• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Acknowledgement
 Table of Contents
 List of Tables
 Introduction
 Description of the Gear and the...
 Historical trends in shrimp landings...
 Shrimp landings and by-catch of...
 Summary and conclusions
 Literature cited
 Appendix 1: Bait shrimp fishery...






Group Title: Technical paper / Florida Sea Grant College ; no. 40
Title: Bait shrimp fishery of Biscayne Bay
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Permanent Link: http://ufdc.ufl.edu/UF00075991/00001
 Material Information
Title: Bait shrimp fishery of Biscayne Bay
Series Title: Technical paper Florida Sea Grant College
Physical Description: 16 p. : ill. ; 28 cm.
Language: English
Creator: Berkeley, Steven A
Pybas, Donald W
Campos, Wilfredo L
Florida Sea Grant College
Publisher: Florida Sea Grant Extension Program, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1985
 Subjects
Subject: Shrimp fisheries -- Florida -- Biscayne Bay   ( lcsh )
Fishing baits   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 14.
Statement of Responsibility: Steven A. Berkeley, Donald W. Pybas, Wilfredo L. Campos.
General Note: Grant NA80AA-D-00038.
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
 Record Information
Bibliographic ID: UF00075991
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 13841352

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Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page
    Acknowledgement
        Acknowledgement
    Table of Contents
        Table of Contents
    List of Tables
        List of Tables
    Introduction
        Page 1
        Page 2
    Description of the Gear and the Fishery
        Page 2
        Page 3
        Page 4
        Page 5
    Historical trends in shrimp landings and abundance
        Page 6
        Page 7
        Page 5
        Page 8
        Page 9
    Shrimp landings and by-catch of juvenile gamefish
        Page 10
        Page 11
        Page 12
        Page 9
    Summary and conclusions
        Page 13
        Page 12
    Literature cited
        Page 14
    Appendix 1: Bait shrimp fishery questionnaire
        Page 15
        Page 16
Full Text

7P- 4


Bait Shrimp Fishery of Biscayne Bay



by
Steven A. Berkeley
Donald W. Pybas
Wilfredo L. Campos


FLORIDA SEA GRANT COLLEGE


Technical Paper No. 40












BAIT SHRIMP FISHERY OF BISCAYNE BAY


Steven A. Berkeley
Donald W. Pybas
Wilfredo L. Campos





Florida Sea Grant Extension Program
University of Florida
Gainesville, FL 32611






Project No. IR-83-9
Grant No. NA80AA-D-00038



Technical Papers are duplicated in limited quantities for specialized
audiences requiring rapid access to information. They are published with
limited editing and without formal review by the Florida Sea Grant College
Program. Content is the sole responsibility of the author. This paper was
developed by the Florida Sea Grant College Program with support from NOAA
Office of Sea Grant, U.S. Department of Commerce, grant number
NA80AA-D-00038. It was published by the Sea Grant Extension Program which
functions as a component of the Florida Cooperative Extension Service, John
T. Woeste, Dean, in conducting Cooperative Extension work in Agriculture,
Home Economics, and marine Sciences, State of Florida, U.S. Department of
Ccamerce, and Boards of County Comnissioners, cooperating. Printed and
distributed in furtherance of the Acts of Congress of May 8 and June 14,
1914. The Florida Sea Grant College is an Equal Employment-Affirmative
Action employer authorized to provide research, educational information and
other services only to individuals and institutions that function without
regard to race, color, sex, or national origin.



TECHNICAL PAPER NO. 40
November 1985








ACKNOWLEDGMENTS


This report would not have been possible without the assistance of many individuals
in the bait shrimp fishery. The authors would like to extend their thanks and appreciation
to the boat captains and wholesale dealers who gave their time to be interviewed and to
Ronald Dalton and Howard Carrington whose logbooks were so invaluable. Other
individuals we owe special thanks are James Luznor Sr., James Luznor Jr., John Knecht,
James Todd, John Tyler, and Benny Jeffus.

In addition to these individuals, we extend our grateful thanks to: Pat Cope and
Janice Schneider for their assistance in the project; Bill Mattila for drafting the figures;
and Tina Murray for her tireless preparation of manuscript revisions.







TABLE OF CONTENTS

Page
Acknowledgment ii

List of Tables 1V

List of Figures iv

Introduction 1

Description of the Gear 2

Description of the Fishery 2

Historical Trends in Shrimp Landings and Abundance 5

Shrimp Landings and By-Catch of Juvenile Gamefish 9

Summary and Conclusions 12

Literature Cited 14

Appendix I .15







LIST OF TABLES


1. Yearly mean catch of bait shrimp per boat-night in the Biscayne Bay
commercial bait shrimp fishery, 1971-1983.

2. Recreationally and/or commercially important species caught by commercial
bait shrimp vessels in Biscayne Bay: Estimated annual catch by the entire
fleet in numbers in weight and mean number caught by entire fleet per 1000
shrimp

3. Recreational and/or commercial species caught by commercial bait shrimp
vessels in Biscayne Bay: mean and minimum-maximum sizes (forklength)
recorded.


