli: golden trout. Salmo agiiahonira:
cutthroat trout. S. clarki: coho salmon,
Oncorhynchits kisiiicli: chum salmon. O. keta;
Chinook salmon. O. tshawytscha: kokanee or sock-
eye salmon. O. nerka: and Atlantic salmon, Salmo
salar.

One of the basic advances in trout and salmon
rearing is in the area of nutrition. Fish diets are now
compounded as carefully and scientifically as diets
for domestic animals. The basic nutritional needs of
most species of trout and salmon have been defined
by such workers as Phillips (1970) and Halver
(1970). and diets are formulated to meet these
needs. Proximate analysis of typical trout and salm-
on diets are as follows:

Si

arter diets
up to

Grower diets
8 weeks to

8

weeks old

%

maturity

'7r

Protein

48.4

42.9

Fill

13.2

9.5

Moisture

4.1

6.0

Ash

10.5

10,4

Fiber

3.9

4.1

NFE'

19.8

27.1

Available ene

Tgy:

Kcal/kg

3.315

3.315

Cost kg

$0.31

$0.3!

' NFE = nitrogen free extract.

Mechanical fish feeders are coming into wide-
spread use and arc taking o\er the role o\' feeding

70

the precise quantities of feed at prescribed inter-
vals. The more advanced of these devices monitors
water temperature, fish size, and adjusts the daily
ration accordingly.

Where the pondfish culturist is basically an
ecologist. the trout and salmon culturist is a
physiologist. He must know the requirements for
space, for the physical and chemical components of
the water, and for the nutritional requirements of
the fish. Through careful control of these factors,
each kilogram of trout or salmon produced may
require as little as 1.2 kg of feed.

Growth rates can be calculated with utmost accu-
racy. Haskell (1959) concluded that the increase in
length of trout up to 25 cm in size is at a constant
rate. He developed a ""temperature unit" theory in
which he states that the growth rate can be pre-
dicted for any temperature between 3.7° and
!5.6°C. We have found it practical to restate
Haskell's hypothesis to include 0°C as the zero
point for growth and consider it to be a straight line
relationship when plotted against time up to 15°C.
This has proven a useful tool in projecting growth
rates and forecasting the time when the fish will
reach a given length.

Fish densities in trout and salmon rearing ponds
are not as critical as the quality and quantity of the
water flowing through the unit. Ample exchanges of
water between 0° and 2rC.. free of to.xic metals
such as zinc, copper, and manganese,- and from ex-
cessive levels of such gases as nitrogen, are essen-
tial. Oxygen levels must be maintained above 5 ppm
throughout the tank, and ammonia should not ex-
ceed 1 ppm for long periods of time. If these water
quality criteria are met, most salmonids can be
reared at densities exceeding 50 kg/M^.

The raceway, a linear pond whose length is ap-
proximately 10 times its width, has been the most
popular type of rearing unit for salmonids in the
United States up to this time. Second in popularity
has been the circular pond. Many other types of
ponds have been tried, but have not been widely
adopted. In 1958 Burrows and Combs at Longview,
Wash., developed a circulating pond that is being
widely copied in the northwestern United States.
This pond is rectangular in shape, but employs turn-
ing vanes to cause the water to flow in a circular
pattern. The merits of this pond are its higher water
\elocities and thorough circulation w hich give good
distribution of feed and render the pond virtually
self cleaning. The increased velocities improve
stamina and result in better survival of the fish fol-

lowing stocking. Water supplies, both entering
and leaving a fish pond, must be monitored for their
chemical content. Sufficient oxygen must be sup-
plied by the incoming water to permit the fish to use
the food. The relationship between food eaten and
the oxygen required is so constant that many fish
culturists calculate the oxygen content of the water
entering a pond as a means of determining the carry-
ing capacity. Investigations indicate that 100 g of
oxygen are required to metabolize 450 g of trout
pellets (1,200 calories) (Willoughby, 1968). This
1.4:5 ratio should hold constant over the tempera-
ture range of 4°-16°C.

While oxygen is usually the first limiting factor in
the hatchery environment, it is not the only one. As
oxygen is used to break down foods for energy and
growth, by-products are formed. Prominent among
these are carbon dioxide and ammonia. Carbon di-
oxide poses few problems. Ammonia, however, is
another matter, as it is very difficult to remove by
mechanical means. Thus, when water is reused
from one fishpond to another, it can be aerated to
renew its oxygen content but ammonia continues to
accumulate and soon reaches toxic levels.

A recent development which has revolutionized
fish culture in the United States is the use of bacte-
rial filters, which convert free ammonia to more tol-
erable nitrates. This development has opened up
possibilities for a tenfold increase in the quantity of
fish that can be reared in a given water supply. This
reconditioning system makes it possible to reduce
the quantity of freshwater by as much as 95%.

The Dworshak National Fish Hatchery,
Ahsahka, Idaho, utilizes a water reuse system for a
part of its ponds. This hatchery began operation in
1968. There are 84 circulating ponds, 25 of which
operate on the water reuse system. In this system
approximately 10% of the water used in the ponds is
added as fresh water after being filtered, disin-
fected, and either cooled or heated. The water goes
through aerators for oxygenation and is supplied at
the rate of 27 liters/sec to each pond. When water
returns from the ponds, it goes through biological
filters where the pH is buffered and ammonia ox-
idizes to harmless nitrates.

The hatchery was designed and built to replace
the spawning and nursery areas for the steelhead
trout which will be lost by the construction of the
Dworshak Dam. In addition to the rearing of
steelhead trout for release into the north fork of
the Clearwater River, this station is also participat-
ing in the management of the reservoir above the

71

dam. At the present time, the hatchery is rearing
catchable size rainbow trout for stocking the reser-
voir. In addition, there is a limited number of cut-
throat trout on hand which will be used for brood
stock as a source of eggs for future stocking pro-
grams. In addition to these, it is expected that
this hatchery will also supply kokanee salmon for
the reservoir.

The first year's operation of the Dworshak
hatchery started with the collection of eggs from
trout transported to the hatchery from the trap at
the dam site during the period of October 1968-May
1969. The fish reared in the untreated water for 2 yr
from the 1969 brood year were released in the
spring of 1971. At the same time, the 1970 brood
year fish reared in the controlled environment of the
reuse system were also released. The controlled
environment of the reuse system made it possible to
rear fish to migrating size ( 17 cm) in 1 yr instead of
the 2-yr growing period that is required when the
untreated water is used.

DISEASE CONTROL

In 1968, the federal government of the United
States imposed regulations requiring that salmonid
fish and eggs imported into the country be free of
whirling disease, caused by the protozoan
Myxosoma cerehralis, and viral hemmorrhagic sep-
ticemia. The regulation is intended to protect the
nation's fishery resources from fuilher introduction
of these two fish diseases. It may also serve as a
model for adoption by other countries similarly
concerned about protecting their own resources.
This regulation is included in Title 50, Code of Fed-
eral Regulations.

Increased traffic in fish and eggs has spread the
virus disease, infectious pancreatic necrosis, in 10
yr from the nonheastem section of the country into
the trout and salmon producing areas of the West.

The detection of this virus cannot be accom-
plished by border inspections: consequently, control
had to be effected at the originating hatchery. Sev-
eral states now require that eggs or fish entering the
state be accompanied by a certificate of health. But
separate actions by the states can only be partially
successful, and to effect a coordinated nation-wide
program, federal legislation has been introduced in
the Congress. If passed, the bill will regulate the
interstate and foreign commerce of fish for pur-
poses of disease control.

FISH TRANSPORTATION

Fish hatcheries in the United States utilize many
diversified types of distribution equipment from
40-liter cans to elaborate tanks equipped with aera-
tion devices and oxygen equipment. However,
most hatcheries today generally use truck mounted
distribution tanks. Hauling capacity is governed by
volume of water in the tanks, design of tank, aux-
iliary equipment used, and size and species offish
being hauled. Various materials such as wood,
plywood, fiber glass, steel, and aluminum are used
for construction of tanks. Fiber glass-plywood
tanks are becoming very popular because of such
advantages as lightweight, low cost, good insula-
tion, and strength. Insulated units, having recir-
culating water systems and an o.xygen supply, can
be used to haul loads in ratios (unit weights offish
to equal unit weight of water) of 1.1:5 for trout and
1.2:4 for channel catfish, Maloy (1966).

There are reports of varying degrees of success in
increasing hauling ratios by use of sedative drugs
and buffer agents. Phillips and Brockway (1954)
found that starvation of fish before shipment and
the maintaining of low water temperatures were
more effective than the addition of chemicals.

Ma.xwell and Thoesen (1965) reported on the
successful hauling of large quantities of rainbow
trout and largemouth bass fingerlings by airplanes
equipped with water tanks. Sealed plastic contain-
ers, 2 mil and thicker — packed in insulated outer
cartons, partially filled with water, and inflated with
oxygen — are used successfully by many hatcheries
for surface and air transportation of fish. A typical
shipment is 50,(K)0 bass fry in 3.8 liters of water for
a period of 48 hr.

A recent development in the field of fish trans-
portation is the "Tish pump." The fish pump is a
modified fruit pump which was initially used to
transfer vegetables, fruit, dead fish, and seafood.
The pump is especially designed to eliminate sharp
edges in the pump body and to allow unobstructed
passage of water and produce. The water serves as
a cushioning agent.

The pump comes in two diameters. 12 and 15 cm.
The 12-cm size is used for fish up to 15 cm in length
and the 15-cm size handles fish up to 47 cm in length.
The California Department of Fish and Ciame tested
this pump and found that 900 kg of trout could be
loaded into a tank truck in 6 min with slight loss of
time due to crowding racks. Other tests indicate that

200 kg of trout per minute can be loaded onto trucks
from concrete raceways.

In addition to loading distribution trucks and
transferring fish between ponds, the pump can be
attached to a grading device. With this device about
200 kg of fish per minute can be sorted by size.

TRAINING SCHOOLS

The federal government operates three in-service
training schools for training fish culturists. These
schools are located in Spearfish. S.Dak.; Marion,
Ala.; and Leetown. W. Va. They were established
to provide essential technical training in the field of
fish hatchery management. Operation of the
schools is oriented to the activities of the Bureau of
Sport Fisheries and Wildlife and includes such to-
pics as nutrition, pathology and disease control,
I fish-cultural development, and general fish hatch-
ery management. In addition, strong emphasis is
placed on the use of hatchery fish in managing open
waters.

Although the primary goal is to provide trained
fish culturists for the National Fish Hatchery Sys-
tem, there has been increased interest in recent
years from state and foreign agencies in sending
trainees to the schools. The trainees may already
have a broad academic background in biology, but
the art of application must be learned through prac-
tice. The training schools serve as a link between
the academic world and the actual hatchery opera-
tion. In fact, T. Sana, a native of Japan, completed
our fish disease course at the Leetown National
Fish Hatchery last year.

this man-made habitat. They will migrate to the
ocean to live and grow. Three to seven years later
they will return to the Sacramento River as vigor-
ous fighting game fish and also valuable, nutritious
food. Some individuals may weigh 30 kg, and where
1 kg of fish migrated to sea from the spawning
channel, 50 kg will return. Most of the returning fish
will be captured by either sport or commercial
fishermen before they reach Tehama-Colusa, but
sufficient numbers will reach the canal to assure
perpetuation of the run.

Operation of the spawning channel is both an
engineering and a fish cultural challenge. The en-
gineering challenge will be in operating the mam-
moth traveling bridge which will service the canal.
The bridge will span the canal, and travel its length
via motorized carriages running on rails along the
sides of the canal. It will serve as a working plat-
form from which biologists and engineers can ma-
nipulate both the fish and their environment for
optimum production. An underwater viewing
chamber will be suspended from the bridge to per-
mit the observation of the movements and behavior
of the fish. Elaborate gravel cleaning devices will
flush deposited silt from the channel after each
spawning season. Young fish will be sorted,
counted, and representative numbers marked as a
means of evaluating the contribution to the Pacific
salmon fishery.

These and other changes that have taken place
during the last few years in fish hatcheries, reflect
an emerging scientific approach to the ancient art of
fish culture.

TEHAMA-COLUSA SALMON
SPAWNING CHANNEL

A totally different approach to intensive fish cul-
ture is the Tehama-Colusa multipurpose water di-
version project and spawning channel in California.
Built to divert water for irrigation purposes from the
Sacramento River, the upper 5.5 km of this canal
will function as a spawning channel for 60,000
Chinook salmon.

Access to the spawning channel will be control-
led to allow optimum numbers to lay their eggs at
one time. The eggs will incubate in the canal, and
the resulting young fish will live and be fed there
until they are ready to migrate to sea.

When the spawning channel reaches full capac-
ity, up to 60 million chinook salmon will begin life in

REFERENCES

BOWEN, J. T.

1970. A history of fish culture as related to the develop-
ment of fishery programs. //; N. G. Bensen (editor). A
century of fisheries in North America, p. 71-9.1. Am.
Fish. Soc. Spec. Publ. 7.
BURROWS, R. E., and H. H. CHENOWETH.

1970. The rectangular circulating rearing pond. Prog.
Fish-Cult. 3::67-80.
BURROWS. R. E., and B. D. COMBS.

1968. Controlled environments for salmon propagation.
Prog. Fish-Cult. .M):I2.V136.
DAVIS. H. S.

1953. Culture and diseases of game fishes. University of
California Press, Berkeley. 323 p.
HAGEN. W.. and J. P. O'CONNOR.

19.'i9. Public fish cuhure in the United States, 1958. A
statistical summary. U.S. Fish. Wildl. Serv.. Circ. 58,
44 p.

73

HAl.VER. J. E.

1970. Nutrition in marine agriculture. Mar. Agric. p.
75-102.
HASKELL, D. C.

1959. Trout growth in hatcheries. N.Y. Fish Game J.
6:204-237.
MALOY. D. R.

1%3. Hauling channel catfish fmgerlings. Prog. Fish-Cult.

25:211-212.
1966. Status offish culture in the North .American region.
Proceedings of the FAO World Symposium on Warm-
Water Pond Fish Culture, p. 125-132.
MASON. H. W.

1882. Report of operations on the Navesink River. New
Jersey, in 1879. in collecting living striped bass for trans-
portation to California. U.S. Comm. Fish and Fish., Part
7, Rep. Comm. 1879:663-666.
MAXWELL, J. M., and R. W. THOESEN.

1965. Lake Powell stocking story. Prog. Fish-Cult.
27:115-120.
PEARSON, J. C.

1938. The life history of the striped bass, or rockfish.
Rocciis sa.xalilis (Walhaum). Bull [U.S.] Bur. Fish.
28:825-851.
PHILLIPS, A. M, JR.

1970. Trout feeds and feeding. In Manual offish culture.
Part 3.85,49 p. U.S. Bureau of Sport Fisheries and Wild-
life.

PHILLIPS, A. M, JR.. and D. R. BROCKWAY.

1954. Effect of starvation, water temperature, and sodium
amytal on the metabolic rale of brook trout. Prog. Fish-
Cult. 16:65-68.
RANEY, E. C. E. F. TRESSELT. E. H. HOLLIS. \ D
VLADYKOV. and D. H. WALLACE.
1952. The striped bass, Rocciis sa.xalilis. Bull. Bingham
Oceanogr. Collect., Yale Univ. 14(l):l-55.
SPEECE. R. E.

1973. Trout metabolism characteristics and the rational
design of nitrification facilities for water reuse in hatch-
eries. Trans. Am. Fish. Soc. 102:323-334.
STEVENS. R. E.

1966. A report on the operation of Moncks Comer Striped
Bass Hatchery, 1%1-1965. South Carolina Wildlife Re-
search Department, 25 p. [Mimeograph.]
TUNISON, A. V.

1951. Comparison of fish food costs in federal hatcheries
in 1945 and 1949. Prog. Fish-Cult. 13:121-128.
WHITE. J. T. (editor).

1971. Live fish transfer pump reduces harvesting costs.
Am. Fish Farmer and World .Aquacult. News 2(2):I2-14.
WILLOUGHBY, H.

1968. A method for calculating carrying capacities of
hatchery troughs and ponds. Prog. Fish-Cult. 30:173-
174.
1971. A new look at hatcheries. Sport Fishing US.A, p.
359-369.

GENETICS OF THE AMERICAN OYSTER,
CRASSOSTREA VIRGINICA GMELIN

A. CROSBY LONGWELL'

INTRODUCTION

The development of refined culture techniques
for the commercial East Coast American oyster,
Crassostrea virginica, at the U.S. government's
Milford Laboratory (Loosanoff and Davis, 1963),
along with the opening of experimental and com-
mercial shellfish hatcheries in the United States,
have led to an interest and modest support of genet-
ic research on the oyster (Longwell, 1969; Long-
well and Stiles, 1970). Our growers ofC. virginica,
whether dealing with a wild oyster set in the field or
with their own hatchery products, are faced with
the dilemma of cultivating an organism which does
either exceedingly well producing a superabun-
dance or does very poorly, both for reasons seldom
known. Part of the hoped for process of bringing
this oyster under some greater measure of control
by the cultivator necessitates some information on
its genetic and breeding system. This is particularly
so for profitable hatchery production and for the
best pond culture. Knowledge of oyster genetics
would also be of value for the special stocking of
decimated beds or for the introduction of stock to
previously uncultivated beds in the wild.

CHROMOSOME BASIS OF C. VIRGINICA'S
BREEDING SYSTEM

An examination of the male gametogenesis and of
the spawned and fertilized eggs of C. virginica
revealed that its meiotic system, fertilization, and
cleavage are of the typical type found in most higher
plants and animals (Longwell and Sfiles, 1968a). The
oyster is not characterized by any anomalous
chromosome behavior as, for example, is the honey
bee, which would frustrate breeding plans based on

' Milt'ord Laboratory. Middle Atlantic Coastal Fisheries
Center. National Marine Fisheries Service. NOAA. Milford.
CT 06460.

successes in higher organisms. Interestingly, the
fate of the fertilizing sperm can be followed from the
time of its entry into the egg until the fusion of its
chromosomes with the chromosomes of the female
gamete on the first cleavage spindle (Fig. 1). It
should be noted that any cytogenetic examination of
the eggs of at least this species of oyster must be
preceded by treatment of the eggs with methyl al-
cohol and chloroform in a micro-Soxhlet apparatus
to remove interfering yolk granules (Longwell and
Stiles, 1968b).

There are 10 pairs of chromosomes at metaphase I
of meiosis in the mature spawned eggs of C. virgini-
ca (Longwell, Stiles, and Smith, 1967). Genes are
linked together then in 10 different groups. At least
in the female the chromosomes indicate that there is
a small amount of recombination or crossing-over of
the genes making for genetic variability without
which there can be no improvement by selective
breeding. There is no evidence for any sex chromo-
somes. This is in keeping with the protandric nature
of this oyster. See Figure 2.

The chromosomes of C. virginica are all short,
about the same length, and hardly any of them read-
ily distinguishable from the others on any basis. This
makes for difficulty in their detailed study ( Fig. 3.4).

Also studied were the chromosomes of the
Japanese oyster, C. gigas; the Puerto Rican oyster,
C rhizophorae: the European flat oyster, Ostreu
editlis; the U.S. West Coast small Olympia oyster,
O. liirida; and the horse oyster, O. equestris. All of
these species of both the viviparous Crassostrea
genus and of the larviparous Ostrea species have the
same number of chromosomes as C virginica. Also,
insofar as can be discerned, the chromosomes of all
these species are metrically and morphologically like
those of C virginica (Longwell et al., 1967). Menzel
(1968b) in Florida has examined several other
species of these two oyster genera. He further found
no variation in chromosome number and morphol-
ogy. At least at the chromosome level then there

75

%^

^ <

' » ^^ Ten chromosomes
^^ ' ^ V t ^'^ oyster sperm

/

Ten chromosomes
of female oyster
gamete

Figure I. — The coming together on the tlrst cleavage spindle of
the 10 chromosomes of the male and 10 chromosomes of the
female gamete of the American oyster. Crassostrea virginicci.

A }

*d

r

V

Figure 2. — The 10 pairs of chromosomes of the mature, spawned
egg of the American oyster. Ciass<ntie<i virf;iiuc(i.

76

a

-;

^
•

>;

#1

-»*

>«

r

^«

7

6

1

5

4

3

'

•

■

2

'

1

m sm

m

sm

m sm

L<

Dng

h/

led

i u

n

S

h o

- 1

Figure 3. — The 20 chromosomes of an early cleavage in ihe
American oyster, Crassoslrea virginica (after colchicine treat-
ment).

Figure 4. — Diagrammatic representation ot'the American oyster.
Cidssosliea virgiiilcii. chromosomes based on their lengths and
position of their spindle attachment regions.

I I

should be no barrier to the making of fertile hybrids
between the species within these two genera or even
between these two genera of oysters. No species of
the third oyster genus, Pycnodonte, has yet been
examined chromosomally probably because of the
difficulties of obtaining these noncommercial forms
which occur as singles in deep water.

To date, there have been no indications for any
chromosome polymorphism in any of the popula-
tions of C . virginka in Long Island Sound nor in any
other population thus far examined from as far north
as Prince Edward Island, Canada, to' as far south as
the State of Virginia. Ahmed and Sparks (1970) may
have uncovered a chromosome polymorphism in
marine mussels; Staiger (1957) found extensive
polymorphism of chromosome numbers in a marine
gastropod mollusk: and Battaglia (1970) has re-
ported extensively on genetic polymorphisms in
marine copepods. Chromosome polymorphisms aid
the population in making rapid adjustments to fluc-
tuations in the local environment.

In contrast to the population, species, and generic
constancy of the chromosomes of the oyster, early
developmental stages of C. \iri>inica are marked by
a high frequency of variation in chromosome number
(Stiles and Longwell, unpublished data). Fertilized
and cleaving eggs from a series of about 15 mass-
spawned groups, with a total of 835 spawning oys-
ters, had an average of about 269f postfertilization
genetic abnormalities. Abnormalities of chromo-
some number were present in 129? of the eggs. It
appears that the sensitivity of this oyster egg to all
kinds of environmental distresses results in acute
effects at the chromosome level. This should make
the oyster an excellent assay species for detecting
genetically damaging and zygote-destructive pol-
lutants (Stiles and Longwell, in press).

INBREEDING C. VIRGINICA, ITS EFFECTS
AND THE SPECIES MATING SYSTEM

Inbreeding to some extent will accompany mass
selection in commercial hatcheries. More extreme
forms will eventually be used to develop lines for
subsequent hybridization in hopes of so obtaining
hybrid vigor.

Full-sib crosses of C.riri^inica made over a period
of a year gave consistently poor development to the
straight-hinge larval stage. An investigation into this
revealed that marked fertilization and early de-
velopmental failures were occurring in these crosses
(Longwell and Stiles, 1973). In 5 of 9 cultures thus

far studied carefully, an average of 63*^ of the sib-
crossed eggs remained unfertilized. Only \Wc of the
eggs of the contemporary between-line crosses or
outcrosses to unrelated wild oysters remained unfer-
tilized. Only 39? of cleavages in the sib-crossed eggs
were normal. In the controls 70% of the cleavages
were normal. Parthenogenesis averaged 109? in the
inbreeding crosses and 0.59f in the controls. See
Table 1. Some of the inbreeding crosses were
characterized by polyspermy. In others there was a
degeneration of the one or more sperm that had
penetrated the egg.

A second, more extensive series of sib crosses
with their contemporary control interline crosses
showed essentially the same crossing difficulties.
The incidence of ineffective fertilization was higher
than in the first series. Only 469? of the fertilizations
actually achieved with sibling sperm activated the
eggs to normal development, contrasted to 989?
when the sperm of nonrelated oysters of other lines
was used. Parthenogenesis was also higher; only 7%
in the controls but 299? in the sib crosses.

Prolonged fertilization attempts increased the
number of eggs fertilized in sib crosses by 20%. It,
however, also led to more polyspermy, and there
was more degeneration of sperm in the cytoplasm of
the eggs. Such late fertilizations seldom seem to be
effective.

These crossing barriers are interpreted as meaning
that a strong outbreeding system in C. viiffinica
must, at least in some individuals in some popula-
tions, be reinforced by a system of gamete cross
incompatibility with a basis in genetic factors. This
system must operate to prevent the crossing of
gametes of closely related oysters with similar
genes. Inbreeding is thereby discouraged, and out-
breeding promoted. Incompatibility genes are
known to be highly mutable. An increased cross-
ability of C. virf^inica full- and half-sibs originating
from irradiated gametes so supports this interpre-
tation.

