466

ECOLOGY OF THE GULF OF MEXICO COMMERCIAL

SPONGES AND ITS RELATION TO THE FISHERY

by John F. Storr

Marine Biological Laboratory

LIBRARY

JUL 3 1964
WOODS HOLE, MASS.

SPECIAL SCIENTIFIC REPORT-FISHERIES Na 466

UNITED STATES DEPART^«ENTjm^J>JIE_INT^^

This work was financed by the Bureau of Commercial
Fisheries under Contract No. 14-19-008-2486 with funds
made available under the Act of July 1, 1954 (68 Stat. 376),
commonly known as the Saltonstall-Kennedy Act.

UNITED STATES DEPARTMENT OF THE INTERIOR

Stewart L. Udall, Secretary

James K. Ciirr, Under Secretary

Frank P. Briggs, Assistant Secretary for Fish and Wildlife

FISH AND WILDLIFE SERVICE, Clarence F. Pautzke, Commissio?icr

Bureau of Commercial Fishekies, Donald L. McKernan, Director

ECOLOGY OF THE GULF OF MEXICO COMMERCIAL
SPONGES AND ITS RELATION TO THE FISHERY

by
John F. Storr

Contribution No. 192 from the Marine Laboratory, Institute of Marine Science,

University of Miami

United States Fish and Wildlife Service
Special Scientific Report — Fisheries No. 466

Washington, D.C.
March 1964

CONTENTS

Page

Introduction 1

The commercial sponges 2

Sponge species 2

Wool sponge (Hippiospongia lachne de Laubenfels 1936) 2

Yellow sponge (Spongio barbara Duchassaing and Michelotti 1864) 4

Anclote yellow sponge ( Sporagja anclotea de Laubenfels and Storr 1958) 4

Key grass sponge (Spongia graminea Hyatt 1877) 4

Gulf grass sponge (Spongta graminea tampa de Laubenfels and Storr 1958) 5

Finger sponge {Axinella polycapella de Laubenfels 1953) 5

Glove sponge (SpoTigta cheins de Laubenfels and Storr 1958) 5

Other commercial sponge species 5

Sponge fibers 5

Sponge grading 6

Reproduction of sponges 8

Process of reproduction 8

Relationship between sponge concentration and larval production 10

Potential larval production related to volume of sponge 12

Optimum temperatures for larval production 12

Temperature and size at maturation 14

Growth of sponges 15

Method of determining growth 15

Yearly growth factor 17

Growth formula 18

Life span 18

Healing and growth of cut surfaces 19

Cultivation of sponges 19

Sponge cultivation in the Bahamas 20

Advantages and disadvantages for cultivation 20

Distribution 23

Determination of distribution 23

Concentration of sponges and extent of sponging area 23

Distribution in diving and hooking depths 27

Causes of short-term variations in landings , 27

Factors affecting dispersion 28

Calculated rate of dispersion 30

Structure of the ocean bottom in sponging areas 30

Bottom slope and sediment zones 30

The sponging bars 31

Sponging bars in relation to surrounding bottom 33

Sediment distribution across the bar 33

Ecological relationships 35

Salinity tolerances of sponges 35

Temperature 36

Effect of water currents on sponges 37

Competition for space 39

Animals and plants associated with wool sponges 39

Total sponge species and their distribution 40

Sponging grounds and zones 44

Depth zones 45

iii

Page

Disease, parasites, and epizoics . . . . , 47

The 1938-39 sponge disease 47

The 1947-48 sponge disease 48

Other detrimental effects 48

Parasites and epizoics 49

Commercial sponge production 51

Production after the 1938-39 sponge disease 51

Production after the 1947-48 sponge disease 51

Needs of the sponging industry 54

Analysis of the yearly take and value of sponges, 1950-56 55

Probable reason for annual fluctuations in landings 56

Present status of the sponge industry 57

Methods of harvesting 57

Cleaning of sponges 59

Selling and sharing system 59

Amount and value of sponges sold 60

Take per unit of effort and historical analysis 60

Probable sponge distribution in 5 and 10 years from 1957 64

Discussion and recommendations 65

History of decline in sales from 1938 65

Purposes of recommendations 66

Recommendations 67

Establish a 6-inch size limit 67

Improve fishing techniques 68

Transplant sponges 69

Institute further biological research on the commercial sponges 69

Acknowledgments 70

Literature cited 71

Appendix 73

iv

ECOLOGY OF THE GULF OF MEXICO COMMERCIAL
SPONGES AND ITS RELATION TO THE FISHERY

by
John F. Storr, Ph.D.
Department of Biology
State University of New York
Buffalo, New York

ABSTRACT

The results of 2 years of study on the ecology of the commercial sponges and
the relationship of sponge ecology to the commercial sponge fishery are discussed.
A review and fiber analysis of the various commercial sponge species are pre-
sented. Reproduction of sponges is reviewed, and the effects of temperature and
population concentration on reproduction are discussed. Data on the growth rate of
wool sponges are presented, and a growth formula calculated. Temperature,
salinity, depth of water, water currents, dispersion, population concentration,
disease, commensalism, rock bar communities, and other environmental relation-
ships are discussed. The sponge fishery from 1936 to 1958 is reviewed along with
an analysis of take per unit of effort, sponging methods, and relationship of fishing
and take to the sponge ecology. Present status of the industry is reviewed, and
recommendations made that might assist in increasing the harvest of sponges.
Projected increases in sponge population and sponging areas are analyzed.

INTRODUCTION

Although the first record of sponge taking in
Florida dates from 1822, it was not until 27
years later (1849) that domestic sponges be-
came a commercially valuable product in the
United States. By the time diving gear was in
use for sponging in 1905, concern was already
being expressed about conservation of this
valuable resource. This concern resulted in 4
years of extensive research (Moore, 1910a,
1910b) on sponge cultivation methods. His re-
ports also included descriptions of sponging
methods, the sponge grounds, and the com-
mercial species of sponges.

No other major investigation of the Florida
sponges was undertaken until the outbreak of
the sponge disease in 1938. The results of this
investigation was reported by Galtsoff (1942)

and Smith (1941). In 1947 and 1948, the State
of Florida Board of Conservation authorized
the University of Miami Marine Laboratory to
make limited surveys of the Florida sponge
grounds between Key West and Carrabelle. This
resulted in the published accounts of the eco-
nomic history of the industry (Smith, 1949;
Storr, 1956), a report of the expeditions
(Dawson and Smith, 1953), and a description
of the commercial and noncommercial sponges
collected (de Laubenfels, 1953). Meanwhile,
by 1951, production had fallen to less than
3 percent of the 1936 peak and the dollar re-
turns had declined to less than 3 percent of the
1946 value when more than $3 million worth
of sponges were sold.

Because of this drastic decline in abundance
of sponges, the Sponge and Chamois Institute of
America and the sponge producers at Tarpon

Note.--The study was made during 1955-57 while author was at the University of Miami Marine Laboratory.

Springs, Fla., requested the U.S. Fish and Wild-
life Service to make an investigation. The
Service contracted with the Marine Laboratory
of the University of Miami in 1955 to carry out
a scientific investigation of the commercial
sponges of Florida. The investigations were
financed with funds made available under the
Act of July 1, 1954 (68 Stat. 376), commonly
known as the Saltonstall-Kennedy Act.

Purposes of the investigations were to learn
more facts about the sponges themselves, to
study the relationships between sponges and
other organisms, and between sponges and
their environment, to study the ways in which
these relationships affect sponge abundance
and harvest, and to make recommendations
leading to an increase in abundance of sponges
and their harvest. The principal results of the
investigations and a review of the status of the
industry are presented in this paper.

Sponges constitute one of the principal divi-
sions of the animal kingdom. They live and grow
exclusively underwater, both fresh and salt.

Sponges are simple multicellular animals
made up of several specialized types of cells.
Differentiation into definite tissues is incom-
plete; consequently, there are little coopera-
tion and coordination among parts of the body.
The several types of cells are supported by the
skeleton.

Sponge skeletons are of spicules or a net-
work of pale brown fibers. Elasticity of the
fiber skeleton gives rise to the familiar term
"spongy." Sponges are of all sizes and shapes,
and the living sponges have many colors. The
striking characteristic, yielding the scientific
name Porifera, is the abundance of small in-
halent openings (pores) through the surface.
Other apertures, called oscules (oscula), are
exhalent; these are usually larger in size and
fewer in number than the pores. Water con-
taining both food and oxygen is taken in through
the pores and discharged through the oscules.

Reproduction is by several means. Sponges
have a high ability to restore lost parts by
regeneration; a whole new sponge can grow
from just a small piece. All fresh-water and
some marine sponges reproduce asexually by

means of gemmules; these embryos are formed
simply by assembly of a few amoebocyte cells.
Reproduction is also accomplished sexually by
the union of sperm and egg cells.

THE COMMERCIAL SPONGES

Commercial sponges are taken in the United
States only along the coast of Florida, from
depths of 1 to 150 feet. Sponges may be able
to live at even greater depths. The principal
coastal areas of distribution prior to the
disease of 1938 were from Carrabelle to Tampa
Bay in the upper Gulf; Cape Romano, Ten
Thousand Islands, Cape Sable, and Florida Bay
areas on the southwestern Florida coast; and in
the Keys area from the Dry Tortugas to Bis-
cayne Bay.

Sponge Species

Of the eight or nine species of marketable
sponges within these coastal areas, only five
have any commercial value at the present
time. These are described below in order of
importance together with the approximate
yearly percentage of total take and value based
on the 1955 and 1956 landings. A number of
these sponges are also shown in figure 1 and
listed in table 1.

Four commercial sponges have been de-
scribed and assigned specific names for the
first time by de Laubenfels and Storr in 1958.
This new naming appears to clarify the rela-
tionships of the Florida commercial sponges.

Wool sponge (Hippiospongia lachne de Lau-
benfels 1936). — The wool sponge is rounded,
with a diameter to height ratio of from 2 : 1 to
1:1. When alive the sponge is black, the color
changing to a light gray at the base. Wool
sponges that grow in shallow water are much
darker than those found in deeper water. The
surface of this sponge is usually covered with
blunt points, and the sides of the sponge have a
number of small inhalent openings, the oscules
(the large openings on the top), varying from
1/2 to 1-1/4 inches in diameter. Commonly the
oscules are surmounted by thin-walled chim-
neys up to 2 inches in height, and are normally
larger in shallow-water sponges. The average
size (used throughout this paper as measure-
ment of the diameter) of this sponge being taken

Figure 1.— Six species or subspecies of dried and cured American commercial sponges.

3

Table 1. — Comparison of commercial sponges

Common name

Scientific name

Color
(in life)

Shape

Average

Distri-
bution^

Value ^

Height

Diameter

Inches

Inches

Cents

Wool

Hippiospongia lachne

Black

Rounded

7

9

All areas

70

Velvet

H. gossypina

Black

Rounded

6-8

7-10

None

None

Anclote yellow

Spongla anclotea

Black

Hemisphere

A

6

D.

35

Yellow

S. barbara

Creamy tan
to black

Rounded

5

7

All areas

35

Glove

S. cheiris

Black

Beehive

7

6

D, G.

20

Key grass

S. graminea

Black

Inverted cone

6

6

G.

None

Gulf grass

S. graminea tampa

T.ight drab

Thick-walled
vase

12

10

A to F.

35

Reef

5. obliqua

Black

Roxmded with
flat surfaces

A

3

SE Bahamas

None

Wire

S. sterea

Brown

Lumpy mass

8

12

A, B. 2

None

Finger

Axinella polycapella

Orange red

Bush like

20

1/2"
Branches

All areas

15

-"■ See fig. 15 and appendix A for areas indicated by letter.

^ Only in water more than <V0 feet deep.

^ Average value of one sponge to the fisherman in 1953.

at the present time is about 7 inches. When
cleaned and cured the wool sponge is light tan.

The wool sponge is the basic sponge of com-
merce making up 90 percent or more of the
entire take of sponges on a per piecei basis
and about 95 percent of the cash returns. Aver-
age value per piece is close to 70 cents.

Yellow sponge ( Spongio barbara Duchassaing
and Michelotti 1864).— This sponge is black,
dark brown, or creamy tan in color depending
on the area and depth from which it is taken.
The smooth rounded shape is much like that of
the wool sponge with the exception that the
oscules are never surmounted by chimneys as
is common in the wool sponges. When cleaned
the fibers are yellowish in appearance, hence
the name.

1 Per piece is a trade method of referring to an in-
dividual sponge. Sponges have been sold by the pound,
but are normally bought from the sponge fishermen by
the bunch. This refers to a number of sponges strung
on a line and tied to forma ring. The number of sponges
on a ring may vary according to the size of the sponge
and the kind of sponges.

The yearly take of yellow sponges is at
present less than 6 percent of the total take
by pieces and the value per piece one-half of
that of the average price for wool sponges.

Anclote yellow sponge (Spongia anclotea de
Laubenfels and Storr 1958).— This sponge is of
very minor commercial importance. Its color
and the appearance of its surface fibers are
quite like the yellow sponge. Its entire surface,
however, is thrown up into anumber of distinct
lobes, each with an oscule. It is commonly
found north of Anclote Key in shallow water.

Key grass sponge ( Spongia graminea Hyatt
1877)'. — This sponge was originally described
as the Florida grass sponge, but it differs
greatly from the one found in the Gulf. It is
usually 5 to 6 inches in height, is black, and
lives in shallow water of less than a few
fathoms. The top of the sponge is flat or

t De Laubenfels (1936) may be in error in identifying
the grass sponge, rather than the glove sponge, as Spongia
graminea. If SO then the designation of the glove sponge
as Spongia cheiris (de Laubenfels andStorr, 1958) is also
in error.

concave and is usually made up of a number of
oscules up to one-quarter of an inch in
diameter. When cleaned, the edges of the
oscules are quite thin and feathery and in most
cases form chimneys an inch or so in height.

In Biscayne Bay and the Bahamas this sponge,
or a variant, grows into a rounded form with
very tall chimneys. These latter sponges are
light in weight and have little total spongin fiber
material. Numbers of this type now appear on
the market but bring a very low price.

Gulf grass sponge (Spongia graminea tampa
de Laubenfels and Storr 1958).— In life the Gulf
grass sponge has a smooth surface and a light
drab color. It is roughly vase-shaped, but under
good growth conditions the inside of the vase is
almost completely filled in. Sponges of this
latter form have a fine texture and good market
value. When cleaned the color is light tan.

The number of grass sponges taken every
year varies considerably but is usually between
4 to 6 percent of the total take. The value is
about the same as that of the yellow sponge.

Finger sponge (Axinella polycapella de
Laubenfels 1953). — The finger sponge has a
bushlike shape in which each of the branches is
about one-half inch in diameter (fig. 1). The
color in life is bright orange-red. These
sponges grow from 2 to 3 feet high. This is the
only commercial sponge containing spicules. It
is harvested in very limited quantity although
it is common in the Gulf.

When cleaned, the sponge is pale tan to cream
in color. It is used in making swab applicators
for liquid shoe polish or for similar purposes.
A good- sized sponge sells for about 15 cents.
There are no records of the number taken or the
total value for this sponge.

Glove sponge (Spongia cheiHs de Laubenfels
and Storr 1958). — This sponge is almost black
in color, subconical in shape with the skeleton
thrown up into perpendicular folds or ridges
on the sides. The top of the sponge contains
one large oscule. When cleaned the sponge is
also light tan in color.

The sponge has very poor quality and is
easily torn. The yearly take is normally less

than 0.5 percent of the total production. Value
of the sponge per piece over the years has been
from 4 to 12 cents with an average value of
about 6 cents. The glove sponge and the finger
sponge together probably make up less than 1
percent of the total value of all sponges taken.
It is found in the Anclote Key area and along
the Florida Keys.

Other commercial sponge species. — The
wire sponge ( Spongia sterea de Laubenfels and
Storr 1958), which wasformerly of minor com-
mercial importance, is now no longer in de-
mand although a few are found in the Gulf
northwest of Cedar Keys at depths of 40 feet
or more. In deep water they grow to 30 inches
in diameter.

The reef sponge ( S. obliqua Duchassaing and
Michelotti 1864) is probably not taken commer-
cially at present; there is no official record of
its having survived the disease periods in
Florida waters.

The velvet sponge ( Hippiospongia gossypina
Duchassaing and Michelotti 1864) was found
principally in the waters off the Keys. The
usual habitat was in living coral areas at depths
of 3 to 25 feet. At one time this sponge made up
a large portion of the take from this zone and
also from the Bahamas where the favorable
ecological conditions produced a grade of
sponge almost equivalent to that of the wool.
The 1938 fungal disease appears to have
destroyed this species. None have been re-
ported in the Bahamas since the disease.

Sponge Fibers

The basic desirable qualities — ability to hold
water, compressibility, resiliency, and tough-
ness— of a sponge are all dependent upon its
fiber pattern and structure. The sponge fiber
is composed of a kind of keratin, spongin,
closely related to the collagens. Keratin itself
is made up of iodine and amino acids — lysine,
arginine, cystine, phenylalinine, and glycine.
(Block and Boiling, 1939).

The ability to hold water and compressibility
are a result of both pattern and size of the
fibers. Von Lendenfeld (1889) showed that:

1. Compressibility of the sponges is
partly dependent upon the shape of the mesh-
work. The more regularly polygonal the meshes

the harder the sponge. The greater number of
simple branching of the fibers, the softer and
more absorbent the sponge.

2. The sponges with connecting fibers of
about .02 mm. thickness appear to be the most
elastic. The thicker the fiber, the more rigid
the sponge. Finer the fibers, softer the sponge.

3. If any of the fibers of the sponge con-
tain foreign bodies, these fibers are readily
crushed when the sponge is compressed and the
sponge loses its elasticity.

4. The more numerous the fibers per unit
of volume, the greater the capillary action
and the more water the sponge can hold.

The above fiber characteristics are of
interest because of the differences between
the fiber structure of the main commercial
species of sponges and the differences between
the fiber structure of wool sponges growing in
different ecological conditions. The series of
photomicrographs in figure 2 illustrate the
variations.

In the wool sponge fibers, figure 2a, the
individual fibers are very fine, about .02 mm.
in diameter. By comparison with other sponges
the meshes are much smaller; this property
gives the wool sponge the ability to hold much
larger quantities of water than any other
sponge and also makes it softer to the touch.
All fibers are much the same size, and in the
area of the conules, as shown in the photograph,
the fibers tend to be clumped together, giving
greater support at the sponge's surface.

Two distinct kinds of fibers are found in the
yellow sponge and all others of the genus
Spongia. The ascending or principal fibers are
normally oriented perpendicular to the sponge
surface. These usually contain bits of fine
sand or spicule particles from other sponges
as inclusions within the fibers (fig. 2b). The
mesh, or secondary, fibers may be two or
three times as thick as the thickest fibers of
the wool sponge. The meshwork also con-
tains more interconnections than that of the
wool sponge.

The looser meshwork of the yellow sponge
does not make it possible for this sponge to

hold as much water as the wool and allows the
sponge to be torn more easily. With the heavy
fibers perpendicular to the surface, the sponge
is torn into segments under any hard usage.

In figure 2c of the grass sponge fibers, the
coarseness of the individual fibers and the
fairly regular pattern make this sponge feel
hard. The large size of the meshes prevents
this sponge from holding much water.

The arrangement of the fibers of the glove
sponge, figure 2d, is much the same as the
yellow sponge although the meshwork is finer.
Unfortunately the entire sponge is arranged in
narrow perpendicular columns (fig. 1) with
deep clefts between so that the sponge is very
weak and easily torn into sections.

The fiber arrangement of the wire sponge,
figure 2e, is latticelike, the meshes very
regular and entire in shape. This arrangement
combined with the large mesh size makes the
sponge incapable of holding water and renders
it almost valueless commercially; however, it
would serve as good insulating material.

The fibers of the finger sponge, figure 2f,
are arranged very differently than those of the
other sponges. The core is made up of a regular
meshwork of fibers arranged in line with the
branch. In the outer part the fibers are per-
pendicular to the branch and are fairly loosely
grouped.

Sponge Grading

The desirable commercial qualities pos-
sessed by a sponge such as softness, fineness,
absorptiveness, toughness, elasticity, and dur-
ability depend on: (1) the species of sponge and
(2) the type of physical environment in which
the sponge grows. Considerable skill (and
honesty) is attributed to sponge graders who
separate the wool sponges into a number of
grades. Other species of sponges are not
usually graded at present because of the small
take. The method of grading has at times been
very complex.

Sponge grade is determined by texture,
shape, and solidity.

1.0 mm

Figure 2. — Photomicrographs of fibers of the principal American commercial sponges, a. Wool
sponge fibers, b. Yellow sponge fibers, c. Fibers from Pepperfish Keys grass sponge, d. Fibers
of glove sponge from the Gulf of Mexico, e. Fibers of wire sponge from north of Cedar Keys,
f. Cross section of one branch of a finger sponge.

REPRODUCTION OF SPONGES

Little is known about the embryology of
commercial species of sponges although con-
siderable work has been done with noncom-
mercial species closely related to commercial
types. Similarity of the reproduction process
in the various orders studied suggests that the
basic pattern of reproduction found applies to
most sponge species. The present study con-
centrated on the gross examination of wool
sponges for larvae and on the reproduction
cycle as related to total sponge productivity.

With this consideration in mind, an exten-
sive program of examination of living sponges
in the field was carried out. Sponges were
collected and preserved every month and ex-
amined for larval content. This program was
carried on for almost the entire 2-year in-
vestigational period. The actual collection and
preservation was done by crews of sponge
diving boats.

Process of Reproduction

The spermatozoa and ova produced by
sponges are similar in structure to those of
other members of the animal kingdom. The
spermatozoa, about 0.05 mm. in length, are
produced in large numbers close to the walls
of the smaller excurrent canals. Spermatozoa,
when mature, are released into the open water.
To effect fertilization the spermatozoon must
be taken up by an egg-producing sponge in the
incurrent flow of water. Since spermatozoa
enter an egg-producing sponge by chance,
their concentration in the water influences the
number of eggs fertilized and the number of
larvae developed.

Once a spermatozoon is in one of the
sponge's chambers it is taken in either by one
of the choanocytes (collared cells) or by an
amoebocyte. The cell picking up the sperma-
tozoon is termed a carrier cell, and in the
sponge species studied by Duboscq and Tuzet
(1937) this function was fulfilled by either
choanocytes or amoebocytes, depending on the
species of the sponge. If the spermatozoon is
taken up by a choanocyte, this carrier cell
loses both its collar and flagellum and takes
on the appearance of an amoebocyte. The cell

picking up the spermatozoon is usually the one
closest to an immature ovum. Once within the
carrier cell the spermatozoon loses its tail
while the head and body enlarge two to three
times.

The presence of the spermatozoon in the
carrier cell close by apparently triggers the
immature ovum (which at this stage in the
reproduction process is about 15 microns in
size (Duboscq and Tuzet, 1937) into activity.
The ovum fuses with two amoebocytes called
the nurse cells; then the ovum enlarges. The
actual transfer of the sperm is accomplished
through a canal which develops from the outer
part of the ovum to the nucleus. The young
embryo enlarges to about 0.5 mm. and becomes
surrounded by a hyaline capsule. Maturing
embryos sometimes occur singly but more
often are found in groups of 10 to 15 (fig. 3b).

The color of the fertilized ovum in the early
stages of cleavage is whitish. As the embryo
matures it becomes a dark olive green with
one end more deeply pigmented (fig. 3c). The
final stage in development of the larval form
is the growth of a crown of cilia at one end.
At this point the larva is released into the
nearest excurrent canal and expelled into the
water where it continues to live as a free-
swimming larva for a period of from a few
hours to several days.

