History and development of surf clam harvesting gear / Phillip S. Parker

c 55. W. UMFS c\RC-l>U4

NOAATR NMFSCIRC-364

A UNITED STATES
DEPARTMENT OF
COMMERCE
PUBLICATION

***T °'C<fc.

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NOAA Technical Report NMFS CIRC-364

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

History and Development of
Surf Clam Harvesting Gear

PHILLIPS. PARKER

SEATTLE, WA.
October 1971

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U.S. DEPARTMENT OF COMMERCE

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Robert M. White, Administrator

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Philip M. Roedel, Director

NOAA Technical Report NMFS CIRC-364

History and Development of
Surf Clam Harvesting Gear

PHILLIPS. PARKER

c
O

5
O

SEATTLE, WA.
October 1971

For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C., 20402 - Price 30 cents Stock number 0320-0035

Clam boats dredging for clams with wet (hydraulic) dredges along the east coast of the United States.

CONTENTS

Page

Introduction 1

Manual collecting methods 2

Hand collecting 2

Rakes 2

Tongs 2

Power collecting methods 2

Scraper-type dredges 2

Hydraulic dredges 4

Experimental gear 7

Vessels 12

Summary 12

Literature cited 13

FIGURES

Page

1. — Raking and tonging for surf clams from a dory in shallow water

depths 3

2. — Types of rakes used for hand collection of surf clams 4

3. — "Long Island" hydraulic bar clam dredge of the type which became

popular with the Long Island clammers 5

4. — Early model hydraulic dredge showing sled under bag, one of the
early modifications which led to the development of the standard

dredge with its after-cage built of steel bars 5

5. — Photograph of largest hydraulic jet dredge in use today by the surf
clam industry. This is an 84-inch dredge used aboard the 136-ft

Gail Borden 6

6. — Gasoline-driven pump on the deck of a clamming vessel 7

7. — Classic 40-inch hydraulic jet dredge used by the majority of fishing
vessels operating along the coast of New Jersey and Maryland dur-
ing the late 1950's and up to the present time 8

8. — Drawing of a 48-inch hydraulic clam dredge built for clam survey
work aboard the National Marine Fisheries Service research vessels

Delaware and Delaware II 9

9. — Constant delivery pump system aboard the Gail Borden.

A — Separator, where all material transported up discharge hose
empties for washing and separation of clams from the rest of the
material. B — Escalator, where surf clams enter to be carried
up to sorting table or unit. C — Clam jetting water hose. D —
Air hose. E — Transporting hose, for carrying material from up-
take unit to separator. F — Waste discharge units, through which
other material is dumped back overboard 10

in

10. — Constant delivery pump system dredge aboard the Gail Borden.
A — Clam jetting water supply hose. B — Compressed air hose.
Air is supplied through this hose to the uptake unit where it mixes
with the water in the hose, generating the upward movement of
water within the hose. C — Receiver. Material jetted out of
bottom and picked up by the dredge knife passes into this area
and then into the uptake of the discharge hose. D — Transport-
ing hose for carrying dredge material from receiver to separator ... 11

11. — Electrical submersible pump used for supplying water to dredge jets.
A — Submersible pump discharge opening, 8-inch inside diam.
B — Strainer surrounding pump, mesh size approximately 1-inch2.
Any object passing through this strainer will pass through pump . . 12

12. — Electrical submersible pump shown as mounted to 48-inch clam
dredge. A — 8-inch discharge, connected to header. B — Water-
tight electrical junction. C — Header 12

13. — Clamming vessel showing adaptation of gear to take dredge in over

the stern while steaming 13

14. — Stern chute clam dredge ramp used aboard Delaware II 14

15. — A converted shrimp boat. One of the several different vessel types

which were converted for surf clam dredging 15

IV

History and Development of Surf Clam Harvesting Gear

By

PHILLIP S. PARKER, Fishery Biologist

National Marine Fisheries Service1

Exploratory Fishing and Gear Research Base

Woods Hole, Massachusetts 02543

ABSTRACT

The development of harvesting gear for surf clams, Spisula solidissima, along
the eastern coast of the United States is reviewed from early times up to the
present.