Genetic systems of cross incompatibility prevent-
ing inbreeding exist in an estimated 3,000 higher
plants (Brewbaker, 1964; Williams. 1964). The only
carefully studied case in animals though has been in a
marine organism — the hermaphroditic ascidians
(Morgan. 1924, 1942a. 1942b). Some of these are
self-fertile, others self-sterile, with some variability
between geographic races. Other groups having in-
breeding incompatibility often shou interspecies
crossing barriers as well. From the pioneering work
of Imai in Japan ( Imai and Sakai, 1961 ) and the later

78

Table 1.— Fertilization failures, cleavage failures, and parthenogenesis in

full-sib crosses of Crassostrea virginicci and in contemporary control

outcrosses and between-line crosses.

9c of 100 ripe

^; of 100

eggs

'7c of

eggs

with normal

with normal

100 eggs

bivalents remain-

cleavages

with

partheno-

Type of (

cross

ing

unfertilized

2 polar bodies

genetic

Contemporary •

control

0

99

0

outcrosses and

0

92

0

between-

line

27

62

0

crosses

25

25

2

Full-sib

56

5

6

crosses

77
35
47
39
81
68
93
68

0
6
0
0

1
1

4
6

9

20

12

21

7

3

11

3

work of Menzel {1968a) we know that such crossing
barriers do exist between oyster species.

Some of the difficulties of inbreeding C. vir-
ginicci in the face of gamete cross incompatibility
might somehow be compensated for by making prac-
tical use of the parthenogenesis induced in the incom-
patible matings. A variety of physical and chemical
agents and other means can be used to overcome
these crossing barriers, as done in other organisms.

As for the less intensive, lower level of inbreeding
which will accompany mass selective breeding, in-
compatibility will tend to keep the level of inbreeding
lower than would otherwise occur. This will some-
times work in the breeder's favor, other times
against him. When too much inbreeding is practiced
too fast, fertilization failures should occur.

In a third group of sib-inbred and between-line
crosses of C. virginica. food and water levels were
adjusted every other day to number of surviving
larvae (Longwell and Stiles. 1973). For the period
12 to 17 days, survival of the outbreds was 6 times
greater than for the inbreds. In a highly fecund out-
breeding species as the oyster a large number of
defective recessive genes can be expected to be har-
bored. On becoming homozygous with inbreeding
these will increase total mortality. [Battaglia (1970)
has found marine cope pods to be extremely sensitive
to protracted inbreeding, as are perhaps most highly
fecund outbreeding marine species.]

Measurements were made on a total of 1,562 lar-
vae of this series and a least squares analysis of
variance done. Looking to the means and standard
errors which were quite small — 0.7 to 3.0% —
differences in larval lengths between the in-
breds and outbreds became apparent by day 6 with
differences becoming more pronounced as time
progressed (Fig. 5).-

These measured differences between inbreds and
outbreds point to considerable genetic variation in
these oyster stocks. Judging from these results alone
there is a good basis for expecting improvements in
hatchery-produced C. virginicci by selective breed-
ing.

Considering the high degree of inbreeding depres-
sion and the high mortality of inbred larvae thus far
encountered, it can be anticipated that commercial
breeders of C virginicci will probably find it neces-
sary to hybridize highly selected lines for marketing.
Certainly they will have to hybridize intensely in-
bred lines. No spat have yet been obtained from any
of the full-sib crosses made at the Milford Labora-
tory with the exception of some from the irradiated
lines. While some portion of this failure to obtain

■' Statistical analysis was done by Ruel WiKon of the Biomelri-
cal Services. Livestock Research Staff. Agricultural Research
Center. ARS. U.S. Department of Agriculture. Bellsville. MD
20705.

Comportion of Iht Growth RotO

0( Inb'Od onO OutOrtO Lorvot

Of Ifn ft«ntfico" 0>»tt'

6 B 10 12

Ag« of Lorwoe <n Ooys

Figure 5. — Comparison of the growth rate/of inbred and
outbred larvae of the American oyster. Crassostrea vir-

i;inicii.

inbred oysters is undoubtedly attributable to the
sporadically and unpredictable poor water quality at
the Milford Laboratory, much of it represents the
severity of the effect of enforced inbreeding of this
oyster. This is particularly significant in that the
inbreeding cultures were initiated with unusually
large numbers of eggs, as compared to the far smaller
population numbers available for studies with
species of higher organisms.

Imai and Sakai (1961) detected and made some
measurements of inbreeding depression in C. i,'i,i;as.
Lines of C gii^'n-'i were lost in the third generation
of full-sib crosses.

SELECTIVE BREEDING OF C. VIRGINICA

Quantitative, commercially important traits are
controlled predominantly by exceedingly large
numbers of either of two types of genes. The effect of
one type is additive: the effect of the other is non-
additive. It is the additive type that responds to
molding and change by selective breeding. The herita-
bility of a trait is a measure of this additive genetic
variance as separated from the other type and from
the total phenotypic variance. Heritability estimates
can be used to predict progress by selection (see
formulae in Fig. 6).

Theoretical heritability estimates should be read-
ily obtainable in the oyster in one generation for any
number of commercial traits by crossing the divided
lots of eggs of several females by several different
males. Contemporaneous cultures of such crosses
should provide enough full-sib. and maternal- and
paternal-half-sib families for an analysis of variance.

From the results of this analysis heritability esti-
mates can be derived directly.

This was attempted several times to estimate
heritability of growth rate for laboratory-reared C .
virginicti larvae and spat. Unfortunately, in spite of
its merits, this method did not prove successful at the
.Milford Laboratory. This is because these very
high larval mortalities experienced at the laboratory
so much of the time seldom leave enough contem-
porary culture families for statistical comparisons.
However, in a commercial-scale pilot hatchery at
the University of Oregon operating under better
environmental conditions heritability estimates for
several different characteristics of C. gigiis were
obtained recently (Lannon, 1972). It is also proba-
ble that C. gigas is more vigorous and easier to
handle in artificial culture than C. virginicci.

In one series of these diallel crosses of C. virginica
at Milford enough larval families did survive long
enough in sufficient numbers to obtain a rough esti-
mate of heritability of larval growth to the larval age
of 2 wk. This estimate, 24%, is in the medium-to-
low range.

Realized heritability estimates, as opposed to
such theoretical heritability estimates, can be ob-
tained from selection experiments. Selection exper-
iments can also tell something about the duration of
the response to selection, and about the limits of
selection response for different coetTicients of in-
breeding, and selection differentials. Such experi-
ments would fare better under the variable culture
conditions at Milford than the diallel crosses of the
theoretical estimates.

BASIC FORMULA FOR SELECTIVE BREEDING

Annual Progress for Trait
Being Selectively Bred For -

Heritability =

Heritability x Selection Differentiol
Generotion Interval

Variation Oje to Additive Genetic Vorionce
Total PVienotypic Voriance

Selection Differential -

Difference Between Selected Oysters and Average of All Oysten
Fratn Which Selected

Generation Intervol =

Average Age of Oysters at Time of Reproduction

Figure h. — Basic formulu for selecli\e breeding
of ov sler.

80

A large selection experiment is currently under-
way for spat and juvenile growth rate of C vir-
ginica. It is intended to keep this breeding experi-
ment going at Miiford for an indefinite number of
selection generations to estimate the duration and
extent of response for a particular inbreeding coef-
ficient and selection differential to upward and
downward selection for growth rate. It is hoped to
keep the experiment going on a scale large enough
to provide seed oysters of known genetic back-
ground for other projects

A carefully chosen collection of about 6.000 wild
C. virginica was set up for mass spawning. Some
nonlocal C. virginica were included in this group
with the hope of increasing the base of genetic varia-
bility (Fig. 7). Of the approximate 6,000, 835 oys-

ters spawned. Of these spawners. 859? were from
Long Island Sound and the rest from areas extending
from Prince Edward Island, Canada, to Virginia.

Several million eggs from 835 spawners were cul-
tured, and the resulting larvae reared to metamor-
phosis. About 8,000juvenile oysters were obtained.

At the age of 1 yr a portion of the surviving
juveniles was selected on the basis of their size. The
population was divided into a large-selected group, a
small-selected group, and a nonselected population.
The selection differential for the large juveniles was
18%; forthe small juveniles, 8%. The first generation
has been obtained from mass spawnings of the two
selected populations, and from the random-
breeding, unselected Fi control population. This
first generation from selected parents is currently

Figure?. — Mass spawning of a group of .American ov>ters.(:ra.».s().\7;<'(/ \iri;inica. from different geographic areas.

81

being selected itself and spawned for the second
selected generation of spat.

Larval data collected in the course of rearing these
progeny of the tlrst generation to be selected are
showing, as did the larvae from a prior spawning of
the same animals which failed to give set, a correla-
tion between selection for juvenile oyster size and
larval growth rate. This correlation could be a
nongenetic one or a significant genetic one.

First realized heritability estimates are being
made on measurements of the spat from the first
selected generation of parents at 33 days postsetting.
Data are not yet fully analyzed. Nonetheless, pre-
liminary calculations indicate the heritability for fast
growth to this age to be high, 93%.

Considering these estimates, and the possibility in
the oyster of very high selection differentials, hatch-
ery breeders should be able to improve growth rate
of their oysters. This could be done by mass selec-
tion without recourse, for some cycles of selection,
to family performance records or progeny testing
which are time consuming and costly. Problems will
probably arise from inbreeding. Commercial shell-
fish hatcheries seem prone to start selection pro-
grams with too few oysters. Because the spawn of a
single, excellent cross might fill even a good-sized
commercial hatchery, the problem is accentuated.

Selection progress is being made for resistance to
the microsporidian MSX disease of C. virginica in
the U.S. mid-Atlantic states by both natural selec-
tion on the wild beds and in a small artificially
selected experimental stock (discussion at 63rd Joint
Annual Convention between Shellfish Institute of
North America. Pacific Oyster Growers Associa-
tion, and National Shellfisheries Association. June
1971. Seattle, Wash.). Overa period of years the C.
virginicu oysters of Malpeque Bay, Prince Edward
Island, Canada, slowly but certainly made them-
selves resistant to the Malpeque disease through the
agency of natural selection (Needier and Logic,
1947).

HYBRIDIZATION OF C. VIRGIMCA

Plants and animals are artificially crossbred or
hybridized in order to combine in the offspring some
of the desirable characteristics displayed by either
set of parents. Another purpose of crossbreeding or
hybridizing is to utilize the effects of hybrid vigor. In
different species, in addition to the general effects of
hybrid vigor, there can be an increase in size some-
times accompanied by partial or complete sterility;

increased reproductive capacity sometimes accom-
panied by a reduction in another character: in-
creased environmental range, or ability to live in a
range in which either parent is unable to live: greater
uniformity among individuals. Often hybrid vigor is
concentrated in a critical stage of early life. Unfortu-
nately, there is no way of predicting for any species
just how to obtain hybrid vigor. Inbreeding lines
might be test-crossed with one another each genera-
tion so that selection can be practiced in terms of the
potential of the separate lines for producing
heterosis on crossing (see Fig. 8).

Hybridization for the sake of combining the desir-
able genes of two different types sometimes takes
the form of upgrading practiced when the overall
performance of the import is better than the local,
but when the local is superior in some particularly
important traits related to local environmental con-
ditions. The initial hybridization is followed by
backcrosses to the import with either natural or arti-
ficial selection. Another way of combining the
characteristics of two types is the introgression of
special desirable foreign genes into the local stocks.
This is accomplished by backcrossing the hybrid to
the local type again with either natural or artificial
selection.

Hybridization of C. virginicu might supply a less
sensitive, more vigorous larval form better able to
hold up to the vicissitudes of the hatchery. Hybrids
could furnish a diversification of the U.S. EastCoast
oyster crop. It is a fact that the close cultivation of
any species facilitates the spread of disease. Diver-
sification can break the wildfire spread of a disease
by the interdispersal of resistant types. It can assure
some marketable crop when the disease toll of the
susceptible type is greatest. Were more known about
the genetics of different geographic populations of
C rirginica, some of the fear might be diminished of
experimental transplantation of oyster set to com-
mercial beds badly in need of seed from areas where
it occurs in great abundance and goes to waste.

C. rirginicti occurs extensively over an unusually
wide range of temperature, from cold to subtropical,
along the .Atlantic coast from the Gulf of St. Law-
rence to the Gulf of Mexico and farther south to
Panama, and around the West Indies. Ihere is evi-
dence for a number of physiological spawning races
within the species. Accumulated experience of
growers of C. virginicu indicates that these oysters
transferred from one region to another often fail to
thri\e in the new environment. No douht. as in C.
gigds (Imai and Sakai. 1961). there are real genetic

82

Reciprocal Recurrent Selection

Oyster

Line A

Oyster Line B

Oyster Generation 1

Population A

1

-<

Population B

1

i

Selection on
basis of

Test cross

Selection on
basis of

'

\

Discard
or

Market

Line or
Pupulation A

Line or
Population B

Generation 2

1

1

Select on
basis of

1

+

1

Test cross

Select on
basis of

X

1

Line or
Population A

T

Line or
Population B

Generation 3

1

1

Selection on
basis of

i

1

Test cross

Selection nn
basis of

Figure 8.

— Reciprocal recurrent selection
of oyster.

'

Discard

or
Market

adaptations to local conditions, as well as subtle
genetically based morphological and biochemical
differences in the different populations (Stauber,
1947. 1950; Loosanoff and Nomejko, 1951: Hillman,
1964: Numachi, 1962: Loosanoff, 1969).

Old, well-established subspecies usually have
gene combinations so well adapted to the environ-
ments they occupy that any new gene combinations
created by hybridization will nearly always be less
favorable. If, however, hybridization takes place in
an unstable environment, some of the vast array of
segregates appearing in later generations will very
likely be better adapted to the new field environ-
ment than any individual of the parental group.
They could also be better adapted to the artificial
environment of a commercial hatchery or experi-
mental shellfish laboratory.

Inclusion of nonlocal C. virginica in several of the
individual mass-spawned groups that made up the
foundation stock of the selection experiment already
referred to had no measurable adverse effects in
respect to percentage fertilization and percentage
development of the eggs to the straight-hinge larval
stage. Numbers of dead larvae and abnormal larvae
at this stage were not increased— just as many larvae
reached setting. There was an increase in the inci-
dence of polyspermy, but this seemed to have no
adverse effects.

WildC. virginica sampled from approximately 25
different sites — from areas farmed commercially and
from nonfarmed areas, from Prince Edward Island.
Canada, to Greenwich, Conn. — are being test-
hybridized.

To date, individual hybrid crosses along with ap-
propriate local and nonlocal control crosses have
been made between Long Island Sound oysters and
oysters from:

Prince Edward Island Martha's Vineyard, Mass.
Maine Niantic. Conn.

New Hampshire Greenwich, Conn.

Some spat have been obtained from all these cross-
es. Fj segregates have been obtained from Niantic
and Prince Edward Island hybrids. At least these
hybrids are fully fertile.

Fertilization records, larval culture histories, and
spat records of all these hybrids and control crosses
are being studied. Data accumulated up to the pres-
ent time appear to show to following:

1. Lack of any crossing barriers between Long
Island Sound oysters and the populations thus far
crossed with the exception of some oysters from
Maine which may be developing an incipient cross-
ing barrier.

2. Good performance of all the hybrids as larvae.

83

3. But outstanding peiformance of Maine hybrids
as larvae and early postselting spat.

4. A hybrid growth rate of the spat in the first year
slower than that of the local controls, but betterthan
that of the nonlocal controls.

5. Extremely poor growth of the older spat of
Maine hybrids and of the Maine x Maine controls
with total mortality before the second year. Maine
hybrids did better though than the Maine x Maine
control.

Full fertility was found in some geographic hy-
brids of C. i,'/>rt,s. along with fertility of their Fi (Imai
and Sakai. 1961). Generally speaking, the
crossbreds had a higher degree of hardiness, as com-
pared to the inbred strains, and a greater adaptation
to environmental conditions. Morphological charac-
teristics fell between those of the strains crossed as
did growth, weight, index of meat weight, and
glycogen content.

Some years ago H. C. Davis of the Milford
Laboratory crossed C. viri>inica with C. ^igas
(Davis, 1950). Fertilization took place readily, cell
division was normal, and early veliger larvae were
obtained. However, they all died before reaching
the umbo stage. Imai and Sakai (1961) obtained the
same result. They further found both crossing bar-
riers and hybrid inviability in crosses of C. gigas
with C riviilaris and C. echinatu. More recently,
Menzel (1968a) reported obtaining a few spat from
the hybrid cross of C. virgiiiica with C. gigas, and
some spat from crosses of other species with C
virginica. Interspecies crosses, at least those in-
volving C. virginica. in general, though appear dif-
ficult to obtain and difficult to culture successfully
(Menzel, 1967, 1971). Recently, a cross of C. vir-
ginica with C. angulata. the Portuguese oyster, re-
sulted in 209? of the eggs developing to the
straight-hinge larval stage (Stiles. 1973). All of the
larvae, most of which were abnormal, died shortly
after this. Cytogenetic examination of this inter-
species fertilization revealed 35% of the eggs to be
unfertilized. Another I09f had a very delayed fer-
tilization. Polyspermy occurred in 35% of the eggs.
Sperm nuclei were abnormally large and irregular in
259f of the eggs. Cleavage was irregular in y'r .
Nuclei of the early larval tissues were abnormally
vacuolated and highly irregular in shape. Adult oys-
ters were reared from the hybrid C. gigas x C.
angulata made by Imai and Sakai (1961).

Difficulties in obtaining species hybrids of oysters
should not be viewed altogether pessimistically.

Some of the methods used in plants and other ani-
mals to break down gamete cross incompatibility
barriers, as in inbreeding, would, no doubt, be useful
in accomplishing interspecific fertilization in the
oyster. The problem of hybrid inviability might be
overcome by crossing large enough numbers of indi-
viduals, carrying larger than usual cultures, by cross-
ing different races of the species involved, or with
mutagenic agents, if direct hybrids between the de-
sired species are not possible even then orare sterile,
the use of a third "bridging"" species can sometimes
circumvent the barrier.

Currently the only reliable way to achieve pure
hybridization in the oyster without any contaminat-
ing nonhybrids is to make single crosses of individual
oysters spawned separately, a tedious process not
commercially practical. This is so since the oyster
cannot be sexed until spawning and because the
oyster once sexed can reverse its sex. One male
spawning in a group of intended female hybrid par-
ents would fertilize all the eggs before the desired
hybrid cross could be achieved. This problem could
possibly be solved through the use of some sperm
inhibiting agents in the mass-spawning population
intended for use as the pool of female parents in the
mass hybridization.

EFFECTS OF IONIZING IRRADIATION
ON C. VIRGINICA

Mutation breeding has been scarcely attempted in
economically useful farm animals. This is because of
the high cost of culling out the large numbers of
individuals carrying the great numbers of lethal or
subvital mutations due to the low reproductive rate
of mammals. Because of the oyster's tremendously
high reproductive rate and the insignificant worth of
a single oyster, there would be no such limitations on
mutation studies, or breeding with mutations in the
oyster.

Some irradiation-mutation studies were mitiated
inC. virginica for the basic information that could be
derived, and to determine the radiosensitivity of this
mollusk. a member of a group about which there is
relatively little such information (Fig. 9) (Longwell.
1969; l.ongwell and Stiles. 1970: I ongwell and
Stiles, unpublished data).' There is. of course, the
probability of practical application of such informa-
tion in the future. For example, irradiation might

■' Irradiation was carried oul at the Brookhaven National
Laboratory with the assistance and advice of A. H. Sparrow.

84

WAKWItO

00 NOT
10IT£«

ACXj--

%

^..i/a^-J^

\ \ r^. :\

Figure 9.-

-Adult American oyster. Crassostrea virginica. set up for gamma-irradiation at the Brookhaven National Atomic Energy

Commission Laboratory.

have use in sterilizing highly selected strains of a
commercial hatchery to increase somatic growth and
to prevent competitor companies from breeding the
strain. Irradiation might be used commercially to
induce parthenogenesis in obtaining instant, one-
generation pure homozygous individuals. A mutant
larval form with a larger mouth could increase the
types of algae an oyster larva would find acceptable
as a food since the larva would then be able to ingest
larger sized algal cells.

Gamma rays from a Cs'^^ source extending from
65 to 10.000 R administered to large, old wild adults
in 1 hr. and from 220 to 20.000 R administered in 1
and 2 hr to wild spat about 9 mo old were not suffi-
cient to establish an LD.^dfor C.viri^inica. The lethal
dose must be affected by the season of the year the
oysters are irradiated, as well as by size of the oyster

and shell thickness. These oysters and spat were
irradiated in the spring of the year as they were
coming out of their winter dormancy. Germ-line
primordia were beginning active mitoses.

Gross cytological study of the gonads of the
gamma-irradiated adults revealed that even the max-
imum dose of 10.000 R did not adversely affect the
production of gonadal material. Instead, the treated
group as a whole had roughly about 209? more
gonadal bulk than did the control group: also, there
were fewer sexually undifferentiated oysters in the
treated group.

Spawning performance of the irradiated adults
was better than that of the controls. Some adult
oysters receiving the maximum 10.000 R spawned.
However, none of the ju\eniles receiving more than
8,000 R spawned.

85

Cytogenetic study of spawned eggs X-irradiated
at a rale of 164 R/15 sec and then crossed with
untreated sperm showed chromosome damage to
begin at 500 R. By 2. (KM) R such damage was pro-
nounced. The highest dose used on the eggs was
4,000 R.

In terms of the numberofset produced and surviv-
ing for I yr from cultures of 500.000 fertilized eggs.
even the lowest dose of 125 R of X-rays administered
at a rate of 199 R/lOsec to pooled sperm crossed with
untreated eggs had a slight effect. By 2,000 R the
number of these spat was reduced appreciably. At
3.000 R there was hardly any. and none at all at doses
above this. From 4.000 R on there was a clear, strong
drop in percent development of the eggs to some
cleavage stage and percent development to the
straight-hinge larval stage. There was an increased
percent of abnormal straight-hinge or 2-day-old lar-
vae. The highest dose used on the sperm was 10,000
R. See Table 2.

The overall performance of the larval and spat
cultures from the Fi of the gamma-irradiated oysters
and from the Fa of the irradiated sperm lines has
been characterized by an increased incidence of ab-
normal larvae at the straight-hinge stage, increased
mortality at all the early larval stages, heterosis of
the surviving larvae, and possibly some heterosis
also in the young spat. This extra vigor must be due
to the increased genetic heterozygosity resulting

from the irradiation. Irradiation lines are also
characterized by a greater crossability of sibs. as
mentioned earlier, and also by a greater success of
the inbreds. Improved crossability of sibs can
likewise be attributed to the increased heterozygos-
ity that results from induced mutations and to muta-
tions of the cross-compatibility genes themselves as
well. There has been very little morphological
change in either the larvae or spat as a result of the
irradiation.

Fertilization and early cleavage stages of these
crosses have increased polyspermy, more spindle
disturbances, more abnormalities of chromosome
number, more chromosome rearrangements, ab-
normal coiling of the chromosomes, and abnormal
nuclei. These are all classic signs of irradiation dam-
age to the genetic material.

LITERATURE CITED

AHMED, M.. and A. K. SPARKS.

1970. Chromosome number, structure and autosomal
polymorphism in the marine mussels \t\liliis ectiilis and
Mytilus ctilifornianus. Biol. Bull. (Woods Hole)
138:1-13.

BATTAGLIA, B.

1970. Cultivation of marine copepods for genetic and
evolutionary research. Helgolaender wiss. Meeresun-
ters. 20:385-392.

Table 2. — Summary of the culture history of crosses of I wild adult x pooled irradiated
sperm of 5 wild adult Cntsso.strea virginka.

% development

"^ development to

Cf 2-day

Dose of

to some

straight-hinge

culture

Numbers of spat

X-irradiation

cleavage stage

larvae

abnormal

surviving 1 yr

125 R

26

25

i:

1057

250 R

23

20

27

126
(most lost)'

500 R

19

16

46

1022

I.OOO R

28

25

24

790

2.0(X) R

19

16

45

468

3.000 R

20

15

53

7

4.000 R

25

15

69

0

5.000 R

6

2

■ 95

0

7,500 R

1

0.5

80

0

10.000 R

0.3

0.2

100

0

Control 1

30

27

25

1167

Control 2

20

16

53

168
(most lost)'

Control 3

33

30

23

1151

'.Accidental loss of l;ir\;ie in culture process.

86

BREWBAKER, J. 1-.

1964. Agricultural genetics. Prentice-Hall. Englewood
Cliffs. N.J.. 156 p.
DAVIS. H. C.

1950. On interspecific hybridization in Ostrea. Science
111:522.
HILLMAN. R. E.

1964. Chromatographic evidence of intra.specific genetic
differences in the Eastern oyster. Crassostrea
virginica. Syst. Zool. 13:12-18.
IMAI, T.. and S. SAKAI.