After being released from the sponge, the
larva must come in "contact with clean hard
bottom to develop successfully into a mature
sponge. Some attach to sea grass, sea whips,
mollusk shell, bits of coral, etc., and attain
some size, but being poorly anchored they are
usually washed about and killed.

Observation of a '•pawning sponge by W.
Smith, Nassau, Bahamas, (personal communi-
cation) showed that all the embryos in a velvet
sponge matured and were released within a 4-
week period.

Majority of the eggs and embryos are de-
veloped in the lower two-thirds and toward the
central part of the wool sponge (fig. 3a) with
very few eggs developing in the peripheral
portion. One phenomenon associated with the
production of eggs is the loss of living material

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within the sponge itself so that the skeletal
spongin fiber makes up a much larger per-
centage of the central mass after egg produc-
tion has actively begun. Loss of living material
causes a darkening of the internal portion of
the sponge, and the beginning of this darkening
can be observed in figures 3a and 3b, which
are sections of sponges just attaining egg-
producing size.

Relationship Between Sponge Con-
centration and Larval Production

Field observations of the number of eggs
produced by individual sponges and the per-
centage of sponges producing eggs in any one
area point to important relationships between
sponge concentration and reproduction. During
July 1956, more than 50 test dives of approxi-
mately 2 hours each were made. The relative
concentration of the sponges on each rock bar
was calculated from the number of sponges
taken on each dive.

Although the information shown in table 2
does not lend itself to detailed analysis, some
tentative conclusions can be obtained from the
data gathered, supplemented by direct observa-

tion of other sponging areas. Verification of
these can be established in future work.

1. There may be a critical density of
sponges required for optimum pro-
duction of larvae. — If the concentra-
tion of sponges of 5-1/2 inches or
over was of the order of 11 per acre,
over 85 percent were producing larvae.
Of more significance is the fact that
the density of the larvae in these
sponges was approximately 500 per
cubic inch. At some stations where
the concentration of sponges was three
or less per acre, only 30 percent or
less of the sponges were producing
larvae and in these cases the density
of the larvae in the sponges was never
more than 50 per cubic inch. This
would give a total ratio of reproductive
potential of the sponges in the two
areas of about 30 to 1.

The data must be interpreted with
reserve. Concentration of the sponges
is not the only factor in assuring opti-
mum fertilization and production of
larvae. A sperm-producing sponge is a
necessary element in the concentra-
tion.

Table 2. — Concentration of wool sponges collected in July 1956 for determination

of larval content

[Number of sponges]

Station

Total sponges

Under 5-1/2"

5-1/2" diameter

Total sponges

No.^

taken per acre

diameter

and over

with larvae

Number

Number

Number

Number

XVII

11

0

11

9

XVIII

1

0

1

0

XXIII

2

2

0

0

XXIV A

U

11

3

3

B

15

8

7

6

C

5

0

5

A-

D

A-

0

4

A

XXV

4

1

3

2

XXVI A

25

24

1

^1

B

5

0

5

4

XXVII

2

0

2

2

XXVIII

20

18

2

^2

XXIX

9

6

3

0

XXX

7

6

2

0

XXXII

5

0

5

4

XXXIII A

A-

1

3

2l

B

3

2

1

0

XXXIV

1

0

1

0

'^ Locations of these stations are shown in figure 10.
^ Very few larvae in any one sponge.

10

The process of fertilization of the
ova within the wool sponge suggests
that for almost every sperm taken in,
one egg will be fertilized and mature
to the larval stage. The number of em-
bryos produced, therefore, will be in
direct ratio to the number of sperm
entering the sponge. Further, the num-
ber of spermatozoa being taken in will
be in direct relationship to the con-
centration of sperm in the water sur-
rounding the egg-producing sponge.

2. Sponges possibly can reach a size and
shape that inhibits the production of
eggs and larvae. — Sponge fishermen
have observed that when they formerly
found densely populated beds of very
old doughnut- shaped sponges there
were few if any young sponges develop-
ing. Doughnut- shaped sponges were ob-
viously past their optimum size of
development. Extensive fishing of these
beds resulted in the appearance of large
numbers of small sponges the follow-
ing year. (Regrowth of pieces of sponge
left on the bottom when the large
sponges are torn free could account for
the small sponges.) The possibility is
suggested that when a wool sponge
reaches a 12-inch size and begins to
form into a ring, it may be in a period
of senescence. (See section on growth
for a discussion of this phenomenon.)
At this point the food intake may be
below the demands of the living tissue,
and there may not be sufficient food
reserves for the larvae to become vig-
orous enough to leave the sponge. If
they do leave they may not be strong
enough to attach and metamorphose
into young sponges.

Since small pieces of even the largest
sponges can be used successfully in
cultivation and these grow into vigorous
young sponges, the argument cannot be
used that the tissues of the large
doughnut- shaped sponges become too
old to produce ova.

3. Wool sponges may not be capable of
self-fertilization.— If sponges were

able to self-fertilize, the sponges found
in areas of low sponge concentration
would have as many larvae as those in
areas of high sponge concentration. At
many stations in area D (see appendix)
where only few sponges were encoun-
tered, none contained developing
larvae.

4. Sponges less than 5-1/2 inches in
diameter may not be the sperm-pro-
ducing sponges. — The presence of
large numbers of sponges of less than
5-1/2 inches in diameter had no rela-
tionship to the percentage of mature
sponges that were producing larvae.
For example, on one bar, Station
XXVlll (table 2), the concentration for
all sponges was 20 per acre but only 2
per acre for sponges of mature size.
The mature sponges here had very low
egg counts.

5. From the evidence gathered there
is an indication that only 1 out of every
200,000 or more larvae actually settles
on the bottom and grows to maturity. —
On five bars, in less than 24 feet of
water where intensive work on the
ecology and growth of the sponges was
carried out, of the 108 sponges meas-
ured, the ratio of mature sponges to
sponges of less than 5-1/2 inches in
diameter, was 1: 3.6. A number of the
sponges were obviously regrowths
from old torn bases. I assume that the
number of mature sponges present was
barely enough to maintain the concen-
tration of sponges at the level observed.
Since the average mature wool sponge
in the area was little more than 6
inches in diameter and sponges of this
size produce an estimated 200,000 or
so larvae per year, it would appear that
this level of egg production in this area
is the minimum production per mature
sponge required for maintenance of the
population. Almost all of the sponges
over 6 inches in diameter were being
harvested each year in the area. It may
be suggested that if the average diam-
eter of the mature sponges in an area
Is only 6 inches and all sponges over

11

this size are being steadily removed,
insufficient larvae are being produced
to bring about an increase in the
sponge population. As a result the
concentration of sponges will remain
at an almost constant level.

Potential Larval Production Related
to Volume

The average size of the mature sponges in
an area is also an important factor in bring-
ing about an increase in sponge population as
well as the concentration of sponges of mature
size. On a volumetric basis the ratio of the
volume of a 6-inch diameter sponge to sponges
of 7 to 11 inches in diameter is revealing.

It is the total volume of reproducing sponge
material present in an area and not the number
of sponges alone which must be considered. It
may be seen from table 3, for example, that
an 11-inch sponge may produce more larvae
than six 6-inch sponges.

Optimum Temperatures for Larval
Production

Larval production cycle throughout the year
and the relationship of temperature to this
cycle were determined by monthly collections
of wool sponges made during most of the 2-
year study period. Diving boat crews collected
and preserved the sponges for later examina-
tion at the Marine Laboratory of the University
of Miami. During each of the field trips, large
numbers of sponges were also examined for

larval production and size of the sponges at
maturation. Well over 700 sponges were ex-
amined during the study.

Probably the longest and most complete
records of sponge larval production were ob-
tained by F. G. Walton Smith (personal com-
munication). These records are for the breed-
ing cycles off Tumeffe, British Honduras.
Information regarding the larval production
cycle in the Bahamas was also available. The
combination of three cycles plus parallel
records of monthly mean water temperatures
from the corresponding areas are presented
in figure 4.

The temperature data were obtained from
U.S. Department of Commerce Special Publi-
cation No. 278 (1955), which gives the surface
water temperatures at tide stations along the
Atlantic and Gulf of Mexico coasts. Accuracy
to within 3°F. is claimed, depending on the
location of the tide station on the shore.

Data on larval production are given as the
percentage of sponges producing larvae of the
total number examined each month. Cedar
Keys data are for the area from Tampa Bay
to St. Marks. Data from the Bahamas and
British Honduras were obtained from F.G.
Walton Smith.

The two critical temperatures in the larval
production cycles appear to be 73° F. and 84° F.
In the Cedar Keys area, larval production
begins as soon as the mean monthly tempera-
ture rises to about 73° F. and increases

Table 3. — Potential larval production related to volume

Diameter

Ratio to
6" sponge

Potential larvae being
developed ■"■

Yearly production^

Inches

Number

Number

6

1 : 1

60,000

200,000

7

1.6 : 1

96, 000

320,000

8

2.<; : 1

144,000

480,000

9

3.5 : 1

210,000

700,000

10

4.7 : 1

282,000

940,000

11

6.2 : 1

372,000

1,240,000

■"■ With the observed number of larvae in a 6 inch sponge being taken as unity.

^ Based on length of larval production season and length of time for maturation of

one larva (4 weeks)

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13

rapidly until the temperature exceeds 84° F.
With a further rise of 2 or 3 degrees in
temperature the number of sponges producing
larvae falls from 70 percent or more to about
25 percent. Even with a drop in temperature
the percentage of sponges producing larvae
continues unchanged until the temperature is
below 73° F. at which time larval production
ceases.

In the British Honduras area the cycle is
more complex. Here the monthly mean water
temperature never falls much below 79° F. In
the late winter and early spring when the tem-
perature is rising, larval production also in-
creases but again, as the temperature goes
above 84° F., the number of sponges producing
larvae declines and finally tapers off to about
7 percent. As the temperature falls below
84° F., larval production increases but never
more than 50 percent of the sponges are gravid.
When the temperature again begins to rise in
the next yearly temperature cycle, it is accom-
panied by a rapid increase in larval production.

The production peaks in the Bahamas follow
the same pattern, as in British Honduras. The
first peak, in April, May, and June, occurs
while the temperature is rising. There is a
decline when the temperature is above 84° F.,
with a second peak in larval production in
November and December when the temperature
again falls below 84° F. This second peak ap-
pears to be very slow in starting, and part of
the peak actually occurs while the temperature
is below 73° F. The temperature data for the
Bahamas were obtained from a study by C.L.
Smith (1940) and were early morning tempera-
tures.

It would be expected that there would be
optimum temperatures which would stimulate
the production and release of the sexual prod-
ucts (in this case the sperm) and also increase
the receptiveness of the eggs for fertilization.
Shortly after the sperm are released, the egg-
producing sponges would have enlarging em-
bryos which would be readily visible to the
naked eye. Minimum temperature for the re-
lease of the sperm appears to be about 73° F.
Above 80° F. there apparently is a much
stronger stimulus for this release and a much
larger percentage of sponges are producing

larvae. Above 84° F. either the sperm are not
released from the male sponge (or become im-
potent), or the eggs become unreceptlve, for
larval production ceases. There seems to be no
ready explanation why larval production re-
mains at a very low level after the tempera-
ture declines below 84° F, The data from
British Honduras and the Bahamas indicate
that a long period of time is required by the
sponges to recover their ability to reproduce
in quantity while temperature is declining. In
the Cedar Keys area the temperature declines
so rapidly that before this recovery can take
place the temperature drops below 73° F. and
larval production ceases.

The longer reproductive period of the
sponges in British Honduras results in much
greater egg production than in the upper Gulf
area even though the peak of productivity is
higher in the Cedar Keys area than in British
Honduras. Total larval production in the Cedar
Keys area is only about 63 percent of that in
British Honduras (fig. 4). When the size at
maturation is taken into account, this dis-
crepancy may be somewhat increased. Sponges
as small as 2 inches in diameter will produce
eggs in the warmer waters of British Honduras
(F.G. Walton Smith, personal communication),
while in the upper Gulf eggs are not normally
produced by sponges until they are between
5 and 5-1/2 inches in diameter. Thus, if the
percentage of sponges producing eggs and
larvae in British Honduras is estimated, al-
most all the sponges would be potential egg
producers. In the upper Gulf, on the other
hand, only sponges above 5 inches in diameter
have been used to obtain the data; and if all
sizes of sponges were considered, the actual
percentages of egg-producing sponges would
be reduced to about one-third of that indicated
in figure 4.

Temperature and Size at
Maturation

In the Gulf north of Tampa Bay (area D)
the minimum diameter of wool sponges pro-
ducing larvae was 5 inches. North of Cedar
Keys (areas A and B) the minimum diameter
for mature sponges, generally speaking, was
5-1/2 inches. Only four or five sponges (out

14

of the 700 examined) less than 5-1/2 inches
were found to be producing larvae. In the Key
Largo area, the minimum size for mature wool
sponges was 3 inches; in the Bahamas, W.
Smith (personal communication) reported that
the minimum size was 4 inches. In British
Honduras sponges as small as 2 inches in
diameter may produce eggs.

When in each area the size at maturation of
the wool sponges was compared with the water
temperature, there was a very close relation-
ship between the number of months per year
in which the temperature in an area was greater
than 80° F. and the minimum size of mature
wool sponges (fig. 5). The curve in figure 5
represents a relationship between size at
maturation (larval-production size) and the
variation of temperature at different geograph-
ical points. It is likely that a very similar
relationship exists between size at maturation
and the variation of temperature with depth of
water. Bathythermograph recordings show that
in the upper Gulf, for example, temperatures
of more than 80° F. are to be found as deep as
120 feet during July. Insufficient data exist to
plot the duration of this temperature at various
depths throughout the year. It is possible that
dispersion of wool sponges to deep water areas
in the Gulf may be retarded by the effect of
temperature on the sexual maturation of the
sponges.

1

;ea a

.AREA D

\

3AHAMA

i

\

AREA G

\

0

z

i

t

5

T

d 1

NUMBER OF MONTHS TEMPERATURE > 60* F

Figure 5, — Temperature - size at maturation relation-
ship for wool sponges in various areas. (See appen-
dix a for areas.)

Since temperature is a factor in the breeding
cycle of the wool sponge, variation of water
temperature from year to year will affect
larval production. It is possible also that long
periods of optimum temperature could bring

about an earlier maturing of the sponges and
total egg productivity would be increased as
a result (fig. 5).

GROWTH OF SPONGES

Method of Determining Growth

Sponge growth was studied during the investi-
gation by a series of underwater field tests in
the northern Gulf. In all, 108 sponges of the
three principal species (wool, grass, and
yellow) were measured and tagged for growth
rate studies. Eleven were cut off, measured,
and tagged for regrowth study. One hundred
sponge cuttings were set out to observe their
growth rate, and a number of plain cement
bricks were placed in the areas to try to ob-
tain sponge settings. Sufficient data were
obtained to construct a growth curve only for
the wool sponge.

The sponges were tagged by running a
stainless steel or Monel wire through the
sponge and around a brick. Each cement brick
was code numbered by cuts in the edges (fig.
6b). The three dimensions of the attached
sponge was then measured with a modified
sliding square.

It was necessary to examine seven or eight
sponging bars before locating one that had a
sufficient number of sponges growing on it to
justify establishing a station. When located,
each of the five selected stations was posi-
tioned by (a) placing a buoy, the most practical
method, (b) making compass sightings, (c)
timing course runs from stationary objects in
the water, e.g., the coastal bird racks (plat-
forms constructed in the shallow water for
collecting guano), and (d) laying of wires on
the bottom in set directions from the bar for
locating by dragging later.

Losing buoys, changing work boats and com-
passes, taking of sponges by sponge fisher-
men (even though more or less unintentional),
and dying from adverse ecological conditions
contributed to our inability to recover a con-
siderable number of tagged sponges. Despite
these losses, I obtained enough data to establish
a growth rate for the sponges in the Gulf area

15

■*#^

m

Figure 6a.--Measuring sponges underwater during the field studies. Lightweight
Navy diving gear was used throughout, air being supplied from the surface.

Figure 6b.— A wool sponge measured and tagged for growth studies. The brick
is code numbered by the notches on three of the upper edges and attached to
the sponge by a Monel metal wire. This sponge was on a rocky bar in the
northern Gulf in 20 feet of water. To the left are a number of Area clams,
algae, and noncommercial sponges. This is typical rock bar appearance.

16

north of Piney Point. It is unfortunate that the
growth rates of the sponges in the area off
Cape Sable in the south could not be estab-
lished as well, as this would have assisted
greatly in understanding the relationship of
temperature and sponge growth.

To obtain the growth curve for wool sponges
in figure 7a, the growth data from each tagged
sponge was recorded individually on a graph
and the mean slope between them taken as the
average growth rate of the sponges. The re-
sults obtained by compilation of the data in
this way agreed well with those obtained by
Moore (1910b). The data gathered indicated
marked variation of growth between sponges
on the same bar.

^

^

oaaiFvt

^

SMOOTHED

X

^

y

y

y

A

Pm-ATEO

_^

/^

1

m

r'»

AGE IVEAflS AND yONTHS)

Figure 7a.--Growth rate of wool sponges. The light line
is based on observation dsta of the growth of tagged
sponges on bars in the upper Gulf. The heavy line is
the modified growth curve, dashed portions extrapo-
lated.

r"-"

=-

—

^

^-^

r""

.-==

:=SS--

/

r

^

1

AGC IN YEARS

Figure 7b.- -Volume-diameter relationships in the wool
sponges. Solid line based on observed growth rates.
Lower dashed line beyond 6-inch diameter based on
the growth formula. The upper dashed line of the
growth curve represents the more probable growth
rate under natural conditions as discussed in the text.

Moore determined the average yearly in-
crease in diameter of wool sponges to be be-
tween 1 and 1.2 inches, beginning with a cutting
of 10 cubic inches. For a comparable 4-year
period the yearly increase of wool sponges
growing naturally on the bottom determined
by the short-term experiment during the
present investigation was 1.25 inches.

Yearly Growth Factor

Growth may also be expressed in terms of
a growth factor, the number of times a sponge
increases in volume during a 1-year period.
With Moore's method the growth factors deter-
mined for the present experiment from the
growth curve were:

Second year of growth - 3.2
Third year of growth - 2.0
Fourth year of growth

1.6

The average growth factor for this 3-year
period was 2.3. Moore obtained a growth factor
of 1.9 for cultivated sponges in shallow water
at Anclote Key for a comparable period and
size of sponge. Crawshay (1939), reviewing
experiments with sponge cuttings at Tumeffe,
British Honduras, considered a growth factor
of 2.0 or more as adequate and 2.5 as good. He
also considered a growth factor of 3 or more
as high and suggested that the exceptional ac-
cumulation of waste matter which could accom-
pany the high food intake necessary to maintain
this growth factor might be unhealthy for the
sponge and result in disease. This could happen
with any deterioration of optimum growth
conditions.

With a growth factor of 2.3 during the first
few years of the growth of the sponge found in
the upper Giilf, a sponge would require about 3
years to reach the legal size of 5 inches in
diameter from the time of attachment of the
sponge larva and almost 4 years before the
sponge was 6 inches in size. A listing of vari-
ous growth factors obtained during the past and
present experiments show wide variation for
comparable growth periods:

Sugar Loaf Key, Florida (Moore,

1910b) 1.86

Anclote Key, Florida (Moore,

1910b) 1.91

17

Piney Point, Florida (personal

observation) 2,27

Abaco Island, Bahamas (Crawshay,

1939) 2.34

Turneffe, British Honduras

(Crawshay, 1939) 2.94

Growth Formula

When the annual rates of increase between
units of diameter were plotted, it was found
that for growth beyond a diameter of 3-1/2
inches the growth factor could be expressed
by the standard formula:

y= Ae^'^

where y = annual rate of increase - the
growth factor
X = radius of the sponge in inches at
beginning of a year
and A and B are constants, while
e is the base of the Naperian
logarithms.

This is assuming a regular spherical shape
for the sponge.

For the particular values obtained on the
growth rate off the Piney Point area the
formula, modified for ease in working, be-
came:

y = 1 + 11. 2e

■1.07X

Since the data gathered were for diameters
of from 2 to 7 inches, the use of this formula
for extrapolation of the curve beyond 7 inches
was particularly useful (fig. 8). The formula
indicates that growth will almost completely
stop when the sponge reaches a 12- inch diam-
eter. This is confirmed in the observed
growth of wool sponges by the death of the
central portion of the sponge when this diam-
eter is reached. The form of the sponge from
then on becomes more and more doughnut in
shape. Continued growth beyond a 12-inch
diameter suggests that one other growth factor
operates as the sponge approaches the limit
of growth indicated by the formula. Since the
sponge is uniform in structure and the intake
of water carrying the food is through the sides,
the greatest amount of food uptake is in the

y

4

'^^^

.-^^7, ■--

ion

io«

S."

"""""vl?

*'•

<

a:

^^\.i

^

S^X>4.

5

Z

z

RADIUS (INCHES)

Figure 8.- -Growth factor for wool sponges. Radius in
inches vs. the logarithm of the growth factor. The
upper curved broken line is comprised of the per-
centage volume increase plus 1, which gives the fac-
tor of growth for any size of sponge from 3-1/2 to 12
inches in diameter.

periphery of the sponge. This area, therefore,
continues to grow vigorously, but the rate of
food intake is not sufficient nor the rate of
food transfer through the sponge efficient
enough to support active metabolism in the
central portion of the sponge when the diam-
eter of the sponge is 12 inches or over. The
growth formula obtained would probably be
directly applicable to the rate of sponge growth
except for this phenomenon of sponge physi-
ology. It has been observed in doughnut-
shaped sponges of large size that the ring is
little more than 6 to 9 inches thick.

The rate of growth in diameter indicated by
the growth formula (fig. 7) appears to be valid
for the first 5 or 6 years. Beyond this point
the growth rate must be assumed to be some-
what less than indicated by the formula,
the increase in diameter gradually approach-
ing a uniform rate as the sponge assumes the
doughnut shape.

Life Span

Little is known of the life span of wool
sponges although the records have indicated
that they can live at least 25 years. Presum-
ably, the limiting factor to continued growth is
the capability of the sponge to draw in suf-
ficient food for self-maintenance. Any lack of
food intake is counteracted in part by the dying
of the central portion of the sponge so that
after a certain point in growth in diameter, the

18

volume of the sponge remains a constant in
relation to the surface area.

If the size of the sponge were periodically
reduced by dividing it into cuttings, it may be
that the original sponge material could be
kept living indefinitely, assuming favorable
growth conditions. This has been done in part
in the Bahamas' sponge plantation where
sponges have been cut several times from the
same base. Some of the bases are close to
16 years of age and are repeatedly developing
new upper growths.

Several individual sponges of noncommercial
varieties have been observed by me for over
15 years. These sponges had reached 3 feet
in diameter when first seen. This may be the
maximum size obtainable under the local con-
ditions present, for after a winter when tem-
peratures were unusually cool a decline in
size was noted. Similar reductions in size of
sponges growing in aquaria were observed
when water temperatures dropped suddenly.
This reduction in size seems to be related
only to temperature changes.

An examination of the ecological conditions
existing in each area indicates that food supply,
temperature, and water currents are the pri-
mary factors affecting the growth rate. The
effect of these factors on growth will be dis-
cussed in the section on ecology.