LIST OF FIGURES


Figure

1. Typical roller frame trawl used in Biscayne Bay bait shrimp
fishery

2. Present and historical bait shrimp fishery areas in Biscayne Bay

3. Mean yearly bait shrimp catch per boat-night, 1971-1983

4. Monthly bait shrimp catch per boat-night in the Biscayne Bay
bait shrimp fishery, 1971-1983


Page

3


Table


Page








BAIT SHRIMP FISHERY OF BISCAYNE BAY


Steven A. Berkeley
Donald W. Pybas
Wilfredo L. Campos


Introduction

A small but valuable live bait shrimp fishery has existed in Biscayne Bay since at
least the early 1950s. In recent years there has been increasing pressure from
recreational fishing and environmental groups to eliminate this fishery from the Bay
because the fishing activity is generally thought to be deleterious to the environment
and/or destructive to juvenile game fish.

Opposition to this fishery is as old as the fishery itself. In 1952, the Florida State
Board of Conservation initiated a study of the commercial fisheries of Biscayne Bay
(Siebenaler, 1953). According to the author, "the need for the study arose from a fear
that commercial fishing was harmful to the fish stock and the general ecology of the bay.
Agitation to close the bay to commercial fishing has been insistent over a period of years,
but no information has hitherto been available on which to judge the merits and
consequences of such action." Woodburn et al. (1957) discuss the impact of the live bait
shrimp fishery on the environment and on game fish in the Cedar Key-Naples area in
response to concern being voiced at that time by sports fishing and conservation interests.
Tabb (1958) presents results of a study by the Florida State Board of Conservation to
investigate "reports of damage to grass flats and destruction of sport and forage fishes
caused by bait shrimp operations in Biscayne Bay." Tabb and Kenny (1969) discuss the
history of Florida's live bait shrimp fishery and again cite the concern of anglers that the
fishery causes habitat damage and juvenile fish mortality. The studies cited above all
concluded that: 1) bait shrimp trawling is not deleterious to sea grass; 2) the mortality of
food and/or game fish due to bait shrimp fishing is negligible. However, these studies
discuss the fishery as it existed 20 or 30 years ago, after only a few years of operation.
As demand for live bait shrimp increased, so did the size of the fleet and the pressure on
the resource. Thus, many of the concerns presently being voiced need to be examined
once again. This study was initiated to update the existing knowledge of the bait shrimp
fishery in Biscayne Bay and document historical trends in number of participants, fishing
methods, fishing area, seasonality, total catch, catch-per-unit-effort, disposition of the
catch, and economics of the industry.

The data base consists of: a) individual vessel logbooks containing information on
number of shrimp caught per boat per night; b) by-catch species composition from two
years (1982-1983) of data collected aboard commercial bait shrimp vessels in Biscayne
Bay; c) interview of commercial bait shrimpers and bait shrimp distributors; and d) some
additional information from a two year (1982-1983) fisheries assessment program in
Biscayne Bay.



STEVEN A. BERKELEY, former Research Associate with the Rosenstiel School of
Marine and Atmospheric Science, University of Miami, currently on the staff of the South
Atlantic Fisheries Management Council. DONALD W. PYBAS, Marine Extension Agent
for Dade County, Florida, Florida Sea Grant Program. WILFREDO L. CAMPOS,
Research Assistant, Rosenstiel School of Marine and Atmospheric Science, University of
Miami.








Description of the Gear


A brief description of the gear and fishing methods is given in the sections which
follow. A more complete discussion can be found in Tabb and Kenny (1969). The roller-
frame trawl used today in the Biscayne Bay live bait shrimp fishery evolved over many
years, but has changed relatively little since at least the 1960s (Tabb, 1958; Tabb and
Kenny, 1969). Otter trawls were used during the early years of the fishery but because
they were believed to be destructive to the habitat (particularly seagrass beds) an
alternative gear was sought. The roller-frame trawl was developed specifically in
response to this need as a non-destructive alternative to the otter trawl, which was then
prohibited. The roller-frame trawl proved to be more efficient than the otter trawl and
was readily accepted by fishermen. The roller-frame trawl, as the descriptive name
implies, consists of a net attached to a metal frame with a slotted roller along the entire
lower portion of the frame (Figure 1). Metal or fiberglass finger bars are placed 12-2
inches apart vertically along the front of the frame to prevent clogging of the net with
seagrass, algae or debris and to protect the live shrimp catch by excluding large objects.
The roller is the contact point with the bottom and, therefore, the trawl rolls over
seagrasses without uprooting it.