1961. Study of breeding of Japanese oyster. Crassostrea
.WM.v. J. .Agric. Res. 12:125-171.
LANNON. J. E.

1972. Estimating heritability and predicting response to
selection for the Pacific oyster Crassostrea
villus. (Abstract.) Proc. Natl. Shellfish. Assoc.

LONGWELL. A. C.

1969. Oyster genetics: Research and commercial
applications. Conference on Shellfish Culture. April
1968. at Suffolk Community College, Selden. Long Island.
N.Y.

LONGWELL. A. C. and S. S. STILES.

1968a. Fertilization and completion of meiosis in spawned
eggs of the American oyster, Crassostrea virgiiiica
Gmelin. Canologia 21:65-73.
1 %8b. Removal of yolk from oyster eggs by Soxhiet extrac-
tion for clear chromosome preparations. Stain Technol.
43:63-68.

1970. The genetic system and breeding potential of the
commercial American oyster. Endeavour 29:94-99.

1973. Gamete cross incompatibility and inbreeding in
the commercial .American oyster. Crassostrea virf;inica
Gmelin. Cytologia 38:521-533.

LONGWELL. A. C. S. S. STILES, and D. G. SMITH.
1967. Chromosome complement of the .'American oyster
Crassostrea virginica. as seen in meiotic and cleaving
eggs. Can. J. Genet. Cytol. 9:845-856.
LOOSANOFF. V. L.

1%9. Maturation of gonads of oysters. Crassostrea vir-
ginica. of different geographical areas subjected to rela-
tively low temperatures. Veliger 11:153-163.
LOOSANOFF. V. L.. and H. C. DAVIS.

1963. Rearing of bivalve mollusks. In F. S. Russell
(editor). Advances in marine biology, vol. 1, p. 1-136.
Academic Press. London and New York.
LOOSANOFF. V. L., and C. A. NOMEJKO.

1951. Existence of physiologically -different races of oys-

ters. Crassostrea virginica. Biol. Bull. (Woods Hole)

101:151-156.
MENZEL. R. W.

1967. Hybridization in species of Crassostrea. (Abstract.)

Proc. Natl. Shellfish. Assoc. 58:6.
1968a. CytotaxonomyofspeciesofclamsfMerrpnon'«)and

oysleTs(Cras.wstrea). Proc. Symp. on Mollusca, Part 1 . p.

75-84.
1968b. Chromosome number in nine families of marine

pelecypod mollusks. Nautilus 82:45-60.
1971. The role of genetics in molluscan mariculture. Am.

Malacol. Union Bull., p. 13-15.
MORGAN. T. H.

1924. Self-fertility in Ciona in relation to cross-fertility. J.

Exper. Zool. 40:301-305.
1942a. Cross- and self-fertilization in the ascidian

Styela. Biol. Bull. (Woods Hole) 82:161-171.
1942b. Cross- and self-fertilization in the ascidian Molgula

manhattensis. Biol. Bull. (Woods Hole) 82:172-177.
NEEDLER. A. W. H.. and R. R. LOGIE.

1947. Serious mortalities in Prince Edward Island oysters

caused by a contagious disease. Trans. R. Soc. Can.,

Ser. 3. 4U5):73-89.
NUMACHI. K.

1962. Serological studies of species and races in

oysters. Am. Nat. 96:211-217.
STAIGER. H.

1957. Genetical and morphological variation in Purpura

lapillus with respect to local and regional differentiation of

population groups. Ann. Biol. 33:251-258.
STAUBER. L. A.

1947. On possible physiological species in the oyster

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1950. The problem of physiological species with special

references to oysters and oyster drills. Ecology

31:109-118.
STILES. S. S.

1973. Cytogenetic analysis of an attempted inter-species

hybridization of the oyster. Incompatibility Newsletter.

No. 3. p. 41-45. Association EURATOM-ITAL., P.O.

Box 48. Wageningen, The Netherlands.
STILES, S. S.. and A. C. LONGWELL.

In press. Fertilization, meiosis and cleavage in eggs from

large mass spawnings of Crassostrea virginica Gmelin.

the commercial American oyster. Caryologia.

WILLIAMS. W.

1964. Genetical principles and plant breeding. Blackwell
Scientific Publications, Oxford, 504 p.

87

RECENT DEVELOPMENTS IN SHELLFISH CULTURE ON THE

U.S. PACIFIC COAST

JOHN B. GLUDE'

OYSTERS

Two species of oysters are produced in the States
of Washington, Oregon, and Cahfornia in the bays
shown in Figure 1. The small native oyster, Ostrea
liirida Carpenter, 1863, is found in all three states,
but is raised commercially only in the southern part
of Puget Sound. Wash. Production is low, but prices
are extremely high since this oyster is served as
a specialty in seafood restaurants.

The major species produced on the West Coast of
the United States is the "Pacific" oyster,
Crassoslrea gigas Thunberg, 1793, which was first
introduced from Japan about 40 yr ago. Except for
the period 1941-46 seed oysters have been imported
from Japan each year. Periodically local reproduc-
tion occurs and U.S. growers are able to augment
their seed supply by collecting spat locally.

Major oyster producing areas are Willapa Bay,
Grays Harbor, and Puget Sound in Washington;
Tillamook, Yaquina, and Coos Bays in Oregon:
Humboldt Bay, Tomales Bay, Morro Bay, and
Drakes Estero in California.

The major part of U.S. West Coast production
comes from Washington, as shown in Figure 2. Peak
production of over 10 million pounds of shucked
meats was reached in 1954 to 1956. Since that time
production has decreased to a mean of 6.4 million
pounds for the period 1966-70.

Oyster production in California increased rapidly
from 1954 to 1957, exceeded 1 million pounds of

meats from that time until 1965, and decreased
somewhat in the following years, but again exceeded
1 million pounds in 1970.

Oyster production in Oregon reached nearly 1
million pounds per year in 1950 to 1952 and then

N^^

PUGEJ SOUND

BRITISH COLUMBIA

GRAYS HARBOR —
WILLAPA BAY ,

t )/sEATTLE^

^WASHINGTON

TILLAMOOK —S

\^ ^^^ i

YAQUINA^=~^

>

COOS —/

OREGON y

HUMBOLDT A"**"^
BAY ~p

w:

SAN \y

FRANCISCOVJ

/ NEVADA

ICALIFORNiA L

LOS ANGELES — \

|mexico\

IDAHO

' Deputv Regional Director. Northwest Region. National
Marine Fisheries Service. NOAA. Seattle. WA 98U)9.

Figure 1. — United States Pacific coast.

89

CALIFORNIA

Figure 2. — Production of Pacific oysters, Crassosslrea gigas.
on the U.S. Pacific coast.

900

eoo

700
600-
500
400
300
200
100

Figure 3.— Production of clams on the U.S. Pacific coast.

dropped to about one-half million per year, and con-
tinues at about that level.

CLAMS

Several species of clams are harvested commer-
cially on the U.S. Pacific coast. The razor clam.
Siliqini patiihi (Dixon. 1788), and the Pismo clam,
Tivela stiiltorum (Mawe, 1823), occur on the open
wave-swept ocean beaches. Although both of these
species were originally harvested commercially, the
growing trend toward recreational fisheries has re-
sulted in a disappearing commercial fishery. Only a
few areas remain on the Washington coast where
commercial harvesting of razor clams is still permit-
ted; but each weekend during the open season up to
25.000 recreational diggers attack the beaches hop-
ing to obtain their limit of 18 clams each.

Other species grouped in the category of "hard"
clams found in protected bays and inlets provide a
significant commercial fishery. Species include the
native littleneck or rock clam. Protothaca slamincci
(Conrad. 1837): the butter ch\m. Sa.\:iJ(>iniis niiliali
Conrad. 1837: and the introduced Japanese lit-
tleneck or ■■ Manila" clam. Tapes scnucleciisscita
(Reeve. 1864).

The commercial demand for hard-shell clams is
very good and prices are high in comparison to oys-
ters. Production does not meet the demand and sig-
nificant quantities of hard-shell clams are imported
from British Columbia. Canada. There is very little
"farming" of these clams and production is based on
harvesting natural populations, principally upon
privately-ow ned or privately-leased intertidal lands.

Clam production on the U.S. Pacific coast is cen-
tered in Washington with production ranging from
400.000 to nearly 1 million pounds of meats per year,
as shown in Figure 3. Although production has var-
ied during the past 20 yr. no clear production trend is
evident from these records which include all species
of clams. Decreases in commercial production of
razor clams are largely offset by increased harvests
of hard clams.

The few protected bays and inlets along the
Oregon coast produced between 100.000 and
200.000 pounds of clam meats per year for the period
1948-55 and have since dropped to a lelativeK low
level.

Commercial clam production in California was
never great and has been negligible in recent years.

In both Oregon and California the tourist demand
for hard-shell clams, as well as razor and Pismo
clams, has utilized an increasing proportion of the
available supply.

ANALYSIS OF TRENDS IN OYSTER
PRODUCTION

There are several factors which help to explain the
decrease in production of Pacific oysters during the
past decade, as shown on Figure 4. .\ major factoi- is
the limited U.S. market for oysters. The United
States per capita consumption of fisherv products
generally has remained nearly static for a number of
years at about 1 I pounds, and per capita cimsiimp-
lion of oysters during ihis period has acIualK de-
creased. There has been little or no market promo-

90

tion by the oyster industry which is poorly organized
and made up of many small companies.

Although the quality of oysters produced and
marketed as a refrigerated, raw, shucked product is
generally good at the time the oysters leave the plant,
the delay in the distribution, especially to more dis-
tant areas, results in a significant decrease in quality.

Distribution to the Rocky Mountain and Mid-
West states from the Pacific coast is more difficult
now because Railway Express, which utilized rapid
passenger trains, has become less available as trains
are being discontinued because of the general trend
toward air travel. Transportation of oysters by air to
many of these locations is not economical because of
the small volume to be shipped. All of this has re-
sulted in curtailment of oyster markets in a large
portion of the United States.

Another factor is the competition for the fresh-
oyster market from East Coast or Gulf of Mexico,
the American oysters, Crassostrea vir^inica
Gmelin. Much of the production in these areas is
from public beds which results in a low price when
oysters are abundant, and a high price when oysters
are scarce.

Oyster production on the Atlantic coast was gen-
erally low for several years following the major mass
mortalities of oysters caused by the Haplosporidian
Minchinnia nelsoni which began in Delaware Bay in
1957 and spread to Chesapeake Bay during the fol-
lowing 2 or 3 yr. During this period the demand for
Pacific oysters expanded and prices increased dur-
ing the years 1960-61 and again between 1966 and
1967. More recently, production of low-priced oys-
ters on the East Coast has increased, causing a re-
duction in market demand for Pacific oysters. Mar-
ket price of oysters on the Pacific coast has remained
static for the past 4 yr even though costs generally

Table 1. — Wholesale price of shucked Pacific oysters,
Cntssostreii fii^as. in Seattle, Wash., cost index and oys-
ter price adjusted to 1958 base.

Oyster price

adjusted to

Year

Oyster price

Cost index

1958 base

Dollars/gal

Implicit price
deflator

Dollars/gal

1958

4.10

99.97

4.10

1959

4.00

101.66

3.93

1960

4.10

103.29

3.97

1%I

4.80

104.62

4.59

1962

4.75

105.78

4.49

I%3

4.50

107.17

4.20

1964

4.50

108.85

4.13

1965

4.55

110.86

4.10

1966

5.75

113.95

5.05

1967

6.75

117.59

5.70

1968

6.75

122.31

5.52

1969

6.75

128.11

5.27

1970

6.75

134.86

5.00

Figure 4. — Pacific oyster. Crassostrea f;i.'!".'>. production and
cost index.

have increased during this period, as indicated by
Table 1 and Figure 4.

The price per gallon of oysters shown in Table 1 is
somewhat misleading since this is the price paid by
wholesalers for shucked oysters delivered to Seattle,
Wash., for the fresh-oyster trade. During recent
years when supplies have exceeded the market de-
mand for fresh oysters, it has been necessary to
divert a part of the production into canned oysters,
smoked oysters, or oyster stew. The price of oysters
for a processed product must necessarily be lower
than the price for fresh oysters. Therefore, the aver-
age price received by many growers was signifi-
cantly less than that indicated on Table 1.

Efficient growers have reduced production during
this period and now use only their best land. This
reduces their costs by increasing the yield per unit
area and by reducing the time required for a crop to
reach marketable size.

Another factor which has increased costs has been
the lack of local setting during the past ?< yr. Locally
produced seed is generally less costly than imported
seed, especially for those growers who are able to
collect their own seed from natural reproduction.
Also, the price of imported seed has increased re-
cently and many growers hesitate to invest in seed
because of the squeeze between increasing costs of
production and limited demand at static prices.

91

In summary, production of Pacific oysters has
decreased to fit the present market. Marginal pro-
ducers have dropped out, and efficient producers
have curtailed production. Prices have remained
generally static, whereas costs have increased pro-
ducing a generally unfavorable profit picture for the
Pacific coast oyster industry. Given increased de-
mand at profitable price levels, production could be
greatly increased.

NEW DEVELOPMENTS IN OYSTER
PRODICTION

Specialty Products

Hidden in the statistics, because of low volume, is
a newly developed market for "specialty" oysters.
These are partially grown Pacific oysters, usually
marketed under the trade name "yearling" oysters.
These oysters are about 3 inches in length, similar to
the size marketed in Japan, and are suitable for the
raw half-shell trade, oyster cocktails, stews, sauteed
oysters, etc. This product has a much better market
acceptance than large Pacific oysters which must be
blanched and cut into pieces before cooking.

The market for yearling oysters is rather limited,
production costs are high and volume is low. but
these oysters sell for two to three time the price of
standard-sized oysters. Turnover is rapid because of
the short time required to grow marketable-sized
oysters. All factors considered, several small com-
panies have been able to improve their profit picture
by producing this specialty product.

Another development is a patented process which
reportedly produces superior frozen oysters. This
process consists of hand-shucking, partial cooking,
breading, and rapid freezing. This product retains
the flavor well and resists oxidation during frozen
storage. Although relatively expensive to produce
because of the costs of hand-shucking, this product
is finding good market acceptance. Frozen oysters
can be shipped by surface transportation which is
cheaper than the air shipment required to deliver
fresh shucked oysters to distant markets.

Increasing Use of Ofi'-bottom Culture

Although off-bottom culture of Pacific oysters has
been used in Japan for many years, this method has
only recently gained acceptance on the Pacific coast

of the United States. This is mainly because exten-
sive intertidal areas have been available for oyster
culture and production of oysters on bottom is less
costly than production off-bottom.

Within the past 3 yr. however, several oyster
growers have begun oyster culture using rafts or
racks, and those who have been able to market a
specialty product at a higher price have been quite
successful. One company has constructed simple
rafts using styrofoam for flotation and suspends seed
oysters on wires below the rafts in a protected part of
Puget Sound, Wash. After 15-18 mo those oysters
which have reached commercial size are marketed,
and the rest are placed on-bottom for another grow-
ing season. These small oysters are well accepted in
the Seattle market at higher than average prices, and
it appears that this production method will be
economical.

Several Oregon growers in Yaquina Bay near
Newport. Oreg., suspend Fiberglas- trays of oysters
below rafts and market these oysters at a small size
in restaurants in Portland, Oreg. These growers
have found that tray culture is somewhat more ex-
pensive than "string" culture, and they may discon-
tinue the use of trays.

One company at Eureka. Calif, has an extensive
system of racks placed along the banks of channels in
Humboldt Bay. Oysters raised on these racks grow
faster than those on bottom and are generally in
better condition.

It has also been observed that mortality of oysters
suspended from racks is lower than that of oysters
placed directly on the tide flats. Oyster mortality on
the beds in Humboldt Bay in 1971 was recorded as
409c by pathologists of the C alifornia Department of
Fish and Game, whereas mortality of oysters sus-
pended from racks was lO'/c.

Although rack culture generally is more costly
than "on-bottom" culture and requires special loca-
tions, there is a belief that Pacific oysters raised
off-bottom have a milder flavor than those raised
on-bottom. An organoleptic test to Compare the
flavorof oysters reared under various conditions will
be conducted by the Washington State Depailment
of Fisheries and the National Marine Fisheries Ser-
vice in Seattle during November 1971.

Raft culture has many of the advantages of rack
culture and also provides more latitude in selection
of locations since rafts can he anchored in waters of

- Reference to trade names does not imply endorsement by the
National Marine Fisheries Service. NOAA.

92

various depths. The principal requirements for raft
culture are 1) shelter from storms, 2) sufficient
depth, and 3) permits from local zoning authorities
and Corps of Engineers for anchoring rafts.

An anticipated development is a system of grow-
ing oysters on submerged rafts or racks. This system
will probably be necessary in areas where recrea-
tional use of the water surface for fishing, boating,
etc. would make it difficult to obtain permission for
raft culture. Engineering designs for structures
needed for this type of culture have not yet been
completed, but might be patterned after the sub-
merged racks which are used in French Polynesia for
pearl oyster culture to avoid storm damage and foul-
ing.

Use of "Unattached" or "Cultchless" Seed

Pacific Mariculture, Inc. near San Francisco,
Calif., has patented a process of producing indi-
vidual seed oysters which have several advantages.
This seed is readily available at any time of the year
and can be shipped economically by air freight. Sur-
vival during shipment and after planting has been
excellent and the individual oysters develop a un-
iform shape which makes a very attractive prod-
uct.

Disadvantages of "unattached" seed are that it
requires special handling in screen trays, and this
requires a large amount of hand labor. Growth is
generally poor in trays unless there is adequate circu-
lation of water which contains adequate food sup-
plies. These individual oysters must be quite large
before they will stay in place on oyster beds which
are exposed to waves, currents, or storms. This
limits the use of this seed for traditional oyster farm-
ing and requires development of new aquacultural
systems. It appears that "unattached"" seed will be-
come an important factor during the next few years,
provided specialty markets can be developed for the
product.

During March 1971, I made experimental plant-
ings of ""unattached"" Crassosrrea ^sii^cis seed from
the Pacific Mariculture hatchery at several locations
in the Fiji Islands. Survival ofthis seed was excellent
and growth was satisfactory after the spat were
cemented to fiberboard (Masonite or asbestos
board) squares strung on wire or rope and suspended
below rafts. It appears that this method v\ill be ap-
plicable any place where hydrographic conditions
permit the use of rafts or racks and where labor costs
are low.

Air Shipment of Anesthetized Oyster Larvae

Pacific Mariculture, Inc. has recently patented a
method for temporarily suspending activity of ma-
ture oyster larvae. With this method it is possible to
air ship large quantities of mature oyster larvae in
small containers from California to oyster culture
areas. At these locations larvae are placed in tanks of
warm water with suitable cultch materials. Attach-
ment is completed within 2 hr. This method avoids
the cost of shipping heavy "mother"" shells or other
cultch materials since one-half million larvae can be
shipped in a '/2-liter bottle. Oyster growers can then
"set"" the larvae on desired cultch materials and
plant them on their oyster beds. This method needs
further development to improve its reliability, but it
appears probable that this will be accomplished in
the near future and that this method will find applica-
tion in many places.

Investigation of Causes of Oyster Mortality
on the Pacific Coast

Mortalities of 10-70% during the second or third
summer after planting Pacific oyster seed has been
observed at several locations along the Pacific coast.
The most severe mortalities have occurred in south-
ern Puget Sound and part of Willapa Bay in Washing-
ton, and Humboldt Bay in northern California.
Negligible mortality levels have been observed in
British Columbia, northern Puget Sound and Hood
Canal in Washington, Oregon bays, and elsewhere
in California.

Generally, heavy mortalities occur near the heads
of bays which are warm and muddy with high nutri-
ent levels, abundant phytoplankton, where oysters
grow rapidly and fatten well. Mortalities generally
occur during a few weeks in midsummer when the
oysters are in spawning condition. It has been ob-
served that mortalities have been more severe
during warmer years.

Investigations during the past 5 yr by state
fisheries agencies of Washington, Oregon, and
California and by the laboratory of the National
Marine Fisheries Service in Oxford, Md., have
failed to detect a specific cause for this mortality.
Tests for Lcihyiintli(>niy-\(i marina which causes ex-
tensive losses of oysters in the Gulf of Mexico and
Minchinnia nelsoni which kills oysters in
Chesapeake and Delaware Bays have proved nega-
tive. Although numerous microorganisms have been
observed in the thousands of oysters examined from

93

the Pacific coast, none have occurred consistently
enough to indicate that they are associated with the
observed mortalities.

In a new project, agraduate student at the Univer-
sity of Washington College of Fisheries in Seattle is
investigating the relationship between the bacterium
Vibrio anquiUaritm or V. ptiraluiemulyticiis and oys-
ter mortalities. He has observed that Vibrio can kill
oysters at elevated temperatures in laboratory ex-
periments, but field tests have not yet been
made.

Efforts of Washington State Department of
Fisheries have recently been reoriented to develop
new oysterculture techniques which will circumvent
oroffset mortalities. Forexample. transplanting par-
tially grown oysters to low mortality areas before the
second summer when heavy mortalities begin seems
to be a practical solution. Also, improvement of
handling methods for seed to reduce losses would
help to offset mortality which might occur during the
second summer.

In summary, mass mortalities significantly reduce
production and profits in specific locations, but
other areas remain unaffected. Research to deter-
mine causative factors is still in progress.

NEW DEVELOPMENTS IN CLAM
PRODUCTION

Ocean beaches on the Pacific coast are owned by
the states and held for public use. This prevents the
private commercial development of farming for
species such as the razor clam or Pismo clam which
occur only in this habitat.

The inteilidal zone in bays or estuaries is also
owned by the states, but much of this land, espe-
cially in the State of Washington, has been sold to
individuals who are usually the owners of the adja-
cent upland. Large areas of intertidal zone have also
been leased by the states to individuals or companies
for special purposes, such as oyster and clam cul-
ture. Subtidal bottoms also can be leased to indi-
viduals or companies for aquaculture.

Farming of clams has not reached the stage of
development attained by oyster culture. The few
commercial clam farms on the U.S. Pacific coast still
depend upon natural setting to restock their beds.
Clam farming is still only selective harvesting of a
natural crop to obtain the greatest yield.

Until recently there has been no source of "seed"
clams which might be used for planting on private
lands and this has been a major deterrent to clam

farming. Now a commercial hatchery in California
has successfully produced large quantities of young
Manila clams and has offered these for sale. Test
plantings have been made in Willapa Bay, Wash.,
and in some other locations, but it is too soon to
evaluate the success of these ventures.

I had the opportunity in March 1971 to obtain a
small quantity of these seed clams from California
and to plant them in trays in the Fiji Islands. Survival
of clams was excellent, but growth was not outstand-
ing. This experiment is still in progress, but it is
already apparent that the first step in the develop-
ment of commercial farming forclams, availability of
seed, has been accomplished. With the large demand
for clams and the limited supply, it is likely that a
new clam farming industry will develop in Washing-
ton State within the next few years.

Three new developments in the utilization of
natural stocks of mollusks occurred in Washington.
Exploratory diving and population assessment by
scientists of the Washington State Department of
Fisheries have shown that less than 5*^ of the
geoduck clam, Fanope ^cnerosa Gould, 1850, are
exposed at extreme low tide. Before this discovery it
was thought that the geoduck was a scarce species
which needed stringent regulation to prevent over-
harvesting. No commercial digging had been permit-
ted and the recreational or personal use limit was set
at three clams per day.

Now Washington has surveyed subtidal beds and
established a system for leasing areas for commer-
cial harvest by scuba divers using suction pumps.
The product is now achieving market acceptance
and a new industry has been established.

Another species of clams, Mya arenariu
Linnaeus, 1758, known as the soft-shell clam in New
England and Chesapeake Bay, is present in
Washington but has not been utilized commercially.
This clam has a somewhat less attractive appearance
than the local littleneck and butter clams, and tradi-
tionally it has not been marketed in the Pacific
Northwest. Heavy concentrations of soft-shell
clams are found in muddy or sand\ beaches, usually
at the mouths of rivers, but areas suitable for these
species are rather limited.

Recently several individuals or companies have
begun harvesting soft-shell clams using two types of
hydraulic dredges to minimize labor costs. One type
similar to that used in Chesapeake Bay is operated
from a boat and consists of a digging head which is
forced through the bottom and a conveyor to bring
the clams to the surface. The second type is hand-

94

operated at low tide, but uses water pressure to wash
the clams out of the bottom.

The quality of the soft clams in Washington is
comparable to those from Chesapeake Bay or New
England. If harvesting and shipping costs are not
prohibitive, it is likely that a new industry for soft-
shell clams will become established in the Pacific
Northwest.

Large populations of the blue mussel, Mytiliis
edulis Linnaeus, 1758, occur in Puget Sound, Wash.,
but this species also traditionally has not been fully
utilized in the United States. Pugcl Sound mussels
are comparable to the European mussels in quality
and the paralytic shellfish poisoning caused by their
feeding on the dinoflagellate Gonyaulax, which
sometimes limits mussel harvesting along the ocean
coast, is not a problem in the inshore waters of
Puget Sound.