Healing and Growth of Cut Surfaces

Part of the field study on growth was ex-
perimentation on regrowth of the sponge from
the cut base to show the possible value of
cutting the sponge from the base rather than
using a hook to remove the sponge. Weekly
observations were made of the cuttings of wool
and yellow sponges attached to cement bricks
In aquaria with running salt water. Most
closely related to the field experiments were
the observations made on the healing of the
cut surfaces and the external evidence of re-
organization in the canal system of the sponge
cuttings.

Initial healing and sealing off of the cut sur-
faces took place within a few hours after
cutting. After 3 days, primary healing of the

cut surface had occurred and a new outside
surface layer laid down. At the end of 2 weeks
the cut surfaces had become black in color,
and within the month the exposed internal canals
had filled in. A number of small volcanolike
oscules had also developed, from which a
noticeable current of water passed.

The bases of the sponges in the field study
were examined about 3 months after the top of
the sponges had been removed by cutting. The
appearance of the regrowth from the cut base
was essentially that of a number of small
coalescing sponges. These bases had retained
their original mass and had developed a number
of prominent oscules about one-half inch in
height scattered over the cut surface. Because
of its relatively thin layer of living material
on the rock, the sponge had not had sufficient
food reserve to fill in all the larger exposed
canals and only a dermal layer had been laid
down. Beyond the formation of the oscules no
real growth had been made in this relatively
short period of time.

CULTIVATION OF SPONGES

Aristotle in 350 B.C. noted the regrowth of
sponges from torn bases. There are records
of experiments of sponge cultivation during the
18th century in the Mediterranean Sea, and
many experiments have been carried out since
that time in various Mediterranean countries,
British Honduras, the Bahamas, and Florida.

From the time that sponging became an im-
portant industry in Florida, the harvesting
methods have been deplored as destructive
and sponge cultivation has been suggested as a
remedy to assure an adequate continuing har-
vest. The most extensive cultivation experi-
ments attempted were by Moore (1910b). In
the several cultivation experiments tried in
Florida, the sponges were grown on metal
spikes, wire, and cane, with cement triangles
or discs used as the bases for attachment.
All the experiments eventually ended because
the sponges were destroyed either by storms
or by the spongers, some of whom were
opposed to the experiments. Principal source
of failure was the poor locality chosen for the
experiments.

19

Sponge Cultivation in the Bahamas

Choice of locality for growing good-quality
sponges is of particular importance. In some
cases in the Bahamas it was found that a 3-
inch sponge cutting would grow to 8 or 10
inches in size within 2 years; however, quality
of such sponges was extremely poor. The
best grade of sponges was produced by 3-inch
cuttings that increased to an 8-inch size in
3 years, a rate of about 1.6 inches per year.

Several attempts at sponge cultivation have
been carried out in the Bahamas since the
early 1900's with some degree of success.
Wilfred Smith of Nassau had about 200,000
velvet and wool sponges "planted" just previous
to the 1938 disease that wiped out the entire
sponge industry in the Bahamas. The present
plantation at Pot Cay, Andros Island, Bahamas,
is being maintained by Henry Thorn, and
sponges are being grown successfully although
not on an active commercial basis.

In an unpublished manuscript on sponge culti-
vation by W. Smith of Nassau, a complete out-
line is given for successful sponge cultivation
methods. With his permission a very brief
summary is given here.

The "wild" sponges to be used as cuttings
were gathered by the crew of a small sloop
within a 30-mile radius of the plantation. The
sponges as gathered were stored or held in the
fish well of the sloop or in a fish scow, in
either case the sea water having free access to,
and circulation around, the sponges. A full load
to make 3,000 sponge cuttings could be collected
in about a week if the weather was favorable.
At the plantation the sponges were strung on
wires and fastened to the bottom for a week.
This method assured that only healthy sponges
were used in planting; the ones that died during
the holding period were cleaned for sale.

The planting uritconsistedof four men work-
ing from three dinghies — the live sponges were
kept in the fish well of one dinghy, 8-inch flat
dry stones in the second, and the third was used
to ferry stones from the shore to the planting
unit. In planting, the sponges were cut with a
sharp knife into pieces about 3 inches across,
tied to the stones with a length of palmetto

string made from splitting a palmetto palm
leaf and dropped overboard 3 feet apart
(fig. 9). Planting was on firm mud bottom in
about 6 feet of water where there was a good
but not excessive flow of the tide. It was also
important that the choice of locality be in an
area where the salinity of the water would never
fall below 32 %q , (see section on salinity
relationships for more detail).

Within 2 weeks after planting the raw sur-
faces of the cuttings had healed over com-
pletely and turned black. Within 6 weeks the
cuttings had normal color. The second phase
in the growth was the withdrawal of living ma-
terial from the sharp corners of the cuttings,
the exposed skeletal material rotting and
sloughing away. By the end of the first 6-
month period the new sponge was rounded out
by new growth.

Advantages and Disadvantages for
Cultivation

There have been many advocates of sponge
cultivation. Some have even stated that cultiva-
tion was an absolute necessity for the survival
of the sponge industry. Such a strong opinion
can be understood because of the obvious dif-
ficulty in obtaining wild sponges, lack of
assurance in maintaining a constant supply,
the considerable difficulties that have been
encountered in trying to bring about an under-
standing of the need for sound conservation
practices, as well as the attractive assets
cultivation has been said to offer. The more
obvious advantages and disadvantages of sponge
cultivation are listed below.

The major advantages would be:

1. The planting operation is a relatively
simple one, the basic materials (sponge,
rock, and tying strings) can be gathered
in the area. This does not rule out the
possibility of using an improved base of
cast cement and a better grade of tying
material.

2. Sponges can be concentrated in a small
area. In many places one cutting can be
placed per square yard. Loss of time in
harvesting is thus minimized.

20

4?iJ.>^4-^'*

Figure 9,--Cutting sponges for cultivation. A 2-year-old sponge has been cut from its base, bottom left, and
the top part divided into quarters. One of the quarters has been attached to a rock, while another is being
threaded on a string of dry palmetto leaf in preparation for tying to a rock.

3. Harvesting of the sponges is a simple and
controlled operation, the sponges being
taken up only when an order has to be
filled. The remaining sponges continue to
grow.

4. If the sponges were cut from the rock
base rather than pulled or torn off, the
remaining base would act as a fresh
cutting and the operation of harvesting
and planting is thus accomplished at the
same time (fig. 9).

5. Growing sponges by cultivation also
offers the advantage of some control over
quality, size, and shape through the
proper selection of the growth area and
the growth period. It might be possible to
increase quality and value by selecting
only the best sponges for cultivation.

6. The heavy concentration of sponges in the
cultivation area would result in produc-
tion of large numbers of eggs and larvae.
If the plantatidVi were in the region of
good natural sponging ground where the
bottom was suitable for attachment of the
larvae, large numbers of naturally grow-
ing sponges could be expected to set with-
in a 2- or 3-mile radius of the plantation.
The harvesting of these sponges would
add to the total returns.

The major disadvantages encountered in any
attempt at sponge cultivation would be:

1. The lengthy process of selection of a
growing area which would assure the
development of a good grade of sponge
in the shortest possible time. This might
require the use of a series of test areas.

21

over a considerable period of time; or,
the plots to be cultivated could be located
near areas known to grow superior in-
dividuals.

2. A long-term lease of the bottom spong-
ing rights would have to be obtained.

3. The necessity for constantly patrolling
and protecting the plantation area from
vandalism or theft would be expensive.

4. The possibility of almost complete loss
of several years of work by storm is
always present.

5. W. Smith (personal communication) stated
that during 1938 the sponge disease killed
almost all of the sponges in areas where
there was a high sponge concentration.
On the other hand, a much larger per-
centage of the sponges in areas of low
concentration were able to survive. This
at least suggests that with cultivated
sponges at concentrations of one per
square yard any sponge disease would
spread rapidly from one sponge to the
other and quickly result in large numbers
of free-floating or free-swimming stage
of such disease organisms. Once started,
therefore, a disease that would normally
be only somewhat destructive in natural
sponge beds might quickly reach epi-
demic proportions in a cultivated bed.

6. Because of the slow growth rate of
sponges it would not be until the fourth
year that any returns could be expected
and not until the seventh that the planta-
tion would be fully productive.

A rough schedule for planting and harvesting
using the methods described above for the
Bahamas would be as follows:

1. Planting would be carried out during a
limited part of the year when weather
conditions would be most favor able, using
a crew of about nine aboard a sloop to
collect the sponges and a crew of four to
plant the cuttings in the selected area.

2. Under actual conditions as many as 1,500
cuttings can be planted in 1 day by the

crew of four, but the problem of gather-
ing stone and sponges to maintain a supply
for the planters would become increas-
ingly difficult. Assuming that one good-
sized sponge would supply 8 cuttings,
about 7,000 "wild" sponges would have
to be gathered to plant 50,000 cuttings.
A rate of 50,000 plantings per year would
have to be maintained for the first 3
years. During the fourth year two plant-
ing crews could do all the work, harvest-
ing the first year's planting of cuttings
and replanting part of these. Assuming a
maximum mortality of 20 percent during
the 3 years of growth, 40,000 sponges
could be harvested during the fourth year.
Since it is possible to cut the sponges
from the base and still have a very good
product, the 40,000 living sponge bases
would be essentially replanted cuttings.
Assuming, after 3 years, the program of
the plantation is to plant 100,000 cuttings
per year, 10,000 to 15,000 of the harvested
sponges would have to be cut to be used
for replanting during this fourth year to
bring the total number of cuttings to the
desired 100,000 level. This would leave
between 25,000 and 30,000 sponges for
marketing, yielding about $15,000 at
present average market prices. It is quite
conceivable that the cultivated sponges
would be a quality product and bring in a
somewhat higher price.

3. The same schedule of partial harvesting
and replanting would have to be main-
tained during the fourth, fifth, and sixth
years.

4. During the seventh year it would be pos-
sible to harvest 80,000 of the original
100,000 planted sponges of which 5,000
would have to be sacrificed for cuttings.
A number of sponges might be deformed
by the proximity of plants or alcyonarians
growing on the sponge or the stone base.
These deformed sponges could be cut up
for seed; the loss of the 5,000 would not
necessarily represent an unexpected
heavy loss of revenue.

The 75,000 sponges harvested yearly would
represent about one-quarter of the 1955 or
1956 yield from the entire Florida area, where

22

at least 140 men working full time are required
merely to gather the sponges. On the basis of
manpower alone, therefore, it would only re-
quire 8 to 10 men to produce as many sponges
by cultivation as 35 or more men harvesting
naturally growing sponges at the present rate
of production once the plantation was in full
production.

Establishing sponge plantations along the
coast of Florida presents several additional
problems that would be less serious in an area
such as the Bahamas.

1. Turbidity of the water along the Florida
coast is much greater than in the Baha-
mian water because of greater land drain-
age and differences in the type of soil.
Poorer underwater visibility would in-
crease the difficulty of planting and
gathering the sponges. There is also the
danger of periodic mortality due to fresh-
water runoff.

2. Heavier water traffic over potential plan-
tation areas would require closer super-
vision of the grounds.

3. On the west coast of Florida the diving
boat crews find that the water is suf-
ficiently calm and clear enough for work
only about 100 days each year. On the
shallow larger banks of the Bahamas,
where the water is crystal clear, the
number of work days would be expected
to be considerably higher.

From the standpoint of quality the logical
choice for a sponge plantation off Florida would
be in the Rock Island area, probably in the
region of the Econfina flats off the Econfina
River. From the standpoints of faster growth
and availability of quantities of natural sponges
the area off Cape Sable would be the most
profitable. In the northern part of the area,
the winter weather is rather severe for water
work and in addition, there is the constant
danger of freshening of the sea water. In the
southern area off Cape Sable there are rela-
tively few days when the water is sufficiently
clear for work of any kind underwater.

Some parts of the Florida Bay area in the
vicinity of the lower keys would appear to be

a practical area for a plantation. Much would
depend on the quality of sponges that could be
produced there.

DISTRffiUTION

Determination of Distribution

Distribution of the commercial sponges in
the Gulf was determined on three survey trips.
On the first two trips, 1 did the diving; on the
third trip, two regular sponge divers did the
surveying. The first trip was made with a small
pleasure craft in September 1955. This cruise
surveyed the area from Tarpon Springs to St.
Marks in water depths from 6 to 60 feet. The
second trip was made aboard a regular diving
boat in November 1955 when the area from
Tarpon Springs southward to the Ten Thousand
Islands was explored. The third field trip,
again aboard a regular diving boat (Ellni), was
made in July 1956 and covered the area from
Tampa Bay to Carrabelle. This trip was made
to survey the bottom at depths from 50 to 100
feet to establish the outer limits of commercial
sponge distribution.

In the three field trips, 88 diving stations
were established in the area between Tampa
Bay and Carrabelle, with well over 100 dives
being made (fig. 10). Nine stations were south
of Tampa Bay, but these did little more than
verify the scarcity of sponges between Tampa
Bay and the area seaward of Everglades City.
A careful survey of sponging areas from Plan-
tation Key to Key Largo was made on the
Florida east coast from chartered small open
boats; my assistant, Robert Work, and I made
about 40 dives on 11 stations in this survey.

From the information obtained on the field
trips plus additional information from the
spongers themselves it has been possible to
construct a diagram of the present distribution
of the commercial sponges (fig. 11). This dis-
tribution diagram represents only the areas
where commercial sponges are found at the
present time (1958) in the upper Gulf and does
not indicate the density of the population.

Concentration of ^onges and Extent
of Sponging Area

Density of the sponge population on the bars
is important economically as well as

23

Figure 10.--Diving stations, Tampa Bay to Carrabelle. Each station numbered with Arabic numerals represents two
to four 2-hour periods by the author. Stations numbered with Roman numerals represent exploratory dives made
by sponge divers on the June 1957 expedition.

24

CARRABELLE

I'ST. MARKS

HHATCHEE

r "IPRF^FMT DISTRIBUTION (1956)

ETO^ ADDITIONAL AREA IN 5 YEARS
E2SZSI3 ADDITIONAL AREA IN 10 YEARS

7 FATHOM LINE

13 FATHOM LINE

-< CURRENT DIRECTION

SCALE I ■ 1 = 10 MILES

Figure 11. —Probable distribution of sponges in 5 and 10 years (from 1958). This figure also shows present distri-
bution and the water current pattern.

25

biologically, as shown in the section on repro-
duction of sponges. It is necessary for each
sponge diving crew to gather from 125 to 150
sponges per day of effort, or 12,500 to 15,000
per year. This number gives only the minimum
return required for operation of the boat, with
the shares to the members of the crew provid-
ing only the minimum for existence.

Several methods have been tested to esti-
mate the average density of the sponges on the
rock bars. The best and most practical method
found is a calculation based on the area cov-
ered daily by the diver, the total number of
days of work annually, and the average number
of sponges taken by each diving boat. It has
been estimated that the diver walks at an aver-
age rate of one-half mile per hour and can see
about 15 feet on either side. The rate of walk-
ing varies greatly according to the concentra-
tion of the sponges, slowing down when the
sponges are numerous and increasing where
the sponges are scarce. Underwater visibility
also varies from day to day.

The two divers aboard each boat work under-
water for a total of 10 hours per day out of the
12-hour working day. Poor weather conditions,
travel time, and time lost in port reduce the
number of working days to 100 per year. Multi-
plying the distance in feet traveled by the divers
in 1 day by the width of the area searched and
dividing this total area by 43, 560 (the number of
square feet in 1 acre) provides a calculation
of the area covered by the divers in 1 day. The
area is about 18 acres. At this rate, the area
covered in 1 year by the divers of one boat
would be 1,800 acres or 2.8 square miles. The
1957 fleet of seven diving boats would there-
fore cover some 19.6 square miles per year.

The total sponging area being used by the
divers may be estimated as follows:

1. At the present time the mean diameter of
the wool sponges being taken by the
divers is 7 inches. Since the smallest
legal size is 5 inches, the sponges taken
have to range between 5 and 9 or more
inches to obtain this 7-inch average.

2. The growth rate above a 5-inch size is
approximately 1 inch per year, and
therefore it will be necessary to exploit

at least part of the total sponging area only
once every 5 to 6 years to obtain sufficient
numbers of the larger sponges to main-
tain the 7-inch average size. As a basis
for making a calculation of the total area
being worked by the divers, the assump-
tion is made that all the sponge-producing
bars are worked at least once in every
5-year period.

3. To search all the sponge-producing area
once in a 5-year period requires that the
total area covered would be three times
that covered in any 1 year, and this would
represent the total sponging area avail-
able and being worked by the diving boats
at the present time. This total area would
therefore be 59 square miles in extent.
All factors considered, this appears to
represent a minimum estimate.

Lack of adequate data makes it Impossible
to estimate the area covered by the sponge
hookers. Since the average size of wool sponge
being taken by the hookers is about 6 inches in
diameter, it appears that the available shallow-
water hooking area is being covered far more
thoroughly than the bottom below the 20-foot
depth. Using a total of eight diving- boat equiva-
lents' for the number of hooking boats working
and the same process of calculation, the area
being worked by the hookers is less than 40
square miles in extent.

Average daily take has been estimated by the
spongers for each area (see fig. 15 for areas)
and is given in table 4 along with the calculated
concentration of the legal- sized sponges per
acre, based on the above calculations. This
concentration agrees very closely with that
observed during the present investigation of
the sponge beds.

Based on several counts of the number of
sponges on a bar and the measurements of the
sponges, there are on the average three sponges
less than 5 inches in diameter to each one more

' Diving-boat equivalents are calculated in section on
"present status of the sponge industry."

26

Table U. — Daily take and density of sponges by areas, 1957

Area-"-

Low take

High take

Average take
(estimated)

Average density per
acre of legal-size
sponges

A

80

250

125

6.9

B

70

2225

130

7.2

C

200

<il5

300

16.6

D

125

365

230

12.7

E

100

300

200

8.3

F

250

1,115

660

36.6

■'■ See appendix A and figure 15 for details of areas.

2 High concentrations of sponges found only in shallow water.

than 5 inches (legal-sized sponges). The popu-
lation density of wool sponges of all sizes in any
area will, therefore, be about four times that
given in table 4.

In areas A and B* the low number of sponges
taken per day is in part offset economically by
the better quality of sponges taken in these
areas and the correspondingly higher price.
On the other hand, large number of sponges
taken in area F is not as profitable to the
sponger, because these sponges are inferior to
those from other areas and bring a much lower
price.

In all areas except F the concentration of the
wool sponges is not dense enough to expect any
sudden increase in the number of sponges
through natural propagation. In area F, how-
ever, the spongers reported substantial in-
creases in the concentration of sponges between
1954 and 1957, and this recorded concentration
of about 36 legal-sized sponges per acre would
appear to be above the level necessary to not
only maintain but increase the population of
any given area. Because of the increased
turbidity, which limits underwater vision, and
the higher concentration of sponges, which
slows the diver's progress, the density of
sponges per acre indicated in table 4 for area
F is low. Density per acre may be as much as
50 percent greater than shown.

Distribution of Diving and Hooking
Depths

The data on the landings of sponge from the
Tarpon Springs Sponge Exchange enabled us to

< See appendix and figure 15 for details of areas.

obtain the distribution of the various commer-
cial species of sponges by depth. The diving
boats are limited by law to work in water of
more than 21 feet (3- 1/2 fathoms). The hooking
boats on the other hand usually work in water
from a fathom or more to less than 21 feet.
By separating the landings of divers and
hookers the relative distribution of the sponges
in depth can be estimated. The market returns
for the years 1955 and 1956 have been analysed
on this basis (table 5).

Table 5 does not give a completely accurate
picture of the comparative harvest by divers
and hookers. As we shall see later, the aver-
age size of sponges landed by the two methods
differs quite considerably. Wool sponges taken
by diving boat crews are about 50 percent
greater in volume than the average size taken
by the hooking method. Thus the deeper water
area is producing about 50 percent more
sponges by weight than indicated when the
method of comparison is only by the number
of sponges.

Causes of Short-Term Variations
in Landings

Unfortunately the records of landings for
1950-56 are not complete; only 1955 and 1956
records are sufficiently accurate for tabula-
tion. Although any analysis of the situation
based on these 2 years alone is not indicative
of trends in productivity of the sponge beds,
several observations can be noted from the
table above and from available information ob-
tained from the sponge fishermen.

27

Table 5. — Number and percentage of sponges taken by species and depth

Species and year

Depth

Less than 21 feet

More than 21 feet

Wool:

1955:

Number

Percent

1956:

Niomber

Percent

Yellow :

1955:

Number

Percent

1956:

Number

Percent

Grass:

1955:

Number

Percent

1956:

Number

Percent

Glove :

1955:

Number

Percent

1956:

Number

Percent

192,215

59.9

164,711

48.6

11,881
92.7

26, 166
85.3

7,660
91.6

18,317
91.7

90
100

976

97.6

128, 552
40.1

173,931
51.4

945
7.2

4,505
U.7

698

8.4

1,647
8.3

0

0

54
2.4

In the shallow-water area the wool sponges
have had a setback during the 2-year period
(1955-56). This was the result of local losses
of sponges by a disease in the shallow area
just north of Tarpon Springs and the dying of
large numbers of wool sponges in the shallow
water north of Steinhatchee after the hurricane
in October 1956. This latter loss was probably
caused by a freshening of the water (see sec-
tion on sponge disease). These losses are only
temporary, and the situation is expected to
return to normal within a few years in these
very limited areas. In the deeper water the
concentration of wool sponges is increasing and
additional areas are coming into production.
Part of the increase in landings can be at-
tributed to the increased number of diving
boats. The increase in the numbers of wool
sponges is very slow, and, in my opinion, there
is not likely to be any sudden expansion of the
sponge population.

There are too few yellow and grass sponges
on the bars as yet to make any prediction of the

trend. In 1957, however, it appeared that the
population of these sponges in some areas
was sufficient for large numbers of larvae
to be produced and their numbers to increase
rapidly during the following few years. Land-
ings in 1958 and 1959 carried out this predic-
tion.

Factors Affecting Dispersion

One of the more important aspects of the
present study was to determine what factors
were affecting the dispersion of the wool
sponges and how fast this dispersion was taking
place. With this information it should be pos-
sible to predict with some degree of accuracy
the new areas that will be producing sponges
within a given number of years, the extent of
those areas, and the potential landings of
sponges. These facts are of considerable im-
portance to both the sponge producer (the
sponge fisherman) and the sponge distributor,
who must have some idea of future production
in order to know what long-range advertising

28

and sales campaigns should be carried
on.

Given a breeding population of sponges,
three major factors affect dispersion:

1. The direction, rate of flow, and charac-
teristics of the ocean currents in the
sponge-producing area.

2. The duration of the larval stage.

3. The growth rate of sponges to maturity.

There are two types of ocean currents —
tidal and semipermanent — affecting the dis-
persion of the free larval stage of the sponge.

Measurements of the tidal flow and its cal-
culated excursion show that in the upper Gulf
the total distance traveled by the water during
a tidal period is about 2 miles where the depth
of the water is 24 feet. Excursion varies ac-
cording to the depth of water; in water of
roughly three times the above depth, excursion
is about one half.

The normal direction of the tidal flow is
approximately at right angles to the coast and
has a more or less elliptical excursion. Com-
pared to the strong inshore current that flows
parallel to the shore, the back and forth move-
ment of the tide is relatively ineffective in dis-
persing the larvae in any set direction.

Tidal excursion is important, however, to the
fertilization process since it carries released
sperm back and forth over the sponge-produc-
ing area, greatly increasing the chances of
fertilization. Wave action plays a similar role
on a much smaller but still important scale.