Early clamming was done by hand using rakes or tongs, while today the in-
dustry depends upon large, efficient dredges operating from stable vessels. Little
gear development took place prior to World War II; however, since that time, the
industry has made rapid strides in the development of harvesting gear. Today
this trend is still very much in evidence, with gear constantly being modified for
adaptation to newer vessel types.

Most gear development work has been the result of the surf clam industry
itself. However, the Federal Government, in cooperation with industry, has de-
veloped several pieces of equipment for adaptation to clamming gear.

INTRODUCTION

The history of the development of harvest-
ing gear for surf clams, Spisula solidissima,
along the eastern coast of the United States
has been only touched upon by various authors
reporting on this species. However, to date,
no comprehensive description of the gear has
been written. Prior to World War II, the ef-
fort for development of this type of gear was
rather limited. Probably this was because the
harvesting equipment used at that time was
sufficient to maintain an adequate supply of
surf clams for both fish bait and the limited
market available for human consumption. The
World War II years, with the search for good

1 Formerly Bureau of Commercial Fisheries Explor-
atory Fishing and Gear Research Base, Gloucester,
Mass. 01930.

sources of high protein food by both Govern-
ment and industry, provided the impetus for
a tremendous increase in the market demand
for surf clams. Due to this demand, rapid de-
velopment of a variety of surf clam harvesting
gear followed. Many kinds of dredges were
devised by the industry before the hydraulic
jet dredge was developed. Different types of
hauling gear and boat sizes were also tried
during this period.

Today further radical changes are being
made to the so-called "standard" hydraulic jet
dredge in an effort to increase its efficiency.
Prior to 1963, clam gear research and devel-
opment were exclusively pursued by the surf
clam industry. This group had been respon-
sible for almost all of the changes in the de-
sign and modification of the clam harvesting
equipment. However, units of the National

Marine Fisheries Service are now actively co-
operating with the surf clam industry and are
expending considerable time and effort in the
development of new types of clam harvesting-
gear suitable for use in exploratory surveys
and biological studies.

MANUAL COLLECTING METHODS

Hand Collecting

In all probability, the first surf clam harvest-
ing method employed in this country was that
practiced by the American Indian. Goode
(1887) quotes one of the earliest "tracts" writ-
ten upon our natural history, Wood's "New
England Prospect" (1634), which says that
along Nahant [Massachusetts] Beach, the sea
"after storms casts up greate store of greate
Clammes which the Indians taken out of their
shells conny home in baskets," and which also
says "Clammes as big as a halfe-penny loof,
which are greate dainties amongst the natives."

Another early and simple method of harvest-
ing was employed by farmers along the New
Jersey coast, who, after finding large quantities
of surf clams washed ashore by severe storms,
would shovel them into their wagons to be
hauled away for field fertilizer, for hog and
poultry feed, or for use as bait. At about the
same time (approximately 1878), a new fish-
ery was beginning at Dennisport, Mass., where
the surf clam was harvested by means of clam
rakes operated from dories which were either
hand or sail propelled. This method of dory-
hand raking for clams was only used out to
about V/o miles from shore (Fig. 1). The
rakes were made of iron with wooden handles
and measured from 20 to 27 ft in length; the
rake heads had 17 to 25 teeth and cost from
$5 to $8 apiece (Fig. 2). Most of the raking
was done in water depths of about 8 ft and
at ebb tide, although at times the fishermen
worked as deep as the length of the rake (ap-
proximately 18 ft) and tong handles would
permit (Goode, 1887). Potato forks or sim-
ilar instruments are used to harvest the surf
clam in certain areas of Canada.

Rakes

There are two types of rakes used in the
commercial fisheries today. These are the com-
mon clam rake and the bull rake (Fig. 2) . The

common rake is similar to a garden rake except
that the teeth are larger and sharper. It is
equipped with a wire mesh basket or "apron"
which holds the catch, and it is generally used
in very shallow water. (A modification is used
in Maine for gathering Irish moss (Dumont
and Sundstrom, 1961).)