Recently, through efforts of the marketing
specialists of the National Marine Fisheries Service,
local restaurants have begun to serve mussels and
the product seems to be gaining acceptance in the
Pacific Northwest. There are substantial natural
stocks of mussels which could be harvested if a
market develops. Also, it would be possible to sup-
plement natural production by applying mussel farm-
ing techniques used in Holland, Spain, and else-
where as the market expands.

COASTAL ZONING

People in the United States are becoming increas-
ingly aware of the need to protect the environment
from industrial or residential development. This
need is especially apparent along the shoreline
where several classes of users compete for space.
Shellfish farmers are finding difficulty in obtaining
approval from local "zoning boards" to anchor rafts

for oyster culture in areas where shoreline residents
want to use the water surface for boating, fishing,
water skiing, etc. Even the installation of pilings or
stakes marking boundaries of shellfish beds or
wharfs for unloading the product are being ques-
tioned.

At the same time there is a majoreffort to maintain
or improve water quality in the bays and estuaries
and to eliminate sources of industrial and domestic
pollution. These public effoils will help to assure
continuation and expansion of aquaculture which is
a "clean" industry. Furthermore, aquaculture pro-
vides a good economic justification for maintaining
high water quality in inshore areas.

Federal and state legislation has been passed or is
being considered to establish authorities and proce-
dures for zoning the shoreline for special purposes.
If fish and shellfish farmers can present a convincing
argument, it is likely that certain areas will be re-
served for aquaculture with assurance that water
quality will be maintained at acceptable levels.

CONCLUSION

In conclusion, oyster production on the Pacific
coast is limited by demand, but the potential exists
for greatly increased harvests through application of
modern methods of aquaculture.

Clam production is limited by natural supply.
Clam farming has not been developed but, now that
seed of at least one species is available, it is likely
that commercial clam culture will develop rapidly in
the Pacific Northwest.

Water quality will not be a limiting factor if the
present awareness of the importance of the envi-
ronment is translated into action to control pollution.
Coastal zoning is a threat to aquaculture in some
areas but could protect those areas which are most
important for production of fish and shellfish.

95

SEAWEED CULTURE IN JAPAN

ROBERT WILDMAN'

The culture of marine algae, primaril\ for human
consumption, is a large and expanding industry in
Japan. At the present time, the growing and har-
vesting of Porphyra, "nori,"" is considered to be
one of the most profitable fisheries in Japan. In con-
trast, seaweed culture is still in a research phase in
the United States. Our demand for marine algae is
much more limited in terms of both total volume
and number of species. This is mainly due to the
fact that few Americans eat the plants as such. Our
use of seaweed is almost entirely in the form of
phycolloids extracted from the plants, and to a very
limited degree, as fertilizers and food. These uses of
several species of marine algae and the recognition
that the U.S. possesses a limited supply of the three
or four most used species has led to seaweed cul-
ture on an experimental basis in this country. How-
ever, we have not and, in the foreseeable future,
will not place the amount of our coastal waters
under '"cultivation" as has Japan. Another impor-
tant difference between the United States and
Japan is that the seaweed beds can be harvested
only by fishermen's cooperative associations in
Japan whereas in this country the harvesting is done
by industrial firms either directly or through con-
tractors. The cooperatives are responsible for the
management and protection of these resources
while in the United States such efforts are rarely
required by the government but are usually volun-
tary.

PORPHYRA (NORI)
Culture Techniques

The most extensively cultivated seaweed in
Japan, nori. has been groun since about 1600 (Ta-
mura. 1966). The earl v culture techniques consisted of
setting bundles of twigs in estuaries on which the

' Prognim Director. OtTice of Sea Grant. NOAA. Washing-
ton. D.C. 20:.\v

spores settled and grew, and the mature plants were
harvested. The nori harvest grew gradually until the
end of World War 11 and is now six times that of the
prewar level. Much of this increase was made possi-
ble by dramatic improvements in culture techniques.
Two other factors were the establishment of
cooperative unions which increased the profit to the
grower and increasing coastal eutrophication which
resulted in more fertile waters in many new areas,
while the latter is the less important factor.

At first bamboo twigs replaced the tree twigs, then
these were replaced in many areas by nets which
were still placed in the water to collect the spores.
This use of net collectors is thought to be responsible
for a doubling of production, but the discovery by K.
M. Drew of the Conchocelis stage in the life history
o{ Porphyra enabled the Japanese to make the in-
creases in production to the current level. The
fisherman or cooperatives are now able to artificially
"seed" their nets through the controlled culture of
the Conchocelis stage, which in turn releases the
spores to attach onto the nets in tanks or in the sea.
(See Suto's paper in this report for a complete de-
scription of this process.) When the nets are "in-
noculated" in tanks, the nets are rotated slowly in
the tanks containing the Conchocelis and then trans-
ported to the growing area where they are attached
to the bamboo poles. This procedure allowed the
nori grower to control the seeding of his collectors
and thus, be more confident of his crop in areas with
a good natural population. It also provided a means
of growing nori in regions which had experienced a
shortage in natural spores, especially in western
Japan.

With the advent of the use of the Conchocelis
— spore culture technique, the predominant species
used changed from Porphyra lenera to P. yczoensis
which could withstand higher salinities. In many
areas P. tencra and P. yezoensis are grown in the
inner parts of bays and estuaries with P.
p.seiiilollneari.s being grown in the deeper waters. In

97

the former situation, the nets (18.2 m x 1.3 m) are
stretched between bamboo poles stuck to the bot-
tom, with the nets being tied at the mean water level.
The nets with P. pseudolineciris growing on them
float on the water surface, anchored to maintain their
position, and kept on the surface by glass or plastic
floats.

Recent work by Imada and co-workers has
yielded results that could increase the production of
nori. This research indicated that amino acids are
effective growth promoting substances for Porphym
and that the exposure of the fronds to air by tidal
fluctuations is a significant factor in disease control
(Imada, Saito. and Teramoto, 1971). Crossing ex-
periments by Suto between different species of cul-
tivated Porpliyra succeeded, the cross developing
to the Conchocelis phase. Other attempts at cross-
ing monoecious and dioecious species, and between
species with different chromosome numbers were
not as successful (Suto, 1971).

Production and Use

The demand for nori in Japan and the increasing
production capability have resulted in a very sig-
nificant industry. In 1970. about 60,000 hectares
(150,000 acres) of coastal waters in Japan were
being used for nori cultivation. This acreage pro-
duced nearly 6 billion sheets of the dried product
worth 70-80 billion yen per year (approximately
$230 million). Each paper-thin sheet is 20 cm (8 in-
ches square and weighs about 3 g. In addition, 200
million sheets are imported from Korea, a number
now limited by an import restriction and one which
could be increased to I billion sheets in the future
(see Suto).

Approximately 60,000 fisheiTnen are now cultivat-
ing nori. setting about 10 million nets each year and
realizing the 509f (Furukawa, 1971) to 70% (see
Suto) net income for their efforts. This level of pro-
duction is required to meet the needs of the average
Japanese who consumes 50-60 sheets of nori per
year. The price of nori, up to $15 per kilogram dry
weight (nearly $7 per pound), is a major factor in
making this the most profitable of all fisheries in
Japan.

Problems and Needed .Advances

In spite of the high level of productivity, the
Japanese recognize the need to increase their pro-
duction and improve the profit potential of this

fishery. Briefly summarized, these problems and ac-
tivities are as follows. (Again, see Suto's paper in
this report for a more complete description of them. )

1. Development of new nori grounds or improve-
ment of old ones, using the new net collector
techniques, the floating net cultures and coastal
engineering works (pilings to protect growing
areas, deepening such areas to increase water
exchange, etc.). This would bring new areas into
production to replace old ones lost because of
pollution and increase the productivity of existing
areas.

2. Prevention of large-scale fluctuations (heavy
losses) yearly production primarily through dis-
ease control. This is done partially now by pre-
venting overcrowding of the nets in the growing
areas and by refrigerating the "buds'" (juvenile
plants, 5-50 mm in length) at -20°C. This re-
frigerating procedure is applied to a large part of
the newly hatched fronds essentially for the pro-
curement of frond stocks. These stocks are used
to replace poorer quality fronds in the growing
areas. By refrigerating these buds, the '"weeds"
(such as Enteromorpha) and diatoms are killed,
and the development of a parasitic fungus is pre-
vented. By 1970, one-half of all culture nets used
were refrigerated using this technique (Okazaki,
1971). Most of the diseases or diseaselike prob-
lems are not well understood, or. in many in-
stances, not even identified. Frequently, the
plants appear to be infected by a fungus, but this
could be caused by environmental or physiologi-
cal conditions (temperature, salinity, malnutri-
tion, etc.). Most of these conditions are called
various kinds and colors of "spot disease" or
"rots," but the exact causitive agent is not iden-
tified.

Work reported recently by Ishio and his co-
workers identified pollution from chemical plants
as a cause of one type of algal disease. A "can-
cerous"" disease observed in Porpliyra in shallow
coastal waters polluted by industrial wastes was
shown to be related to contact between the fronds
and the contaminated bottom mud. The mud was
extracted and it was found that the carcinogenic
fraction contained a mixture of organic com-
pounds discharged by a dye factor) which uses tar
distillates as raw materials (Ishio. Yano. and
Nakagawa. 1972).

3. Mechanization of nori cultivation and processing.
With the current labor shortage in Japan and other

98

industries drawing workers away from the
fisheries, with the resultant rising labor costs, as
much of the growing, harvesting, and processing
of the nori must be mechanized as possible. Even
so, the nori fishery is not suffering nearly as se-
vere a problem as that facing the oyster fishery.

4. Eutrophication in the coastal areas around
Japan. This, in fact, is going on, and it may pro-
vide nutrients to the nori cultivating areas to
some e.xtent, but most of the causative elements
of coastal eutrophication such as industrial dis-
charge, domestic sewage, and agricultural run-
off contain undersirable constituents. Industrial
pollution, particularly that which contains cad-
mium, mercury, and other highly toxic elements
poses a much greater threat to nori cultivation.
Pollution of all kinds is now a very serious prob-
lem for Japan, but their heavy dependence on
seafood, much of which comes from their coastal
waters, makes marine pollution a very real health
and economic threat.

5. Potential for oversupply with its resultant
economic effects. With the high prices, the
growers are obviously attempting to increase
their total production. The success of efforts to
expand the nori growing areas, solve the disease
problems, eliminate pollution problems, and
mechanize the industry will all lead to increased
production. Further, the growing tendency of
separating the producers and processors into
separate operations will cause the producers to
grow more algae to maintain their income level.
Another possibility is that with the increasing
mechanization and increasing size of cultivation
operations, fewer workers and separate
operators will be needed. Thus, many nori
fishermen will be moved into other types of em-
ployment.

VNDARIA (WAKAME)
Introduction

In comparison to nori, cultivation of the brown
alga, Utnhiriti. is of relatively recent origin. The
amount of wakame grown is still significantly less
than nori, but is increasing rapidly from almost zero
production in 1963 to over 60.000 tons in 1970. This
exceeds the amount being harvested in Japan from
natural beds. This alga, one of the Laminariales. is
not native to .American waters.

Culture Techniques

In the spring when the mature plants release the
zoospores, "collector strings"" are hung in the water
on which the spores attach and the sporophytes
grow. As with nori, this seeding now takes place in
tanks although in the past it was done in the sea
near natural beds. Also, past efforts to expand the
beds have included creating new substrate surface
by dropping rocks onto the bottom and exploding
existing rocks with dynamite in areas with natural
populations of Unclaria. A wide variety of other
techniques have been experimented on over the
past 55 yr with some success (Tamura, 1966).

However, currently the collector string method is
used in which the mature sporophylis are partially
dried, placed into the tanks of fresh seawater and
the released zoospores settle on a lOO-m long string,
previously wound around a vinyl plastic frame. The
frame is removed after 1-2 hr and transferred to a
l-m deep culture tank for the summer season. When
the young plants reach about I mm in length (in the
fall), the strings are transferred to rafts in the sea.
The plants are harvested when they reach about 1 m
in length.

Attempts to produce hybrids of three species of
Undarin have met with some success, indicating
that at least closely related species can be crossed
(Saito, 1971).

Problems

If the strings are placed on the rafts before the
water temperatures have dropped to 15°C, serious
fouling can occur. Also, if the rafts are located in a
rough water area and left floating on the surface, the
young plants can be seriously damaged. In these
areas the rafts can be anchored to a depth of 1 m to
avoid this problem. Other problems which are not so
easily remedied include some bacterial diseases and
grazing of the young plants by isopods and gas-
tropods. One last potential problem is the indication
that production is increasing to the point of equal-
ling, if not exceeding, the demand for wakame in
Japan.

LAMINARIA (KOMBU)
Introduction

Many species of this genus are used by the
Japanese as food: several of them being cultivated at
the present time. While important as a food and as a

99

source of alginic acid, kombu is still not in as great a
demand as are nori and wakame.

Culture Techniques

The cultivation, dating back 250 yr, is quite differ-
ent than that for nori and wakame. Kombu produc-
tion is increased primarily through the improvement
of available substrate and control of harmful
"weeds"" such as PhyHospadix, a marine sper-
matophyte. The latter is accomplished by dynamit-
ing to clear the PhyHospadix from areas suitable for
growth oi Laininaria. The former involves the plac-
ing of additional large rocks on the seabed on which
the plants may grow or, in some instances, using
artificial substrate such as various shapes of con-
crete. In addition, some cultivation has been done
using a hanging culture system (line and float).

Problems

Liimiiuiria is one of the many valuable marine
algae which have been plagued by the phenomenon
called "iso-yake"" by the Japanese which prevents
the plant from adhering to the bottom. Apparently,
the cause of this problem still has not been identified,
but it usually occurs in areas where the bottom is
covered with coralline algae. Some investigators
have advanced the theory that this results in a "des-
ert" condition with very little in the way of edible
seaweeds available to shellfish in the area. Thus, if
juvenile plants of Lam in aria and other such algae
begin to grow, they are grazed off rapidly.

In this same vein, the .lapanese have determined,
as we have in California, that abalone are found only
where their primary source of food (brown algae-
kelps) is available (R. Burge, pers. comm.). In many
areas, the brown algae are completely lacking and,
thus, coastal waters in which abalone could grow,
are not usable for cultivation. A very large-scale
experiment is planned to begin in 1972 which will
involve the establishment of a large kelp bed in a bay.
if this is successful. 10 million abalone seed per year
for 3 yr will be introduced into the kelp bed. This
could lead to a new technique for expanding the
capability of the Japanese for producing both
l.diiiiiKiriii and abalone (Hisashi kan-no. pers.
comm.).

Other possibilities being researched include the
development of techniques for cutting the normal
2-yr growth period to harvest down to I yr
(Hasegawa. 1972). This has been accomplished and
should lead to significant production increases.

GELIDIUM AND OTHER
AGAROPHVTES (TENGLSA)

Introduction

Perhaps the most familiar algal extract to Ameri-
cans because of its wide use as a component of
bacterial growth media in both educational and med-
ical facilities, agar is used for similar purposes in
Japan. It is harvested for both domestic and export
purposes, including sales in the United States.
However, to meet the demand of the processors,
Japan must now import about 5,500 tons of the
12.000 tons dry weight used in agar production.

Many red algae belonging to the families
Gelidaceae and Gracilariaceae serve as the source
of agar, but (Iclidiiim is the most important genus in
both Japan and the United States.

Culture Techniques

While much of the raw material for agar produc-
tion is harvested from natural beds, some artificial
propagation is practiced and has been for about 3(X)
yr. In the past, this has consisted largely of increas-
ing the available substrate by throwing large rocks
into the coastal waters in areas near existing beds
where spores will be sufficiently abundant to seed
the rocks. Other efforts to increase the supply of
agarophytes have included mechanical cleaning of
the rock surfaces, eliminating weeds (Ecklonici and
Eiscnia) from Gelidiiiiii beds, growing young plants
to harvestable size attached to ropes hanging from
floating lines, and, more recently, fertilizing the
coastal water in which the algae are growing
(Yamada, 1972). In this last effort, a lump of fer-
tilizer (in the form of urea, ammonium sulfate, or a
"nitrogen/phosphate mixture"") is placed on the
seatloor in the Gelidiiim bed and allowed to dis-
solve slowly. While this has succeeded on a com-
mercial scale, the economic feasibility of this prac-
tice has not been fully demonstrated as yet.

Problems

Gelidiiim and its relatives are among the har-
vested seaweeds known to suffer from the iso-yake
phenomenon. To date it has not been possible to
control the release of spores from Gelidiiim as has
been done with many other algae. Ability to do this
would make the establishment of nev\ populations
much more certain. Another potential problem is
Korea's growing production and export of agar
v\hich could create an excess and result in a profit
loss for Japan.

100

ANALYSIS OF SEAWEED CULTURE
IN JAPAN

Although the Japanese are still encountering many
problems in optimizing the culture of the several
species of marine algae, they are able to produce
nearly as much as they need. Their real problems of
the future appear to lie in the fields of I ) undesirable
pollution, 2) oversupply with its resultant lowering
of price, and 3) idealizing the labor situation (im-
proved working conditions, keeping wages and pro-
fits in line with other industries in Japan, keeping
sufficient workers in the industry and finding ac-
ceptable employment for any excess over that
which is needed, etc.).

Many of the techniques developed in Japan could
be used by U.S. industry, but we face many problems
which the Japanese do not. Our labor costs are al-
ready so high that nearly all seaweed farming in the
United States would have to be essentially totally
mechanized. Since the principal uses of seaweed in
America are for nonfood purposes, the price paid for
raw material will remain quite low. It is very
doubtful that the public will allow the surface of our
coastal water to be covered with a bambo-net type
system used for Porphyra except in some very re-
mote areas, such as in southeastern Alaska or on
U.S. controlled islands.

BIBLIOGRAPHY

FURUKAWA. A.

1971. OutlineofthemarineaquacultureinJapan.Jap. Fish.
Res. Conserv. Assoc.

HASEGAWA. Y.

1972. Forced cultivation of l.iiniimiria. In I'roc. Seventh
Internatl. Seaweed Symp., Sapporo. Japan. Aug. 8-12.
1971, p. 391-.'!9.'!. Univ. Tokyo Press.

IMADA. O., Y. SAITO, and K. TERAMOTO.

1972. Artificialcultureof laver. //I Proc. Seventh Internatl.
Seaweed Symp., Sapporo. Japan, Aug. 8-12. 1971, p.
.^58-363. Univ. Tol<yo Press.

ISHIO, S., T. YANO, and H. NAKAUAWA.

1 972. Cancerous disease of Porphyra tenera and its causes.
In Proc. Seventh Internatl. Seaweed Symp., Sapporo,
Japan, Aug. 8-12, 1971, p. 373-376. Univ. Tokyo Press.

OKAZAKl. A.

1971. Seaweeds and their uses in Japan. Tokai Univ. Press,
165 p.

SAITO, Y.

1971 . On the effects of environmental factors on morpholog-
ical characteristics of Undaria pinnalij'ula and the breed-
ing of hybrids among the genus Undaria. Seminar on the
Contributions of Culture, Laboratory, Field and Life His-
tory Studies to the Systematics of Benthic Marine Algae
of the Pacific Abstracts, Jap. -U.S. Comm. on Sci. Coop.,
p. 18-19.

SUTO, S.

1971. Variation in species characters of Porphyra under cul-
ture condition. Seminar on the Contributions of Culture,
Laboratory, Field and Life History Studies to the Sys-
tematics of Benthic Marine Algae of the Pacific Ab-
stracts. Jap. -U.S. Comm. on Sci. Coop., p. 28-29.

TAMURA.T.

1966. Marine aquaculture. 2nd ed. (Translated from the
Japanese by M. I. Watanabe, p. C-1 — A2-30; available
U.S. Dep. Commer.. Natl. Tech Inf. Serv.. Springfield.
VA. as PBI94051T.)

YAMADA. N.

1972. Manuring for Gelidium. In Proc. Seventh Internatl.
Seaweed Symp., Sapporo, Japan, Aug. 8-12, 1971. p. 385-
390. Univ. Tokyo Press,

101

FRESHWATER FISH CULTURE IN JAPAN

HARVEY WILLOUGHBY'

INTRODUCTION

The following observations on Japanese Fish Cul-
ture were made during field travel in Japan in the
period October 20-27, 1971.

SALTWATER TROUT CULTURE

My only observation of trout culture in seawater
was at Ogatsu Bay in Miyagi Prefecture. John Glude
and I travelled to Ogatsu Bay in the afternoon of
October 20. with Akimitsu Koganezawa. Chief of
Shellfish and Fish Research for the Migayi Prefec-
tural Station.

The principal trout culture installation was a new
commercial hatchery just getting into production at
Karakuwa. This is a commercial venture operated
by a Fishermen's Cooperative Association. The sta-
tion consists of a small hatchery building and six
large circular rearing ponds. Each pond has a supply
line for fresh water and one for seawater.

Each pond also is equipped with its own built-in
recirculating system and filter. Since the rearing
facilities were completed too late to rear fish for the
current year's stocking of the rearing pens in Ogatsu
Bay, the fish were to be shipped in from another
location and acclimated to seawater at Karakuwa
before being transferred to the seawater rearing
pens. Koganezawa explained the procedure to be
used as follows:

The trout are hatched in fresh water and reared in
the conventional manner until they are approxi-
mately 150 g each. At this time they are separated as
to sex and the females are acclimated to seawater.

The acclimatization process requires from 12-20
davs. Seaw ater is mixed u ith the fresh water at a rate

' Chief, DM^ionof Fish Hatcheries. BureauofSport Fisheries
and WildHI'e. L .S. Department of the Interior. Washington. D.C.
20^40: piesent address; Bureau of Sport Fisheries and W'ildHfe.
L S Department of the Interior. P.O. Box l^ASb. Denver. CO

s()::.s.

that increases the salinity level in the rearing pond by
approximately 10% per day. At a couple of points
during the acclimatization period, salinities are held
static for one or more days to let the fish become
adjusted to the change. Average survival is 70%.
Growth in seawater is very rapid. Average size at
harvest after 10-12 mo in seawater is 1 .5-2.0 kg. This
is approximately double the growth rate in fresh
water, and the price is approximately double that of
freshwater-reared fish. Sea-reared trout were com-
manding 600-800 yen/kg compared with the market
price of 300 yen/kg for farm raised rainbow trout.

SALMON CULTURE

From October 21 to 23, I visited the Island of
Hokkaido to view salmon management operations.

The organization of the Hokkaido salmon pro-
gram is impressive. Overall program direction and
principal research activities are conducted from the
central headquarters in Sapporo. Regional field
supervisors at six locations direct the field work
carried on at 41 hatcheries and a number of fish
collection stations.

On October 22, I visited several chum salmon
(Oncorhynchus keta) hatcheries on the Tokachi
River in the vicinity of Obihiro. The annual spawn-
ing run of chum salmon was in progress, and I was
able to observe the seining of these fish at an irriga-
tion dam which blocked their upstream movement.
Approximately 100 million eggs were being incu-
bated in the three hatcheries visited.

The following day, October 23, I visited the head-
quarters of the Hokkaido Salmon Hatchery
Fisheries Agency in Sapporo where I met the Direc-
tor. .Ayahiko Hemmi. Later in the day. Toshinobu
Tokui and 1 travelled to Lake Shikotsu and visited
the kokanee salmon hatchery.

Kokanee salmon fO. ncrkci kciiiwrliii are native to
only two lakes in Japan, both on the island of Hok-
kaido. They have, however, been widely trans-

103

planted and now occur in about 20 lakes. Lake
Shikotsu. a large natural lake on Hokkaido, contains
a population of kokanee salmon and is the site of a
hatchery devoted to the propagation of the species.
Because of the low mineral content and consequent
low productivity, it is difficult to maintain a satisfac-
tory commercial harvest of kokanee salmon in Lake
Shikotsu without depleting the spawning population.
Officials of the Hokkaido Salmon Hatchery are
searching for sources of kokanee salmon eggs with
which to supplement their own supply. They have
requested eggs from the State of Montana, but to
date have not been able to get any.

1 concluded my visit to Hokkaido by touring the
Chitose Hatchery where an extensive expansion
project is underway. 1 believe this is the oldest
hatchery in Hokkaido. It rears chum salmon and
rainbow trout iSalmo iiuinJneri). The capacity of the
expanded hatchery will be about 13 million eggs.