Semipermanent currents in the Gulf, how-
ever, are most important for the wider disper-
sion of the commercial sponges from their
present limited distribution. These are the
northward inshore current and four offshore
eddies, the latter dispersing the sponges sea-
ward. The current pattern in figure 1 1 has been
modified from the determination of the Gulf
currents along the west coast of Florida made
by members of the Red Tide Project at the Ma-
rine Laboratory of the University of Miami. The

distribution pattern of the sponges along the
coast north of Tampa Bay coincided almost
exactly with what one would have expected to
find as a result of these current directions.

The most important single current for sponge
distribution at present is the inshore current
that lies between the shore and the 50 to 60 foot
depths. This current flows more or less
parallel to the shore. Current flow was meas-
ured by dropping a series of drift cards in the
area off Piney Point in the upper Gulf at various
distances from shore. In June 1957, drift cards
released about 4-1/2 miles offshore in 20 feet
of water were picked up south of Alligator
Harbor. The rate of flow estimated from these
cards was 5 miles per day. Those drift cards
dropped 10 miles from land in 35 feet of wa^er
were picked up near Panama City; the estimated
rate of flow was 8.2 miles per day. Between
the time of dropping and the time of recovery
the wind was very light, and shore recoveries
were made a day or so after the beginning of a
strong southerly wind. Depending on the
strength and direction of the wind, variations
in direction and rate of flow would be expected
in water of this depth. The summer current,
as measured by the drift cards, is probably
fairly consistent since the summer winds are
usually light and from the southeast. Majority
of the sponge larvae are released between May
and August.

The three eddies between Tampa Bay and the
Cedar Keys area are between 20 and 25 miles
in their greatest diameter where water depths
are 50 to 100 feet (fig. 11). Estimated current
velocities in these eddies is 1 mile per day.

The most northerly eddy, located south of
St. Marks, is 50 miles in its greatest diameter;
and since the shoreward side of the eddy is
part of the inshore current, the velocity of the
northern part of the eddy is similar to that of
the inshore current. With the shoreward side of
the eddy flowing in much the same direction as
the prevailing winds in the area there are times
when the velocity of the current in the eddy
should increase substantially. The seaward
movement of the eddy, off Carrabelle, would
retain much the same velocity as the shore
current, because much of the water moves
Gulfward with the eddy. In the deeper water

29

the offshore current flowing counter to the
shore current flows at about 11 miles per day.
The northern eddy is by far the most important
to both the present and future distribution of
the sponges to the deeper water areas of the
Gulf.

Several other features of the current pattern
over the sponging grounds are important for
sponge distribution. In the area just west and
north of Indian Rocks, 15 miles north of Tampa
Bay, the set of the current is generally shore-
wards. Lack of commercial sponges in any
area upcurrent from Indian Rocks and the con-
stant shoreward set of the current appear to be
the primary causes in limiting the occurrence
of commercial sponges to the Indian Rocks
area and downcurrent from this area. In this
case the movement of the permanent current
is possibly preventing the spread of commer-
cial sponges to a large area just north of Tampa
Bay which is now supporting a very healthy
population of noncommercial species and which
appears to have all the essential ecological
characteristics necessary for the growth of
commercial types of sponges.

Lack of active circulation of the water by the
semipermanent currents in the area just north
of St. Martins Reef Light and Anclote Key may
be responsible for the present scarcity of
sponges in the shallow water of this area. The
few sponges found here on the field trip were
aU more or less the same size, indicating that
larvae had been brought into the area during one
or two short periods when the current had
swung towards shore. No sponges of less than
legal size were seen in the 10- to 2 5- foot
depths north of St. Martins Reef Light.

Calculated Rate of Dispersion

The only way an area can become repopulated
naturally by commercially valuable sponges is
by the drifting of their planktonic larvae into
the area. These larval stages last several days
at most (Duboscq and Tuzet, 1937), which limits
the distance sponges are dispersed. No work
has been done to date with life span of com-
mercial sponge larvae. To calculate the rate
of dispersion of the sponges, I have made an
arbitrary estimate that the larval stage lasts
a maximum of 4 days.

If it requires 4 years for a sponge to mature
in the upper Gulf, the annual dispersion rate is
approximately equal to the current flow per day
during the reproductive season.

STRUCTURE OF THE OCEAN
BOTTOM IN SPONGING AREAS

Bottom Slope and Sediment Zones

The composition of the bottom sediments
within the sponging area of the Gulf south of
Cedar Keys and the slope of the bottom give
considerable information with regard to the
general type of sponge habitat. Fortunately a
detailed report of the area has been made
(Society of Economic Paleontologists and Min-
eralogists, 1955), and most of the following
description is based on this report, with
specific details added from personal observa-
tion.

The bottom west of Tarpon Springs is fairly
representative of the entire northern sponging
area from Tampa Bay to Carrabelle. The aver-
age slope is 2.6 feet per mile. This slope is
maintained to the 180-foot depth and comprises
the inner shelf.

From the shore to the deeper water, the un-
consolidated sediments can be divided into a
series of zones roughly parallel to the coast.
In the inshore zone, about 20 miles in width,
the sediments are relatively uniform in struc-
ture, composed chiefly of quartz sand, with
phosphorite grains abundant locally. The sedi-
ment also contains shell, coral fragments,
calcareous algae, and sponge spicules. The
quartz particles contribute more than 50 per-
cent to the makeup of these unconsolidated
sediments and are for the most part fine to
medium in texture, similar to the material
brought down by the rivers or found along the
shore.

Many local concentrations of medium and
coarse quartz and phosphorite sands occur
within the shore zone, often mixed with coarse
sandy limestone fragments and foraminiferal
tests, primarily those of Archaias angulatus.
The sandy limestone and the fossil foramini-
feral tests probably originated from the out-
croppings of Pleistocene limestone exposed on

30

the inner shelf. The local concentrations of the
above materials are, therefore, those which one
would expect to find in the vicinity of the rocky
sponging bars.

The zone seaward of the inshore or quartz
zone is a quartz-shell zone in which the shell
material replaces the quartz in making up
more than 50 percent of the sediment. This
zone also averages about 20 miles in width but
may be only a mile or so wide in parts of the
sponging ground further northward. Local con-
centrations of sediments around the rocky out-
croppings are similar to those found in the same
areas shoreward. The other constituents of the
sediments are similar to those found inshore,
with the shell and other sediments of marine
origin becoming more predominant seaward.
No quartz sand is found seaward of this zone.

Further seaward from the quartz-shell zone
the other zones in order are: broken shell,
algal sand, oolite sand, and foraminiferal sand
and silt. Within the limits of the previously
worked sponging grounds (less than 130 or 140
feet in depth) parts of the broken shell and
algal sand zones may be found (fig. 12).

The rocky portion of the sea bottom is com-
posed of lithified sediments of cemented lime.
These consolidated sediments have been identi-
fied as soft marly limestone, sandy limestone,
and dense, fine-grainedlimestone. Much of this
material is similar to that found on land. Ap-
parently all the limestones were deposited
during the times of the changing sea level in
the Pleistocene. Much of the rock outcropping
on the sea bottom has been eroded and worn
down by physical and biological means. The
edges of the outcroppings are usually rounded,
rarely rough or jagged, except where there is
a distinct edge exposure of a bed of rock. The
divers report that along much of the northern
coast between the 60- and 70-foot marks, the
outcroppings of rock are very rough and "high"
(up to 12 feet), supporting little sponge growth.

The unconsolidated sediments form a rela-
tively thin layer over the surface of the rock.
The slope of the bottom is so gradual that the
waves have little if any effect in moving the
sand in any one direction. There is sufficient
evidence to show that occasionally during

storms wave movements are sufficiently strong
to clean off the rocky areas and wash away the
sediments from the edges of sponging bars.

The Sponging Bars

Clean exposed rock is essential for the
attachment of wool and other species of com-
mercial sponges. The limestone rock bars
supporting sponge growth may have areas of a
few square feet to many thousands of square
yards. Much of the bar rock is at the same
level as the surrounding bottom or only a few
inches higher. In many cases also the rock
has been fractured in two directions roughly
at right angles to each other, so that the bars
are frequently composed of rectangular-
shaped or diamond-shaped pieces 4 feet by 6
feet in size. The appearance depends upon the
layer or bed of rock exposed.

The spongers refer to several different kinds
of rock bar. Flat bar refers to flat rock usually
covered by a thin layer of sand, high rock to a
bar made up of smooth rectangularly shaped
pieces as described above, which are 2 or more
feet above the lowest level of the bar, and
rough bar to rock that is jagged. Any bar may
be a combination of these types.

Along most of the west coast of Florida, rock
bars usually do not rise more than 1 or 2 feet
above the lowest level of the bar. This lowest
level does not necessarily correspond with the
level of the surrounding unconsolidated bottom.
The highest rocky reef found along the west
Florida coast lies between the 40- and 65-foot
depths and extends in a northwest direction
from Anclote Key to a point southwest of Cedar
Keys, an area approximately 8 miles wide and
50 miles long. On parts of this reef the rock is
as much as 12 feet in height, rough, and pro-
vides excellent fishing and sponging.

In the shallower water area down to depths
of 60 feet the sponging bars are normally sur-
rounded by a growth of eelgrass or marine
flora. Bars are usually bordered by a strip of
open sand, 20 or more feet in width, which is
free from almost all plant growth. The rocky
edges of the bars do not support a heavy growth
of marine animals or plants, and there is con-
siderable evidence to show that these edges

31

Figure 12.— Sediment zones of the upper Gulf of Mexico off the Florida coast, based on the Society of Economic
Paleontologists and Mineralogists (1955). Enclosed area starting at Cedar Keys area extrapolated.

32

are periodically covered with sand. This sand
tends to kill off many of the attached animals
and plants. The edge of the bar is a particu-
larly favorable zone for the setting of wool
sponges and is the area the spongers work
most intensively. Toward the central portion
of the bars or where individual sharp- sided
rocks are to be found, the surface of the rock
is covered with a heavy population of sponges
and other types of attached animal and plant
life.

Sponging Bars in Relation to
Surrounding Bottom

Contrary to the ordinary concept of sub-
marine rocky outcroppings, many sponging
bars are not above the general level of the
surrounding bottom but actually anywhere from
a few inches to as much as 6 feet lower. This
phenomenon is of considerable assistance to the
sponge fishermen. In deeper or slightly murky
water where it is impossible to locate a bar
visually, sounding leads are used. In most
cases the sand sample brought up by the soaped-
end of the lead gives the necessary informa-
tion about the closeness of a rock outcropping.
In many cases, however, a sudden deepening
of the water is indicative of the presence of a
bar in the immediate area; and if two sounding
leads are being used, a deeper sounding on
one side is sufficient indication to tell on which
side of the boat the bar is to be found.

A series of echo sounding recordings was
obtained in the upper Gulf. These recordings
show graphically and in condensed form the
bottom contours near the sponge or fish bars.

Figure 13 shows five selected sonic record-
ings of the bottom contour. Figure 13a is the
tracing of echoes off a fairly flat bottom, taken
while we moved from the shore towards deeper
water. The grassy bottom with the soft under-
lying fine sediment material gave an echo that
caused a wide recording on the tracing. In the
center portion of the recording, the echo trace
is narrow, thus indicating hard bottom. This
rocky bar was unusually flat, and very little
plant or animal life of any kind was to be found
on this bar area.

In the second tracing three bar areas are
shown (fig. 13b). On the extreme left is a
tracing of high rock.

The next three tracings of bars in deeper
water show the effect of the softer sediments
found at these depths in the area southeast of
Piney Point. A much thicker line is made by
the echoes off these softer sediments covered
with marine vegetation. In the central portion
of the third tracing, a very rough rocky bar
is indicated by the jagged thinner tracing fig.
13c. On the fourth tracing a rough rocky bar
is recorded (fig. 13d). The last recording
shows most clearly the edges of the bar in
the central portion of the tracing. These bars
were 4 to 5 feet below the general level of the
bottom.

I consulted a number of oceanographers, who
agreed with me that the bars lying below the
general level of the bottom remain free of silt
only because of wave action. Over open bottom
the heavy growth of eelgrass and other marine
plants and the flatness of the bottom offer very
little resistance to the movement of the water
so that little turbulence is developed. During
diving I observed that the water among the bases
of the plants moved little if at all with the
motion of the waves. Over the rocky bars,
however, the many larger growths of coral,
sponges, and other bottom animals, as well as
the irregularities of the bar itself, create
considerable turbulence during the passage of
the waves.

Examination of many bars leads to the con-
clusion that during long periods of calm weather
the bars are gradually encroached upon by the
finer sediments normally held in place by the
mat roots and rhizomes of marine vegetation.
Eelgrass is known for its role as a sediment
trap. During heavy wave activity from storms
or the passage of hurricanes through the Gulf
as observed in October 1956, turbulence over
the bar areas results in the uprooting of
quantities of marine plants and the shifting of
large amounts of sediment, as a result, some
parts of the bar areas are uncovered while
others are laden with sediment.

Sediment Distribution Across the
Bar

The bar areas support not only sponges, but
also populations of animals and plants that
form calcareous shells or skeletons. Most

33

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bars. Each section between the vertical Unes represents a distance of about 400 feet.
Individual tracings explained in text.

34

important of these are the corals, Solenaster
hyades, two species of OcuZina coral, and vari-
ous species of the alga Halimeda. The clam.
Area zebra, is also important for it is found
attached in great quantity on the bar rock, and
on some bars is of importance for the attach-
ment of wool sponges.

Calcareous sediments form from the break-
down of these corals and the various animals
that live on the central parts of the sponge bars.
Sorting of these sediments is brought about by
wave activity, and there is a gradation of the
sediments from coarse to fine from the central
areas of the bars to the edges.

To assess the effect of the large produc-
tion of calcareous material in the loose sedi-
ments, series of sediment samples were taken
at evenly spaced intervals from the central
part of the bar area to the edge. The results
of two such series, one selected from an iso-
lated bar in 25 feetof water off Piney Point and
the other from a bar in 1 6 feet of water off the
mouth of the Aucilla River, represent the ex-
tremes of the samples taken (table 6).

Samples from the central portion of the bar
had large percentagesof the sediments over 0.5
mm. in size. This coarse material was made up
primarily of fragments of coral, moUusk
shells, sea urchin tests, and other skeletal re-
mains. Toward the edge of the bar and in the
grassy area around the bar, the sediment size
was finer. The sample series from the isolated
bar shows the effect of the shifting of the finer
sediments, principally quartz particles, onto
the bar area. This particular series was taken
after very rough weather which upset the
normal sorting action described above.

The series of samples taken from a bar in a
very rocky area off the Aucilla River reflects
the effect of the addition of large amounts of
calcium to the sediments in the area. In this
case the sediment sample taken from the grassy
region off the bar area contains more cal-
careous material than did the central part of the
bar in the series from Piney Point.

Although much variation in sediment dis-
tribution across a bar is to be expected, the
sample series from the Aucilla River area

indicates the importance of a bar area in the
production and addition of calcareous material
by animals and plants to the unconsolidated
sediments. This was apparent from visual
observation of the sediments.

ECOLOGICAL RELATIONSHIPS

Salinity Tolerances of Sponges

Little is known about the salinity tolerances
of commercial sponges other than wool
sponges. A number of wool sponges shown to me
by divers had lost most of the living material,
leaving the remainder of the sponge with clean
skeletal fibers. The divers attributed the dying
of the sponges to "fresh" water. Such sponges
were not more than normally odoriferous, but
there were no signs of decay or disease even
when examined microscopically. Such sponges
are commonly found west of the mouth of the
Suwannee River in the area where fresh- water
discharge would be expected. Salinity data from
the Red Tide Cruise of June 1956, carried out
by the Marine Laboratory of the University of
Miami, show salinities as low as 27.7 %q , in
this area extending as much as 5 miles from
land.

In October 1956, during a sponge investiga-
tion field trip to the area just north of the
Steinhatchee River, a large number of sponges
appeared to be affected in much the same way
as those off the mouth of the Suwannee River.
Later the hookers and divers reported that
large numbers of wool sponges in the shallow
water zones from Piney Point to St. Marks had
been killed. There was every indication that the
destruction of the wool sponges was related in
some way with a tropical storm which had
passed northward through the New Orleans
area a few days before. Tagged sponges at one
of the buoyed stations were examined and found
healthy before the storm. Seven days later they
were dying off. Within this period the Stein-
hatchee River (fig. 10) had begun to flow for
the first time in 4 years; the initial flow was
particularly strong, following exceptionally
heavy rainfall.

Water samples from St. Marks to Stein-
hatchee taken 6 days after the beginning of the
outflow showed lowered salinities throughout

35

Table 6. — Percentage occurrence of sediments according to particle size and
percent calcium content in sediment samples from sponge bars

Particle Size

Samples from bar at
Piney Point-"-

Samples from bar off
Aucilla River-"-

1

2

3

4

1

2

3

4

0.5 nun. ■•■•■■•••••

32.7
39.6
27.3
.3
15.2

9.7
23.9

1.9
7.8

5.2

24.8

67.4

2.4

6.6

4.4

68.0

26.3

.3

6.6

59.2

20.7

17.4

2.6

66.8

43.9
24.5
24.9
6.5
57.9

22.6

25.7

47.9

4.8

33.8

19.4

27.9

0.125 mm. -0.25 mm

0.125 mm

45.5
6.-6

Percen't calcium

23.8

■"- Numbers refer to samples taken at evenly spaced intervals from the central
part of the bar to the edge.

the area. With normal salinities above 36 /q^ ,
the samples showed that salinities just above
33 %Q were common. One salinity was
31.04 %„ .

In addition to
sponges, almost

the mortalities of the wool
all of the Styela plicata tuni-
cates had died as well. Since these are notably
intolerant to lowered salinities (Van Name,
1954), 1 believe that water conditions were the
cause of the wool sponge deaths. With the ex-
ception of two or three noncommercial sponges,
very few other sponges and sessile animals
showed any adverse effects.

There is a possibility that the first heavy out-
flow of the river may have moved shorewise as
a parcel of low salinity water which would have
been dispersed or mixed only after a number of
days. The time lapse between the first outflow
and the sampling would have allowed sufficient
time for the lowest salinity water to have moved
out of the sampling area.

Moore (1910b) in his experiments with culti-
vating sponges at Anclote Key determined that
salinities of 27.5 %^ were detrimental to wool
sponges while salinities of less than 26 /^^
were lethal. In the Bahamas, W. Smith re-
ported that salinities of less than 32 °/ are

'CO

very harmful to sponges; however, his culti-
vated sponges were in water less than 6 feet
deep in a very different ecological situation.

Elevated temperatures also have detrimental
effects on wool sponges, and it is probable that
the combined effect of elevated temperatures
and salinities not quite as low as 26 °/ would
be lethal. °°

The commercial sponges appear to be able

to withstand very high salinities. The salinity

of the water over the Andros banks, a sponging

area in the Bahamas, is often as much as

46 °/ .
'oo

Temperature

Temperature effects on wool sponges ob-
served during the present investigation are:

1. There is an optimum temperature range
in which wool sponges produce eggs in
quantity.

2. There is a clinal effect on the size of the
wool sponges producing eggs.

3. Sudden changes in temperature cause
withdrawal of the living tissue with re-
gression in size.

The first two of these temperature relations
were discussed previously in the section on
reproduction.

From the evidence at hand, commercial
sponges appear to have a tolerance range from
as low as 50° F., as observed during the study,
to at least 95° F. (W. Smith, personal com-
munication).

During the laboratory experiment carried on
from September 1955 to June 1956, a number of
yellow sponges and wool sponge cuttings were
maintained in salt-water aquaria and the effect
of changes in temperature on these specimens
was observed. Photographs of these sponges
were made at 2-week periods and later at

36

monthly intervals until the experiment was
terminated by the sponges' dying during an
accidental stoppage of the water flow.

The effect of temperature on growth is shown
by a series of photographs of a whole yellow
sponge (fig, 14). The first of these photographs
was taken within 4 days after the sponge had
been taken from the sea and placed in the
aquarium. At that time the temperature range
over a period of a week was between 80° F.
and 85° F. The appearance of the sponge at this
time was normal.

The second photograph was taken in Decem-
ber, almost 3 months from the time the sponges
were placed in the aquaria. During this 3- month
period the temperature had gradually de-
creased to 70° F. Observations made on the
sponge at this time showed that there had been
an increase in size of almost one-quarter of an
inch in diameter. This increase in size was
made despite the necessary healing of the
sponge base, the change to a much different
environment in the aquarium, and probably a
lowered food supply.

The third photograph of the series shown was
taken a month later in January 1956, 6 days
after the temperature had dropped from 70° F.
to 62° F. within a 6-day period. This sudden
drop in temperature was the apparent cause
for the very considerable withdrawal of living
material from theperiphery of the sponge. This
withdrawal amounted to more than one- quarter
of an inch in places. Close examination of the
sponge at this time showed that the "skin "was
as healthy at this lower level as before, and
the only apparent change was the exposure of
the ends of the spongin fibers. The photograph
shows clearly that the bared fibers are light in
color while in places the healthy "skin" of the
animal shows through as black. Within a few
months the exposed fibers rotted away and the
sponge again appeared normal but reduced in
size.

Similar, but not as severe, withdrawal of
tissue inward has been observed during the
field studies (fig. 17, p. 50) and in preserved
material collected in the winter. A number of
sponges have been taken which had the fibers
of the conules exposed for one-eighth of an
inch or more.

When the temperature is 80° F, to 90° F,,
sudden increases in temperature have been
reported by F. G. Walton Smith to be detri-
mental to commercial sponges.

Effect of Water Currents on Sponges

Mean tidal flow along most of the coast in
water depths of 24 feet is about one-half of a
knot. The rate of flow is affected by bottom
contour and modified considerably by the rate
of flow of the inshore current which travels at
a rate of at least one-third of a knot in water
of a 40-foot depth.

Commercial sponges grow well in water cur-
rents with this rateof flow. In areas, such as at
Indian Rocks, a current of 2 knots or more may
be responsible for the rapid growth of some
sponges and other bottom inhabitants. Wool
sponges in this area were not affected greatly
except that the conules were longer and the
oscules higher, up to 2 inches in height. These
sponges had heavy overgrowths of tunicates and
algae which distorted their shape, and at times
were deformed by the crowding of other sponges
on the bar.

The grass sponges in this strong tide area
were growing in conical rather than vase
shape, with the central portion completely
filled in. This was true also of the same spe-
cies of sponges in the Cape Romano area
where strong tides were found. These grass
sponges were soft in texture and commanded a
higher price than other grass sponges on the
market, having a texture and use comparable
to the finest Mediterranean sponges.

There is a noticeable change in the appear-
ance of wool spongesfrom water of less than 12
feet to those sponges from 40 and more feet in
depth. Sponges from shallow water have up to
twice as many conule tufts per square inch. The
oscules of wool sponges from shallow water are
as much as 1-1/4 inches wide while those from
the deeper water are rarely more than three-
quarters of an inch wide and usually less. Only
slight differences were found in the actual
weight to volume ratio from the different
depths, the shallow-water sponges being
lighter. There was a noticeable difference
in compressibility and strength of fiber;

37

A J If t <

pM*,

■'iSl^''*'

1

D

MUif'pi'I'i

I'l'il'il t'i'i'|-i'|-|'i"l'

33

Figure 14. — Effect of temperature variation on a yellow sponge maintained in an aquarium with running salt
water, a. A few days after being put into aquarium, b. Three months later with 1/4-inch increase in diam-
eter, c. Withdrawal of living material and baring of spongin material, 6 days after a rapid fall in tempera-
ture, d. Two months later, with spongin beginning to slough off.

38

compared to the deeper water sponges the
shallow-water wool sponges are very soft and
weak. A study of the microscopic structure of
the fibers shows that fibers from shallow-water
sponges are finer and more loosely connected
than those taken from sponges that grew in
deeper water.