The bull rake, used generally in New Eng-
land, is a large implement with a head between
20 and 30 inches wide (Fig. 2). It has long,
curved teeth which are about 9 inches long.
Unlike the common hand rake, the bull rake
does not have a basket or apron, its handle is
usually longer, and it is used in deeper water
than the hand rake (Dumont and Sundstrom,
1961).

Like the common rake, the bull rake has nu-
merous modifications. One of these is called
the Shinnecock rake. This rake is used only
in Maryland. Its long, curved teeth are pro-
gressively shorter toward the ends of the rake
head (Fig. 2) and are shaped to form a basket
in which the clams rest as they are raised from
the bottom (Dumont and Sundstrom, 1961).

Tongs

Another implement used during the early
days of the industry for gathering surf clams
was the hand tong (Fig. 1). Hand tongs are
actually a pair of rakes attached to the ends
of two long poles which are up to 20 ft in length
and are fastened together like a pair of scissors
with the fulcrum near the lower end. A bas-
ket-like frame is attached to the back side of
each rake in order to hold the catch (Dumont
and Sundstrom, 1961).

The production potential of rake and tong
gear was obviously limited, and before any
large expansion could take place in the surf
clam industry, development of more efficient
harvesting gear was necessary.

POWER COLLECTING METHODS

Scraper-Type Dredges

During the 1920's, scraper-type dredges
were developed which could be towed behind
power boats. These were usually 18 to 28
inches wide with a knife blade (rather than
teeth) located in front of a scoop which sloped
upward and backward toward a bag for hold-

Figure 1. — Raking and tonging for surf clams from a dory in shallow water depths

ing the catch. The blade scooped into the
bottom to a depth of 6.5 to 9 inches. The so-
called "Sheepshead Bay" dredge had a more
or less straight leading edge to the knife and
was adjustable to a desired depth. These
dredges were towed by a rope, usually fastened
to a special stanchion, and were hauled aboard
either by a towing rope or by an additional
steel cable attached to the dredge. Both meth-

ods used a powered winch (Westman-). No
further significant changes were made in the
dredges for many years. However, the design
of some dredges became slightly modified, e.g.,
the knife was rounded so that the leading edge
became an arc.

- Westman, J. R. 1946. On the origin, development
and status of the surf clam industry, 1943-45. New
York Conservation Department, Bureau of Marine
Fisheries. Unpublished manuscript, 10 p.

Experiments were made with sleds under
the bag in attempts to clear the mud away
from the clams more rapidly. In spite of these
modifications, the scraper dredges piled up the
sand badly, which choked the forward parts
of the bag (Westman, see footnote 2). Be-
cause of the deficiencies in these dredges, as
well as undesirable results from their oper-
ation, experiments were conducted in the mid-
1940's by the surf clam industry which led to
the development of the more efficient hydraulic
jet dredge.

Hydraulic Dredges

The hydraulic jet dredge was developed by
jetting water directly into the conventional
"dry" dredge. The first units built were small
but were effective enough to prove their super-
iority over simple scraper dredges. One of the
main advantages of the hydraulic jet dredge
was its tremendous reduction in the number of
broken clams and damaged meats taken in the
catches. By utilization of the water jets, the
area that could be dredged during a tow was
more than doubled. This made possible the
commercial harvesting of clam populations of
far less density than was previously feasible.
Furthermore, regions of hard bottom which
were previously unsuitable for dredging now
became productive.

Many experiments using different types and
orientation of jets were made. Also, trials
using various types and sizes of water pumps,
as well as types and sizes of hose, were con-
ducted before the major difficulties were over-
come and boats of the commercial fleet were
converted to hydraulic jet dredge gear.

The most popular of the early types of
dredges was the "Long Island" hydraulic bar
clam dredge (Fig. 3) with three jets (West-
man, see footnote 2). Water was pumped to
these jets by a gasoline-driven pump located
aboard the fishing vessel through a 2^-inch
canvas fire hose. Special hose was later de-
veloped by the rubber industry for this spe-
cific purpose. This new hose could withstand
internal pressures up to 150 psi even with ex-
tensive outside wear from the abrasive action
of sand, gravel, etc.