In summary. I was impressed by the sheer volume
of salmon released from the hatcheries in Hokkaido.
These hatcheries incubate over 500 million eggs per
year. The breakdown by species is approximately
S59c chum, 10% pink iOncorhynchus gorbuscha),
and about 5% masu^O. mason). The chum salmon
are fed for 70-90 days and released in early spring.
The return after 2 or 3 yr at sea is consistently be-
tween 1 and 2%. an excellent return figure by stan-
dards achieved at Pacific salmon hatcheries in
America.

On Sunday afternoon of October 24, I visited the
Tansui Fish Research Laboratory in Tokyo.
Yamakawa and his staff showed me the laboratory
and explained their research projects.

This is a national laboratory devoted to the prob-
lems of freshwater fish culture. Their principal work
is on the diseases and nutritional problems of eels,
ayu. carp, and trout. The principal investigators pres-
ent during my visit were: Takeshi Nose who was
working on the nutritional requirements of eels,
Hiroshi Kawatsu on disease and microbiology of
freshwater fishes, Shimadju on ayu culture, and Inui
on hepatic diseases of eels.

I visited the Nikko Branch of the Freshwater Fish
Research Laboratory, which is located on Lake
Chiizenji in Nikko National Park. The Chief of this
laboratory was Yoshikazu Shiraishi, who passed
away during his official travel to South America in
1972.

Lake Chuzenji is one of the feu publicly owned
bodies of fresh water in Japan where public spoil
fishing is permitted. This cold-water lake contains

populations of the native Japanese salmon, On-
c(>rli\)uliii.s mason, or cherry salmon, and various
exotic salmonids such as rainbow and brook trout.
Scientists at the Nikko Branch of the Freshwater
Fish Research Laboratory, are investigating the
population dynamics, the fish movements within the
lake, the characteristics of various species of sal-
monids, including hybrids, and the management of
trout in populations in streams. The interests of
Yoshikazu Shiraishi and his staff parallel those of
management biologists everywhere who are
charged with maximizing sport fishing yield in
fresh waters.

COMMERCIAL TROUT FARMS

Accompanied by Soichiro Shirahata, biologist
with the Nikko Branch of the Freshwater Fisheries
Research Laboratory, I visited trout farms and fish
processing plants in and around Fujinoyama City,
Shizuoka Prefecture, on October 25.

The Shizuoka Prefectural hatchery and laboratory
produces 30 million rainbow trout eggs annually.
They make extensive use of light to control time of
spawning. This management technique makes it
possible to provide eggs for their customers over a
period of several months. The manager, Matsuura,
reported that in one instance they were able to get
three spawns in 2 yr from a pond of fish by regulating
the photoperiods.

Matsuura and his staff are faced with a formidable
labor problem of removing dead and infertile eggs by
manual means. They were quite interested in slides 1
showed them of a mechanical egg picker in use at the
Dworshak National Fish Hatchery in Idaho.

A thriving sport fishing business is operated by the
Shizuoka Prefectural Hatchery. Some 10.000 fisher-
men per year participate in fee fishing in a stream
running through the hatchery grounds. As I under-
stand it, the provision of sport fishing facilities is a
condition of granting a commercial hatchery license
in some, if not all, prefectures in Japan.

Trout farms in Shizuoka Prefecture, and 1 assume
they are typical of Japanese trout farms in general,
are as modern and efficient as any I have seen. The
fish are reared in raceway-type ponds with a high
rate of water exchange. The food is pelleted dry
food, commercially manufactured. Ihe chemical
analysis is very close to that used in the United
States and a 1.4 conversion ratio of food into fish
tlesh also approximates that achieved at successful
hatcheries in the United States.

104

The Fuji Rainbow Trout Breeders Association
operates a processing plant in Fujinomiya City. The
association president, Watanabe, and the plant man-
ager, S. Aoki, conducted me on a tour of the modern
facility that processes 1 ,000 tons of rainbow trout for
export each year. During my visit, trout were being
packed in 5-lb packages for export to the United
States.

My impression of the Japanese trout farming busi-
ness is that it operates on a very low margin of profit
and is successful only by virtue of its operating effi-
ciency at all levels. For example, the retail price for
farm raised trout is approximately 300 yen/kg. This
can be compared to the price of salmon which ranges
from 550 yen/kg upward and tuna which sells at 600
yen/kg and upward.

Watanabe and his associates are quite concerned
over the restrictions of our salmonid import regula-
tions. These require certification that all salmonid
fishes entering the United States from foreign coun-
tries are free of the virus causing viral hemorrhagic
septicemia and Myxosoma cerebnilis. the causative
organism of whirling disease. I discussed these regu-
lations with Watanabe, S. Aoki, and T. Sano, vi-
rologist at the Tokyo University of Fisheries, who
serves as advisor to the Cooperative on Fish Dis-
eases. These gentlemen feel that since neitherof the
two diseases in question have ever been found in
Japan, our regulations requiring that certification as
to disease status be based upon specified sampling
and analytical procedures, places an unnecessary
hardship on exporters. After reviewing their prob-
lem and discussing it with our own experts in the
United States, it appears that Sano and the disease
technicians at the prefectural laboratory had misin-
terpreted our instructions and were indeed perform-
ing more laborious inspections than required. I have
attempted to clarify these points by letter since my
return to the United States.

EEL CULTURE

Eeh.AniiiiilUijciponicti. are an important species
in Japanese freshwater fish culture. They command
premium prices at all times. For example, in 1969.
when the production in Shizuoka Prefecture was
15.000 tons, the price ranged from 774-1,400 yen/kg.
In 1970, a year of low production, the price range
was 1,037-1,718 yen/kg.

The culture of eels in Japan goes back 150 yr, and
despite great effort by scientists, culture methods
have not changed much. Since the eel is catadro-
mous, spawning occurs at sea and the young migrate
to fresh water where they grow to adulthood. The
Japanese eel culture industry is based on the capture
of young eel as they migrate to fresh water during the
months of December to March. Size at time of cap-
ture is about 3 inches in length. Introduced into
ponds, and fed a diet of either chopped fish or chop-
ped fish and pelleted feeds, they reach a market size
of 18-24 inches in 12-18 mo.

The principal restriction on the volume of eel cul-
ture in Japan is availability of fry. Scientists are
attempting to overcome this problem by breeding
eels in captivity, but so far little or no success has
been achieved.

The Tokyo University of Fisheries operates an eel
culture research station on Lake Hamana in
Shizuoka Prefecture near the City of Hamamatsu.
This well-equipped and well-staffed laboratory is
conducting basic research on the problems as-
sociated with the culture of eels, mullet, carp, and
various other species, including largemouth bass.

The shortage of native eels forculturing purposes
is compounded by other problems connected with
culture of the species. Principal among these is dis-
ease. In 1970, disease took an unusually heavy toll of
eels in Shizuoka Prefecture. That year the industry
was hit by an epidemic of a new disease, named
branchionephritis by S. Egusa, Tokyo University of
Fisheries. This epidemic took 2,600 tons of finger-
ling and yearling eels during the first half of the year.

Supplemental stocks of A .japonicci are purchased
from Taiwan and New Zealand, but these and other
foreign sources cannot fulfill the need, and the
Japanese are turning more and more to Europe for
the Atlantic eel, /I. anguilla. In 1971, 34,000 kg of
glass eels from Europe were imported. So far, the
results with/1 . anguilla have been less than satisfac-
tory, because of disease and nutritional
problems.

I concluded my trip to Lake Hamana by dining on
smoked eel at the Prefectural hotel and dormitory.
I was so impressed by this product that I purchased
cans of smoked eel to take home with me.

105

SHELLFISH CULTURE IN JAPAN

WILLIAM N. SHAW

INTRODUCTION

Japan has long been recognized as a leader in the
aquaculture of molluscs. In 1969, approximately
560,000 tons (with shell) of shellfish were harvested
(Japanese Fisheries Association, 1971). Principal
species under cultivation include Pacific oysters,
Crassostrea gigas, scallops, Patinopecten yessoen-
sis. and the abalone, Haliotis discus. Several species
of clams and snails also play an important role in the
total production figures, but these are mostly caught
from wild populations and are not farmed to any
extent.

During my short tour of aquaculture sites in Ja-
pan related to the UJNR (United States-Japan Nat-
ural Resources) Aquaculture Panel, I concentrated
my effort on surveying the areas where oysters,
abalone, and scallops are being farmed. An over-
view based on these visits is listed below.

OYSTERS

Oyster production in Japan has shown a steady
increase in recent years. From 1958 to 1968, landings
rose from 151,894 tons (with shells) to 265,881 tons
(Furukawa. 1971). Production declined slightly in
1969 when 245.000 tons were harvested (Japanese
Fisheries Association, 1971).

A major reason for the increase in production is
the expansion of the hanging method of oyster cul-
ture, raft, longline, and rack. By using the third
dimension, the yield per acre is greatly increased
over the bottom or sowing method. Furukawa (1971)
estimates that the oyster yield from raft culture in the
Hiroshima Prefecture is 20 tons of oyster meats per
acre per year. These figures compare favorably with
Ryther and Bardach's ( 1968) estimate of 23.3 tons
per acre per year.

The entire industry is dependent on the natural

' Middle Atlantic Coastal Fisheries Center. National Marine
Fisheries Service. NO.A.A. Oxford. MD 21654.

production of seed oysters. Both scallop shells
(northern and southern variety) and oyster shells are
used for cultch. Shells are strung on wires ('/2-inch
bamboo spacers are used to separate scallop shells)
and draped over racks. Following setting, the seed
caught on scallop shells is used domestically while a
considerable portion on oyster shells is exported to
the United States and France.

Twomajorareasofoysterproduction were visited
during the tour — Miyagiand Hiroshima Prefectures.
In addition, we visited Lake Hamana, the only
saltwater lake in Japan, where shallowwater rack
culture is being carried out.

According to Furukawa (1971), Miyagi Prefecture
produced 3,814 tons ofoyster meats in 1968,orabout
9.3% of the total Japanese production. Matsushima
Bay has been one of the most important culture areas
in Miyagi Prefecture. In 1959, 1,456 tons of shelled
oysters were harvested. However, beginning in 1961
mass mortalities occurred in Matsushima Bay. Total
annual losses from 1961 to 1964 were 62. 5, 41. 6, 42. 3,
and 51.9%, respectively (Kan-no et al., 1965).

From our on-site visit of Matsushima Bay, it was
apparent that the Japanese had solved their oyster
mortality problems by converting the Bay's use from
oyster culture to seaweed culture. Very little oyster
culture in the Bay proper was observed.

Yet, total oyster production for Miyagi Prefecture
has declined only slightly. The Japanese have ex-
panded raft and longline culture in areas outside
Matsushima Bay.

One big industry in the Miyagi Prefecture is the
exportation of seed oysters. On our tour, we had the
opportunity to visit this operation at Watanoha
as they were preparing seed for air shipment to
France. Oyster seed, which is hardened on racks
for 3 mo, is brought ashore in small boats. The
seed (all caught on oyster shells) is removed from
the galvanized wire strings, placed in baskets,
and thoroughly washed. It is then culled into
single pieces and examined for predators; all shells
with six or less sp^t are discarded. The good shells

107

are placed in freshwater for 1 hr to kill flatworms.
P\eiid(>M\li>cluis sp. After a quick saltwater dip (5 to
10 sec), 750 spat-laden shells are placed in shipping
cases. Before wrapping, a random sample of 50
shells are taken out of the case and the number of
seeds counted. Within 48 hr after crating, the seeds
reach France.

The French's interest in Japanese seed has come
about only in recent years. Heavy mortalities have
occurred among the Portuguese oyster. Cmssostrea
ani^iihita. in France, and the government has banned
the importation of Portuguese oyster seed in their
country. In its place, they are now importing seed
from Japan.

The new competition for Japanese seed could
have two implications in the U.S. Pacific coast oys-
ter industry: 1) the cost of Japanese seed to the
United States could increase, and 2) because the
French have entered the market, there could de-
velop a possible shortage of Japanese seed for im-
portation to the United States. In 1972, heavy sets of
Pacific oysters occurred on the west coast, so the
need for Japanese seed, at least in that year, was
considerably less.

About 77% of the total oyster production in Japan
comes from Hiroshima Prefecture (31,188 tons of
meat out of a 1968 total of 40,928 tons). Furukawa
(1971) states that a total of 10,962 rafts (9.1 x 18.2 m
average size) are utilized in the Prefecture.

During our tour of the area, seed oysters were
being strung on galvanized wire and suspended from
bamboo rafts. Initially, 1.600 strings (wrens) are
suspended. As the oysters grow, the number per raft
is reduced to 800. On each string, about 15 m long,
spat bearing scallop shells are separated by a 9-inch
bamboo spacer.

Each raft is constructed out of bamboo logs. A
typical raft. 20 x 9 m, is supported by 25 styrofoam
floats, each the size of a 50-gal oil drum. Fifteen
floats are located down the center of the raft while
two series of five floats are located along the outer
edge. An iron cable runs down the center of the raft
and is the connecting link between each series of four
or five rafts. The rafts are held in place by six (5 tons
each) concrete anchors. A typical raft, including
labor, costs about $350 and takes a crew of four 1 day
to build.

As in Miyagi Prefecture, the entire industry is
dependent on natural setting. No attempt is being
made to supplement natural sets with hatchery-
reared stocks. The seed is caught in the intertidal
zone on scalli^p shells draped over racks.

Several problems are facing the oyster industry of
Japan. Of considerable concern is the increased
threat of both domestic and industrial pollution. In-
dustries are located in areas adjacent to oyster grow-
ing and setting areas. Further expansion of such
industries could seriously affect the oyster industry.

Because the bulk of oysters in Japan are grown
off-bottom, a considerable amount of labor is in-
volved. In recent years, there has developed a seri-
ous labor shortage in the oyster industry. Young
people do not wish to follow their parents in this line
of work. Thus, simplification of techniques and de-
velopment of mechanization in the oyster industry is
urgently needed (Fujiya. 1970).

ABALONE

Abalone production in Japan has increased from
4.600 metric tons in 1964 to 6.500 metric tons in 1970.
One possible reason for this increase is the effect of a
large seed planting program. According to Sanders
(1971). there are 16 laboratories in Japan artificially
producing 2 to 3 million seed abalone annually.

A typical laboratory is the Kanagawa Prefectural
Fisheries Experimental Station located on the island
of Joga Shima near the City of Miura. Their quota,
which is set by the government, is to produce about
300, OOA seed abalone annually.

At the Station, mature abalone are induced to
spawn by first air-drying and then placing them in
shallow, standing water tanks which are exposed to
sunlight. Apparently as the sunlight heats the water,
the abalone spawn.

The fertile eggs are transferred to setting tanks
located inside an adjacent building. These tanks are
covered with black plastic sheeting to eliminate
light. The larvae, which require no supplementary
feeding, set in about 1 week on special plastic plates.
These plates have been previously exposed to run-
ning seawater in order to obtain a film of diatoms, the
food of young abalone. Since the larvae swim near
the surface, the water is slowly raised in the setting
tanks so that the setting abalone are distributed as
evenly as possible on the plates. Once setting is
over, the plates are transferred to outdoor tanks
where the abalone continue to feed on the diatom
film until they reach 5 to 10 mm in size. They are then
removed from the plates and placed on either tiles,
oyster shells, stones, or cross-shaped plastic config-
urations. At this stage, they are fed macroscopic
algae such as Ulva and Laminur'ui. When the
abalone are approximately 2.5 cm in size (about 8 mo

108

to 1 yrold), they are sold to the fishermen for 10 yen
each. The growth rates in the area of the Kanagawa
Station are as follows:

f;e in yr

Size in cm

1

2.5

2

6.0

3

11.0

4

14.0 (market size)

The hatchery-reared abalone acquire a green shell
coloration which natural populations do not have.
This green ""tag" helps to evaluate the government's
success in this seed planting program since the color
persists throughout the abalone's life. It has been
estimated, on preliminary results, that there is a 10%
recovery on planted seed (Ryther, 1968).

In addition to the Prefecture laboratories which
are producing seed abalone, there are Regional
laboratories (equivalent to Federal laboratories in
the United States) which are studying the biology of
abalone. One such laboratory is the Tohoku Re-
gional Fisheries Research Laboratory located in
Shiogama, about 10 miles northeast of Sendai. Sev-
eral studies on the growth of abalone are now un-
derway. These include studies on the growth of
juveniles using different varieties of diatoms and the
growth of older forms on different varieties of sea-
weeds.

Shogo Kikuchi. biologists at the Tohoku Labora-
tory, is initiating a large-scale study where he will
establish an artificial kelp bed in one of the Japanese
bays. It is planned to plant the area with 10 million
seed abalone. There are many areas in Japan where
abalone set but do not grow or survive due to the lack
of macroscopic algae. The development of artificial
kelp beds may help to solve this problem. Kikuchi
plans also to keep a close watch on invading pred-
ators and develop control methods if such invasion
does take place.

The only commercial company producing seed
abalone in Japan is the Oyster Research Institute.
The Institute is located on Mohne Bay near the City
of Kesenuma. Under the initial leadership of Takeo
Imai, the Institute has become famous throughout
the world for some of the basic studies in molluscan
aquaculture. Since the untimeK death of Takeo Imai
in 1971, Hisashi Kan-no of the Tohoku Laboratory
has been .Acting Director.

The tank farm at the Institute has been described
in a number of papers (Imai, 1967: Ryther, 1968:
Costlow, 1969). .M the time of my visit, 80^ of the
tanks (there are 180 in all) were devoted to abalone

culture. The remainder contained oyster and scallop
seeds.

At the Institute, abalone are spawned in early
September and the larvae are caught on plastic plates
(coated with Platymonas and Navicula) similar to
those used at the Kanagawa Station. As the juveniles
grow, they are removed from the plates, placed in
plastic containers wrapped in netting, and resus-
pended from the floating tank farm. Twice a week
the abalone are fed seaweed such as Ulvci and
Laminciria. When they are 20 mm or larger, the
Institute sells them to the fishermen for 1 yen/
mm.

The Institute has a cooperative program with the
Sendai Thermal Power Station located near Shio-
gama on Matsushima Bay. Young abalone (1 to
2 mm in size) are transferred in the fall from the
Institute's installation at Mohne Bay to tanks at the
Power Station. Using the heated water from the
Power Station, the young abalone grow four to five
times faster than in the natural environment. When
the abalone are 1 cm in size, they are transferred
back to the tank farm at Mohne Bay. Lack of sea-
weed around the Power Station and costs for collect-
ing or buying seaweed are the main reasons for
moving them back to Mohne Bay at the 1-cm size.

Because the preliminary results were so promis-
ing, the Power Station had built five new canvas-
lined, steel-frame tanks. Each tank, 20 x 1 x Vi m
deep, can hold 60,000 seed abalone. Plans are to
build up to 50 of these tanks in the next few years
with a goal of producing 10 million seed abalone
annually. All the equipment, including installation,
is being paid for by the power company.

SCALLOPS

The sea scallop fishery reached its peak of produc-
tion in 1934when80,000metric tons (in shell weight)
were harvested. Since then, production has declined
and only 6,000 metric tons were produced in 1968
(Sanders, 1971). With the increased expansion of
off-bottom culture, scallop production has been in-
creasing in the past few years. The Japanese esti-
mate that 40,000 metric tons would he produced in
1972 and possibly 100,000 tons in 1974.

In Mutsu Bay, the longline method of culturing
scallops has been expanding in recent years. Here
longlines are used not only for collecting seed but
also for growing the scallops to market size. A scal-
lop longline differs from those used in oyster culture
in that there is a second buoyed line 3 to 8 m below

109

the surface. It is from this lower line that seed collec-
tors and cages for growing scallops are attached.

Scallop spawning in Mutsu Bay begins in March,
peaks in early April, and is over by mid-April. The
larvae life is about 35 days (temperature during this
period ranges from 7° to 12°C). The fishermen put
out their seed collectors in early May.

Initially, seed scallops were caught on suspended
Cyprus branches, but now over 50% of the collectors
consist of plastic web bags filled with used gill nets.
Eventually, most collectors will be of this type. In
1971. 2.3 million bag collectors were used and 40
billion seeds were collected in Mutsu Bay.

Before the young scallops lose their byssal
threads, they are removed from the bags and placed
in pearl nets. As the scallops grow, they are transfer-
red to new pearl nets with larger mesh size. At about
4 cm, the scallops are either planted on the bottom or
placed in circular or book nets and resuspended from
the longline. The suspended scallops reach commer-
cial size, 10.5 to 1 1.0 cm, in about 2 yr. It costs the
fisherman approximately 14 yen/scallop to raise it to
market size using the longline method. In turn, he
can sell the scallop for 30 to 60 yen apiece.

Unlike the sea scallop fishery of the United
States, the Japanese save all the scallop shells.
These are bagged and shipped to the Inland Sea
where they are used as cultch for catching seed oys-
ters.

One of the principal laboratories involved in sea
scallop research is the Aquaculture Center located
on Mutsu Bay near the City of Asamushi at the
northern end of Japan's main island of Honshu. The
Center is a new installation that opened in April
1968. One of its largest programs is related to the
propagation of sea scallops. Their goal is to produce
1 million seed scallops annually using hatchery tech-
niques.

The Oyster Research Institute is also culturing
sea scallops at their tank farm.

Scallops are induced to spawn using both natural
and conditioned stocks. Over 200.000 seed scallops
are cultured annually. They are suspended from the
tank farm in book nets, circular nets, and pearl nets

until a size of 2 to 3 cm is obtained. The scallops are
then sold to local fishermen who grow them sus-
pended from rafts. When the scallops are approxi-
mately 5 cm in size, the fisherman drills a hole in the
ear(wing)of the scallop, threads a nylon line through
the hole, and ties it to ropes suspended from rafts.
They reach market size (12 cm) in about 2 yr (Cost-
low, 1969).

LITERATURE CITED

AUSTRALIAN FISHERIES.

1971. Australian studies Japanese fish culture techniques.
Aust. Fish. 30(IO):3-7. 9.
COSTLOW. J. D. JR. (editor).

1969. Marine biology. Vol. V. Proceedings of the Fifth In-
terdisciplinary Conference on Marine Biology. Gordon
and Breach. New York. 606 p.

FUJIYA, M.

1970. Oyster farming in Japan. Helgolaender wiss.
Meeresunters. 20:464-479.

FURUKAWA, A.

1971. Outline of the Japanese marine aquiculture. Jap.
Fish. Resour. Conserv. Assoc. Tokyo, .39 p.

IMAI, T.

1 967. Mass production of molluscs by means of rearing the
larvae in tanks. Venus 25:159-167.

JAPANESE FISHERIES ASSOCIATION.

1971. Fisheries of Japan - 1971. Jap. Fish. Assoc. Tokyo,
45 p.
KAN-NO, H., M. SASAKI. Y. SAKURAI. T. WATANABE.
and K. SUSUKl.
1965. Studies on the mass mortality of the oyster in Mat-
sushima Bay. 1. General aspects of the mass mortality of
the oyster in Matsushima Bay and its environmental condi-
tions. [In Japanese. English abstr.] Bull. Tohoku Reg.
Fish. Res. Lab. 25:1-26.
RYTHER. J. H.

1%8. Invertebrate and algae culture. In The status and
potential of aquaculture. particularly invertebrate and
algae cultures. Vol. I. Part U. p. 1-261. .Am Inst. Biol.
Sci.. Washington. DC . ( Distrib. by: Clgh. Fed. Sci. Tech.
Inf.. Springfield. Va.. as PB 177 767.)
R'l THER. J. H.. and J. E. BARDACH.

1968. The status and potential of aquaculture. In The status
and potential of aquaculture. particularly invertebrate and
algae culture. Vol. I, Part I, p. 1-45. Am. Inst. Biol. Sci..
Washington. D.C. (Distrib. by: Clgh. Fed. Sci. Tech. Inf..
Sprmgfield. Va.. as PB 177 767.)

110

CRUSTACEAN CULTURE

CORNELIUS R. MOCk'

SHRIMP, PENAEUS JAPONICUS

One of the most valuable marine species in Japan
is the "kuruma-ebi," Penaeiis japonicus, shrimp
fishery, which commands a price of 7-30 U.S. doUaFS
per kilogram, at the Tokyo Central Fish Market.
Although this price is high compared to U.S. prices,
it is due to the fact that the Japanese people demand
live shrimp for the preparation of a delicacy known
as tempura.

Over the years much time has been spent develop-
ing methods of holding this species in ponds and
rearing it to market size. Even though the Japanese
have successfully reared shrimp through several
generations, they explained that it was not economi-
cal to rear shrimp to sexual maturity because it was
time consuming and because the fecundity of the
females was reduced. Therefore, gravid females are
purchased directly from the commercial fishing
fleets and then spawned.