Competition for Space

Two methods of evaluating bottom popula-
tions were attempted: (1) measuring the con-
centration in small quadrants using general
groupings of attached animals and plants and
(2) a more extensive study identifying plants
and animals in defined bar areas.

In the first study the bottom flora and fauna
in a number of lO-foot squares were evaluated
quickly using an arbitrary method of division
of the bottom growth into groups (table 7).
Since loggerhead sponges are generally over
1-1/2 feet and up to 3 feet in diameter, these
sponges are listed separately as one group.
The average size of the other sponges is be-
tween 4 and 6 inches. The concentrations for
each area are also divided into two regions —
shallow- water, less than 21 feet, and deeper
water, more than 21 feet.

There seems to be no direct connection
between a heavy bottom population and the
concentration of wool sponges. Rather it is the
indirect effect of concentrations of bottom
animals, which provide a sediment trap that
excludes the wool sponge from most areas of
higher concentrations of animals. This sedi-
ment is reduced or almost entirely removed
only during stormy weather, the heavy wave
action cleaning off the edges of the bar at the
same time and making these areas available
for wool sponges.

Animals and Plants Associated with
Wool Sponges

In addition to those animals and plants
intimately associated with the wool sponge as
cohabitants, there is a considerably larger
group of sessile forms found on the adjacent
bottom forming an ecological group to which
the wool sponge belongs. To determine this
group, collections of the sessile plants and
animals were made at each of the shallow-
water stations of the first two major field
trips. We intended that these collections would
establish a record of bottom forms by area
rather than by stations. Sponges were the only
group for which complete occurrence records

Table 7. — IVpical concentrations of animals and plants in 10-foot squares

on rock bars

Area^

Sponges

Alcyona-
rians

Sessile
mollusks

Sea
squirts

Algal
plants

Corals

MLlle-
pora

All^

Logger-
head

A: <21'

>21'

1
12

4
1

4
5

16
28

12
34

25

30

6

2

0
0

B: <21'
>21'

13
8

4

1

10
3

24
40

20
35

43
6

0
2

0
0

C: <21'

27

6

5

3

2

8

0

0

D: <21'
>21'

23
21

3
2

8
24

8
20

9

16

17
28

0
3

0
0

E:.<21'
>21'

58

1
2

8
21

3

35

2

41

3
18

3
3

0
0

F: <21'

15

2

7

4

0

8

2

0

G: <21'

2

0

25

0

0

9

4

3

■"■ Areas are given in appendix.

^ All sponges except loggerheads since these are three to six times average
size of other sponge species.

39

were attempted. In other groups of animals
and plants only those most commonly occurring
were regularly collected and/or recorded.

Twenty-three sessile animals and plants
were recorded 25 percent or more of the time
as being found growing on the same bar as the
wool sponge (table 8). Of these, 10 were found
at 50 percent or more of these same stations.
These 23 animals and plants represent the basic
ecological group associated with the wool
sponges. Where wool sponges are absent, the
presence of this group will possibly indicate
an area where ecological conditions are favor-
able and into which wool sponge might be trans-
planted successfully.

If suitable substrate is limiting the attach-
ment, it might be practical to use "cultch."
The cultch would have to be of a fairly large
size to hold the sponges firmly on the bottom.

Several sponges were found only once or not
at all on the same bar with wool sponges. This
appears to be of no significance and seems to
indicate either their scarcity or the fact that
they were overlooked at other stations. These
sponges were: Callyspongia arcesiosa, Neo-
petrosia longleyi, Aulena Columbia, Fibulia massa,
Iligginsia strigilata.

Total Sponge Species and Their
Distribution

Counting both those sponges collected in the
Keys area and the west Florida coast, we
collected and identified 83 species in 58 genera
(table 9). This is only a part of the collection
record of a largenumber of plants and animals.
These data will be published elsewhere. The
major portion of the identification of the
sponges was made by Robert Work, who
assisted during the first year of the

Table 8. — Record of association with wool sponges, by percentage of stations

25 percent to 50 per-

50 percent or more

cent of stations

of stations

Sponges :

Danvinelta milllen

X

Irrinia campana

X

Ircinia fascicalata

X

Ircinia strobilina

X

Spongia graminea

X

Verongia longissima

X

Callyspongia vaginalis

X

Microciona juniperina

X

Axinella polycapella

X

Spheciospongia vesparia

X

Geodia gihberosa

X

Sea whips and feathers:

Antillogorgia acerosa

X

Eunicea sp .

X

Leptogorgia virgulata

X

Pterogorgia guadelupensis

X

Corals :

Oculina robusta

X

Oculina varicosa

X

Solenaster hyades

X

Mollusks:

Area zebra

X

Sea squirts (tunicates):

Clavelina gigantea

X

Styela plieata

X

Algae:

Avrainvillea Levis

X

Sargassum filipendula

X

40

Table 9. — Distribution of sponges by area from collections made in 1955-57

off the Florida coast

[ 'indicates probable new species.]

UMML

Sponge species

Are

a^

No.

A

B

C&D

E

F

G

Porifera - sponges:

Order - Keratosa:

Aplysilla sulfurea

t2

1

1

1

Tl

Aulena Columbia

5^

1

1

Darwinella miilleri

T

1

1

2

1

Dysidea crawshayi

2

2

Tl

U.2i.l^

Dysidea etheria

1

Dysidea IS^i*

1

1

Hippiospongia lachne

T4

4

6

3

2

1

lanthella ardis

1

2

3

2

2

T

Ircinia campana

T5

11

7

10

T7

T8

hcinia fasciculata

T3

9

3

2

Tl

T7

Ircinia strobilina

1

5

2

T3

T9

Spongia cheiris

2

3

Spongia anclotea

2

Spongia graminea

3

Spongia graminea tampa

T2

4

1

1

1

Spongia sterea

1

1

T

Spongia barbara

T2

1

1

1

Verongia fistularis

1

1

1

1

^4.257^

Verongia longissima

Tl

3

3

5

1

Tl

1

Order - Haplosclerina:

Callyspongia arcesiosa

1

Callyspongia Sp.*

1

Callyspongia vaginalis

T2

5

5

2

5

T6

Dasychalina cyathina

Tl

Fibulia massa

1

Tl

Fibulia nolitangere

Tl

Haliclona rubens

2

1

2

T5

7
4.280

Haliclona subtnangularis

1

1

2

Haliclona sp.*

1

Haliclona variabilis

1

1

2

1

2

5

Haliclona viridis

Tl

2

4

2

T3

lotrochota birotulata

Tl

Neopetrosia longleyi

1

2

T3

3

4.282

Patuloscula procumbens

1

4.251

Xytopsene sigmatum
Xestospongia muta

Order - Poecilosclerina:

1

1

T2

4.275

Agelas (? ) conifera

1

4.246

Allantophora sp.*

1

1

See footnotes at end of table.

41

Table 9. — Distribution of sponges by area from collections made in 1955-57

off the Florida coast--Continued

[ 'indicates probable new species

.]

UJML

Area-"-

Sponge species

No.

A

B

C&D

E

F

G

4.252

Axociella spinosa
Desmacella pumilio

1

1
1

Lissodendorjx isodictyalis

1

2

2

4.274

Lissodendoryx sp*

1

8

Merriamium tortugasensis

1

5

1

4.284

Microciona juniperina
Mycale angulosa

1

3

2
1

2

2

1
T3

Tedania ignis

2

3

1

2

Thalyseurypon vasiformis

Tl

1

3

4

2

4.265

Toxadocia sp.*

1

4.256

Toxemma tubulata (?)

1

4.259'^

Xytopsues griseus

3

3

T

1

Order - Halichondrina:

Axinella polycapella

Tl

7

3

6

T2

Tl

4.249

Axinella Sp .*

1

4.271

Axinella sp*
Halichondria melanadocia

1

1

Higginsia strigilata

1

1

1

Homaxinella rudis

2

1

2

1

Tl

1

Homaxinella waltonsmithi

Tl

4

1

2

1

4.253
4.261^

Hymeniacidon heliophila

1

Thrinacop flora funiformis

1

4.255

Trachyopsilla sp *

Order - Hadromerina:

1

1

4.279

Aaptos aaptos
Aaptos bergmani

1

1

1

Anthosigmella varians

T

3

3

4

T4

8

Cliona caribboea

Tl

1

1

4

3

4.269

Cliona lampa

T

3

1

T

4.262

Cliona sp.*

1

Placospongia melobesioides

2

1

T

Spheciospongia vesparia

T3

7

3

7

T4

TIO

Spirastrella coccinea

Tl

1

1

1

4.260

Terpios fugax
Order - Epipolasida:

1

Crypto te thy a crypta

3

2

5

4.270j_o

Epipolasis angulospiculata

1

4.268

Stellettinopsis detostea
Tethya actinia

1

1

Tethya diploderma

1

1

3

1

1

T

Trachygellius cinachyra

1

1

See footnotes at end of table.

42

Table 9. — Distribution of sponges by area from collections made in 1955-57

off the Florida coast- -Continued

[•indicates probable new species.]

UMML

Sponge species

Area-"-

No.

A

B

CScD

E

F

G

Order - C!horistida:

Cinachyra cavernosa

1

1

3

3

1

T

4.263
4.272

Cinachyra sp*
Geodia gibherosa
Myriastra debilis
Myriastra kallitetilla
Stelletta grubii
Unimia trisphaera

Tl

Tl

T

4
1

3

1

1
4
1

1

1
2
1

1

Tl
1
1

Order - Carnosa:

Chondrilla nucula

1

1

1

1

Total number of stations per area: Area A, 10; area B, 13; area C & D, '.'; area E, 14; area F, 8; area G, 11.
T indicates that this species was only taken by Tierney during the Marine Laboratory Gulf of Mexico Expedi-
tions in 1947 and 1948 (de Laubenfels, 1953).

3 The numbers in the area columns indicate the number of stations in the area at which the sponge was taken and
recorded.

^ UMML (University of Miami Marine Laboratory) numbers are catalog numbers of specimens and indicate those
specimens identified by Willard Hartman. These sponges are preserved in the museum collection. The identification
of a number of other species was confirmed by Hartman,

^ Specimens indicated by UMML numbers 4.257 and 4.259 could only be identified to family and order.

^ UN-IML number 4,278 was identified as Callyspongia near ramosa, a sponge found in the waters of Australia
and New Zealand but not as yet described from Florida or the West Indies,

'^ UMML number 4.280 in Halidona near simulans a sponge most like the European simulans and likewise not as
yet described from Florida and the West Indies.

8 UMML number 4.284, Microciona juniperina is a very common small bright red sponge which is found in a
number of forms, either uniformly ranxsse or leaflike. At least eight form variations were collected and are repre-
sented by separate specimens in the museum collection. When it is possible to collect a large enough series of
these forms, several species may be identified.

^ UMML number 4,261 is Thinacophora funiformis. This record may be the first since it was originally taken by
the Challenger Expedition off Bahia, Brazil.
■'■'-' UMML number 4.272, Stellettinopsis detostea has heretofore only been recorded from Bermuda waters.

investigation. Any sponges that could not be
identified readily or about which the identifica-
tion was at all doubtful were sent to Willard
Hartman, of the Peabody Museum of Natural
History, The preliminary but detailed exami-
nation of the specimens submitted to him in-
dicates that at least 13 probable new species
of sponges were collected (table 9).

A comparison was made between the species
of sponges collected during the present investi-
gation and those recorded by the 1948 survey
of the sponge beds and identified by de Lauben-
fels (1953), In the northernmost range, area A,
only four of the stations reported in -the 1948

survey lay within the same general area as that
of the present investigation. Twenty-four
species of sponges were collected in area A in
1948. Of these, 18 were retaken in the same
area during the present survey, with all but 4
of the 24 being recorded from other areas. The
velvet sponge was one of these four, while the
other three were similar to those described by
de Laubenfels as being new species taken for
the first time.

In the Florida Keys and Ten Thousand
Islands areas, 35 species of sponges were
recorded by the 1948 survey. Seven of these,
were not taken during the present survey, and

43

three others were taken but not in these areas.
Of the 59 identified species collected by us,
34 were different from those recorded in 1948
in the same areas. In all, 11 species taken by
the 1948 survey in the same general areas ex-
plored by the present investigation were not
recorded as being taken a second time.

The temperatures are based on the nearest
permanent tide station data. Check of the cruise
data of the Red Tide project at the Marine
Laboratory indicates that temperature data are
accurate for the areas indicated.

In table 10 the lesser number of species re-
corded from area A may be partly due to the
fact that although very intensive work was done,
only a few bars were surveyed. The population
make-up of individual bars will vary greatly
even within a limited area, and it would there-
fore be necessary to examine a large number
of bars to obtain a true population sample.

In area F the several stations southwest of
the Cape Romano buoy yielded a number of
sponges which could not be identified with cer-
tainty. These stations were in an area where
the flow of the tidal current was strongest. Gen-
erally speaking, the sponges found at these sta-
tions were growing more profusely, the shape
and texture varying greatly from that of the
same species in zones where the tidal flow was
less. These differences in shape, texture, and
internal structure (purely ecological varia-
tions) made identification of many of the species
difficult.

Sponges recorded from area G represent
those species collected in the upper Keys from
Miami to Plantation Key. The combination of the
collections made in areas F and G were used to
make the comparison with the 1948 collection

from the Key West and Ten Thousand Islands
areas.

Area G is the only ecological zone that differs
physically from all the others. This area is the
coral reef zone of the upper Keys, and the
slope of the bottom, nearness to land, and
proximity to the Gulf Stream and deep open
ocean set this zone apart ecologically from
the others. The lesser number of species found
indicate that this is an unfavorable habitat for
many sponges.

A comparison of the number of species in
each area with the yearly mean temperature
(table 10) suggests that the optimum water
temperature for the growth and existence of
most species of sponges is about 75° to 76° F.
Of greater importance ecologically than the
mean temperature of an area is the tempera-
ture range. There is a difference of 52° F.
between the lowest and highest recorded
monthly temperature in area A while the dif-
ference is 35° F. in area F. In addition, as
indicated by a study of yearly weather condi-
tions, there is far more likelihood of sudden
changes in area A than in area F. In the case
of Florida sponges, (1) some species are in-
capable of reproducing effectively in colder
water, (2) the mature sponges are killed by
sudden water temperature changes, and (3) the
prolonged low water temperatures of the winter
found in the northern Gulf kill the sponges or
drastically deter growth.

Sponging Grounds and Zones

A full description of individual productive
sponge beds has been made by Moore (1910a).
Little can be added to that description as the
names or areas have not changed appreciably.

Table 10. — Distribution of species by number in each area

Area

A

B

C&D

E

F

G

29

56.5
71.4

34

59.7

72.4

45
2 62.5
73.5

53

65.3

75.6

44

71.8

79.6

37

Lowest monthly mean water
ten^ierature - °F'''

71

Yearly mean water tempera-
ture - F

78.5

^ Based on U.S. Department of Commerce Special Publication No. 278.
Average between Cedar Keys and St. Petersburg recordings.

44

The present most important sponging area ex-
tends from Anclote Key to St. Marks, a dis-
tance of about 200 miles. From Piney Point
north to St. Marks the present Florida law
states that the diving boats cannot work within
10 miles of land and are limited to working in
water depths of more than 3-1/2 fathoms
between Tampa Bay and Piney Point.

The entire sponging area along the Florida
coast has been divided by the spongers into
smaller regions, the sponging grounds (fig.
15). The primary reason for this division is
the practical necessity of being able to desig-
nate the particular area in which a boat is to
work or has worked. In part also this division
serves to delineate individual sponging grounds
that differ ecologically. Different grounds
possess varying types of bottom and produce
distinct ecological types of sponges. Sponge
fishermen claim that the appearance and feel
of a sponge indicates to them what part of the
sponging area it was taken, within a 10-mile
section of the coast. Differences in appear-
ance of sponges from various localities are
certainly apparent, even to the inexpert eye.
At times the division of the area into grounds
also carries with it a connotation of texture
and quality; for example, the term "Rock
Island" (wool) sponge is equivalent to a grade
of sponge and is used as a marketing term.

For ease in analysis of various factors on the
sponge beds as a whole the grounds have been
grouped here as areas (fig. 15, detailed
description in appendix).

Only limited portions of all the total spong-
ing area, except area F, have concentrations of
sponges comparable to those found before the
first disease period, 1938 (table 4). The im-
portance of each of the areas to the industry
cannot, however, be judged alone by the con-
centration of the sponges. Quality of the
sponges is also important, for it is often
better to take fewer sponges of higher quality
than more sponges of lower quality. Generally
speaking the quality of the sponges is better
in areas A, B, and C. South of these areas,
the sponges are progressively more open-
textured and weaker. This is true of both the
wool and the grass sponges. In area F off
Shark River, for example, the sponges have a

much lighter texture and less desirable shape
than those from area A (Rock Island). A load
of sponges from area F may have only two-
thirds the value of the same quantity from
area A. Grass sponges from the Florida Keys
generally are of poor quality and may only
command a third of the price of those taken
at Anclote Key.

On the other hand, the Florida Keys glove
sponge is of much better quality than those
found off Anclote Key. The range of this sponge
is from the Florida Keys area to just south of
Cedar Keys. At the present time the concen-
tration of the glove sponge is much higher in
the Keys area than at its more northerly
limits.

Depth Zones

The sponging areas may be divided into
three distinct depth zones:

Shallow 40 feet and less

Middle 41 feet to 80 feet

Deep 81 feet to 120 feet

The shallow zone (fig. 15) is the only area
now worked extensively by the sponge fisher-
men. During 1956 some good-sized sponges
were taken in water as deep as 55 feet, and as
indicated by the deep-water survey of the pres-
ent investigation, some quantities of wool
sponges occur in limitedareasin water as deep
as 80 feet.

The Florida State law limiting the sponging
depths of the diving boats was drawn up by the
Florida State Conservation Department as the
result of an agreement between the hook boat
spongers and the diving boat crews.

The hook boats usually work in water of 20
feet or less, and the diving boats, because of
the age and physical condition of the divers,
rarely work in more than 40 feet. Most of the
diving is done in the 20- to 30-foot zone.

Most of the yellow, grass, and glove sponges
are found in the shallow water. The shape of
the wool sponges in this zone is somewhat
more flattened than those from deeper water,
the ratio of the diameter to height varying
from 2 : 1 to 4 : 3. Those wool sponges growing

45

vSr MARKS

AREA

GROUNDS

A

1. CARRABELLE
2 ECONFINA

3. ROCK IS.

4. PINEY PT

5 N PEPPERFISH

6 S. PEPPERFISH
■7 CEDAR KEYS

8 CEDAR KEYS HIGH ROCKS"

9. PORT INGLIS
10 BIG BANK REEF
1 1 ANCLOTE KEY
12 HIGHLANDS

»«s/^f''^''~~%^ECONFINA R

B

C

CARRABELLE y^

^^^ 1 / rockV.

^-:::il 1 / IS X,

1 2 / .\kEAT0NS BEACH

D

^ ^/■^>^0G IS. ' .' / 3 y'^ 1 1

J//,,y'^y \ .. / / y VINEY PT

^^ .•... V '■■ i'- ■■■ / ....... /^ /'^((STEiNHATCHEE

o ° o 5 \PEPPERFISH

E

\ Vf SUWANNEE R
V : _, . ° . ?CEDAR KEYS

■-- %v -r t •■■■./ .-

(.'./ .. -o ^ O •:/ -S-'

\cRYSTA

10 Y^

L R

\

\
— \

^ : "o I

c . ^ /

<ft --: ♦ f

■| ST MARTINS /
1 LIGHT C

\ •, 11 /

• ANCLOTE KEYV ^TARPON SP

RINGS

v

K ?

l<)

?

13 FATHOM LINE

21 FATHOM LINE

\ \ ( v:;

1 1

1

1

) \

_L

SO"

Z9°

28°

84° 83°

Figure 15.— Sponging areas of the upper Gulf of Mexico (see appendix for details).

46

in less than 10 feet are often deformed by their
close proximity to other bottom-growing forms
or have algal plants, bryozoans, or other ani-
mals growing on the surface. In addition the
texture of the sponge fibers is more open and
the oscules larger.

In the middle zone no glove or grass sponges
are to be found. Considerable quantities of
yellow sponges were formerly found in the
middle zone along with wool and wire sponges.
Now majority of the yellow sponges appear
in shallow water. In the middle zone the best
areas for wool sponges wasformerly inthe 60-
to 80- foot depths. The wire sponge is nor-
mally not found in the shallow water but
occurs in water of 40 feet or more. Wool
sponges in the middle zone are usually slightly
taller with a ratioof diameter to height of 1 : 1
or greater. The texture is also fine, and the
shape well rounded, so that sponges from this
depth or greater have always brought a good
price.

In the deep water the best production was
found at the 85-foot and 100- to 110-foot depths.
The importance of this zone, as a sponge pro-
ducer before the disease of 1938, can be esti-
mated from reportsof the daily take of sponges.
It is said that up to one thousand pieces of wool
sponges were taken per day of effort. Five
divers were used in rotation in this depth, each
diver remaining only about 15 minutes on the
bottom. The quantity and size of the sponges
made such methods profitable. Deep water pro-
duced the best grade of sponges, with an esti-
mated 12 to 18 inches average diameter, some
considerably larger. The sponges were wider
near the top than at the bottom, and the esti-
mated ratio of diameter to height would have
been 3:4 or 3:5 or greater. In deep water
large 3-foot wire sponges were also seen in
quantity but never taken because of their very
low value.

DISEASE, PARASITES, AND
EPIZOICS

The 1938-39 Sponge Disease

Some of the earliest reports of sponge losses
are recorded by Rathbun (1887), who lists
heavy losses during the years 1844, 1854, 1878,

and 1890. At that time the most heavily worked
beds were those in the Florida Keys and Florida
Bay areas. It is interesting that these years of
sponge mortality coincide with heavy outbreaks
of red tide, caused by GymreoAnmm brevis (Fein-
stein, 1956). Rathbun (1887) refers to poisonous
colored waters about the reefs and in Florida
Bay with sponge losses occurring at the same
time.

Brice (1898) describes heavy losses of
sponges in the Knight Key to Cape Sable area
when the sponges "rotted internally" and died
in large numbers. F. G. Walton Smith (1941)
described similar mortalities caused by a
fungus in British Honduras, the Bahamas, and
throughout the Gulf in 1938-39. The fungus was
tentatively identified by Galtsoff (1942) as
Spongiophaga communis. Carter (1878) first olv
served a fungus parasite on sponges. If the
disease described by Brice is the same as
that found in 1938-39, occurrences of this
fungal disease are very rare indeed. Occur-
rences of "poisoned waters "and fungal disease
were undoubtedly made possible by special
combination of oceanic conditions that led to
sudden blooms of the causative planktonic and
fungal organisms. It has been difficult to obtain
any knowledge of this fungal sponge disease
since it was impossible to culture the fungus
in the laboratory at the time of the occurrence.
Spongiophaga communis is the only true sponge
disease organism which has been adequately
described and illustrated. This was done by
F. G. Walton Smith in 1941. The disease first
attacked the interior portion of the sponge; here
the organisms are found in greatest abundance
in the narrow zone between the healthy living
tissue and the dead area. The hyphae appeared
in groups as a number of short colorless un-
branched filaments between 0.001 and 0.002
mm, in diameter. Only one end of each fila-
ment was attached to the sponge tissue (fig. 16).
As the disease progressed, a greater and
greater portion of the central mass of the
sponge was affected. The outer skin was finally
pierced, and in a short time the entire sponge
rotted away. The sponge fishermen described
the hooking of a heavily diseased sponge by
saying that the "sponge disappeared in a cloud
of dust."