Bait shrimp vessels are between 25 and 40 feet in length and are rigged with a boom
on each side to tow two nets simultaneously. Each trawl is attached to the vessel by a
galvanized wire or nylon tow line which runs from the tow yoke on the trawl, through a
block at the end of each boom and then to a winch mounted on the deck or top of the
wheel house. The winch is used to raise and lower the booms as well as haul the nets.
Trawl frames are typically 12 feet wide but range between 10 and 16 feet. The nets are
approximately 25 feet long, and are generally made of 3/4 to 1 inch stretched mesh nylon
or dacron bulk netting. Trawling is done at night due to the nocturnal nature of pink
shrimp, the primary target species. Tows are short, averaging 25 minutes, to minimize
mortality.

The catch is either dumped into a screened-off area in the live well or onto sorting
tables. The practice of holding the catch in the live well until shrimp are culled out is
believed to decrease mortality of the incidental species. Shrimp are sorted out and placed
in live wells, and incidental species returned overboard. Sorting is done quickly to
minimize shrimp mortality.

The boats, upon returning, are met by wholesale buyers (truckers). Shrimp are
offloaded into specially built trucks equipped with partitioned tanks and recirculating
pumps, and delivered to retail bait and tackle shops throughout South Florida. Deliveries
are usually completed by 8:30 a.m. The distribution process is accomplished as quickly as
possible to keep mortality at a minimum.

Description of the Fishery

Past and present shrimp fishing grounds in Biscayne Bay are shown in Figure 2.
Little shrimping is now done in the deeper central parts of the bay as was the case in the
1960's (Tabb and Kenny, 1969). It is not entirely clear why the major fishing area shifted
to the west, although this is possibly explained by the previous existence of a closed area.
The near-shore area from Rickenbacker Causeway south to Snapper Creek Canal
(Figure 2) was closed to shrimp trawling at one time because this area was believed to be
a spotted sea trout nursery ground (Tabb and Kenny, 1969). The prohibition against
shrimping in this area was repealed when the special acts of local application were
repealed in the early 1970s.








Description of the Gear


A brief description of the gear and fishing methods is given in the sections which
follow. A more complete discussion can be found in Tabb and Kenny (1969). The roller-
frame trawl used today in the Biscayne Bay live bait shrimp fishery evolved over many
years, but has changed relatively little since at least the 1960s (Tabb, 1958; Tabb and
Kenny, 1969). Otter trawls were used during the early years of the fishery but because
they were believed to be destructive to the habitat (particularly seagrass beds) an
alternative gear was sought. The roller-frame trawl was developed specifically in
response to this need as a non-destructive alternative to the otter trawl, which was then
prohibited. The roller-frame trawl proved to be more efficient than the otter trawl and
was readily accepted by fishermen. The roller-frame trawl, as the descriptive name
implies, consists of a net attached to a metal frame with a slotted roller along the entire
lower portion of the frame (Figure 1). Metal or fiberglass finger bars are placed 12-2
inches apart vertically along the front of the frame to prevent clogging of the net with
seagrass, algae or debris and to protect the live shrimp catch by excluding large objects.
The roller is the contact point with the bottom and, therefore, the trawl rolls over
seagrasses without uprooting it.

Bait shrimp vessels are between 25 and 40 feet in length and are rigged with a boom
on each side to tow two nets simultaneously. Each trawl is attached to the vessel by a
galvanized wire or nylon tow line which runs from the tow yoke on the trawl, through a
block at the end of each boom and then to a winch mounted on the deck or top of the
wheel house. The winch is used to raise and lower the booms as well as haul the nets.
Trawl frames are typically 12 feet wide but range between 10 and 16 feet. The nets are
approximately 25 feet long, and are generally made of 3/4 to 1 inch stretched mesh nylon
or dacron bulk netting. Trawling is done at night due to the nocturnal nature of pink
shrimp, the primary target species. Tows are short, averaging 25 minutes, to minimize
mortality.

The catch is either dumped into a screened-off area in the live well or onto sorting
tables. The practice of holding the catch in the live well until shrimp are culled out is
believed to decrease mortality of the incidental species. Shrimp are sorted out and placed
in live wells, and incidental species returned overboard. Sorting is done quickly to
minimize shrimp mortality.