Once the eggs have hatched, the water is fertilized
to stimulate the growth of diatoms. Predetermined
amounts of fertilizer and seawater are added each
day to the tank until the larval shrimp have reached
the last mysis stage. Brine shrimp nauplii {Artemia
spp.) are fed from the last mysis stage through the
fourth postlarval stage. The shrimp are then fed
fresh meats of clams ( Venerupis philippinanini) and
mussels (Mytilus ediiUs), which are crushed and dis-
tributed throughout the ponds. Because it is too
costly and time consuming to separate the crushed
shell from the meats, the shell eventually covers the
pond bottom, resulting in a substrate that hampers
the burrowing of the shrimps. Thus, ponds must be
drained or dredged periodically to remove the shell
debris.

.Although larval rearing techniques are primarily
the same today as the> were 10 yr ago. research in

' Contribution No. .'4.' from the National Marine Fish-
eries Service. Biological Laboratory. Galveston. Texas.

- Gulf Coastal Fisheries Center. National Marine Fisheries
Service. NO.'X.A. Fon Crockett. Galveston. TX 77.s.sO.

shrimp culture has been expanded due to three im-
portant factors: 1) the rising demand and costs for
fresh food items to be fed to the shrimp: 2) the rising
wages of employees; and 3) disease problems en-
countered.

Of particular interest is the use of a by-product of
soy sauce production, a cake which is ground into
powder to fertilize the water. Not only does it stimu-
late the growth of diatoms, but the larval shrimp also
eat it. As the shrimp grow in size, this powder is
either extruded or pressed into a size suitable for
eating. At the Kagoshima Prefecture Fisheries Ex-
perimental Station, the Director, K. Shigeno, re-
marked that although the shrimp ate this artificial
food and grew to market size, the consumer was not
satisfied with the quality or color of the prawns. He
felt that the problem was primarily a vitamin defi-
ciency. Artificial foods with a variety of additives
are being tested at Shigeno's laboratory.

Research is also being directed toward rearing
prawns to market size in a closed system. A 1,000-m^
cement tank (23 m in diameter and 3 m deep) has
been built at the Tarumizu Kagoshima Prefecture
Fish Experimental Station. The water temperature
can be controlled, and a false bottom with airlift
pipes has been installed as an in-bottom filter.
Twenty-day-old postlarval shrimp have been
stocked in this tank and reared to market size with
good results. However, during two recent experi-
ments a number of problems occurred, resulting in
poor production.

Circulation of the water mass within a rearing
system was emphasized for either fish or shrimp
culture. At Tarumizu Kagoshima Prefecture Fish
Experimental Station the flow was maintained with
water jets, while a large mechanical stirrer was being
tested at Setonaikai Saibai Gyogyo Center. Tamano
Jigyojo.

At the Nansei Regional Fisheries Research
Laboratory. H. Kurata spoke about the natural
waves of P. Ja[>(>iii(ii.s postlarvae that enter the es-
tuaries. Monitoring of these waves now indicates

111

that recruitment is presently less than in previous
years. The total tonnage landed by the commercial
shrimp fleet is also down. Therefore, the concept of
seeding the system with (1.2 x 10") 20-day-old post-
larval shrimp is being tested to see if the system is
still a suitable environment, if production of shrimp
can be stimulated and ifnew areas can be used. Some
shrimp are released directly into the nursery
grounds, while others are placed in a pen (30 x 10 x
10 m) for 2 to 4 wk to acclimate them to estuarine
waters.

M. Fujiya, also of the Nansei Laboratory, began
physiological studies to measure the ""quality'" of
shrimp larvae reared in different ways, by observing
their reaction to anesthetics. His approach is to in-
sert electrodes into the brain of the shrimp and re-
cord their brain waves on an oscelloscope.

H. Hirata, at Kagoshima University, has begun
work on the production of single-species mass cul-
tures of diatoms and their preservation. At present,
diatoms are concentrated and later frozen at 0°C.
They can be held successfully for periods of 30 days
or less. Various other techniques are now being
tested.

Table 1 is part of a statistical report, translated by
Jiro Tanaka. Of particular interest is the number of
tons of P. Jiiponiciis cultured. Since 1967, annual
production has been about 300 tons. Although some
live shrimp are imported, the tonnage is far below the
market demand. The importation of frozen shrimp
has no direct bearing on the live shrimp market.

CRABS, PORTUNUS TRIBERCULATUS

Crabs, primarily Poriuniis trihcniiluins. have
been reared successfully to the 5th generation at the
Yamaguchi Fisheries Experimental Station. P.
trihcrciiUitiis is similar to the American blue crab.
Ccillinectes sapidus. Larval crabs in the zoea I-IIl
stages are fed rotifers, Brdchioniis plicatilis. which
are maintained on freshwater cultures oiClilorclla.

Older stages are fed Anemia, chopped tlsh, and
crushed clams. Since crabs are active and ditTicult to
maintain in a barren enclosure, a series of vertical
netlike structures were placed in the rearing pond.
The growth of natural filamentous algae upon these
structures serves as a hiding place for the crabs.

Unfortunately, fighting over territories and food
results in a high rate of mortality in the pond. Har-
vesting is accomplished by draining the pond and
raking the crabs, a process which is time consuming.
Although the price of these live crabs in United
States is$l. 10 each, their culture is not yet economi-
cally profitable in Japan.

A number of prefectural laboratories rear crabs to
the megalops stage and release them into estuaries.

FRESHWATER SHRIMP, MACROBRACHWM SP.

At the Tokyo University of Fisheries, Ogasawara
and T. Sano discussed the culture of freshwater
shrimp of the species Macrohrachiiim. Eleven dif-
ferent species were being studied. To rear the larval
stages, they indicated that a medium of 50^ fresh
water and 50% seawater was necessary. A diet of
Arteiniii. reared on a freshwater culture of
Chlorella. is fed during the larval stages along with
ground clam (Tapes sp.) meat. When the shrimp are
older, pieces of chicken egg shells are added to sup-
plement the calcium in their diets.

Juveniles of Macrohrachiiim rosenheri^i have
been reared on commercial trout pellets to market
size in 6 mo at the Izu Branch Laboratory. Although
results have been satisfactory, production costs
were not made available.

SPINY LOBSTER, PANULIRUS JAPOMCUS

At Kanagawa Prefectural Laboratory, research
on the spiny lobster, Panulirits japonicus, is being
conducted. Of particular interest is the work of
Inoue who has found that the phyllosoma larvae will

Table 1. — ."XRHual production (in metric tons) of cultured, naturally
caught, and \mipov\ed Penaeus japonicus. 1965-69.

Source

I%4

1965

1966

1%7

1968

1969

—Metric

211

2.479

.36.156

C'lilliired
Natural catch
Imponed'

154

3.184
17.087

95

3.010
21.011

307

2.338

44.466

311

1.884

32.204

295

1.585

48.886

' Prawns in

general.

112

feed on the arrow worm, Sagirta, which is collected
from the natural habitat. After a number of days, the
larvae are then fed Artemici nauplii. Although phyl-
losoma larvae have been reared in 180 days, their
size is smaller than those found in nature. They have
not yet reared the larvae to the benthic stage.

ACKNOWLEDGMENTS

Through the efforts and guidance of M. Miya-
niura, Vice-President of Technical Operations.

Marifarms Incorporated, Panama City, Fla., my trip
was quite fruitful. Not only did he provide me with a
list of places to see and letters of introduction, but
helped arrange for Jiro Tanaka to accompany me
while in Japan. Jiro Tanaka's assistance was in-
valuable.

Their pleasant attitude, cordial response, and vol-
untary gesture of discussing their research clearly
signified the willingness of the Japanese to cooperate
on this joint venture of mariculture.

113

MARINE FISH CULTURE IN JAPAN

JOHN B. GLUDE

INTRODUCTION

The concept of rearing fishes in floating net cages
in sheltered bays or in fish ponds supplied with sea-
water has been applied in Japan to several coastal
species of high value, and commercial ventures are
well established. In 1967 the production of cultivated
marine fishes in Japan amounted to 27,103 tons in
gross weight worth over $24 million and consisted of
98.6% yellowtails, 0.25% puffers or globefish, and
1.2% other marine fishes (Harada, 1970). Production
of yellowtail has increased remarkably in recent
years, as shown by the following table:

Yield of yellowtail culture
iFiirukawa. 1970)

Year

Tons

1961

2,579

1%2

4,758

1%3

5,083

1%4

9,493

1%5

18,083

1966

19,629

1%7

26,712

1%8

30,774

Production of puffers or globefish by aquaculture
has decreased year by year because of the shortage
of seed fish, and by 1968 was only 43 tons
(Furukawa, 1970).

A number of species of marine or anadromous
fish are being cultivated in seawater in Japan on
an experimental or commercial basis, as listed in the
following table:

Species oj fish cultivate tl in seawater in Japan

Seriota qiiinqueraJiata
Seriola purpurescens
Loiiiiirostrnin delicalissimus
Fui;u nihripes ruhripes
Chnsophiys iPai-nisl major

yellowtail

amberjack

striped jack

puffer (globefish)

red sea bream (red porgyi

A canthopagrus schleglii '
Sparus sarha
Oplegnathus fasciatus
Oplegnathus punctatus
Parolichthys olivaceus
Sehaslicus marmoralus
Oncorhynchus keta
Salmo gairdneri irrideiis
Sulvetinus phniiis

black sea bream (black porgy)

silver sea bream

Japanese parrotfish

spotted parrotfish

bastard halibut

scorpionfish

chum salmon

rainbow trout

steel head

' Deputv Regional Director. Northwest Region, National
Marine Fisheries Service. NO.\.A. Seattle. W.A 98109.

' Also listed as Mylio macroccphalus.

The short time available for the present survey in
Japan prevented a complete survey of the status of
aquaculture of each of the species listed above, and
the following summary is based on brief visits to
select locations and several published articles listed
below.

YELLOWTAIL CULTURE

Culture of the yellowtail, Seriola quinqueradiata,
is the most successful marine fish farming venture in
Japan, and production from farming now exceeds
landings from fishing of wild stocks. Yellowtail cul-
ture is conducted by individuals, companies, or
fishermen's associations in floating net cages and in
fish ponds which are made by partitioning sheltered
places from the sea with nets or earthen dams. The
great expansion during recent years is because of the
increase in the number of floating net cages, since
the number of locations suitable for ponds is limited.

Although spawning, fertilization, hatching, and
raising to seedling size have been achieved experi-
mentally for yellowtail, methods have not been de-
veloped to the stage that seedlings can be produced
in commercial quantities for the industry (Harada,
1970). Instead, young fish 5-15 cm in length are
caught 5-15 miles offshore during April and May.
Young yellowtail collect under floating patches of
seaweed, and the fishermen simply encircle a mass
of seaweed and catch the small fish which are placed
in small floating net enclosures. To conserve the nat-
ural resources, the Japanese Government has lim-
ited the number of young yellowtail which may be

115

supplied to all farms in the country from 28,363.000
to 30.780,000 per year (Harada, 1970).

The young yellowtail are reared in small net en-
closures for 1-2 mo until they reach a length of 25-40
mm. These seedlings are then placed in larger float-
ing net cages approximately 6 x 6 x 2 m in which
1, 500-2. .SOO fish can be kept. By December the yel-
lowtail reach a size of 1 .0-1 .5 kg and are shipped to
market.

In southern Japan where the minimum tempera-
ture exceeds ITC, it is possible to hold yellowtail
through the winter and sell them in April when they
reach a weight of 2-3 kg. but winter temperatures
farther north are too low for yellowtail. According to
Fujiya (1969), about 95% of the yellowtail are ship-
ped to market by December. Detailed descriptions
of yellowtail farming procedures are included in
papers by Harada ( 1970), Furukawa (1970). and Fu-
jiya (1969).

Problems of the industry include 1 ) a stable supply
of seedlings. 2) disease control, and 3) adequate food
supply or development of suitable artificial diets.

1 )Stahli' supply ofscedliniis. Production from yel-
lowtail farming is limited to approximately the pres-
ent level because of government restriction on the
number of young fish which can be taken from
coastal waters. According to Harada (1965), it is
highly desirable to produce seedling yellowtail by
artificial fertilization in a hatchery. This has been
accomplished recently on an experimental basis, but
has not been perfected for commercial application.
In the meantime. Harada recommends collecting the
seed (larval or juvenile fish) at as early a stage as
possible and keeping them under careful manage-
ment to reduce mortalities.

Although production could be increased by im-
proving growth rate, reducing mortality, or by ex-
tending the rearing time in places where winter water
temperatures are not too low. ultimate development
of the industry will require maintenance of a spawn-
ing stock, collection and hatching of eggs, and rear-
ing of larval stages to assure a dependable supply of
seedlings.

2) Disease control. The monogenetic trematode.
Beneclenia seriolae. infects the skin of the yellowtail
causing an unsightly appearance, loss of appetite,
weakening or death of the fish. This parasite is con-
siderably less resistant to low specific gravity than
the host fish and consequently is easily controlled by
dipping the infected fish in fresh water for a few
minutes and then returning it to seawater. The time

of dipping must be shorter in the summer (3 min at
26X ) than in the autumn (5 min at 16°C) to prevent
damage to the fish. Since this parasite grows very
fast and becomes adult within 2 or 3 wk. the freshwa-
ter treatment must be repeated frequently during
periods of infection.

Another monogenetic trematode. Av/'/ic iHeter-
axine) helerocercd. infects the gills of yellowtail
causing anemia which may kill the fish. Treatments,
according to Fujiya (1969). include 4-min bath in
water containing 4% salt. 2) dipping in a 1% solution
of "Tremaclean"" for 30 sec, and 3) oral treatment
by including "Bitin"" (4,5-dichlorophenol) in the
food.

The bacteria Vibrio can cause extensive infections
in yellowtail populations. Treatments include incor-
poration of sulfa drugs or antibiotics in the food.

Virus diseases are suspected, but no information
is available concerning these.

The feeding of oxidized, unsaturated fatty acids
contained in fish used as food causes nutritional
diseases of yellowtail. This can be prevented by
feeding white-meated fish instead of anchovy, mack-
erel, and sand lance.

3)Adeqiuitefo()cl supply or development of artifi-
cial diet. Farming of yellowtail in Japan depends on
availability of large quantities of cheap fish suitable
for use as food. These include mackerel, horse mack-
erel, anchovy, sand lance, and saury. With conver-
sion rates of 6: 1 to 8:1 the food must be obtained at
very low price in order to make yellowtail farming
economical. Expansion of the industry or perhaps
even continuation at the present level will require
development of artificial diets which will provide
better nutrition for the fish and reduce dietary dis-
ease problems. Furthermore, the artificial diet must
be available at a price which will permit economic
fish farming.

PUFFER CULTURE

Puffers, also known as globefish or blow fish of the
genus Filial, are in high demand as a luxury food in
Japan even though certain species are extremely
toxic. About 10 species of edible puffers occur in
Japan, but one species. Fuiiti ruhripes nihripes. is
used principally for farming ventures. The toxicity
of puffers changes seasonally, becoming the greatest
in the spawning season from May through June. The
toxic substance "Tetradotoxin" occurs mostly in
the ovary, liver, intestines and skin, and rarely in the
muscle. When prepared carefully by licensed cooks

116

in Japan, puffers are completely safe to eat.

Production of puffers in fish farms has decreased
during recent years because of a shortage of seed-
lings, as indicated in the following table:

Yeur

Prodi.

iilidii ill tons

1964

86

l%5

91

1966

82

1967

53

1%8

43

The farming of puffers is generally carried out in
the warmer part of Japan since the puffers require
water temperatures between 10°and 29°C. Of the 14
management units in Japan, 8 are located in the Seto
Inland Sea. 4 in the west Japan Sea area, 1 in the
east China Sea, and 1 in the north Japan Sea area.

Traditionally, puffer farming depended on the
capture of partially grown fish in the spring, rearing
these fish to market size in net enclosures, and mar-
keting them in the winter when demand and price
were high. Larger fish, 40-60 cm in length, weighing
1.5 to 2.5 kg, can be fed in enclosures from spring to
early winter and then shipped to market. Younger
fish, about 200 g when captured, require another
year before reaching market size.

Methods for artificial propagation of puffers were
developed in Japan in 1960 and are now used com-
mercially. Seedling fish of about 3 g are transferred
from the hatchery to the growing net cages in July
and should average 550 g by August of the following
year. At the end of \V2 yr, the puffers should reach
800 g, the minimum market size, and after one addi-
tional year should weigh 1.5-2.0 kg.

The procedures for rearing puffers are similar to
those used in the culture of yellowtail. Since both of
these fish are carnivorous, fresh or frozen fish, such
as horsemackerel. mackerel, anchovy, sand eel, and
saury are used for food. Minced flesh is recom-
mended for fish less than 100 mm in length, but larger
fish can be fed chopped flesh.

The fish are fed 4 times a day during midsummer, 3
times a day from September to November, and less
frequently during the winter and early spring. Puf-
fers stop feeding in winter when the water tempera-
ture falls below 1 4°C , and this causes a weight loss of
about 109?- during the winter.

Expansion of puffer farming will require greater
production of seedlings through artificial propaga-
tion. Detailed description of procedures used in the
farming of puffers is gi\en by Fujiya in his 1969
paper. "" Farming Fisheries in Japan."

BLACK PORGY CULTURE

The Japanese black porgy, or sea bream, Mylio
macrocepluiliis (also listed as Acanthopui^riis
schlegelii), is a nonmigratory species found in shal-
low water along the coasts of Japan, Korea, Taiwan,
and China. The annual catch of this species in Japan
is 3,600-3.900 tons, about 65% of which is landed in
the Seto Inland Sea (Fujiya, 1969). Black porgy can
be raised in floating net cages or seawater ponds;
and. since this species is more resistant to lower
temperatures than some other species which are
used in aquaculture, the geographical range suitable
for farming is greater. Black porgy are reported to
stop feeding at water temperatures below 10°C but
can survive temperatures several degrees colder.

The species is omnivorous, feedling on mollusks,
crabs, polychaete worms, and seaweeds, so a vari-
ety of waste fishes and unutilized mollusks can be
used as food. With the conversion rate of 3 or 4:1 in
experimental scale farming reported by Fujiya
(1969) forfresh fish diets, commercial culture should
be economical. Market size fish reportedly can be
produced within 16 to 20 mo.

Black porgy farming using "natural seedlings" is
of two types, depending on the size fish which can be
obtained. Small seedlings, 1 to 4 cm in length, are
caught along the coast by seines from late May to
late July. These small fish are put in fine-mesh float-
ing cages for 1-2 mo and then transferred into larger
mesh net cages. Market size fish, about 150 g, can be
expected within 15-18 mo.

The second type of farming depends on capture of
seedlings, 10-15 cm in length (30-50 g in weight), in
set nets or by angling from May to July. Fish of this
size will reach market size after about 6 mo of feed-
ing in floating net cages.

The limiting factor in farming of black porgy is the
supply of seedlings from natural reproduction.

Methods for artificial propagation of black porgy
have been developed in Japan and with a suitable
increase in production of seedlings, porgy farming
can be greatly expanded. Further details concerning
the farming of black porgy are given by Fujiya
(1969).

RED PORGY CULTURE

The red porgy or sea bream, Chrysophrys (Piii;-
nis) major, known in Japan as the "tai" or"madai"
is in great demand since it is the traditional fish
served at celebrations. The commercial catch of sea

117

breams in Japan was nearly constant from 1965 to
1967, butduring 1968 and 1969 decreased slightly to a
level of about 30,000 tons (Japan Fisheries Associa-
tion. 1971).

Research on the farming and artificial propagation
of red porgy began in Japan over 70 yr ago but was
generally unsuccessful until recent years. In 1958
research on artificial propagation was intensified
with more modern facilities are equipment and suc-
cessful results were obtained on an experimental
scale in 1962. By 1965 an experiment in the propaga-
tion of red porgy using artificially produced seed-
lings succeeded at the Propagation Center in the Se-
to Inland Sea. It now appears that a basis has been
established for expansion of red porgy farming, but
this knowledge has not yet been commercially ap-
plied (Fujiya. 1969).

The Association of Marine Stock FarmoftheSeto
Inland Sea was incorporated in 196.'^ to increase the
fisheries resources of the Inland Sea of Japan by
releasing young marine fishes. In 1958, this Associa-
tion produced 166,686 red porgy in a hatchery and
released them into the Inland Sea. The effectiveness
of these plantings in supplementing natural stocks is
now being investigated. The success of this hatchery
also portends the expansion of commercial farming
of the red porgy.

According to Fujiya (1969). larvae of the red
porgy, 2 to 3 cm in length, are usable as seedlings.
They have been grown successfully in floating net
cages using fresh fish meat or pellets as food and
reach market size in 12 to 18 mo.

CULTURE OF OTHER MARINE FISHES

Several other species of marine fishes are being
cultured in Japan on an experimental or limited
commercial basis. These include amberjack, Seriola
purpurescens, and the striped jack, Longirostniin
ch'licdtissiniiis. Both of these species can be cultured
by using the methods which are so successful with
the yellowtail. Teruo Harada of Kinki University is
conducting large-scale experiments in the culture of
these species at the University facility at Shirahama
in Wakayama Prefecture. Commercial culture of
these species is especialK attractive because there is
a demand at prices considerably higher than those
for yellowtail.

Al the same research facilit\ Harada is studying
the artificial culture of many other species of fish
including the Japanese parrotfish, Oplciiiuithiis fas-
iititiis. and the spotted parrotfish. O. piincidtiis. and

the flatfish. Paralkhlhys olivuceus. Ptiralichthys is
in high demand at a price 4 times as great as for
yellowtail, so artificial propagation of this species
should be profitable. Harada et al. (1966) described
growth and rearing methods for the fry of the floun-
der, Paralichthys olivaceus, obtained by artificial
fertilization.

The silver sea bream. Spurns xarbci, is also being
studied at the Shirahama field station of Kinki Uni-
versity.

Another marine fish Sehci.sticiis inarniorcitus.
known as the scorpionfish is artificially produced in
the hatchery of the Association of Marine Stock
Farm of the Seto Inland Sea, and 125,536 juveniles
were released into the Inland Sea in 1968. Similar
releases of sea breams are being made by the Nansei
Regional Fisheries Laboratory, many of which are
tagged to evaluate the success of these plantings.

TROUT CULTURE

Trout have been raised in Japan in fresh water for
domestic and export markets for many years and
standard rearing methods have been developed.

Recently, methods have been developed for cul-
ture of rainbow trout, Salino iiuirdneri irricleiis. in
the marine environment. Three Fishermen's
Cooperative Associations in Japan are now rearing
trout commercially in the protected waters of coastal
bays and estuaries; the most recent a new venture at
Ogatsu Bay in Miyagi Prefecture.

Procedures for marine culture of rainbow trout
described by Akimitsu Koganezawa, Chief of Shell-
fish and Fish Research for the Miyagi Prefectural
Station, are as follows:

Rainbow trout spawn in December in this part of
Japan and are raised in fresh water until the following
September or October. At that time they are accli-
mated to salt water over a period of 12-20 days by
gradually increasing the salinity to that of the marine
environment which is about 34"/(iii. Koganezawa has
determined that mortality during acclimation can be
minimized by increasing the salinity lO'r each day
except at the levels of 409^ and SOCf of the salinity of
seawater which appear to be more critical. The fish
are therefore held at least one extra day at these
salinities.

At the time of transfer to the sea the trout weigh
100-150gand are about lK-23cm in length. The trout
are harvested the following August at 1 .5-2.0 kg, but
some may reach a size of 3.4 kg.

Maximum survival during the marine phase of this

118

aquaculture system is 90%; minimum survival is
60%; mean survival is about 709f . Bacteria of the
genus Vibrio are the major cause of mortahty, but
infections can be controlled to a certain extent by the
use of nitrofuran. sulfa drugs, and terramycin. In the
United States, nitrofuran probably could not be used
for this purpose since it has not been cleared for use
in treating food products by the Food and Drug
Administration.

A new commercial trout farming project was ob-
served at Karakuwa at the head of Ogatsu Bay dur-
ing October 1971. This project, which is operated by
Fishermen's Cooperative Association with the gui-
dance of Koganezawa, included shore-based
facilities for rearing trout and acclimating them to
seawaterand a series of net enclosures for culture of
the trout in the marine environment.

Shore facilities included six circular concrete
tanks, 12 m in diameter and 2.5 m deep, with four
more to be built. The fish will be reared for approxi-
mately 1 yrin these tanks before they are acclimated
to seawater and transferred to the floating net en-
closures. This year, since the project was just begin-
ning, the fish were raised at another location and
were brought to Karakuwa for acclimation to salt
water and transfer to growing pens. A system of
large plastic pipes makes it possible to drain each of
the large round tanks to transfer the 14,000 trout
which will be acclimated in each tank into a long
drainage channel which takes them to the shore
where they can be transferred through pipes into the
floating pens.

The floating pens are anchored in Ogatsu Bay
which is well protected from storms by steep hills.
The water in this area is 10-30 m deep and varies in
temperature from above 8°C during the winter to a
maximum temperature of 23-25°C during the sum-
mer.