Figure 2. — Types of rakes used for hand collection
of surf clams.

The development of the hydraulic jet dredge
did not stop here. Although the basic prin-
ciples remained unchanged, the size and effi-
ciency of the gear were continually increased
during the period 1945-65 (Fig. 4). The dis-
covery of large unexploited surf clam beds off
the coasts of Maryland and New Jersey (in
1949) resulted in a shifting of the center of
the industry from the Long Island area to the
coasts of New Jersey and Maryland. Because
of the increased availability of clams, the in-
dustry was able to expand rapidly and to in-
crease the size and efficiency of the gear used
to fish these beds. Dredge sizes have now
reached a maximum size of 84 inches in width
(Fig. 5).

Correspondingly, the size of water pumps
has been increased to maintain the proper
pressured flow of water required by these
larger dredges. The volume of the pumps has

■S/Cf.

Hose

XO/Vh

tk

Figure 3. — "Long Island" hydraulic bar clam dredge of the type which became popular with the Long Island
clammers. (Drawn by Carl Rich after C. E. Petite and P. W. G. McMullon, Fish. Res. Board Can., Bull. 102,
Ottawa, 1955.)

SLED

DREDGE

KNIFE

Figure 4. — Early model hydraulic dredge showing sled under bag, one of the early modifications which led to
the development of the standard dredge with its after-cage built of steel bars.

Figure 5. — Photograph of largest hydraulic jet dredge in use today by the surf clam industry. This is
an 84-inch dredge used aboard the 136-ft Gail Borden. Note size of auxiliary gear and deck equip-
ment required for the operation of this size dredge. Two 6-inch inside diam. water supply hoses are
required for the jetting action of this dredge on the bottom.

Figure 6. — Gasoline-driven pump on the deck of a
clamming vessel.

been increased from a few hundred gallons
per minute up to 3,500 gpm. One commercial
boat is now using two pumps to supply the
required amount of water. Hose size has been
increased from 21/2- up to 61/^-inch inside di-
ameter with some boats doubling-up on the
smaller 6-inch hose. As the deck-mounted,
gasoline-driven pumps (Fig. 6) became inad-
equate, they were replaced with diesel-pow-
ered units installed below decks. This modi-
fication not only increased the available deck
space but also improved the operational safety
of the vessel.

The dredge most generally used between the
late 1950's and the present has been a 40-inch
model (Fig. 7). This size dredge is particu-
larly suited to the handling and towing capa-
bilities of most of the commercial vessels in
the clam fleet.

Although the size of this dredge is well
standardized, many minor modifications are
consistently being made in an attempt to im-
prove on its efficiency. These modifications
consist mainly of changes in the size and ar-
rangement of the water jets, variations in
placement and shape of the jet manifold,
changes in the volume and pressure of water
supplied to the jets, changes to the shape and
contour of the dredge knife, improvements in
the attachment of the knife to the dredge,
changes of the knife depth setting, variations
of towing speed, shape, and slope of the sled

floor, construction and attachment of the chain
bag, and towing attachment between the dredge
and sled. During this period of development,
local modifications to the dredges reflected dif-
ferences in the characteristics of the areas in
which they were being used. The shape of
the dredge might be slightly different or the
type of jet header and arrangement of the jets
might be different; also, the type and shape
of the knife could vary from area to area. Be-
cause of these variations, the physical state of
the hydraulic jet dredge can be considered to
have been almost constantly changing (Fig. 8) .

EXPERIMENTAL GEAR

As the commercial fishing effort increased
on the larger clam beds which were located
within easy distance from ports and processing
plants, these beds have sustained consistent and
heavy fishing pressure. As the production rate
over these beds leveled out, rich beds located
at greater distances from ports and plants have
been used. However, the balance maintained
between the fishing time to be gained or lost
by traveling shorter and longer distances, vs.
the production rate(s) of the various fishing
grounds, became an important consideration.
It now appears that in order to maintain the
desired production level, either faster boats or
more efficient fishing gear is needed. The lat-
ter proposal seems to be the more practical
solution. One approach to updating or other-
wise improving the gear and fishing method
is to adopt methods and gear used by other
marine industries for use in the surf clam
industry.