The boats, upon returning, are met by wholesale buyers (truckers). Shrimp are
offloaded into specially built trucks equipped with partitioned tanks and recirculating
pumps, and delivered to retail bait and tackle shops throughout South Florida. Deliveries
are usually completed by 8:30 a.m. The distribution process is accomplished as quickly as
possible to keep mortality at a minimum.

Description of the Fishery

Past and present shrimp fishing grounds in Biscayne Bay are shown in Figure 2.
Little shrimping is now done in the deeper central parts of the bay as was the case in the
1960's (Tabb and Kenny, 1969). It is not entirely clear why the major fishing area shifted
to the west, although this is possibly explained by the previous existence of a closed area.
The near-shore area from Rickenbacker Causeway south to Snapper Creek Canal
(Figure 2) was closed to shrimp trawling at one time because this area was believed to be
a spotted sea trout nursery ground (Tabb and Kenny, 1969). The prohibition against
shrimping in this area was repealed when the special acts of local application were
repealed in the early 1970s.









Fig. 1. Typical roller frame trawl used in Biscayne Bay bait shrimp fishery.


I1, V
'1,
.-r~-








FIG.2 Present and Historical Baitshrimp
Fishing areas in Biscayne Bay

:::::MODERATE SHRIMPING.1958
:::::HEAVY SHRIMPING.1958
,MODERATE SHRIMPING,1982

*HEAVY SHRIMPING,1982
PREVIOUSLY MODERATE,
PRESENTLY HEAVY SHRIMPING.







SSnapper -.


Solder
Key


Featherbed
Banks A


Ua.








In 1952-1953 there were 3 bait shrimp trawlers in Biscayne Bay (Siebenaler, 1953).
In 1958 there were 12 boats fishing year-round (Tabb, 1958) and by 1966, there were 46
vessels fishing in Biscayne Bay (Tabb and Kenny, 1969). The number of boats now fishing
in the Bay varies seasonally but never exceeded 28 boats at any one time during 1983.
From a series of boat counts over the year, it was estimated that in 1983 there were 22-
23 bait shrimp boats operating in Biscayne Bay on average.

The fishery is conducted on a per-order basis. Each captain knows, prior to leaving
the dock, what his order is for the night. The working hours of each boat is thus
dependent on the amount ordered and the abundance of shrimp.

The table below shows historical changes in prices paid for bait shrimp at each
marketing step. Figures are means derived primarily from interviews.

1950s 1960s 1970s 1983-84 1985

Ex-vessel (owner-captain)1 $12.00 $15.00 $22.00 $30.00 $34.00

Driver-distributor1 $37.00 $51.00 $55.00

Retail bait & tackle store2 $ 0.35 $ 0.50 $ 0.60 $ 0.75- $ 0.79-
$ 1.25 $ 1.75

Prices vary seasonally and also reflect transportation costs from the area of
capture. Interviews with 4 distributors (truck drivers) who buy from 15 boats indicated
that 52% of the catch is sold outside Dade County.


Historical Trends in Shrimp Landings and Abundance

Data on the commercial fishery were obtained from log books and interviews. Log
books contained information on number of shrimp caught per trip (boat-night). Records of
12,407 boat-nights between 1971 and 1983 were obtained. Mean and standard error of the
number of shrimp per boat-night were calculated by month and year.

Mean catch (numbers) per boat-night from 1971-1983 is shown in Table 1. Catches
have been relatively stable, varying from a low of 5,300 shrimp per boat-night in 1971 to a
high of 7,448 in 1973 with no particular trend (Figure 3). The mean catch per boat-night
from 1971-1983 was 6,182 shrimp.

Shrimp are an annual crop. They enter the Bay in summer as post-larvae, and by
late summer or fall they begin entering the fishery. Prior to the onset of maturation,
they migrate outside the Bay. Although it is not known where the shrimp from Biscayne
Bay end up or even if they survive to spawn, pelagic post-larvae, probably from shrimp
spawning elsewhere, enter the Bay in the next summer, settle out of the plankton and
begin the cycle again.

Reflecting this cycle, bait shrimp catches are lowest in summer and begin to
increase as shrimp are recruited into the fishery (Figure 4). Highest catches are in
winter, after which shrimp begin leaving the Bay. Catches decline, reflecting this


IPer 1,000 shrimp
2Approximate per dozen shrimp--from various sources
5








Table 1. Yearly mean catch of bait shrimp per boat-night in the Biscayne Bay commercial
bait shrimp fishery, 1971-1983.*


Mean number
per boat night

5554
5865
6735
5767
5911
6278
5572
6091
6553
6607
7448
6691
5300



Grand Mean = 6182


Sample size
(boat-night)

1110
1013
832
1059
1057
975
1067
1398
1320
1108
692
631
145



Total = 12407


*obtained from log books



Fig. 3. Mean yearly bait shrimp catch per boat-night, 1971-1983.