In the 1938-39 occurrence of the disease in
British Honduras, the sponge species were

47

.01 mm

Figure 16. --Wool sponge fibers showing fiingal disease
growth. Fungal fibers attached by one end only. Liv-
ing materialof the sponge is indicated by the stippled
areas (after Smith, 1941).

attacked in the following order: velvet, grass,
wool, and reef. In the Bahamas, the order of
attack was different, for the wool sponges
were attacked before the grass.

In British Honduras Spongiophaga was ob-
served growing on the surface of eelgrass,
Thalassia, with no apparent effect on the health
of the plant.

Between 90 and 95 percent of the commercial
sponges were destroyed in most areas of the
Caribbean and Gulf. All the velvet sponges
were destroyed in the Bahamas, and none has
been observed since. Two or three velvet
sponges were taken along the west coast of
Florida in 1947. In 1938 the sponging grounds
in the Gulf along the west coast of Florida
north of Tampa were least affected by disease
with production falling off by 1940 to about one-
third of 1936,

The 1947-48 Sponge Disease

In 1947 commercial sponges along the west
coast of Florida were again attacked by
disease. Immediate investigation by mem-
bers of the scientific staff of the Marine

Laboratory of the University of Miami did not
reveal the cause of this destruction of the
sponges. No evidence of fungal disease was
found, and the oceanographic conditions were
generally within the range common to in-
shore Gulf of Mexico waters.

Other Detrimental Effects

Sponge fishermen claim that a killing off of
sponges in shallow water is sometimes as-
sociated with the occurrence of the "mallee"
(from the Greek "hair"). This mallee is a
heavy growth of fine alga which apparently
covers the rocky bars during the late spring,
the time of occurrence depending on tempera-
ture. After a short period of attached growth,
the mallee breaks loose and rolls or washes
about the bottom, thus making sponging in the
area next to impossible. By inference mallee
has come to mean any heavy bottom plant
growth that finally breaks loose and rolls
about the bottom in large mats 2 to 3 feet deep.
At times this mat is made up of a "sea grass,"
Halophila baillonis Large amounts of other sea
plants may add to the mass. Certainly a col-
lection of this material covering the sponges
would be detrimental. The actual cause of the
sponge destruction accompanying this condition
is unknown. Examination of sponges apparently
affected by a malleelike condition in the
summer of 1956 did not reveal any fungal
disease or other disease organism. The condi-
tion was local in extent, affecting a series of
rather limited areas in the shallower water
just north of Tarpon Springs with serious
effects to the sponges.

Growth experiments by Moore (1910b) and
Crawshay (1939) showed a 2-percent mortality
of sponges during the winter and a 10-percent
mortality in the summer. Total mortality of
sponges during the period required to reach a
6-inch diameter was estimated at 20-30 per-
cent. These percentages represent the expected
mortalities in water depth of 6 feet and in
protected areas where adverse ecological fac-
tors would be expected to be encountered most
often. Mortalities in deeper and more open
water could be expected to be lower.

A sudden freshening of the water in local
areas has also caused considerable loss of

48

sponges. Rathbun (1887), Moore (1910b), Craw-
shay (1939), and others mention both local and
widespread kills due to heavy rains and sudden
runoff from rivers. Most of this type of destruc-
tion occur in relatively shallow water within a
few miles of shore. The salinity tolerances of
sponges and the detrimental effects of tempera-
ture were discussed in the section on ecology.

Parasites an(j Epizoics

With so many animals and plants living in the
mass of the sponge, in the internal canals, or
on the surface, it is difficult to establish which
are harmful and which are merely living in or
on the sponge as epizoics. No detrimental
animal or plant, with the exception of the
disease fungus, can be said to be parasitic ex-
clusively on commercial sponges. Many ani-
mals such as the small snapping shrimps are
found in far greater numbers in the canals of
the sponges than in any other habitat, but no
true case of commensalism can be stated.

Commonly associated with the commercial
sponges and growing on the surface are such
algae as the fairy cup, AcetabulaHa crenulata Sind
Batophora oerstedi, as well as various species
of Halimeda and Other calcareous algae. So
great is the mass of plant material on the sur-
face of some sponges, especially those grow-
ing in the warmer and shallower water, that
the shape becomes considerably distorted.
These plants may not greatly affect the total
growth of the sponge; however, the distortion
reduces the commercial value. Plants that
cover any of the inhalant pores or restrict the
flow of the oscules adversely affect sponge
growth.

Any animal living within any of the inhalant
pores, the internal canals, or the oscules would
be similarly detrimental to the sponge. A num-
ber of 1/2-inch long hydrolds live within the
small inhalant pores of the wool sponge and
stretch out from the sponge. Such hydroids
are commonly associated with other types of
sponges as well, for example, the tubular
sponge, Callyspongia vaginalis. The anemone,
Aiptasia, may form depressions in
the surface of the sponge into which it can
retract.

Various kinds of polychaete worms, some of
considerable length, have been found in the
canals. One common worm was Leodice
spongicola, but there were also a number of
small free-swimming syllid worms and a few
tube-forming terebellids. In some of the non-
commercial sponges, polychaete worms may
be as long as 2 or more feet, although none of
this length were found in the commercial
sponges examined.

Common inhabitants of the larger canals, the
oscules, and shallow depressions on the surface
of the sponge were many small brittle stars
such as Ophiactis savigny. The Starfish,
Echinaster, has been found on sponges which
bear small cuts or lesions in the surface, but
there has never been any evidence that the
damage to the sponge was initially caused by
the starfish.

By far the commonest inhabitants of the
canals of the commercial wool sponge are
various species of the snapping shrimp.
Synalpheus brooksi, S. meclendoni, and S. brevi-
carpus were the three identified. Other shrimps,
such as the portunid CoralUocaris pearsei and the
stomatopod, Gono(/actyZus oerstefft, similar to the
ghost shrimp, have also been found. A number
of species of small crabs of the genus Mithrax
are also common.

Major damage to the commercial value of the
wool sponges is caused by the sponge crab,
Pilumnus sayi, a small hairy animal that may
attain a width of 2 inches. This crab often
occupies a hole at the base of the sponge (fig.
17). The original hole may be the result of
local damage to the sponge, but constant occu-
pation by the crab prohibits regrowth and fill-
ing in of the hole. There is no evidence that the
crab eats any of the sponge. The hole may not
affect the sponge as a living animal but cer-
tainly destroys the commercial value of the
sponge almost completely. Damage by this
crab most frequently occurs to wool sponges
in the Pepperfish Key sponging grounds, just
north of Cedar Keys.

Other Crustacea commonly found in the
canals are ostracods, such as CylindolebeHs
floridana; the amphipod, LeucotAoe spmicafpa,and
various isopods. The barnacle, Balanus decUvis,

49

Figure 17. — Cross section of a wool sponge with hole occupied by a sponge crab, Pilumnus
sayi. The surface of the interior of the cavity is smooth and shows no sign that the
crab eats any of the sponge material. Around the edge of the sponge, bare fibers of
spongin material have been exposed by the withdrawal of living material of the sponge,
probably as a result of sudden lowering of the water temperature. See section on tem-
perature relationship for details.

is sometimes found imbedded in the surface of
commercial sponges but is more commonly
found on the noncommercial species.

Large numbers of developing larval forms of
a tunicate were found attached to the walls of
the canals in almost all of some 200 wool
sponges examined microscopically. These
were microscopic in size and were not identi-
fied. Larger colonial tunicates often attach and
grow on the top or sides of the sponge, usually
affecting the shape.

Many small snails, key hole limpets, and
small bivalves are found in the mass of the
sponge apparently surrounded by the sponge as
it grows. These animals are also found in the
canals of the sponge into which they have
crawled in their search for food. The spongers
believe that some species of the key hole
limpet eat and damage the sponge. Nudi-
branchs have also been found on the surface

of the sponge, especially in the surface depres-
sions. These may also occasionally feed on the
sponge tissue. The basal portion of the sponge
often contains the open-coiled shells of the
snail Vermetus. Fish fry may occupy the canals
of the sponges.

I have noted that many of the finger sponges
bore the teeth marks of fish. The stomach con-
tents of the spadefish, Chaetodipterus faber, shoW
that this fish may be responsible for damage to
finger sponges. Several other unknown species
of fish must also eat this sponge. There is no
evidence that any of the other commercial
species of sponges are damaged by any fish.

The association of many plant or animal
forms with the commercial sponges is ap-
parently fortuitous. Almost any small plant will
attach to the surface, and almost any small
animal that either normally attaches to an
object on the bottom or else seeks shelter in a
protected cavity will live on or in the sponge.

50

Generally those sponges that are growing in
warmer and shallower water have a far greater
number of species of animals and numbers of
individual animals in the canals and on the sur-
face than those found in the more northerly or
deeper ranges of the commercial sponges. Be-
cause of this difference a far greater proportion
of the wool sponges from the northern Gulf are
more perfectly formed than those from areas
such as Cape Sable. The same is true of sponges
from deeper water of 25 to 30 feet, as is shown
by comparing sponges taken by hookers with
those taken by divers.

COMMERCIAL SPONGE
PRODUCTION

Production Before and After the
1938-39 Sponge Disease

Table 11 presents the production and value
of sponges from 1913-62. For the sake of dis-
cussion, table 11 and figure 18 may be divided
into two periods, a predisease period from
1917-38 and a postdisease period from 1938-56.
Without adequate information on the number of
boats operating yearly from 1917-35, it is
impossible to say with certainty what portion of
the variation in productivity is due to the in-
tensity of fishing effort during the predisease
period. From the data available it would appear
that the small changes in the number of fishing
boats would not bring about any appreciable
change in landings of sponges by individual
boats.

It was important, however, to find some ex-
planation for the wide variation in yearly land-
ings that took place during the period 1917-35.
Yearly take was from 267,000 pounds to 468,000
pounds, with an average of about 350,000
pounds. According to sponge fishermen, there
were few additional areas that were harvested
during that period with the exception of the
Cape Sable and Everglades areas in 1936 (often
referred to by the divers as the Key West
area). A considerable portion of the yearly
variation undoubtedly was caused by the effects
of weather on fishing. Observations made
during the past 2 years suggest that some
portion of the variation was probably due to
mortality of sponges in localized areas,
especially in the shallower sponging areas.

This has already been discussed in the section
on disease.

In the postdisease period (after 1938) pro-
ductivity fell within 3 years to two-fifths that
of 1938 or about one-half the yearly average.
There was a levelling off of the yearly take
during the next 5 years despite a 50 percent
increase in the number of boats in the spong-
ing fleet (fig. 18). According to published re-
ports of the Sponge and Chamois Institute,
undersized sponges were being taken in-
discriminately in large numbers during this
5-year period. The rapid increase in the wool
sponge price per pound (table 12), from about
$2 to almost $30, and the reported failure
during the war period to prohibit the taking
and/or selling of undersized sponges encour-
aged this illegal practice to continue without
serious restraint. The effect of taking under-
sized sponges before they had an opportunity
to mature and produce eggs was possibly a
factor in preventing (1) the repopulation of the
deep-water sponge beds and (2) an increase
in the concentration of sponges in the more
limited inshore areas. Had there been a more
extensive distribution of small sponges and
greater numbers of small sponges during the
1947-48 disease period the effect of this disease
would probably not have been nearly as great
as it was. The fact that the total landings of
sponges did not increase appreciably during the
5-year period despite greatly increased effort
suggests that the sponge beds were being de-
pleted. The decline in return per unit of effort
also indicates the steady decrease in the con-
centration of the sponges that took place.

Production After the 1947-48 Sponge
Disease

After the disease of 1947-48, which affected
the Big Bank grounds (appendix, #10) more
than any other, the yearly total of landings
once again fell off rapidly. A large part of this
recorded drop resulted from the withdrawal of
boats from the sponge industry. Return per
unit of effort changed little. Within 3 years
after the disease began only 57 boats were
sponging, and by 1951 only 32 boats remained
in the sponging fleet. Of these, only two were
diving boats. On the basis of the 1955 and 1956
returns, it has been estimated that the return

51

Table 11.

-Weight and value of wool, yellow, and grass sponges sold on the Tarpon Springs Sponge

Exchange, 1913-62

Year

Wool weight

Value

Yellow weight

Value

Grass weight

Value

Total value

Pounds

Dollars

Pounds

Dollars

Pounds

Dollars

Dollars

1913

362,000

586,000

65,000

47,000

56,000

40,000

673,000

19W

332,000

515,000

65,000

26,000

42,000

17,000

558,000

1917

332,000

785,000

76,000

46,000

50,000

27,000

858,000

1918

273,000

554,000

57,000

28,000

17,000

9,000

591,000

1919

364,000

640,000

61,000

39,000

20,005

25,000

704,000

1920

308,000

602,000

61,000

43,000

37,000

30,000

675,000

1921

307,000

492,000

59,000

30,000

26,000

13,000

564,000

1922

418,000

638,000

96,000

38,000

34,000

20,000

696,000

1923

395,000

664,000

73,000

47,000

36,000

16,000

727,000

1924

430,000

672,000

68,000

38,000

6,000

3,000

731,000

1925

396,000

654,000

101,000

48,000

11,000

8,000

710,000

1926

355,000

629,000

46,000

23,000

20,000

13,000

665,000

1927

389,000

814,000

55,000

33,000

20,000

14,000

861,000

1928

359,000

674,000

51,000

29,000

30,000

21,000

724,000

1929

321,000

656,000

57,000

32,000

24,000

14,000

702,000

1930

403,000

750,000

47,000

33,000

22,000

17,000

800,000

1931

267,000

547,000

81,000

39,000

25,000

19,000

611,000

1932

274,000

431,000

75,000

44,000

52,000

29,000

504,000

1933

259,000

352,000

80,000

51,000

20,000

9,000

412,000

193<i,

351,000

572,000

105,000

71,000

29,000

19,000

662,000

1935

270,000

528,000

80,000

67,000

22,000

16,000

611,000

1936

468,000

938,000

122,000

74,000

26,000

17,000

1,029,000

1937

399,000

977,000

130,000

96,000

17,000

12,000

1,085,000

1938

421,000

893,000

92,000

46,000

8,000

6,000

745,000

1939

325,000

916,000

60,000

79,000

24,000

24,000

1,019,000

1940

212,000

826,000

6,000

8,000

13,000

12,000

846,000

1941

167,000

1,244,000

6,000

23,000

28,000

97,000

1,364,000

1942

157,000

1,533,000

5,000

44,000

22,000

123,000

1,700,000

1943

156,000

2,033,000

10,000

97,000

20,000

175,000

2,305,000

1944

161,000

2,257,000

9,000

99,000

22,000

191,000

2,547,000

1945

158,000

2,377,000

8,000

91,000

28,000

248,000

2,716,000

1946

162,000

2,590,000

1947

107,000

1,142,000

4,000

45,000

9,000

58,000

1,245,000

1948

60,240

433,989

5,023

12,865

9,311

10,983

465,937

1949

57,700

455,176

4,550

9,097

6,500

6,530

412,280

1950

15,628

132,843

3,115

9,346

1,106

3,319

145,737

1951

10,984

79,635

381

1,231

318

1,176

82,128

1952

14,298

125,824

1,546

4,639

1,373

4,121

134,871

1953

14,407

117,279

1,115

3,624

795

2,292

123,349

1954

15,523

126,364

942

3,062

859

2,475

131,901

1955

27,020

229,672

1,128

3,951

990

3,456

237,084

1956

25,958

229,688

2,178

10,326

1,375

6,889

247,021

1957

36,396

224,618

5,151

10,689

2,580

9,660

245,339

1958

19,263

197,627

8,200

2,125

1,891

7,270

215,947

1959

23,430

268,861

1,864

8,029

1,544

7,751

284,644

1960

32,540

286,568

1,684

5,905

433

1,562

294,187

1961

34,352

355,239

752

3,629

139

801

359,669

1962

41,510

385,828

1,480

6,333

1,552

9,621

401,815

All weights of sponges are estimated by use of a conversion factor using probable value of sponges
by the pound, calculated yearly by the Tarpon Springs Sponge Exchange. No records available for 1915 and
1916.

52

— 400

C/5
Q

Z

o

a.

CO

o

UJ

300

200

CO

z

Q

Z
<

100

o

1946

1950

1954

Figure 18.— Total landings of wcxjI, grass, and yellow sponges, 1917-58.

obtained by one diving boat is equivalent to the
return obtained by 4.5 hooking boats. On this
basis (table 12) only 11.2 percent of the number
of boats operating in 1946 were still working in
1951.

By 1948 the value per pound of wool sponges
had dropped from a 1946 high of $30 to an aver-
age of just over $6. The total return for the
year 1948 was $466,000 or more than $2 million
less than was received for wool sponges alone
in 1946. Although the return per unit of effort
remained at about the same level and even in-
creased as more boats left the fleet, it was not
possible to operate economically with the
lowered price per pound. As a result, continued
withdrawal of boats took place with a

corresponding decrease in sponge landings so
that by 1951 the total take of sponges was less
than 3 percent of the peak production year of
1936, with a dollar return of less than 3 per-
cent of the peak value year of 1946.

If the sponging fleet had been as large in
1951 as in 1946, the yield per unit effort would
have declined because of the limited sponging
area. In this second postdisease period, a re-
duction in the sponging fleet was accompanied
by a sizeable increase in the take per unit of
effort (as in 1948) — something that had never
happened in the history of the industry.

By 1957 there were 7 diving boats and about
35 hooking boats actively sponging. These boats
landed sponges as an annual rate of about 29,000

53

Table 12.

-Average catch per boat, based upon the sale of wool sponges on the
Tarpon Springs Sponge Exchange from 1935-61

u
cd

X)

rH
O

m

•H

-H

C3
CO

3

to
■p
cd
o

0)
•H rH

■H B

Q 53

m

+j
cd
o
X>

^t

•H O
M rH
O O,

o a

W 0)

Catch per boat
100 's of pounds
per diving boat
equivalent -"^

r-H

CO
Cm

o

OJ (0
d CD

ct; Cd

> 01

!

t-i

(Dry

<D a

O U
•H CD

fn >
(X. CO

Average income
per diving boat
equivalent

Pounds

!^ umber

Number

Hundred Pounds

Dollars

Dollars

Dollars

1935

2'?0,000

54

63

40

528,000

2.00

7,800

1936

468 , 000

53

68

69

938,000

2.00

13,800

1937

399,000

63

60

53

977,000

2.50

12,900

1938

421,000

70

55

51

893,000

2.10

10,900

1939

325,000

73

52

39

916,000

2.80

10,900

1940

212,000

76

50

24

826,000

3.90

9,500

1941

167,000

67

70

20

1,244,000

7.40

15,000

1942

157,000

60

75

20

1,533,000

9.80

20,000

1943

156,000

69

92

18

2,033,000

13.00

22,800

1944

161,000

69

92

18

2,259,000

16.00

25,400

1945

158,000

76

115

15

2,377,000

15.10

22,600

1946

162,000

75

114

16

2,590,000

16.00

25,600

1947

107,000

75

75

12

1,142,000

10.70

12,400

1948

74,000

35

32

20

466,000

6.20

11,200

1949

69,000

28

29

20

412,000

6.00

11,800

1950

20,000

7

27

15

146,000

7.30

11,200

1951

12,000

2

30

13

82,000

7.00

9,100

1952

17,000

4

30

16

136,000

7.80

12,300

1953

16,000

6

34

12

123,000

7.50

9,400

1954

17,000

7

25

13

132,000

7.60

10,100

1955

29,000

8

34

18

237,000

7.80

14,800

1956

29,561

10

36

19

247,000

8.35

14,970

1957

38,514

13

66

14

245,339

6.37

8,759

1958

29,354

10

42

15

215,949

7.36

11,363

1959

26,874

7

3 37

17

284,644

10.59

17,713

1960

34,691

10

^ 40

18

294,187

8.48

15,484

1961

35,243

10

'' 84

12

359,669

10.21

12,405

Ratio of catch of diving boat to hooker boat estimated as 4.5:1 (based on
1955 and 1956 returns).

Price per pound average based on total value divided by total quantity in
pounds sold.

^ Includes one boat equipped for diving.

Includes two boats equipped for diving.

pounds and a value of $250,000, the diving boats
accounting for slightly more than half of this
take. In 1956 as many as 10 diving boats were
operating, but landings decreased because of
insufficient crews.

Needs of the Sponging Industry

From the standpoint of the sponging industry
the greatest need in 1957 was for younger ex-
perienced divers. The average age of the men
on the diving boats was estimated to be well
over 50 years. The labor problem can be solved
in two ways:

First, to attract younger divers from the
Greek sponge industry in the Mediterranean.

This has complications and objections. At the
moment, the Mediterranean spongers are earn-
ing a better wage than formerly because of the
higher price obtainable for sponges in Europe
and America. The immigration problem has to
be overcome, and any request by the sponge
industry to allow these divers to come into the
country meets with objections. Sponge fisher-
men not of Greek descent state that there are
many divers in Florida who would dive for
sponges if the earnings were greater. This may
be so, but no divers are as yet forthcoming.

It could be that the possible high income of
a physically capable and well-trained sponge
diver is not sufficiently appreciated.

54

A comparison of the returns of one 5-month
trip in 1956-57 by the boat with the two
youngest divers (about 40 years of age) com-
pared with returns for the same trip by other
diving boats is rather revealing:

Boat with youngest divers . . . $17,808.00

Boat A 11,434.00

Boat B 9,202.00

Boat C 8,061.00

Boat D 7,136.00

The boat with the youngest divers had a return
that was over 50 percentgreater than any other
boat. (These returns are based on sales in the
Tarpon Springs Sponge Exchange; it is possible
but unlikely that some sponges were sold by
these boats outside the Sponge Exchange.)

for several months and at times for longer
periods. It is the general rule of the diving
boats that the sponges from the 5-month trip,
the "long trip," be sold at the end of the trip
so that the men can receive their shares. The
boat owner or sponsor of the trip is also
anxious to sell the sponges at that time, as
he has been paying out a weekly allowance to
each of the families of the crew throughout the
5-month period. With trips ending as they do in
January and July, these 2 months usually have
the highest sales. It is quite possible, however,
that in December the price may be so favor-
able that the sale takes place during this time
and the totals for the current year are affected
considerably. Heavy sales may take place in
any month if there is a sudden attractive ad-
vance in price.

Even with the boat trip expenses (for 5
months) of $1,800, the diver's earnings would be
$5,500 per year; and if he were captain as well,
his yearly income could be over $7,000.

Second, to recruit divers from the local
area. As pointed out above, an increase in the
actual cash return to the diver would be an
inducement. Better physical facilities for the
crews of the sponging boats would also attract
men.

In table 14, the number of pieces of wool
sponge given per year is fairly accurate for
all years except 1950 when sales were not
recorded on a per piece basis. The figures
have been arrived at by use of the conversion
factor now being used to convert number of
pieces to pounds by the Branch of Statistics
of the Bureau of Commercial Fisheries (table
13). This factor is based on an analysis of data
supplied by the Tarpon Springs Sponge Ex-
change.