Early in 1963, a member of the surf clam
industry became interested in the development
of an airlift system based upon the principle
now used for collecting diamonds off the south-
ern coast of Africa. The principle involved is
that of pumping air down to the dredge where
the air is directed into the bottom of a large
hose extending from the dredge to the boat
deck. The air causes the mixed water-air col-
umn within the tube to become lighter than
the outside water and generates an upward
movement of the water within the hose. The
water flowing into the bottom of the hose to
replace the water which has moved upward

Figure 7. — Classic 40-inch hydraulic jet dredge used by the majority of fishing vessels operating along
the coast of New Jersey and Maryland during the late 1950's and up to the present time. Note that
the dredge itself is all enclosed except for the bottom and forward section of its top. Loose aprons
built out of rings are used to enclose the space between the dredge and sled to prevent loss of clams
between the two units. In addition, chain attachments are used between the two units for towing
purposes. Attached to the sled is the chain bag built of 3-inch scallop rings and connectors. This
dredge is equipped with a straight edge knife. Many dredges use a V-shaped knife that floats on
springs and digs into the bottom only after the water to the jets is turned on. In use of spring-mount-
ed blades, the knife settles into a trough which is jetted out by the water. Dredges with this type
of blade also use a V-shaped manifold as compared to the straight manifold shown her"e. The clam
jetting hose shown has been built especially for clam jetting and has a 5-inch inside diam.

3/j jg to support chain bay

! -i — f^

fyes at front of t/ed t.

Figure 8. — Drawing of a 48-inch hydraulic clam dredge built for clam survey work aboard the National Marine
Fisheries Service research vessels Delaware and Delaware II.

carries the material dredged from the bottom
with it. When fully developed, this system will
offer the possibility of continuous dredging
without interruption and loss of fishing time
for hauling, emptying, and resetting the dredge.
In addition, the catch can be constantly mon-
itored, and small beds can be effectively fished.
After preliminary investigation of the feas-
ibility of this method, Snow Canning Company
of Pine Point, Maine, began to assemble the
needed gear and equipment for building an air-
lift system on their vessel Gail Borden. After
building and pretesting component units of
the system, a working model was given lim-
ited fishing tests during the spring and sum-
mer of 1964. Many "bugs" were found, and
further effort for modifying the system to cor-
rect deficiencies continued. Near the middle
of 1965, the redesigned unit was ready for

further testing (Figs. 9 and 10). While some
minor deficiencies remained, test results were
encouraging enough to warrant the develop-
ment of a complete system for future clam
harvesting.

In addition to these developments, submers-
ible pumping systems have been developed to
replace the older type vessel-mounted pumping
systems used on all the commercial clam boats
today. Such a system has an electrically driven
submersible pump (of sufficient power and
rating) (Fig. 11) mounted on the forward end
of the clam dredge. The discharge end of the
pump is connected directly to the dredge man-
ifold (Fig. 12). Electrical energy is supplied
to the pump from a vessel-mounted generator
feeding power through a watertight power
cable which is stored on a deck-mounted hy-
draulically-driven reel. The main advantage

Figure 9. — Constant delivery pump system aboard the Gail Borden. A — Separator, where all material trans-
ported up discharge hose empties for washing and separation of clams from the rest of the material. B —
Escalator, where surf clams enter to be carried up to sorting table or unit. C — Clam jetting water hose.
D — Air hose. E — Transporting hose, for carrying material from uptake unit to separator. F — Waste
discharge units, through which other material is dumped back overboard.

10

\

-. - f l #7

Figure 10. — Constant delivery pump system dredge aboard the Gail Borden. A — Clam jetting water supply
hose. B — Compressed air hose. Air is supplied through this hose to the uptake unit where it mixes with
the water in the hose, generating the upward movement of water within the hose. C — Receiver. Material
jetted out of bottom and picked up by the dredge knife passes into this area and then into the uptake of the
discharge hose. D — Transporting hose for carrying dredge material from receiver to separator.