The fish are fed ground raw fish and meal, making
a product similar to Oregon moist pellets which is
used in U.S salmon hatcheries. This food has been
found to be better than dry pellets.

Only female trout are used in this type of culture as
they are more disease resistant and are easier to
acclimate to seawater than males. Also, females can
mature in the sea in 2 yr producing healthy viable
eggs, whereas males require fresh water to become
mature. The sorting of male trout from female trout
at a size of 18 cm is a time consuming operation.

The price of marketable trout 1.5-2.0 kg in weight
is 450-550 yen ($1.46 to Si. 79) per kilogram in the
Tokyo fish market. This is about the same price as

yellowtail Seriola. whereas smaller rainbow trout
which weigh 150-200 g each sell for 250-300 yen
($0.81 to $0.97) per kilogram. In comparison, salmon
from natural production sell for 600-800 yen ($1 .95 to
$2.60) per kilogram.

One of the problems of raising rainbow trout in net
enclosures is that they have tender skin and may lose
some scales rubbing against the netting which may
permit the entrance of the bacteria Vibrio. Japanese
scientists have found that adding 10 jig of testos-
terone per gram of food will increase the mucous
production in skin which will protect the scales from
erosion. It is unlikely that testosterone could be used
in the United States for this purpose because it is
considered to be a carcinogen.

Another trout, Salreliniis pliivius, known as the
steelhead, is being reared experimentally in seawa-
ter at the Miyagi Prefectural Field Station at Ogatsu
Bay. According to Koganezawa, S. pluvius spawns
in the headwaters of streams, is very resistant to
changes in temperature, and can be successfully ac-
climated to seawater. Therefore, this is considered a
good species for aquaculture, although it is not
reared commercially at the present time.

SALMON CULTURE

The first Japanese pilot-scale experiments in cul-
ture of salmon in floating net pens in the marine
environment are being conducted at Yamada Bay in
Iwate Prefecture. Yamada Bay is completely en-
closed except for a narrow entrance where the water
is reported to be 90 m deep. Hills protect the inner
bay from storms making it an ideal location for
aquaculture. The Bay is about 60 m deep in the
center, but 15-25 m deep in the area where the
salmon culture rafts were anchored.

The objective of these experiments at Yamada
Bay which was visited in October 1971 is to perfect
methods which could be used commercially to rear
salmon to marketable size in the sea.

The first experiments were with the chum or dog
salmon. Oncorhynchus keta. which had been
hatched at Fishermen's Cooperative Association
hatchery at Miyako Bay just north of Yamada. This
hatchery which is located on the Tsugaruishi River
has a capacity of 50 million eggs and is one of the
many hatcheries operated by local Fishermen's
Cooperative Associations. These hatcheries take
eggs from chum salmon in November, December,
and January when the fish enter the streams, or
occasionally from those salmon which are caught in

119

trap nets in the bays. Afterthe eggs hatch, the fry are
reared until April in an effort to reduce the mortality
of fry which they estimate as 509f in the streams plus
a significant mortality during the month which the
fry spend in shallow bays before going to the sea.

The eggs used in the experiment at Yamada were
hatched on 22 February 1971 and began feeding on 8
April. They were held at the hatchery at Miyako Bay
until 10 May because the holding tanks at Yamada
had not been completed. After transfer, the salmon
were held in fresh water at Yamada until 28 May
when the seawater system was completed. Transfer
to salt water was accomplished in about 24 hr with no
significant mortality.

Because of the delay in completing the floating net
enclosures the small salmon were held in seawater in
tanks ashore until August when the temperature in
the tanks reached 25.8°C. They were then trans-
ferred to the sea. but even there temperatures
reached 24.4°C. These temperatures were too high
and the mean survival was only 42%, although
individual lots had survivals as high as 90%.

According to Chikara lioka, who is in charge of
this Iwate Prefectural Experiment Station, they will
normally rear the salmon in fresh water until June or
July and transfer them into floating net pens before
midsummer. Even so. it appears likely there will be
significant mortalities from diseases such as Vibrio
since surface water temperatures usually reach a
maximum of 22°C according to lioka. Furthermore,
the thermocline is deep in this area, according to
lioka's measurements, and the maximum tempera-
ture difference between the surface and a depth of 60
m is less than 4°C. In midsummer there appears to be
only \°C difference between the surface and bottom
at a depth of 15-25 m where the salmon culture pens
are anchored.

National Marine Fisheries Service experiments
with salmon culture in Puget Sound, Wash., have
indicated increased mortalities due to i'ihrio when
scauatcr temperatures exceed 15^C. On this basis it
appears likely that the high summer temperatures at
\'amada Bay will bo a limiting factor to salmon cul-
ture imless methods can be developed for preventing
or reducing Vibrio infections.

Three kinds of net enclosures were being tested by
lioka and his associates. One type was a floating net
pen similar to those used for the culture of trout or
yellowtail. but with some refinements in the design.
These enclosures were about 6 or 8 meters square
and about 3 m deep with nearly 1 m of the sides above
the surface of the water. The lops were covered w ith

a coarse mesh to exclude birds and the sides and
bottoms were made of about 8 mm square mesh.
These enclosures contained 4,000 young salmon
which by October had reached a length of 20-25 cm.
Another similar pen contained 300 2-yr old salmon
which appeared to be about 40-50 cm in length. lioka
reported that these floating surface pens were satis-
factory except that the nets had to be changed every
month because of heavy fouling by seaweeds.

The second type of enclosure was a middepth pen
which was located at a depth of 10 m to the top of the
net. The enclosure was 10 meters square and 7 m
with a top and bottom. Even at this depth the heavy
growth of seaweed required changing the net about
every 3 mo.

The third type of enclosure was a large octagonal
net 55 m in diameter which extended from the sur-
face to the bottom and was anchored in position. The
net was supported by a series of floats at the surface
and held in contact with the bottom by a lead line.

A horizontal section of fine mesh at the surface
extended inward about 3 m from the vertical walls
and the inner border was supported by net floats
placed about 4 inches apart. lioka had found that the
fish made no attempt to jump over the inner row of
floats and indeed found refuge and shade under the
floating section of the net which rapidly became
fouled with seaweeds.

Feeding was accomplished by rowing a boat over
the top of the net into the center of the pen where the
food was thrown into the water.

Predation by diving water fowl was prevented by
stretching twisted bright-colored plastic tape. I Vi to
2 cm wide, across the enclosure at intervals by tying
it to vertical supports so that it was about I m above
the surface of the water. The apparent movement of
this tape caused by the wind seemed to scare the
birds away. The same system is used to keep birds
away from the rice fields.

The young salmon were fed a dry pellet food that
had been developed for feeding rainbow trout in the
sea. and this was found to be fairly satisfactory. The
fish were fed 3 times a day. and the pellets were
mixed with water before feeding. The Japanese sci-
entists stated it is important to mix the food with
fresh water so that the fish have a source of fresh
water to replace that which the> would normally
receive by eating other fish.

The objective of the Yamada Experimental Sta-
tion is to develop methods for commercial salnmn
culture soanumberofexperimentsarein progress or
planned. Experiments by Koganezawa et al.. re-

120

ported in 1968, indicated that chum salmon grow
more rapidly in brackish water than in fresh water or
salt water. These experiments are being repeated at
Yamada to develop procedures for increasing
growth rate during the time that the tlsh are held in
tanks on shore.

Also, ne.\t year lioka and his associates plan to
transfer chum salmon fry to salt water at various
ages from 9 to 90 days in order to determine the
optimum time. They also would like to test other
species, such as the pink salmon, O. gorhushci, and
the king or chinook salmon, O. tsluiwyr.sclia, from
Hokkaido, and possibly the coho salmon, O.
kisutcli, from the United States.

In summary, the Iwate Prefectural salmon culture
station at Yamada is located at a delightful place for
experimental aquaculture. The only limiting factor
appears to be the high temperature of the water
during the summer and the adverse effects of this
may be overcome by selection of species or races of
salmon, use of hybrids, or treatment to prevent or
alleviate the effects of Vibrio and other diseases
which are accelerated by high temperatures. Both
domestic and export demands are excellent and it
appears probable that commercial salmon culture in
the marine environment will be economical.

BIBLIOGRAPHY

FUJIYA. M.

1%9. Farming fisheries in Japan. Long Island Univ., Grad.
Dep. Mar. Sci. [Processed.]
FURUKAWA, A.

1971. Outline of the Japanese marine aquiculture. Jap.
Fish. Res. Conserv. Assoc. Tokyo. 39 p.
HARADA.T.

196.'!. Studies on propagation of yellowtail (Seriola qiiin-
qiiertiiliiito T. & S. ) — with special reference to relationship
between feeding and growth offish reared in floating net
crawl. [In Japanese. English abstr.] Kinki Univ.. Mem.
Fac. Agric. Vol. 3. 291 p.
1970. The present status of marine fish cultivation research
in Japan. Helgolander wiss. Meeresunters. 20:594-
601.

HARADA, T.. H. KUMAl. K. MIZUNO. O. MURATA. M.
NAKAMURA. S. MIYASHITA. and H. HURUTANl.

1971. On the rearing of young bliicfin tuna. [In Japanese,
English abstr.] Kinki Univ.. Mem, Fac. Agric. 4: 1. '53- 1.56.
HARADA. [., K. MIZUNO. O MURATA. S.
MIYASHITA. and H. HURUTANl.

1971. On the artificial fertilization and rearing of larvae in
yellowfin tuna. [In Japanese. English abstr.] Kinki Univ.,
Mem. Fac. Agric. 4:145-151.
HARADA, T., S. UMEDA, O. MURATA. H. KUMAI. and
K. MIZUNO.

1966. On the growth and rearing methods of the fry of
\\\V2ime (Paratkhlhys olivuceus) obtained by artificial fer-
tilization. [In Japanese. English title) Kinki Daigaku
Suisan Kenkyusho Hokoku (Kinki Univ., Fish. Res. Lab.
Rep.) 1:289-303.

INOUE. M.

1970. Possibility of tuna cultivation and propagation. [In
Japanese. English abstr.] Tokai Univ. Collect. Repr.,
Coll. Mar. Sci., Technol. 4:195-210.

JAPAN FISHERIES ASSOCIATION.

1971. Fisheries of Japan. Jap. Fish. Assoc. 45 p.
KOGANEZAWA. A.

(No date but after 1%6.) Surface culture of salmon and
trout and some problems thereof. [In Japanese.] J. Fish.
Oceanogr. Res. Soc 17:95-101.
KOGANEZAWA. A.. N. ISHIDA. and K. GOTO.

1968. Studies on several diseases of fingerling dog salmon
(Oncorhynchus kela). [In Japanese. English title.] Bull.
Miyagi Prefect. Fish. Exper. Stn. 4:1-7.
KOGANEZAWA. A., N. ISHIDA. K. SUZUKI. K. GOTO,
and H. ABE.

1968. Studies on the growth ot fingerling dog salmon
(Oncorhynchus kcla) in relation to salinity. [In Japanese,
English title] Bull, Miyagi Prefect. Fish. Exper, Stn.
4:1-6.
(No date.) Comparative study of surface and mid-depth
live pens for rearing chum salmon and rainbow trout. Fish.
Cov. Eng. 3(2):37-40.
OKIYAMA. M.

1967. Study on the early life history of a flounder,
Paralkhlhys otivaceus (TEMMINCK et SCHLEGEL).
I. Descriptions of postlarvae, [InJapanese. English abstr.]
Bull, Jap, Sea Reg. Fish, Lab, 17:1-12,

1970, Studies on the early life histor> of the rainbow runner.

Elagiitis bipinniilaliis (Quoy & Gaimard) in the Indo-Paci-

fic Oceans. [In English. Japanese abstr.] Bull. Far Seas

Fish. Res. Lab. 3:167-186.
UDA. M.

1970. Recent advances in fisheries oceanography of Japan

from 1967 to 1969. Jap. Soc. Fish. Oceanogr. Advan. Fish

Oceanogr. 3:171-185,

121

SOME IMPRESSIONS REGARDING GENETICS AND
THE FISHERIES OF JAPAN

A. CROSBY LONGWELL'

INTRODUCTION

This report is based on a tour of Japanese
laboratories concerned with aquaculture or subjects
pertinent to it, 8-13 October 1972; and on atten-
dance at the Second International Ocean Develop-
ment Conference, Tokyo, Japan. 5-7 October 1972.

Tour included: Oyster Research Institute at
Kesen-numa on Mohne Bay; Pearl Research
Laboratory of the Fisheries Agency at Kashiko-
jima, Mie-ken (Director, T. Hayashi); Ocean Re-
search Institute of the University of Tokyo; Nikko
Branch of Freshwater Fisheries Research Labora-
tory at Nikko on Lake Chuzenji (Director, K. Ono-
dera); Tohoku University School of Fisheries; To-
hoku Regional Fisheries Research Laboratory.

BACKGROUND INFORMATION ON
GENETICS IN JAPANESE FISHERIES

There has been, in the past, no overall, concerted
effort at applying genetics to the aquaculture en-
deavors of Japan which are without dispute the most
extensive in the world. Now, however, in conjunc-
tion with a national research program on aquaculture
it appears that some special committee on the appli-
cation of genetics to aquaculture is being organized.

Since the advent of genetics at the turn of the
century, Japan has had a number of highly trained
geneticists, many of world renown, invariably prom-
inent at International Congresses of Genetics.
Breeding sciences and genetics are regarded impor-
tant enough for school children to memorize the
names of famous Japanese (Kihara) and American
(Sears) wheat geneticists. Genetic applications to
breeding have, however, been with few exceptions
in agriculture not in fisheries, the same situation as in
the United States.

' Milt'ord Laboratory. MACFC. National Marine Fisheries
Service. NO.A.A. Milford. CT 06460.

Japan has had nothing at least in recent years
equivalent to the symposium the Russians held in
1968, "Genetics, selection, and hybridization of
fish," published in 1969 (Cherfas, 1969), and trans-
lated in 1972 through the auspices of the National
Oceanic and Atmospheric Administration. (Nor has
the United States.) It is relatively in recent years that
there has been a reinstatement of Mendelian,
"Western" genetics in Russia after years of
propaganda — serving Lysenkoism (which proposed
that most of "heredity" was due to environment).
Perhaps the Russians, with all vested interests in
traditional fields of genetics disbursed, are now more
free to address the reestablished discipline of ge-
netics to the new research challenges of the time
of which aquaculture is certainly one.

In any comparison of the application of genetics to
agriculture and to fisheries, irrespective of what
nation's research programs are being discussed, it
should be noted that even prehistoric man was work-
ing on the cultivation of land crops and domestica-
ting animals. Modem man, on the other hand, is still
for the most part content, correctly or incorrectly,
with leaving marine organisms wild. University
schools of fisheries are dedicated to the advance-
ment of the science and art of fishing wild fish in the
wild. No doubt, this is partly the result of man's lack
of day-to-day familiarity with aquatic organisms,
one measure of his failure to control the seas as he
does land. Also, the advance of civilization necessi-
tated the promotion and ultimate success of agricul-
ture as wild crops and animals disappeared in its
wake. In the same way pollution of the seas may
assure the promotion of aquaculture over the span of
the next few decades.

Whatever the background reasons only presently
is genetics beginning to be applied to the fisheries in
Japan, which rank among the most important indus-
tries of this island nation. By contrast triploid seed-
less watermelons are bred in Japan from sterile
crosses made between special lines, and giant.

123

highly polyploid apples are sold at railroad station
food stands.

Until now there has been no pressing economic
necessity in Japan to employ genetics to produce an
organism better able to perform in an intensive
aquaculture system. Aquaculture could be ineffi-
cient, depend on capture of young wild animals or
gravid females for a kind of semifarming. be labor
intensive, and still be worthwhile as a means of pro-
ducing food and obtaining an income. This is no
longer the case, and the change may be attributable,
in part, to rising labor costs and to increasing de-
mands for high quality seafood by a population with
a higher living standard.

EXPANSION OF INTENSIVE AQUACULTURE,

A PREREQUISITE FOR GENETIC

APPLICATION

Certainly, the genetic study of wild fish popula-
tions has some profound implications for fishery
management. Genetic knowledge of wild popula-
tions, in addition, makes for more judicious selection
from such wild populations of the founding popula-
tions used to breed hatchery stocks with particular
characteristics. The hatchery breeding of special,
though still undomesticated, stocks for release to the
wild represents still another area of genetics little
considered in the fisheries. Such methods have been
employed in forestry and grassland management, at
least, in the United States. However, the deliberate
severe alteration of the genotype of the wild or-
ganism, which aquaculturists need to transform the
wild fish or invertebrate into a domesticated or cul-
tivated form, requires, to begin with, intensive and
fairly successful aquaculture of the organism. For
that reason, it is important to note here the current
status of aquaculture programs in Japan.

At the opening of the Oceanoiogy Conference in
Tokyo (Second International Ocean Development
Conference. 1972). it was indicated in a special talk
that one of five major projects recommended by a
special Council for Ocean Development created in
July 1969, as an advisory organ to the Prime Minis-
ter, was the development offish culture with under-
sea experimental farms. This is, it was explained,
because Japan's coastal fishing has declined owing
to pollution and overfishing, because of the exclu-
sion of Japan from some fisheries in their part of the
world by neighboring nations, and because of an
intensification of the world "fishing race." New
fishing grounds will be developed and underutilized

species exploited. Still of great importance, the
Council believes, will be the switchover in the fish
industry to farming-type endeavors. The necessity
of breed improvement for maximum success in such
intensive culture under artificial conditions seems to
be well understood.

At the same conference Akio Honma from the
Fishery Agency. Ministry of Agriculture and Forest-
ry, gave a presentation on ""Fish farming in Japan."
Honma said that in the fishing field, farming, along
with concomitant management and breeding, has
been applied in the past only to a few freshwater
species and to a few species of seaweeds and crusta-
ceans. Over the years 1962-1966 the government's
Fishery Agency established five Fish Farming Cen-
ters to encourage coastal fishing in the Seto Inland
Sea. The entire Seto Inland Sea is being considered
as one huge pond. Several important marine species
are to be preserved and multiplied. Fry are bred at
the centers and released to the prefectures for raising
and releasing. In this program for the Seto Inland
Sea a certain period of growth will be left to nature
eliminating the necessity of using cheaper fish for the
farming of more expensive fish.

Catching and releasing fry, as a source of seed,
proved entirely inadequate. Seed breeding from arti-
ficially spawned animals is now the work of the
project. It was found that, on the whole, breeding
techniques were inadequate for the scope of the un-
dertakings. (Here, genetic improvement in repro-
ductive performance under artificial conditions
could lead to better breeding techniques in the
hatcheries as an intermediate step in the total pro-
gram. Nothing was said of this. ) The main w ork of the
center is now accordingly the development of mass
production schemes. As the need arises, fishing ex-
periment station and university personnel work to-
gether at the center.

It has become the policy of the government to
subsidize research work for seed production to some
nongovernment public corporation where they be-
lieve management is better. Seed production is the
area to which most money is now being directed.

Efforts are now being made to rear artificially
produced fish to maturity in larger tanks so that they
can subsequently be used to breed another genera-
tion. When this is accomplished, of course, geneti-
cally controlled breeding will be possible.

Systematic work in the release and control of seed
has been limited since so much of the project had to
be aimed at developing seed and better seed-
producing techniques. It was found that, if young

124

prawns are protected for a certain period and re-
leased after adapting them to natural water, 5 to 10%
of the released numbers can be harvested.

As a result of this program, prawn has been pro-
duced on a commercial scale. Also red sea bream,
octopuses, globefish, scorpionfish, sea-eel. blue
crab, and abalone. The prawn project is emerging
from its experimental to a semibusiness stage.

The prawn commonly cultured in Japan is Pen-
aeiis juponiciis. It is one of the most expensive of
seafoods in Japan. Artificial culture techniques for
this species have been developed over the last 10 yr
by fisheries biologists and professional aquacul-
turists. Despite a number of technical and
socioeconomic difficulties in the commercial pro-
duction of prawn in Japan, it is evident to the
Japanese that an increasing demand for prawn and
shrimp will stimulate the development of its culture
as an industry wherever in the world it is at all
feasible. Culture should be particularly promoted in
the untouched, widely ranging swamplands in the
tropical zones. However, presently in Japan, poor
culture techniques, defects in the present system of
intensive culture, laborious rearing operations, ris-
ing land costs, and unfavorable rearing conditions
owing to pollution make for unstable and costly pro-
duction on prawn farms. A decrease in artificial pro-
duction is anticipated. Culturists wonder whether
prawn farms can even be maintained in Japan in
competition with more productive enterprises. Yet,
an overwhelming demand continues to exceed pro-
duction even though at the Tokyo Central Fish Mar-
ket a kilogram of live prawn has been sold for as
much as 8 to 30 U.S. dollars (Second International
Ocean Development Conference, 1972).

The prawn fishery.justasthe shrimp fishery in the
United States, might well be the fishery that would
benefit monetarily most quickly from a well-
integrated, sensibly supported genetics program.

Experimental studies on the hybridization of the
freshwater shrimp are being carried on at the Tokyo
Fisheries University (Uno and Fujita, 1972). Cross-
es of Macrohracliiiim nippoiiense Q x M. for-
luoscnsc -i" and reciprocal crosses were reared
from the larval stage to sexual maturity. Morpholog-
ical comparisons of hybrids to each parent were
made. These interspecies crosses were achieved by
exposing the excised spermatophores to 50% seawa-
ter for 15 to 30 min. and then attaching them to the
ventral thoracic part of the female of the other
species just before she spawned. Such hybrids could
have advantages over nonhybrids for intensive

aquaculture under artificial conditions, or for "col-
onization" of a new area in the wild.

POLLUTION AND INTENSIVE AQUACULTURE
WITH "SEMIDOMESTICATED " STRAINS

Possibly, even before breed improvement, with
concomitant genetic adaptation to the cultivated
state, aquaculture of some ""semidomesticated"
forms will become a success with the disappearance
of their wild progenitors from Japan's coastal wa-
ters, or when these wild forms accumulate enough
contaminants to become unfit for human consump-
tion. Oyster seed production has been eliminated
from around the City of Hiroshima with implications
for the entire fishery. Yet. while pollution of wild
stocks and their demise by marine contaminants may
make some aspects of commercial hatchery produc-
tion more attractive, too widespread pollution would
render even artificial production in natural seawater
virtually impractical. The Japanese regard the future
success of artificial culture to be intimately tied to a
resolution of pollution problems.

APPLIED AND BASIC GENETIC RESEARCH
TO SUPPORT FISH BREEDING

For many years Japan has emphasized applied
research in the fishing fields. A system of extension
services for the fisheries is well established. In the
United States the Sea Grant Program stresses ap-
plied research and extension services, but Japan is
looking in the opposite direction. Unlike the Ameri-
cans, the Japanese have made near maximum and
efficient use of applied research. Now, Japanese
scientists actually carrying out the work and their
research administrators alike are of the opinion that,
to increase further the productivity of their fisheries,
more basic research is required. In the past, such
research has been largely confined to universities
where it has not been well funded and to special
national institutes. Basic research, they believe, is
necessary to develop reliable means of carrying reg-
ularly large numbers offish from egg through sexual
maturity, and this in the face of serious pollution.
Such work should be deliberateh associated with
breed improvement programs, and the Japanese
recognize this. Even if the\ did not. some useful
genetic selection would occur inadvertently.

Food and disease appear to be presently regarded
as more important constraints on aquaculture gener-
ally than lack of special breeds. However, the

125

Japanese regard water quality — pollution — as the
current most serious point to consider in establishing
aqua-farms. In considering this ordering of pollu-
tion, nutrition, then disease, then genetics, in terms
of priority, it should be noted that:

1) Genetics will not succeed in accomplishing
much of anything if the animal, to begin with, is not
reasonably easy to culture;

2) but that genetics can in an early stage of
aquaculture contribute to the development of types
better able to utilize artificial foods, resist disease,
be more vigorous, and develop good gametes;

3) so nutrition, disease, and genetics should not be
regarded, either in the United States or Japan, as
three separate research entities — they overlap.

STORAGE OF STOCKS AND COLLECTIONS
FOR BREEDING PURPOSES

A directory prepared for distribution at the
Twelfth International Congress of Genetics, Tokyo,
1968, lists important genetic stocks of plants and
animals and microorganisms being maintained in na-
tional universities (Oshima. 1968). Tohoku Univer-
sity, Faculty of Agriculture, is named as holding
oyster stocks, but no other fish stocks are listed.
There are plans for establishing future "storage"
centers to maintain genetic stocks. Fish are not men-
tioned in these proposals for storage of genetic
stocks prepared by classic geneticists. "Stocks
would be managed by an expert geneticist so that
uncontrolled, random breeding" of the closed stocks
would not result in genetic changes in the stocks
making them unrepresentative of the genotypes of
the wild populations or cultured lines from which
they were sampled for preservation.