Analysis of the Yearly Take and
Value of Sponges, 1950-56

As sponges have been sold by the piece
rather than the pound since 1951, it is possible
to gain considerable insight into the value of the
sponges and the market since 1950 by analysing
the data available. Because sponges are dried
and cured aboard the boat, there is no need to
sell them as soon as they are landed. If the
price at any time is not thought to be satis-
factory, sale of the sponges may be held over

In table 14, the numbers of yellow, grass,
and glove sponges are not always accurate
since sales slips records indicated that sponges
were sold either on a combined per piece
basis or as bunches. In the latter case the
number of pieces in each bunch could be roughly
calculated only from individual sales records
during some part of the year. Only in 1951,
1955, and 1956 were the sales recorded by
individual pieces, with each species of sponge
being sold separately. Thus, the figures for
these years are the only truly accurate ones

Table 13. — Number of wool, yellow, grass, and glove sponges

to the pound

1

Gear

Wool

Yellow

Grass

Glove

Diving boat
Hook boat

11
16

U
U

18

1<1

20
22

From statistical records of Tarpon Springs Sponge Exchange.

55

Table 14. --Harvest of Florida sponges, 1950-62

Year

Wool

Yellow

Grass

Glove

Number

Dollars

Number

Dollars

Number

Dollars

Number

Dollars

1950..

207,565

132,843

56,056

9,346

19,601

3,319

3,271

229

1951. .

107,456

79,635

3,936

1,231

4,129

1,176

1,444

86

1952..

U0,277

125,824

13,105

4,639

11,579

4,121

4,963

3U7

1953. .

U9,893

117,279

10,476

3,624

6,593

2,292

2,497

154

195-;. .

164,546

126,364

7,471

3,062

3,785

2,475

1,022

J

1955..

320,767

229,672

12,826

3,951

8,358

3,456

90

5

1956..

338,742

229 , 688

30,671

10,326

19,964

6,889

1,033

9

1957. .

477,048

224,618

72,629

10,689

40,764

9,660

1,134

372

1958..

250,169

197,627

115,492

9,128

30,015

7,270

5,166

1,922

1959. .

274,610

268,861

26,096

8,029

22,584

7,751

840

316

I960..

373,940

286,568

23,576

5,905

6,906

1,562

704

152

1961. .

396,232

355,239

11,928

3,629

2,194

801

0

0

1962..

479,150

385,828

20,776

6,333

22,512

9,621

198

33

for all sponges both as to numbers and average
price.

In July 1956, on my recommendation, the
Branch of Statistics of the Bureau of Commer-
cial Fisheries changed the method of gathering
data on the price and quantity of the sponges
landed. These changes will improve the relia-
bility of the statistics on sponge landings and
values and will aid any biological and market
analyses in the future.

There has been a steady increase in the land-
ings of sponges from 1951 onward (table 14).
This increase is caused largely by the in-
creased sponge fleet, except in 1955, when the
number of sponges taken almost doubled the
take of the previous year. It would appear that
a large number of sponges reached egg- produc-
ing size in 1955, and assuming that conditions
for spawning were favorable in 1955, there
should have been a large number of sponges
of legal size from this spawning reaching egg-
bearing size in 1957 and throughout 1958.
Records of landings for 1957 and 1958 indicate
that this probably had come about. During the
first half of 1957 the total landings were almost
equal to the total take of 1956. Unfortunately,
during the late spring and summer there was
a heavy mortality of wool sponges due probably
to freshening of the water. Samples examined
indicated that this was the reason. Conse-
quently, landings fell off during the next two
sponging periods, but reports from the fall
trips of 1958 show that there has been a rapid
return of the sponges, to the level of 1956 at
least.

As long as the sponge fishery is entirely
dependent upon sponges growing in the shallow
area, the fishery will be plagued by intermit-
tent adverse conditions. The industry cannot
be stabilized until the sponges are growing in
quantity in the deeper water.

Probable Reasons for Annual
Fluctijations in Landings

Any probable increase in the number of
sponges growing in shallow water will be predi-
cated on the following:

1. Concentrations of mature sponges in all
parts of the areas are greater than the
minimum required for adequate fertili-
zation.

2. Fishing for sponges will not deplete the
present beds or seriously reduce the con-
centrations below the level required for
adequate fertilization.

3. No serious disease or adverse ecological
condition such as a freshening of the water
will take place.

Records of take per unit effort in various
areas, the wide daily fluctuation of take, and
the several local severe losses of sponges
because of adverse conditions point up the fact
that the concentration of the wool sponges is
erratic on the northern sponging grounds. It is
unlikely that the increase in concentration by
natural reproduction throughout the present
fishing grounds will increase by as much as 60

56

percent in this area during the coming 4 years.
There is, however, the probability that new
areas coming into production may relieve the
pressure on the present sponging areas and
allow them to recover at the above predicted
rate. This phase of the problem is discussed
more fully in the final section of the paper.

Sponge fishermen believe that a major por-
tion of the yearly fluctuation in landings is due
to variation in weather conditions that deter-
mine the number of days of fishing. Some of
the fluctuation in sponge production is un-
doubtedly related to the finding of new sponge
beds, to long periods of inclement or favorable
weather, and to other factors. In 1956 for ex-
ample, the returns by the hooking boats fell
off by 14 percent from the previous year,
principally because of a local sponge disease
north of Tarpon Springs and the destruction
of the sponges by fresh water in the area north
of the Steinhatchee River. Diving boats in-
creased their landings by 26 percent in the
same period because of the excellent produc-
tion in the Cape Sable area.

When reporting various losses of sponges
on the bars, sponge fishermen often state that
only the young sponges were left and the larger
sponges were killed off. Presumably, there-
fore, the younger sponges are more resistant
to disease and adverse conditions than the
mature sponges.

The price per piece for wool sponges has
been dropping steadily since 1952 (table 15).

This decline, however, may be checked, for the
situation in the Mediterranean has changed re-
cently. The Egyptian Government has intro-
duced restrictions on sponging, making it
practically impossible for the Greek sponging
fleet to work along the Egyptian coast. With
the demand for sponges in Europe said to be
increasing, shipments to American buyers
have decreased (table 16). If the demand in
Europe continues and synthetic sponges do not
make further inroads to displace the use of
domestic natural sponges, the present price
and demand may continue.

PRESENT STATUS OF THE
SPONGE INDUSTRY

Methods of Harvesting

At the present time there are three distinct
groups of spongers employing two basic
methods of harvesting — hooking and diving. Two
of these are sponge hookers — one group in the
Tarpon Springs area and the other in the Florida
Keys area. The divers make up the third group.

The Tarpon Springs hookers traditionally
use a heavy round- bottomed dinghy with the
rower sitting on a raised seat in the middle part
of the boat. The hooker kneels in the bow of
the boat with a water glass in one hand and
in the other a long pole with four-pronged
rake or hook fastened to the lower end. The
water glass or glass- bottomed bucket is used

ERRATA — page 57

Table 15. — Average prices per sponge for sponges sold on the Tarpon

Springs Sponge Exchange

Tear

Wool

Yellow

Grass

Glove

Cents

Oents

Cents

Cents

1950

64.

32.

34.

7.

1951

7A.1

31.3

23.5

6.2

1952

39.7

35.4

35.4

6.2

1953

73.2

34.6

34.6

6.2

195^

76.

40.9

65.

6.2

1955

71.6

30.3

41.3

1 ^-^

1956

67.3

33.7

34.5

12.

1957

51 .3

14.7

23.6

32.8

1953

30.7

7.9

24.2

37.2

1959

97.9

30.3

34.3

37.6

i960

76.6

25.

22.6

' 21.5

1961

39. 6

30.4

36.5

•?

1962

SO. 5

30.4

42.7

1 \6,6

Includer^ ml?cellaneous types of riponses.

57

Table 16. — Imports of sponges to the United States'''

Year

Volume

Value

Value per pound

1945

194.6

Pounds
95, 596

328,307
214, 198
355,026
268,055
369,775
281,645
191,776
284,362
191,107
216,348
217,506

Dollars

791,979
3,087,963
1,768,130
2,587,336
1,936,974
2,329,108
2,116,123
1,295,935
1,628,192
1,123,692
1,341,692
1, 291, 567

Dollars
8.22
9.40
8.25
7.27
7 22

1947

1948

1949

1950

1951

6.30
7 69

1952

1953

1954

1955

6.75
5.72
5.88
6.20

1956

5.93

■"■ Published in various sponge and chamois trade reports.

to search the bottom for commercial sponges.
When a sponge is sighted, the hooker directs
the rower to turn the boat in that direction.
When the sponge is within reach, the pole is
lowered quickly to the bottom, and the size of
the sponge is judged by the width of the hook.
If the sponge is large enough, the hook is set
into the base of the sponge, which is then torn
from the bottom with an upward pull. This
method of harvesting often tears off part of
the sponge or leaves a considerable amount of
the sponge base from which a new sponge will
grow. It is quite probable that the number of
torn sponge bases left make it possible for this
hooking method to continue to be used exten-
sively and constantly in the shallow-water
areas without excessively depeleting the sponge
beds.

The hooking method does not produce the best
quality of sponges for three reasons:

1. Normally, shallow- water sponges have
lighter texture and poorer quality than
those found in deep water, except for the
wool sponges growing in the Rock Island
area.

2. Sponges harvested by the hooking method
are often torn.

3. The hookers work the limited hooking
area so constantly that the sponges

never have a chance to grow very large
and the average size taken is about 6
inches in diameter. The wool sponges
taken by the hookers average 16 to the
pound, and those taken by the divers,
11 to the pound. Thus the sponges taken
by the divers are almost 50 percent
heavier.

About 35 hooking boats of various sizes are
operating from Tarpon Springs along the coast
northward of this sponging center. In former
times the standard hooking unit was a 30- to
40-foot schooner with three or four dinghies
in which men worked in pairs. Now, only a
few schooners are used. Small converted
pleasure craft with a crew of two, small
schooners, and a number of small boats that
work from a land base do a considerable
amount of the harvesting.

At least two methods of hooking in the
Florida Keys are different than those found
in the Tarpon Springs area. In one method
only one man works from a dinghy. Using his
hooking pole, he keeps the boat in the center
of a shark-oil slick as the slick is moved
along with the tide. The oil smooths the water
surface and enables the hooker to identify
and hook the commercial sponge on the bottom.
The second method of hooking uses a power-
boat with a long boom lashed across the stern.
Three or four lines with end loops are attached

58

to the boom. The loop in the rope on the boom
is put around the upper end of the hooking pole,
which is then fitted into a hole in the stem
post of the dinghy. The dinghy man lies down in
the boat with his head and shoulders over the
stern and holds the water glass in the eddy
behind the dinghy with little effort. This allows
the powerboat to move along while the men in
their dinghies search the bottom. When a
sponge is seen, the man jerks the pole free
of the stem hole and the rope lopp, and, if the
man is quick, the sponge is hooked while the
dinghy is still moving forward. The powerboat
swings around, and the dinghy is again attached
to the powerboat by the same method. Thirty or
thirty-five miles of ground may be covered in
one day and a large number of good-quality
sponges can be taken. This method is good from
the conservation point of view because smaller
and poorly shaped sponges cannot be taken eco-
nomically.

Diving boats working out of Tarpon Springs
are designed after the original diving boats
used by the Greek spongers in the Mediter-
ranean. They are now diesel-powered, and the
air pump is powered directly from the main
engine. The boats are heavy and seaworthy.

The crew is made up of a captain (who
usually also serves as either the engineer or
one of the divers), two divers, an engineer,
a lifeline tender, cook, and deckhand. In good
weather the two divers put in a 12-hour day
between them, the actual time underwater
being about 10 hours. The diving dress is
similar to the standard deep-water equipment.
The diver jumps off the starboard side of the
bow and can support himself by hanging onto
the weighted dropline that hangs from the bow.

The diver's sponge hook is attached to a short
pole about 2 feet in length and is similar to that
used by the hooker. As the sponges are
gathered, they are kept in a fish- net bag with a
jointed- ring top, the stephani. The diver can
easily control the short pole, so the sponge can
usually be torn cleanly and carefully from the
bottom with a sidewise pull.

Cleaning of Sponges

Once aboard the boat, the sponges are first
squeezed to initiate the degeneration of the
living material, then piled base down to aUow

the "gurry" or decaying matter to drain from
the sponge. The pile is covered with wet burlap
sacking so that the sponges will not dry out.

In warm weather the sponge decays fairly
rapidly and by the next morning the sponges
that were collected the day before are well on
their way toward final cleaning. During the
day the sponges are turned and wet down
several times and by midday or midafter-
noon, they are ready for final cleaning. In
cleaning, the sponges are rinsed in clean sea
water and thrown hard against the deck to
knock out sand and particularly the small
snapping shrimp that lived in the larger
canals of the sponge. The outside of the sponge
is scraped with a knife to remove the last
traces of the "skin." As a final step, the
sponges are wrung out and strung on coarse
cord as a "line," each line holding 150 sponges.
At this point well-cleaned sponges are light
tan in color but the bottom of the base and
inside may be almost black. As the sponges
dry in the sun, the black color disappears.
After drying they are stored in the forward
hold of the boat.

If the rotting is allowed to continue too
long, the spongin fibers are greatly weakened;
the sponge is limp and of poor quality. Wool
sponges cannot be cleaned in fresh water as this
causes them to be dark in color and hard in
texture.

Selling and Sharing System

Ashore the sponges are stored in the Sponge
Exchange, and the day before the sale they are
graded and strung on 5-foot lengths of line,
known as bunches. Each bunch is made up of 20
to 30 or more sponges depending on size. The
sponges are sold to the packers at auction. The
seller has the right to refuse a bid that he
believes to be too low, and this may be done if
there is any hope that the market price will
rise.

One and one-half to two percent of the selling
price is withheld by the Exchange, as a charge
for the use of the storage sheds and other
facilities. If the sponger is a member of the
local Greek Orthodox Church, 3 percent of the
price may be withheld and half of this is given
to the church.

59

The share system for dividing the cash re-
turns is used generally throughout the industry
wherever two or more men work in one boat.
A typical sharing system is that of the diving
boats. At the beginning of a 5-month trip, the
boat is, in a sense, turned over to the crew who
are then responsible for any repairs and loss
of gear during the trip. Returns are usually
divided into 12 shares, but before these are
distributed among the crew, costs are deducted,
such as food, diving dress if needed, boat fuel,
replacement of broken gear, minor engine re-
pair, diving ropes, etc. The remainder is then
proportioned as follows:

1st diver (who may also

act as captain) 2 shares.

2nd diver 2 shares.

Engineer 1-1/2 shares.

Lifeline tender 1-1/2 shares.

Cook 1 share.

Deckhand 1 share.

Boat 3 shares (with

1/2 share going to the captain).

Take Per Unit of Effort and
Historical Analysis

The diving boat is used here as the fishing
unit. It usually employs six men and spends
about 100 days at sea each year. From sales
slips in the Tarpon Springs Sponge Exchange
for the 1955 and 1956 landings, it can be cal-
culated that 4.5 hooking boat units land as
many sponges in 1 year as one diving boat.
Since individual sales by hookers on the Ex-
change may represent the efforts of just one
man, or, as in some cases, the take by two
or three small schooners with crews of up to
five, the hooking boat unit represents the
efforts of more than two men in a dinghy.
The consistent use of a ratio of 4.5 hooking
boat units to 1 diving boat unit, however,
gives as accurate a comparison as is pos-
sible to obtain with the available information.
When all small boats along the Florida coast
are licensed, it will be possible to obtain a
ratio of effort of two- man hooking boats to
one diving boat.

Division of the shares may vary slightly, but
the above is the general pattern.

Amount and Value of Sponges Sold

Until 1951 sponges were sold by the pound.
This practice had certain disadvantages be-
cause of the large number of grades that were
set up and the obvious drawback in making pos-
sible (and almost encouraging) the loading of
sponges with foreign material. The weight of
the sponges was also affected by the amount
of water contained.

In 1951, the method of selling sponges was
changed to price per piece, and cleanliness,
shape, and texture of the sponges were used
as the criteria for value. Unfortunately, any
comparison between yearly take before and
after 1951 is confused by the change, but for
the sake of continuity, the take from 1951 to
the present has been converted into pounds and
presented in figures 18 and 19 on this basis
along with the data from the years 1917-51.
The take of the three principal species — wool,
yellow, and grass — are represented in figure
19, which is the graphical representation of
table 11.

By dividing the total number of diving boat
equivalents into the total catch by pieces or
by weight, the average catch per unit of effort
can be determined. The results give a good
indication of the density of the sponges on the
bottom, because the yearly effort, unless
severely hampered by weather, will be about
the same. In the long run, this information is
the most reliable that can be obtained for any
analysis of the biological situation.

The data on take per unit of effort are given
in table 12 and figure 20. Previous to 1938
there was considerable fluctuation in the return
per unit of effort, the average take per diving
boat equivalent being about 5,100 pounds. In
1936, the year the beds off the Ten Thousand
Islands were first harvested, the return per
unit of effort went up. The effect of the 1938
disease was an abrupt drop in the return per
unit of effort, which continued to drop as the
number of boats increased. Since sponges in
deep water had been killed off by the disease,
the intensity of the fishing effort on the
shallower grounds was greatly increased and
was probably about four times that previous
to the disease.

60

2.5

T r

CO

o

0>

O

I
H

O
UJ
IT

a

z

ID
X

U)

2i
o

0.

- I

1938 1940

1945 1947

1950

1955

I960

Figure 19.— Total take of wool sponges and value, 1937-62. Line A gives the value of wool sponges alone. Line B

gives the total take of wool sponges.

61

^^^

. /

/

\

\

y

^

^^3/

Wdiving

BOAT EQUIVALENTS

1 \

\

1 ^

-1---'
1

-^-•-T.^

\

A-

—

'\-(— HUN

x

■■ —

)REDS OF F
UNIT OF E

OUNDS PEI
FFORT

:

\

\

■'^

•v>\

— ■■'"^ ""ix'

^^^

Figure 20.— Take of wool sponges per unit of effort, 1935-56.

This fishing effort was more than the spong-
ing area could bear. In the period 1941-46 we
find that the size of the sponging fleet increased
22 percent. If it is assumed that the number of
sponges on the bars remained the same, it can
be calculated that the return per unit of effort
would drop by 18 percent. In actual fact the
return per unit of effort dropped by 20 percent
(by weight). When it is considered that during
this time more and more smaller sponges were
being harvested before they could produce eggs,
the fishing intensity would probably have
severely damaged the sponging grounds. The
sudden drop in price immediately after the war
in 1946 and the disease of 1947 brought disaster
to the industry instead.

It may be assumed from the above discussion
that from 1941 to 1946 the number of sponges
on the bottom was the same or nearly so at all
times. It is possible, therefore, to construct a
graph to represent the return per unit of effort
for varying sizes of a sponge fleet when this
level of concentration of sponges is found. This
has been done in figure 21, line A, and the line
interpolated to give the return per unit of effort

if the sponge fleet in terms of diving boat
equivalents were 68. Sixty-eight boats prob-
ably represent the average size of the fleet
before 1938. Line A thus represents the ap-
proximate level of return per unit of effort that
is taking place when the concentration of
sponges on the sea bottom is below replace-
ment level.

Lines C, D, and E in figure 21 represent the
low, average, and high returns per unit of effort
found before 1938. Only the solid part of the
line is supported by data, the dashed portions
being extrapolated. The low return per unit of
effort before 1938, line C, may be interpreted
as being the lowest possible level of return per
unit of effort, and by extension, of the concen-
tration of sponges on the bottom which will
allow rapid recovery of the sponging beds. Any
return per unit of effort, and concentration of
sponges on the bottom, below that represented
by line D would be less than the desired level.
At this level of concentration and a 68- boat
fleet, each boat would be taking about 5,100
pounds of sponges per year, this representing
a concentration of 2.8 pounds per acre (5,100

62

V)
Q

I 60

o
a.

u.
o

to
o

Ui
(T

o

z

5 40
o

■I"

■!■

HIGH TAKE BEFORE 1938

MEAN TAKE BEFORE 1938

!:°^1AKE BEFORE 1938

i"i''±«^i«_^_„U

36

30 m
a.

a:

111

24 a!

in
u

18

30 40 50 60 68 70

NUMBER OF DIVING BOAT UNITS

Figure 21. —Levels of take per unit of effort.

divided by 1,800 - the number of acres cov-
ered by one diving boat in 1 year) or 31 mature
sponges per acre (at a rate of 11 sponges per
pound).

The difficulty in attempting to project the
return per unit of effort, as represented by
line A in figure 21, to a level of 20 boats or
less is in trying to determine the point below
which changes in the size of the sponging fleet
will not affect return per unit of effort. Theo-
retically any decrease in the number of boats
in the sponging fleet should result in a slight
increase in the average return per unit of
effort if they all work the same areas. Since
the boats move in a random pattern while work-
ing the sponge bars in any given area, some
bars will be worked more than once per year,
others only once, and some not at all.

Before 1938 about 68 diving boat equivalents
were working the entire productive sponging
grounds. At the present time only one-third of

the former area is producing sponges. In order
to have the same intensity of fishing on the
present area only 23 boat equivalents would
be required. With the present sponging fleet
of just under 17 boat equivalents the intensity
of fishing effort is below that of 1938 and about
equal to that of a 51-boat fleet working the
entire former sponging area.

In region B, figure 21, the individual dots
indicate yearly returns per diving boat equiva-
lent; the circle, the average value; and the
line, the mean value over the 6-year period,
1951-56. This average take is much below the
very lowest return (line C) for the period
before 1938 and even below that of the average
take during 1940-47 when overfishing was
taking place. The best return per unit of effort,
however, was considerably higher than indi-
cated by the circle at B. The diving boat making
the best return in 1956 landed almost 2,200
pounds of sponges.

63

On the basis of a concentration of effort
equivalent to a fleet of 68 diving boats certain
conclusions may be reached. When the take per
unit of effort is below 2,400 pounds per year
(the 1940-47 average), it should be a clear
indication that overfishing is taking place and
harvesting is retarding the natural replacement
of sponges. The very slow increase in return
per unit of effort during the past 6 years sup-
ports this contention.

Average return per unit per year of effort
during the years 1951-57 was about 1,500
pounds. This indicates a concentration of
sponges on the bottom of about 10 per acre in
the area worked. This concentration is far too
low to bring about any substantial increase in
the number of sponges within a short period of
time. Line C in figure 21 suggests that a mini-
mum of 24 sponges per acre on the sponging
area is close to the lowest concentration neces-
sary for rapid natural repopulation of the beds.

As concentrations of sponges in the present
growing area increase, bringing more of the
area into economic production, and additional
sponging area is added, the fishing effort will
be spread more thinly over the sponging
grounds. This is based on the assumption and
expectation that the sponging fleet will not in-
crease in size because of the limited number of
available sponging boats and experienced
sponge fishermen. Less concentrated sponging
will allow the sponges to increase in size, and
the larval producing potential will rise con-
siderably. As a result, concentrations of
sponges on the bottom may be expected to in-
crease more and more rapidly.

Probable Sponge Distribution in 5
and 10 Years from 1957

By using what we now know about the re-
productive cycle of the sponge, the growth
rate, the rate of dispersion, and the current
pattern, it is possible to make an estimate of
the probable direction and rate of expansion of
the wool sponging grounds during the next 5
and 10 years. Several features of the expected
future distribution are of considerable interest.

Because of the slowness of the eddy circula-
tion, seaward extension of the sponging grounds

all along the western coast from Tarpon
Springs to Steinhatchee will be slow indeed.
Most, if not all, of the spread into deeper
water will have to be by way of an extension
of the sponge producing area into the deeper
water from the northern eddy, south of Car-
rabelle.