11

585#

Figure 11. — Electrical submersible pump used for sup-
plying water to dredge jets. A — Submersible pump
discharge opening, 8-inch inside diam. B — Strainer
surrounding pump, mesh size approximately 1-inch2.
Any object passing through this strainer will pass
through pump.

Figure 12. — Electrical submersible pump shown as
mounted to 48-inch clam dredge. A — 8-ihch dis-
charge, connected to header. B — Watertight elec-
trical junction. C — Header.

of this system is that it does away with hand-
ling the heavy hose required for the older
pumping system while requiring less work to
gear up.

Another recent innovation in clam gear is
the adaptation of the stern trawler type ves-
sel to clam dredging. This is accomplished by
modifying the handling gear so that the dredge
can be hauled in over the stern of the vessel
(Figs. 13 and 14). This method of handling
the dredge, along with some constant delivery
system, may prove to be the most efficient meth-
od of harvesting the sea clam in the future.

VESSELS

Small dories and skiffs were first used by
hand rakers and tongers to collect surf clams
from the shallow waters along the coast. As
mechanical methods for harvesting were de-
veloped during the 1920's, other types of boats
were utilized to handle the new type of equip-
ment. Party boats, skiffs, and conventional
small draggers became the backbone of the
commercial fleet. After widespread use of the
hydraulic jet dredge became established, larger
size vessels were needed. To meet the demand,
regular fishing vessels were converted in order
to accommodate this newer and more efficient
method of dredging. Previously, these larger
boats were generally used as shrimp boats (Fig.
15), oyster boats, fish draggers, sardine boats,
and conventional military boats. The range of
size for these boats is from 31 to 136 ft in
length and from 14 to 160 gross tons. Most
vessels are powered by diesel engines and are
operated, when dredging, by two- or three-man
crews, depending upon the size of the vessel.

SUMMARY

The development of surf clam harvesting
gear is traced from early times to the present.

During this period of time, very little devel-
opment work was accomplished prior to World
War II. After this, rather rapid strides were
made in development work by the surf clam
industry and in the past several years by the
Federal Government in cooperation with the
surf clam industry.

12

The hydraulic jet dredge became the main
piece of surf clam harvesting gear in use today.

Many modifications have been made or in-
corporated into this piece of gear since its in-
ception. Today, the hydraulic jet dredge is be-
ing successfully operated from stern trawler
type of boats.

This gear has been adapted for use on many
different sizes and types of vessels, most of
which have been converted from some other
type of fishery.

LITERATURE CITED

DUMONT, W. H., and G. T. SUNDSTROM.

1961. Commercial fishing gear of the United States.
U.S. Fish Wildl. Serv., Circ. 109, iv + 61 p.

GOODE, G. B.

1887. History and methods of the fisheries. In G.
B. Goode, The fisheries and fishery industries of
the United States. U.S. Comm. Fish and Fish.,
Sect. 5, Vol. 2: 581-615.

Figure 13. — Clamming vessel showing adaptation of gear to take dredge in over the stern while steaming.

L3

Figure 14. — Stern chute clam dredge ramp used aboard Delaware II.

11

.** \_ **

Figure 15. — A converted shrimp boat. One of the several different vessel types which were converted for surf

clam dredging.

i:»

GPO 998-583

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

350. Research in fiscal year 1969 at the Bureau of
Commercial Fisheries Biological Laboratory,
Beaufort, N.C. By the Laboratory staff. No-
vember 1970, ii + 49 pp., 21 figs., 17 tables.

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 table.

352. Upstream passage of anadromous fish through

navigation locks and use of the stream for spawn-
ing and nursery 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 organ-
isms and their environment. By George R.
Snyder, Theodore H. Blahm, and Robert J. Mc-
Connell. May 1971, iii + 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 tables, 10 apps.

UNITED STATES
DEPARTMENT OF COMMERCE

NATION \L OCEANIC a U.'AOSFHERIC ADMINISTRATION

NATIONAL A'^RINE FISHERIES SERVICE

SCIEN.IF'C P'JBLICUIONS STAFF

BLDG. 67, NAVAL GUP'uRT ACTIVITY

SEATTLE, WASHINGTON 98115

OFFICIAL BUSINESS

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