JAPANESE GENETICISTS

In this same directory, names of 944 Japanese
geneticists are registered. Only four are cited as
involved in research on fish: one was listed at the
Nippon Institute of Scientific Research on Pearls,
two as working on the genetics of sexuality in fish,
and one on the genetics of invertebrate sex-
determination. An exhibit, "Genetics in Asian
countries," at this Twelfth International Congress
of Genetics," featured research on the origin, dif-
ferentiation, distribution, and breeding of a number
of plants and animals especially associated with the
life of Asian peoples: nothing was included on fish.

Japan was represented by one of six members of

the FAQ ad hoc Working Party on Genetic Selec-
tion and the Conservation of Genetic Resources of
Fish, which met in Rome in 1971 ( Food and Agricul-
ture Organization, 1972). Their representative was
K. Suzuki, Chief Fish Culture Section. Ueda
Branch of Freshwater Fisheries Research Labora-
tory, Nagano Prefecture. The report published by
this panel is an excellent statement. It is mostly,
however, oriented towards freshwater fish. In this
report the case for widespread utilization of genetics
in the fisheries is put more strongly than presented
here where emphasis is on genetics in the total per-
spective.

JAPAN'S NATIONAL INSTITUTE
OF GENETICS

Japan has an excellent National Genetics Insti-
tute, which consists of 10 departments and was es-
tablished in 1949 as the governmental institute for
fundamental studies of genetics. One of its first di-
rectors was the now retired H. Kihara, world re-
nowned wheat geneticist. In the November 1972
edition of Nature devoted to "Science in Japan"
there is an article by Kihara, "Activities of the Na-
tional Institute of Genetics."

One of the most active groups is the Department
of Developmental Population Genetics. The work
of this group is currently all theoretical and not at all
concerned with fish. Training of this staff though
could be well utilized in fishery research.

The silkworm is a much used organism for genetic
research at this Institute. Genetic mutations inter-
fering with the feeding patterns of the silkworm lar-
vae are being studied. Such mutations no doubt also
present themselves in larvae of marine inverte-
brates, as the oyster, which have delicate hirviil stages
often difficult to culture. Studies on radiation and
chemical mutagenesis are being actively pursued
using the silkworm. Emphasis is on dose-rate ef-
fects. (This is a very important area. There is a
necessity internationally to clarify effects or lack of
effects at very low doses of radiation, something
most difficult to carry out experimentally.) With em-
bryonic death as a criterion, radio-sensitive and
radio-resistant strains of silkworms have been iso-
lated, differences being 6- to 9-fold. Using
Drosophila. induced mutations affecting viability
rather than simply inducing lethality have been
found to occur 40 times as often as lethal mutations.
This work in the field of mutagenesis might be di-
rected toward establishing control standards for

126

marine contaminants as they affect the lethal gene
load and reproductive cells of breeding fish popula-
tions. Recently, workers at this National Institute of
Genetics have developed a very sensitive test sys-
tem for the detection of chemical mutagens in pol-
luted environments.

The Department of Cytogenetics is studying
chromosome polymorphism in populations of the
black rat around the world. With emphasis on the
Japanese population, the aetiology of Down's syn-
drome in humans is being studied. Expertise is cer-
tainly available then for breeding-related cytogenet-
ic work.

Microbial genetics is also being pursued. Training
in such a field could be the basis for studying disease
organisms of aquatic plants and animals.

In the Department of Applied Genetics, rice is
most extensively investigated - aquatic, marine or-
ganisms not at all. A worldwide collection of rice
species is maintained; there is a complete collection
of wheat and its relative species.

OYSTERS OF JAPAN, SPECIFIC USE
OF HYBRIDS AND HYBRID VIGOR

There is a very real separation of Crassostrea
gigcis. commonly called the Japanese oyster, into
several distinct races (Imai and Sakai, 1961).

There may even be a variation in the chromosome
number in some Japanese populations of C gigas.
This is at variance with all the recent reports of
American workers (review, Longwell and Stiles, in
press). However, all the C. gigiis sampled in the
United States for chromosome analysis derive from
seed imported from Japan to the U.S. West Coast,
and most of the spat exported from Japan has been
taken from one particular region.

C. gigas is collected widely in Japan in the shallow
waters on the coast from Hokkaido to Kyushu. Seed
were, until recenth . collected most actively in
Hiroshima, where oyster culture is said to have
begun 400 yr ago. The Miyagi district is next in
production to Hiroshima. Main seed-producing beds
in Japan are Hiroshima, Miyagi, Mie, and
Kumamoto Prefectures. The Miyagi Prefecture is
famous for their export of oyster seed. This is most
likely where most seed imported to the U.S. West
Coast has been originating. Hiroshima culturists sel-
dom bought oyster seed and seldom exported their
seed to other prefectures or countries.

There are 20 different species of oysters in Japan,
all edible. Only three of these are of direct economic

importance. C gigas, C. rivitlaris. and Ostreci nip-
poini .

It is believed that C. lapcioitsi and C. ariaken-
sis. native Japanese oysters, reported some years
ago by Kobayashi (1954) to have four more chromo-
somes than C. gigas, are really C. riviilaris. The
species C. riviilaris is not cross-compatible with C
gigas (Imai and Sakai, 1961). Confusing here is the
fact that American malacologists regard C. laper-
oiisi and C. ariakensis as merely forms of the vari-
able C. gigas.

C. riviilaris. imported with seed of C. gigas. has
been planted in Puget Sound and, according to Galts-
off (1964), has established itself there.

Some of this taxonomic confusion in classifying
oysters may stem from the existence already of sev-
eral hybrid-type populations in the wild. Nothing
was learned in Japan regarding the opinion of some
U.S. workers that C. angiilata, the Portuguese oys-
ter, and C . gigas are the same species.

Lest an understanding of the nature of these
species be regarded as esoteric, it should be pointed
out that such much publicized benefits of genetics,
as miracle rice, resulted from a combination of two
species or varieties. The characteristics of each of
these types of rice were clearly known and under-
stood by the breeders who test-hybridized them
initially along with many others which were not
"miracles" at all.

Part of the vigor of C gigas relative to the more
sensitive commercial East Coast American oyster,
C. virginica, may derive from a slow though steady
rate of introgressive hybridization. That is. by the
addition of other species genes to C. gigas on a small
scale over a long period. It could also derive from
larger scale hybridization in various oyster popula-
tions in the more distant past. Both of these prob-
abilities can be checked experimentally. This is
basic research, of course, but it would provide some
information on how important hybridization pro-
grams are in developing vigorous hatchery stocks.
Such would remove some of the present unavoidable
guesswork as to the usefulness of wide species
crosses.

Spat of C gigas are now being shipped to France
from Japan for planting on oyster beds once popu-
lated by C angiiUiiii. There is a chance of natural
hybridization on the wild beds in France between
imported C. gigas and the remains of the once plenti-
ful C . angiilata populations. These two species read-
ily hybridize in the laboratory, the hybrids survive
and are fertile (Imai and Sakai, 1961).

127

It would be hard to overemphasize the importance
hybrid vigor will have in developing hatchery lines of
oysters, lobsters, scallops, fish and other marine
food animals, and algae. Hybrid vigor is so impor-
tant because, unless artificial seawater is used, water
pollution will always be a threat to the commercial
success of a hatchery. Because a hatchery must
carry its product through its most sensitive larval
stages, in smaller numbers than in the wild, and in
one spot as opposed to many in the wild, water
pollution can have a more disastrous effect in a
hatchery than in the field.

Widespread use of artificial seawater would
necessitate the breeding of lines commercially pro-
ductive in such a media. Drastic changes in the
genotype would most probably be necessary. This is
not a genetic improbability by any means, but
aquaculturists do not give the idea much thought.

LABORATORY VISITS

Even though there has been no general, broad
program of fish or aquacultural genetics in Japan,
some fine genetic research has gone on in various
fishery laboratories. This work has not yet had a
great deal of impact on the general fisheries. It is
related here along with comments and discussions
regarding aquaculture-related genetics. The re-
search cited is a sampling of the sort of work that will
most likely be conducted in the future on a larger
scale.

Oyster Research Institute at Kesen-numa on
Mohne Bay — Oyster, Scallop, and Abalone

The Oyster Research institute at Kesen-numa
(chief researchers now H. Kan-no and T. Seki) de-
veloped, under the leadership of T. Imai, methods
for the artificial rearing of the Japanese oyster, C.
f;if>a.s. This Japanese work paralleled the prior work
of Loosanoffand Davis (1963) of the Milford Biolog-
ical Laboratory, now part of the National Marine
Fisheries Service. From the Kesen-numa Labora-
tory also came a breeding study on C. fiii^'us, which
included the effects of inbreeding, hybridization be-
tween members of different geographic races, and
interspecies crosses using the Japanese oyster as one
of the species parents (Imai and Sakai, 1961). Addi-
tional aquaculture and breeding information is con-
tained in a recent book edited by Imai et at., 1971,
"Through culture in shallow seas (progress in shal-
low seas culture)." This book is now being trans-

lated from the Japanese through the auspices of the
National Oceanic and Atmospheric Administration.
At least for some considerable period of time adult,
fertile hybrids of the cross C. gigas x C. angulata
were maintained at the Kesen-numa Laboratory.

This Institute is now rearing the European oyster,
Ostrea ediilis. which does well in Japan as a hatchery
species. These oysters are sold as spat to growers
and marketed. C. angiiUita is also being reared. No
genetic studies are now being conducted on the oys-
ter.

The sea scallop, Patinopecten, is also being
raised. The scallop fishery still depends on the cap-
ture of juveniles, not on hatchery rearing. However,
at least in Mutsu Bay annual catches of P. yessoensis
fluctuate widely. This is attributed to a natural insta-
bility of the reproduction of this species. Natural
reproductive instability would make this scallop an
excellent candidate for reproduction in the hatchery.
Some of the scallops are known to be functional
hermaphrodites. Use could so be made, for both
experimental and commercial breeding work, of
their rapid inbreeding potential by self-crossing.

Research at the Kesen-numa Laboratory is now
concentrating on the abalone. The market for this
marine gastropod is excellent, and there is an urgent
need to mass produce the young. Unlike the situa-
tion for the oyster and scallop, mass collection of
wild abalone is fairly difficult. Young abalone escape
from the collectors, and in their natural habitat, they
shelter themselves under boulders or rocks. To in-
crease production it is, therefore, essential to pro-
duce the young artificially.

In Japan 10 species of abalone are found. Only
four of these species constitute the staple food
products — HuHutis haliotis discus hannoi, H . dis-
cus, H. sieboldii, and//, gigantea. Of the total catch
H . discus hannoi supplies 58%.

At present, no genetic studies on abalone are
being conducted at Kesen-numa. However, there is
interest in possible genetic causes of the less than
desired percent survival of the young larvae, in the
chromosomes of the abalone, and in genetic resis-
tance to disease. Disease is anticipated as a potential
serious problem in the very intensive system under
which the abalone will be reared. The intensive sys-
tem includes a period of growth in the heated waters
of a nearby power plant at Shiogama. An above-
ground running water tank system contains the
abalone at this time, and a hatchery with experimen-
tal facilities has been built at the power plant near the
tank farm.

128

At the Iwate Prefectural Roes and Fries Distribu-
tion Center the gametogenesis of adult abalone was
observed, as well as the normal development from
fertilized egg to creeping stage larvae (Shibui, 1972).

Once the artificial production of abalone in Japan
progressed to the commercial scale, interest de-
veloped in the potential of interspecies crosses. At
Chikura Branch of Chiba Prefectural Fisheries such
hybrids were made and studied. These were between
H. discus and H. gigantea; between H. discus and
H. sieboldii; and between H. gigantea and H.
sieboldii (Oba, Toyama, and Kaneko, 1972). All
were reared through metamorphosis in the labora-
tory. Hatching, fertilization abnormalities, and shell
form and structure were compared to the parental
characteristics. Such hybrids could have advantages
over nonhybrids for intensive aquaculture under ar-
tificial conditions, or for colonization of a new area
in nature.

Some hybridization work was also conducted at
the Kesen-numa Institute (J. W. McBeth).^

Pearl Research Laboratory of the Fisheries
Agency at Kashiko-jima, Mie-ken

Research is confined exclusively to study of those
mollusks used to culture pearls. Work is ultimately
directed at improving the quality of the cultured
pearl. All the research appears to be basic. It seems
that, because the science and art of pearl culture are
well worked out, these researchers have more free-
dom to pursue fundamental work. There is a persis-
tent near 40% mortality of the pearl oyster, Pinctada
fucata, in the trays and racks used to hold them in the
pearl farming. Mortality appears to be accepted as
part of the business. The demand for pearls has
dropped and there is now a government restriction
on the amount of pearl farming to be conducted.
There are no projects aimed at breeding disease re-
sistant organisms, as those for the commercial
Crassostrea virginica in the U.S. mid- Atlantic
states.

Research is being carried out on the artificial cul-
ture of this pearl oyster's mantle (A. Machii, pers.
comm.). Mitosis and cell proliferation have been
obtained in vitro. American, European, and
Japanese workers can all generally attest to the fact
that success in invertebrate tissue culture has been
most elusive. A persistent measure of culture suc-

cess would find application in numerous fields of
fishery research. It would apply to work on this
epidemic MSX disease of the American oyster,
which just about devastated the oyster industry of
the U.S. mid-Atlantic states a few years ago (Sin-
dermann and Rosenfield, 1967).

Some inbreeding and some hybridization studies
are being conducted on the pearl oyster (K. Wada).^
Also, some studies have been conducted on its
chromosomes in spite of technical problems caused
by the presence of so much yolky material in the eggs
(K. Wada, see footnote 3). This latter work will
probably be published soon. It seems that some re-
search effort will be directed in the future towards
study of biochemical polymorphisms in the wild
stock.

Ocean Research Institute, University of Tokyo —
Genetic Polymorphisms of Wild Populations

In the division. Biology of Fisheries Resources,
studies are being conducted on enzyme variation in
fish populations (Numachi, 1972a).

Shortage of genetic markers has been a handicap
in the study offish genetics. Now variation in differ-
ent enzymes can be used as genetic markers by em-
ploying gel electrophoresis followed by histochemi-
cal staining methods. This method makes possible
an examination of the structure of a population offish
in genetic terms. Identification of self-sustaining
subpopulations of fish is a most basic problem
in fisheries management.

Enzyme polymorphisms reflect a mutation in the
structural gene of the enzyme concerned. A few
years ago variants of enzymes were regarded as rare
events. It is now known that such variants are very
common in most enzymes in various organisms. An
increasing number of electrophoretically distin-
guishable variants has been discovered in fish, as well
as in other organisms. Marine mammals, such as
whales, dolphins, and seals, all contain five lactate
dehydrogenase forms. Their enzyme "patterns" are
similar to those of terrestrial mammals, including
man.

Numachi (1971 , 1972b, c) has specifically reported
in the literature on interspecific and intraspecific
variation of enzymes in fish species and on analysis
of the genetic control of such enzymes in fish — on

- Communication through Japanese staff member acting as
Director at the time.

^ Personal communication from a fellow staff member. K.
Wada was away at a fisheries meeting at the time the laboratory
was visited, so more precise information on this work was not
obtained.

129

electrophoretic variants of catalase in black rock-
fish, Sehastes inennis; genetic polymorphisms of
tetrazolium oxidase in black rockfish; genetic con-
trol and subunit composition of lactate dehydro-
genase in Psciidorashuni puna (a cyprinoid fish):
duplicate genetic loci and variant forms of malate
dehydrogenase in chum salmon. Oncorhyiu liiis
kt'tii. and rainbow trout. Saliiio iniinhieii.

Evidence has importantly been provided for the
tetraploid condition of salmon. This means that salm-
on, like many higher plants, basically have four of
each chromosome instead of the usual two each
found in normal diploid organisms. Diploidy is the
common stale in the animal kingdom. Further ex-
amination of the evolutionary process of salmonids
remains to be done. Already though recognition of
the tetraploidy of salmonids should be of intrinsic
importance in genetic studies. Because of the tetra-
ploid nature of salmon, big salmon obtained by selec-
tion are not a good general example of what might be
expected by similar programs of breeding using truly
diploid species. Tetraploidy lends itself particularly
well to gigantism.

Study of enzyme variation in species transplanted
and farmed in the not-so-distant future will be an
important means of stock identification, and of de-
termining whether desired or unwanted hybridiza-
tion has occurred in the wild between the local and
transplant type. This will be no small job since the
present most effective utilization of different genetic
characters of various populations is still by trans-
plantation of populations and species suitable for the
environmental conditions of the areas intended for
farming (Numachi. 1972a).

Another application of enzyme variants to genetic
improvement of aquatic organisms may be as mark-
ers linked with economic characters. Economic
characters are usually polygenic and so are impossi-
ble to study by simple Mendelian genetics as are
distinct, qualitative, morphological characters.

Nikko Branch of Freshwater Fisheries
Research I^aboratory on Lake Chuzenji

Breed improvement is now regarded as one of the
main problems in the freshwater fish culture in
.lapan. .Some selective breeding is underway at the
Nikko Branch of Freshwater Fisheries Research
Laboratory (for preliminary work on Stilino i^aircl-
iwri see Kato and .Sakamoto. 1969: Kalo. !97()),
Extensive hybridization studies have been carried
out and reported in the literature (Suzuki and Kato.

1966: Kato. 1967: Suzuki and Fukada. 1971. 1972).
Most likely, such programs will be stepped up as
breed improvement is stressed in the future.

It is believed that no fish populated Lake Chuzenji
until 1873 when some local people volunteered to
stock the lake with such fishes as the char and carp.
Since that time, many species of salmonid fishes
have been stocked frequently in the lake. Lhe eggs of
Sahelinusfontinalis, the brook trout, were imported
in 1901 from the United States and fry released in the
lake.

It is well known that distinct species and genera of
fishes hybridize frequently in nature. A considerable
number of natural hybrids has been reported, espe-
cially in the freshwater families — Cyprinidae and
Castostomidae: also, in Percidae. Centrarchidae,
Poeciliidae, etc: and importantly in Salmonidae.
Natural hybrids seem to occur much less frequently
in marine fishes. Information about natural crosses
is most useful in determining the relationship of
groups of fishes.

Natural hybrids between 5. pliiviiis. the Japanese
char, and S. fontinalis were collected from a brook
flowing into Lake Chuzenji. They are estimated to
constitute about 12% of the population at the area of
the headspring.

Growth and survival rates of artificially produced
hybrids between .V. plnviiis and S. fontinalis were
studied from 6 mo after fertilization until they were 2
yr old and compared to the nonhybrid parents. This
was to determine their relative suitabilities for pond
culture. Best growth was in S. fomintilis followed by
the hybrid, then by S. pluvins. Survival rate was
highest in the hybrids. All the hybrids and S. fon-
tinalis came to maturity during this time, but a third
of S. pluvius was still immature. Hybrids were fertile
and. in fiKt, produced a significantly larger number
of eggs than did the nonhybrid parents.

With the hope of directly utilizing the information
obtained to increase annual trout harvests, hybridi-
zation experiments with 62 combinations of Sal-
monidae have been going on since 1965. The purpose
of this work was to find F, hybrids suitable for pond
culture and for stocking lakes or rivers. L'ntil a few
years ago the freshwater fishes of Japan were abun-
dant in nature. They were used mostly by rural peo-
ple as a main protein source. Due to a reduction in
their natural habitats, such fish are now less plenti-
ful. At the same time the demand for them has gone
up. making them a luxury food. Presumably it was
believed that genetic and breeding work would have
some bearing on this situation. It v\as further hoped

130

that some of these hybrid crosses would be sterile.
Sterile hybrids might, because of their sterility, have
a faster rate of growth or greater ultimate size than
fertile nonhybrids.

Hybrid development did occur in all combina-
tions. There were, however, wide differences in sur-
vival rates. Hybrids between 32 combinations
survived until they reached the free-swimming
stage. Nine of these showed survival rates similar or
better than those of parental species. Those combi-
nations that did survive are currently being studied
at later growth stages.

Among hybrid characteristics already ascertained
is a heterosis against disease. This is an important
feature since prevention of epidemic disease is a
serious problem in trout culture.

Even some intergeneric hybridization was
achieved. These hybrids though presented special
difficulties m cultunng and rearing.

Tohoku University School of Fisheries and

Tohoku Regional Fisheries Research Laboratory —

Radiation Effects on Oyster; Seaweeds

The effects of ionizing radiation on Crassostrea
gigas are being studied at Tohoku University (L.
Maeda, pers. comm.). This work may be similar in
nature to some done on C. virginica (Longwell and
Stiles, 1972).

Recent advances in cultural techniques for the
seaweeds, like Porphyra and Undaria, have brought
substantial benefit to a considerable portion of
fishermen engaged in seaweed production in Japan.
(At the same time once important nori grounds about
Tokyo have been irretrievably lost to pollution, and
nori products have come to contain mercury and
cadmium.) Little attention though has been given to
the possibility of artificially crossing seaweed types
to give a more productive, profitable strain. Since
1958, S. Suto has been making interspecies hybrids
always using a local commercial species as one par-
ent. This work has been done with a view of obtain-
ing a new seaweed with good characteristics for
culture (Suto. 1963; also see Suto, 1972). Fortunate-
ly, self-fertilization rates are low, facilitating artifi-
cial fertilization. However, much preliminary work
had to be done before artificial fertilization could
be achieved with certainty. Also, the relationship
between Porphyra species had to be clarified.

Artificial crosses were attempted between five
species of the Porphyra genus, including four local
forms. Crosses occurred easily between any two

species tested. Descendants from crosses of two
dioecious parents and from two monoecious parents
grew normally. Those from dioecious-monoecious
combinations died in mass at a young stage, but left a
few survivors. The three dioecious species studied
appear to be very closely related. At least in hybrids
of the dioecious species, there is normal reproduc-
tion with typical genetic segregation.

Recently, some lines started from an interspecies
hybrid have yielded two and three succeeding gener-
ations. Some of the lines grow more vigorously than
did their native parents.

This work demonstrates that new lavers, more
suitable for commercial production than the present
wild lavers, can be bred. Probably the F, inter-
species hybrids will first have to be subjected to a
program of artificial selection in the laboratory, or
one of natural selection in the wild before being used
commercially.

Introduction to Japan of foreign species of
Porphyra, which may be disease resistant, for field
trials and for use in hybrids with Japanese species, is
regarded important. High quality species already
being utilized are, unfortunately, not the most pro-
ductive, and disease is a factor in lowering produc-
tivity.

There is a likelihood of some natural hybridization
occurring on the wild beds between closely related
species. The genetic and other implications of this
are recognized.

Some cytogenetic studies on P. yezoensis have
been done elsewhere at Nagasaki University Fa-
culty of Fisheries (Migita, 1967). There are three
chromosomes in vegetative and spermatogonial cells
in the leaf thalli, and six chromosomes in fertilized
carpogonia. The haploid chromosome number of
this alga is then three. Meiosis takes place in the cell
division of the conchospore at the time of spore
formation. Such information is pertinent to the mak-
ing of artificial crosses. Also for the artificial somatic
replication of a single plant for multiplication prior to
larger scale commercial production.

Aside from the great commercial value of sea-
weeds in Japan (their most important fishery), the
Japanese probably have here one of the most in-
teresting areas of the future field of marine genetics
with most promise of great commercial application.
This is because plants, in general, lend themselves
so well to genetic study with subsequent genetic
manipulation and because so many genetic and
breeding techniques are so well worked out for
plants.

131

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1969. Genelika selektisya i gibridizatsiya ryb (Genetics,
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Nauk. (TransUited by Israel Program Sci. Transl.. 1972. 269
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FOOD AND AGRICULTURE ORGANIZATION.

1972. Report of the first meeting of the FAO ad hoc
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GALTSOFF. P S

1964. The .American oyslcT C rassostrea virginka Gmelin.
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1971. Through culture in shallow seas (progress in shallow
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IMAl.T.. and S. SAKAI.

1961. Study of breeding of Japanese oyster. Crassostreu
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INTERNATIONAL CONGRESS OF GENETICS,
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KATO. T.

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I9.S4. Uber die chromosomenzahl der zwei arlen von ja-
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133

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DEPARTMENT OF COMMERCE

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

NAIIONAI MARINE FISHERIES SERVICE

SCItNTIfIC PUBLICATIONS STAFF

ROOM 450

I 107 N E 45TH ST

SEATTLE WA flBIOS

FOURTH CLASS

POSTAGE AND FEES PAID

U 5 DEPARTMENT OF COMMERCE

COM 2 1 0

OFFICIAL BUSINESS

Marine Biological Laboratory
Library - Periodicals
Woods Hole, Ma 025^3

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