The most interesting evidence of extension
of the sponging area by this northern eddy was
gathered on the July 1957 exploratory trip.
Five half-hour dives were made at approxi-
mately 3-1/2 mile intervals in 50 feet of water
directly south of the mouth of the St. Marks
River, Stations XXIII and XXIV a, b, c, and
d (see fig. 10). The wool sponges collected or
seen were as follows:

Station XXIII - None

Station XXIV a - Only 2 wool sponges less

than 2" in diameter.
Station XXIV b - 11 wool sponges under

5", 3 over 5".
Station XXIV c - 8 wool sponges under 5",

7 over 5".
Station XXIV d - 4 wool sponges under 5",

5 over 5".

No wool sponges were found west of these
stations; and although the evidence is limited,
the steady change in the ratio of small sponges
to large sponges is indicative of wool sponge
dispersion to the west of this area.

Once the wool sponges are dispersed as far
west as Carrabelle, the meandering southward
current running counter to the shore current
will be primarily responsible for extension into
the deep-water zones.

The only possible exception to the above pat-
tern may be the seaward circulation of water
in the area of the sandy zone off the Suwannee
River. A boatload of 12- to 14-inch wool sponges
was taken in the fall of 1956 on the southern
side of this sand area in 55 feet of water. This
would indicate that a small area in this region
was unaffected by the disease in 1947 and may
have been effective in spreading the wool
sponges seaward since that time. It was im-
possible to explore this area completely as
the area beyond the 60-foot depth was re-
stricted by the U.S. Air Force as a target range.

64

Because of the age and physical condition of
the divers at the present time, most of the
sponging work is done in water less than 40
feet deep. If this situation continues the only
useful extension of the sponging area will be
that from Rock Island to Carrabelle in the
northern part of the sponging grounds. Since
the concentration of sponges in commercial
quantities in the deeper water to 120 feet can-
not be expected for another 15 to 20 years,
this does not entail serious consideration by
the industry at the present time. Concentra-
tion of sponges in quantity in 60 to 70 feet can
be expected in the next 5 or 10 years.

Within 5 years (after 1957), the total sponge
producing area should increase by 50 percent,
of which only 7 percent will lie within the 40-
foot depth, the present range of most of the
diving boats. Assuming sponge concentration
equal to that in the present grounds, the added
area will increase production by only 7 per-
cent. A further extension of 40 percent of the
then existing area in the next 5-year period
will add very little if any available sponging
ground, provided divers are still limited to
less than 40 feet of water. As the sponges ex-
tend into deeper and deeper water, dispersion
may progress more quickly as currents of up
to 11.5 miles per day are recorded for the
area.

A much more important factor to the spong-
ing industry than extension of the beds would
be a sizeable increase in the concentration of
sponges on the bottom. After careful examina-
tion of all the biological data gathered, I
believe that an increase from 40 percent to
60 percent in biological production within a 4-
to 5-year period may be expected through in-
creased sponge concentration, if more diving
boats are not put into operation and no disease
or adverse ecological condition occurs.

In the region of the circular eddy just south-
east of Cedar Keys, an accurate picture of
sponge concentration has been difficult to ob-
tain. Exploration of this area on the field trips
did not disclose any large concentration of
sponges, but, according to reports by some
spongers, there are parts of this area where
sponges are to be found in some quantity. One
take of 3,000 sponges in 40 to 55 feet from

this area had 32 percent larger than 10 inches
in diameter.

Within the limits of the present sponge pro-
ducing area (fig. 11) large sections are not now
producing sponges in quantities great
enough for economical harvesting. Certainly
much of the expected increase in the immediate
future must come from increased concentration
and filling in of those spots where the sponges
are thinly distributed.

The above predictions are based on the
assumption that there are uniform currents
and uniform survival rates of the sponge larvae
from year to year. Temperature patterns,
which control egg production, will vary from
year to year, as will wind pressure and the
resulting changes both in the rate and direction
of the currents. It is quite conceivable that
conditions one year would result in very un-
expected distribution of the sponge larvae in
large quantities, while during another year
the production of larvae would be small or large
numbers would be killed by adverse weather
conditions. In the area north of Cedar Keys,
the large numbers of sponges less than 2 inches
in diameter and the heavy production of larvae
by the mature sponges indicate that in 1955
large numbers of sponge larvae settled on the
bottom. Also, larval production in 1956 and
1957 was high and should have resulted in the
starting of large numbers of sponges. Few
small sponges were observed during the field
trips on the bars immediately north of St.
Martin's Reef Light and in water of less than
40 feet. Few mature sponges in this same
area were seen to be producing larvae.

DISCUSSION AND RECOMMENDA-
TIONS

History of Decline in Sales from
1938

During the past 15 to 20 years, synthetic
sponges have appeared on the market as a seri-
ous competitor for natural sponges. Present
retail sales of synthetic sponges are 10 to 15
times that of the trade in natural sponges, and
more than $20 million of synthetic sponges are

65

sold each year. The decline in the use of natural
sponges can be attributed to several factors.

Before 1938 the sponge industry market for
natural sponges in the United States was
divided, according to Sponge and Chamois In-
dustry trade reports, as follows:

25 percent went to amateur cleaners and
housewives;

25 percent was used by the pottery, tile,
shoe, and miscellaneous manufacturers;
and

foamlike structure of the synthetic tends to pick
up and hold the dirt while the meshwork of the
natural sponge allows the dirt to be washed out
thoroughly. It is not improbable that a synthetic
sponge with the strength and quality of the
natural sponge and with the added advantage
of controlled shape will in time be developed
with fibers so arranged that the synthetic can
be as readily and as thoroughly cleaned as the
natural sponge. Even if this is accomplished,
it would not necessarily mean that a good
grade of natural sponge at a competitive price
could not find a place in the market for special
purposes.

50 percent was sold to professional painters,
decorators, and wall washers.

Cheaper grades of sponges, grass and yellow,
were used by the amateur cleaners and house-
wives while the better grades went to various
industries. With the start of World War II, im-
ports of sponges from the Mediterranean de-
clined. During the war total landings of
sponges in Florida declined about 50 percent as
a result of the 1938 disease. With sponges in
short supply, the price rose steadily. Immedi-
ately after the war, imports of sponges from
the Mediterranean were again resumed — over
$3 million worth in 1946 — with the result that
domestic sponge prices were depressed.

Principal aims of the sponge producer,
therefore, should be to solve the problem of
keeping the price of the natural product down
so that less expensive natural sponges can be
reintroduced into the market for the housewife,
a market that has remained untouched for the
past 15 years. Secondly, there should be an
effort made to reduce the price of the better
grade wool sponges so that they will be more
in line with the competitive price of the syn-
thetic. This can only be done if the sponge pro-
ducers are willing to adopt more efficient
methods of harvesting and better management
of the sponge grounds, which in turn will
assure a large and continuous supply of sponges
at a lower price.

During the war increased prices, short
supply of natural sponges, and the introduction
of an inexpensive synthetic substitute resulted
in the natural sponges being unavailable to the
amateur cleaners and housewives. High prices
also forced industrial users to try synthetic
sponges as substitutes so that part of the
market was lost in this way as well. In the
decorating industry, where the greater per-
centage of the natural sponges were used,
changes in methods and materials, such as the
use of paint for ceilings instead of calcimine,
and higher wages, which discouraged the prepa-
ration of walls by washing, reduced the uses
of sponges by about half in this phase of
industry.

The two principal objections to the synthetic
sponge at the present time are that (1) the
plastic material is not as strong as the natural
spongin fibers of the wool sponge and (2) the

Purposes of Recommendations

My recommendations are made with the fol-
lowing purposes in mind:

1. To increase the number of sponges avail-
able for harvesting so that the return to
the individual sponge fisherman will in-
crease within a reasonably short length
of time.

2. To assure a continued and stable supply
of sponges for harvesting so that:

a. The sponge fishermen will be guaran-
teed a reasonably steady income in the
years to come.

b. The ultimate dealer can depend on a
constant and reliable source of
sponges, for without this assurance it

66

would be impossible to build a sound
and steady trade.

Just as the individual farmer must follow
sound rules and practices for the biological
management of his farm if he hopes to be
successful, so sponge fishermen should follow
a set of rules and practices if they hope to
see an increase in the number of sponges
on the sea bottom and maintain the maximum
harvest of sponges per year that can be
grown.

It has been shown both by experimental cul-
tivation of sponges and the observed concentra-
tion that is to be found off Cape Sable in south
Florida that even when wool sponges are con-
centrated one or more per square yard there is
sufficient food in the water for them to grow
at the maximum rate for that area. It follows,
therefore, that the basic problem is to find
ways and means of increasing the concentra-
tions of sponges on the available, suitable rock
bar areas. Other recommendations made below
suggest that the efficiency of harvesting
methods might be increased and that future
biological investigations should be carried out.

Recommendations

Establish a 6-inch size limit. — This recom-
mendation has been made many times in the
past but has never been acted upon, presumably
because of lack of information on larval produc-
tion. There has never been any direct evidence
presented why a larger size limit is not only
desirable but necessary.

The minimum diameter for egg producing
sponges, with few exceptions, is 5-1/2 inches
in the area north of Cedar Keys and 5 inches
in the area between Tampa Bay and Cedar
Keys. It is obvious that the present 5-lnch
size limit allows the taking of a number of
sponges which have not yet reproduced or are
not reproducing in quantity.

Before a 6-inch size limit is adopted, the
immediate disadvantages and future benefits
need to be reviewed.

1. Immediate disadvantages. — At my re-
quest, the agents of the Conservation

Department of the State of Florida made
spot checks of the percentages of sponges
of less than 6 inches that were being taken
by both divers and hookers. Of the sponges
examined only 15 percent were wool
sponges less than 6 inches in size. This
probably represents a minimum percent-
age, and some of the hooking boats would
probably have some catches with as high
as 25 percent wool sponges.

a. Thus, if a 6-inch size limit were
adopted, loss in catch would be at
least 15 percent but probably not as
high as 25 percent. The loss in revenue
would be considerably less than this.
As priced by the sponge buyers all the
sponges of less than 6 inches in size
have an average value per piece of
less than half that of the average price
for wool sponges. Calculations show
that the smaller sizes of sponges of 5
to 6 inches do not account for more
than 5 percent or 10 percent of the
actual cash value of the total take.

b. In those areas visited by the spongers
every year, especially the hooking
areas, this loss in revenue would be
felt most strongly during the first
year after adoption of a 6-inch limit.
In the second year those 5- to 6-inch
sponges not taken in the area would
have grown to hai-vesting size and the
greater return from these larger
sponges would offset any loss in actual
number of sponges taken during the
next year or two.

c. The diving boats might have to bear a
small loss in revenue from the take of
sponges of less than 6 inches for a 3-
year period since they fish a much
larger area for their catch.

d. The adoption of a 6-inch size limit
while sponge populations are increas-
ing would not affect actual income of
the sponge fishermen because of nor-
mally increasing landings. With ex-
pected increases in landing, the 5-
year period from 1959 onward seems
to be favorable for adopting this
recommendation.

67

2. Future benefits. — a. It has been shown in
previous sections of this report that a
6-inch sponge will produce at least
enough larvae to make possible the
establishing of one and probably more
new sponges. Consequently, with a 6-
inch size limit, every sponge har-
vested will have produced enough
larvae to replace itself. Unless an
area were badly affected by disease
or adverse ecological conditions, a 6-
inch size limit would enable every
sponging area not only to maintain the
present concentration but, because
there will always be a few larger
sponges in each area producing large
numbers of larvae, the total number
of sponges in each area would steadily
increase. No area would be depleted
by overfishing alone if a 6-inch size
limit were adopted.

b. By the end of the fourth year after
the adoption of a 6-inch size limit, a
15- to 25-percent increase in catch
could be expected as a result of the
spawning of those sponges of less than
6 inches that were not taken during the
first year after the size limit was
established. This increase would be a
permanent one with a likely further
increase of over 15 percent every 4
years until an ecological balance is
reached.

c. Food supply is not a factor limiting
the density of sponges on the bottom.
The two possible factors limiting high
concentration on the sponging grounds
north of Tampa Bay would be available
area for attachment and quantity of re-
production. There is much available
clean rock with very low competition
for space on the plentiful rocky bars
in the northern areas formerly
densely populated with sponges prior
to the disease. Availability of space
for attachment and growth of wool
sponges is, therefore, not an im-
mediate limiting factor. Late matur-
ing of the sponges as compared with
those further south, combined with the
harvesting of large numbers of

sponges which have never produced
eggs, is the only apparent deterrent to
increased and heavy concentration.
Regrowth from old torn bases and ex-
cess of larval production by larger
sponges would, it is believed, assure
a steady increase in total sponge popu-
lation up to the carrying capacity of
the bars.

Improve fishing techniques. — 1. A number
of sponge fishermen and scientific
workers have suggested that cutting the
sponges from the rock would leave a clean
base from which a new sponge could grow.
It can be calculated that such a method of
harvesting could increase production by
30 to 50 percent within a 3-year period.

A number of experiments were carried
out to test this possibility. Unfortunately,
it was found that more than 50 percent of
the sponges were growing on irregular
rocky areas and could not be readily cut
from the bottom. Instead, after cutting
was attempted, the sponges finally had to
be torn away, making this type of har-
vesting wasteful of time and effort. In
about 10 percent of the other cases, the
sponge came free of its attachment so
easily that it would have been torn loose
before it was cut. Harvesting sponges by
cutting could be most beneficial but, un-
fortunately, is impractical.

2. Some change should be made in the har-
vesting methods used by the hookers. The
most practical suggestion for increasing
the take by the hookers is the adoption of
the tested method used by the Florida Key
fishermen. This is the use of a larger
power craft and three or four hookers
working individually from dinghies. In
the present hooking method in the north-
ern Gulf, only one man out of two on the
smaller boats and only two out of five on
the hooking schooners are actually har-
vesting sponges. In the Florida Key
method as many as four men out of five
are taking sponges. Individual income
could almost be doubled if this latter
method was adopted.

68

3. Although diving equipment is the most
efficient gear being presently used, its
efficiency could be increased by the use
of lightweight diving equipment. Present
diving equipment and methods requiring
the use of heavy diving gear have one
man at a time harvesting sponges to sup-
port the entire crew of six. Since most
of the diving in the upper Gulf is carried
on in 20 to 35 feet of water, lightweight
diving equipment, such as was used on the
present investigation, could be safely
employed. If 16- or 18-foot boats were
designed with an inboard engine which
could both power the boat and run a com-
pressor for the diver, one or two such
boats could be employed as auxiliary
craft to the present diving boats. By use
of lightweight equipment aboard both the
regular diving boat and the auxiliary
craft, it would be possible to double or
treble the present effort, with very little
added running expense. It would mean
that two or four more members of the
crew would of necessity be divers, in the
latter case the size of the crew would be
increased.

In the Cape Sable area such equipment
would be particularly useful where the
diving is done in less than 25 feet.

With synthetic foam suits, which could be
made for less than $20 each, diving could
be carried on with comfort throughout the
upper Gulf from March through Novem-
ber.

Lightweight equipment, such as the air-
supplied mask, has already been used
with success by individual sponge fisher-
men working from Tarpon Springs.

Transplant Sponges. — Previously it was
shown that sponges transplanted to establish
a sponge plantation resulted in large numbers
of sponges being established naturally in the
area. Transplanting sponges to the area just
north of Tampa Bay might be particularly use-
ful. This area from Tampa Bay to Anclote Key
is not producing wool sponges except in the
shallow water off Indian Rocks and Honeymoon
Island. Two thousand or more mature sponges

transplanted to the area beginning 3 or 4 miles
northwest of the outermost Egmont Channel
Buoy and on the bars in a line west from this
point from 35 to 70 feet could in time populate
the area. Most of the bars in the area have the
appearance of excellent sponging bars and the
noncommercial sponges growing on them are
healthy in appearance. There are no wool
sponges upcurrent from this area, however,
to bring about repopulation of the bars.

Transplanting of mature sponges should be
done at the peak of reproduction, in June and
July, for the transplanted sponges would con-
tinue to release all the larvae they contained.
If the sponges were transplanted at a concen-
tration of 25 or more for each bar, both suc-
cessful fertilization of the sponges and a high
production of larvae each year would be as-
sured. Once established, the sponges even in
deeper water of 70 to 90 feet would increase
the wool sponge growth in the area of Anclote
Key because of the shoreward movement of the
current in this area (fig. 11).

Any other area which is at present producing
very few sponges could be brought into produc-
tion much more quickly by using this same
method of transplanting large mature sponges
from areas of good concentrations. One such
area that is in need of repopulating by this
means is that to the north and northwest of
St. Martin's Reef Light. Before 1947, this
area was quite productive.

Institute further biological research on the
commercial sponges. — Answers to the follow-
ing problems would assist in showing additional
ways and means of obtaining the greatest pos-
sible harvest of commercial sponges from the
sponging grounds:

1. The embryology of the commercial
sponges is not known in detail. Observa-
tion of the larval production suggests that
either the spermatozoa enter the sponge
in clumps rather than singly or that only
certain flagellate chambers in the egg-
producing sponges are capable of pro-
ducing eggs.

2. Much more information is needed on wool
sponge larvae. It is not known with

69

certainty how long the larva lives after
being released. It may be presumed that
during part of the life span the larva
floats at or near the surface as other
larvae do, then towards the end of its
life span it sinks to the bottom for at-
tachment. Underwater observation of
noncommercial sponges closely related
to the commercial sponges suggests that
larvae are released at various stages
after maturation, depending on how deeply
they are buried in the matrix of the
sponge. A number of these larvae may be
released so late in their short life span
that they immediately sink to the bottom
and attach. What percentage, if any, follow
this pattern of behavior would be im-
portant to a better understanding of how
sponge concentrations are increased.

3. The effect of various concentrations of
sponges on rate of reproduction per
sponge needs to be studied in more de-
tail.

4. All five stations established for the study
of growth have been left intact. I recom-
mend that the necessary arrangements be
made to have the spongers not disturb
these areas and that they be marked so
that the sponges could be remeasured for
information on their growth rate.

5. Much more needs to be known about suit-
able habitats for sponges. Reports from
the Key West spongers state that some
wool sponges grow beneath the limey
mud or are at least covered with mud.
Certainly a number of wool sponges will
continue to grow even though half buried
in limey mud or even fine sand.

The industry is at a critical turning point.
There is considerable pressure to expand the
sponging fleet, yet the present catch of the
best and most efficient diving crew is less
than two-thirds the lowest level of take per
unit of effort in the 1917-36 period. Increased
fishing without a 6-inch size limit will only
impede recovery, which at the present time
is progressing as fast as one could hope to
expect of any biological process.

The adoption of a 6-inch size limit will not
solve all the problems besetting the industry by
any means but it is the first step in assuring
that no area will be overfished and that concen-
trations of sponges will become greater even
with increased fishing effort.

It can be only through the close cooperation
between the sponge fishermen, the Tarpon
Springs Sponge Exchange, the sponge packers
of Tarpon Springs, the large sponge dealers in
the north, and the Conservation Department
of the State of Florida that a 6-inch size limit
could be set and maintained. Unfortunately,
everyone concerned must be convinced of the
necessity and value of a 6- inch limit before
adoption of this law is possible.

ACKNOWLEDGMENTS

A considerable amount of help and encour-
agement has been received throughout this
investigation of the commercial sponges. In
particular, mention should be made of Robert
Work, who was the assistant during the first
year of the investigation. M. Gianaris assisted
on two of the field trips. John Maillis of the
sponging boat Elini did an excellent job during
the deep-water field trip in the summer of
1956 and was responsible for collecting sponges
for larval examination during the 1956-57
period. A number of other diving boats also
collected sponge material during the first year
of the investigation. L. Smitzes, President of
the Tarpon Springs Sponge Exchange, and M.
Dritsos, Secretary of the Sponge Improvement
Committee, were both most helpful throughout.
R. M. Ingle and other personnel of the Florida
State Board of Conservation were generous
with both advice and assistance whenever the
need arose.

Bud Taylor of Steinhatchee, whose boat.
Rose Bros. II, was used for all the ecological
studies in the field in the northern Gulf, sup-
plied a keen interest, unstinting help, and
encouragement in carrying out this phase of the
work. Many members of the University of
Miami Marine Laboratory (and my wife) as-
sisted in discussing the various aspects of the
problem, critical reading of the report, and
identification of collected material.

70

LITERATURE CITED

BLOCK, RICHARD, J., and DIANA BOLLING.
1939. The amino acid composition of kera-
tins. The composition of gorgonin,
spongin, turtle scutes, and other kera-
tins. Journal of Biological Chemistry,
vol. 127, no. 3, p. 685-693.

BRICE, JOHN J.

1898. The fish and fisheries of the coastal
waters of Florida. U.S. Commission of
Fish and Fisheries, Part 22, Report of
the Commissioner for the year ending
June 30, 1896 (1898), p. 263-342.

CARTER, H. J.

1878, XVllI. Parasites of the Spongida. An-
nals and Magazine of Natural History,
ser. 5, vol. 2, no. 8, p. 157-171.

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SMITH.

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72

APPENDIX

Sponging Grounds (See fig. 15)

AREA A:

1. Carrabelle grounds - from Dog Island to

St. Marks. Not visited by the spongers
since the 1947-48 season.

2. Econfina grounds - from St. Marks to the
mouth of the Econfina River. Part of this
ground is known as the Econfina flats.

3. Rock Island grounds - from Econfina
River to Keaton Beach. This ground and
the Econfina grounds are used primarily
by the hook boats at the present time.

4. Piney Point grounds - from Keaton Beach
to Grass Island. Used by both the hookers
and divers in their assigned depths.

AREA B:

5. North Pepperfish grounds - from Grass
Island to Pepperfish Key. This includes
the area off the Steinhatchee River. Off-
shore from the mouth of the river a large
quartz sand patch stretches seaward and
is about 8 miles wide. There are only a
few small rocky bars on which the
sponges can grow.

6. South Pepperfish grounds - from Pep-
perfish Key to the mouth of the Suwannee
River. There are few shallow-water rock
bars, and the water is often turbid.

AREA C:

7. Cedar Keys grounds - a wide quartz
sand strip about 8 miles wide separates
these grounds on the north side from the
ones above. The strip of sand lies off the
mouth of the Suwannee River. The south-
ern limits of the grounds is along a line
southwest of Cedar Keys.

8. Cedar Keys High Rocks grounds - this is
the portion of the Cedar Keys grounds in
less than 40 feet of water.

AREA D:

9. Port Inglis grounds - from a line south-
west of Cedar Keys to the mouth of the
Crystal River.

10. Big Bank Reef grounds (or St. Martins
Reef) from the mouth of the Crystal River
to St. Martins Reef Light.

11. Anclote Key - from St. Martins Reef
Light to just south of Anclote Key.

AREA E:

12. Highlands grounds - from Anclote Key
south to Tampa Bay.

AREA F:
(Very little sponging was ever carried on in the
area between Tampa Bay and Sanibel Island. The
primary reason for the lack of sponges is the
relatively steep slope of the bottom.)

In area F the two most common sponging
grounds in the Ten Thousand Islands area are:

13.

14.

Pavilion Key grounds - the flat rocky
bar and gravel area southwest of Pavilion
Key.

Shark River grounds - off the mouth of
Shark River and Cape Sable. This area
was first worked in 1936.

AREA G:

15.

The Keys grounds are confined to very
limited areas at the present time. The
entire area produced more than half the
sponges in the early 1900's when not all
of the west Florida coast sponging areas
were being exploited. Only those grounds
in the Keys area presently producing
sponges are listed below. Production is
low.

Biscayne Bay groimds - between Elliott
Key and the mainland.

16. Hawk Channel grounds - primarily along
the shallow inshore areas of Key Largo
and Plantation Keys.

17. Key West grounds - the most productive
areas at present are close to Big Coppett
Key on the Florida Bay side of the Keys.

MS #1007

73

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