8000


7500


7000


6500


6000


5500


5000
1971 72 73 74 75 76 77 78 79 80 81 82 83


Year

1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972
1971


Standard
deviation

2637
3231
4166
2719
2882
3364
2977
3033
3653
2737
3052
3207
1874


Standard
error

79
102
144
84
89
108
91
81
101
82
116
128
156





Fig. 4. Monthly bait shrimp catch per boat-night in the Biscayne Bay
bait shrimp fishery, 1971-1983. *


8000



7500




7000




6500




6000




5500




5000




4500


J F M A


M J
Month
7


J A S 0 N D


*obtained from log books


1500


III








In 1952-1953 there were 3 bait shrimp trawlers in Biscayne Bay (Siebenaler, 1953).
In 1958 there were 12 boats fishing year-round (Tabb, 1958) and by 1966, there were 46
vessels fishing in Biscayne Bay (Tabb and Kenny, 1969). The number of boats now fishing
in the Bay varies seasonally but never exceeded 28 boats at any one time during 1983.
From a series of boat counts over the year, it was estimated that in 1983 there were 22-
23 bait shrimp boats operating in Biscayne Bay on average.

The fishery is conducted on a per-order basis. Each captain knows, prior to leaving
the dock, what his order is for the night. The working hours of each boat is thus
dependent on the amount ordered and the abundance of shrimp.

The table below shows historical changes in prices paid for bait shrimp at each
marketing step. Figures are means derived primarily from interviews.

1950s 1960s 1970s 1983-84 1985

Ex-vessel (owner-captain)1 $12.00 $15.00 $22.00 $30.00 $34.00

Driver-distributor1 $37.00 $51.00 $55.00

Retail bait & tackle store2 $ 0.35 $ 0.50 $ 0.60 $ 0.75- $ 0.79-
$ 1.25 $ 1.75

Prices vary seasonally and also reflect transportation costs from the area of
capture. Interviews with 4 distributors (truck drivers) who buy from 15 boats indicated
that 52% of the catch is sold outside Dade County.


Historical Trends in Shrimp Landings and Abundance

Data on the commercial fishery were obtained from log books and interviews. Log
books contained information on number of shrimp caught per trip (boat-night). Records of
12,407 boat-nights between 1971 and 1983 were obtained. Mean and standard error of the
number of shrimp per boat-night were calculated by month and year.

Mean catch (numbers) per boat-night from 1971-1983 is shown in Table 1. Catches
have been relatively stable, varying from a low of 5,300 shrimp per boat-night in 1971 to a
high of 7,448 in 1973 with no particular trend (Figure 3). The mean catch per boat-night
from 1971-1983 was 6,182 shrimp.

Shrimp are an annual crop. They enter the Bay in summer as post-larvae, and by
late summer or fall they begin entering the fishery. Prior to the onset of maturation,
they migrate outside the Bay. Although it is not known where the shrimp from Biscayne
Bay end up or even if they survive to spawn, pelagic post-larvae, probably from shrimp
spawning elsewhere, enter the Bay in the next summer, settle out of the plankton and
begin the cycle again.

Reflecting this cycle, bait shrimp catches are lowest in summer and begin to
increase as shrimp are recruited into the fishery (Figure 4). Highest catches are in
winter, after which shrimp begin leaving the Bay. Catches decline, reflecting this


IPer 1,000 shrimp
2Approximate per dozen shrimp--from various sources
5








migration, and generally do not increase again until a new year class enters the fishery in
fall. In the 13 years for which log book records were available, January had the highest
landings in number of shrimp per boat night (7,940) and May had the lowest (4,548).

Catch-per-unit-effort (CPUE) expressed as numbers per boat per night, reflects year
class strength or local recruitment levels if effort remains relatively stable. However,
landings and even CPUE will not necessarily reflect high shrimp abundance because total
effort reflects both market demand and trends in abundance of shrimp. During part of the
year, particularly during years of high shrimp abundance, boats fish to fill orders; when
they have done so, they stop fishing. The result is that during times of high abundance,
catches remain much the same but the time spent fishing decreases. However, since we
expressed CPUE as catch per night, increased abundance would not necessarily be
detected from our CPUE data. A substantial decline in abundance would be reflected in a
decreased CPUE, though, since boats normally fish the entire night.

Historical trends in the fishery were determined from interviews with fishermen and
distributors. A copy of the questionnaire filled out by the interviewer is attached
(Appendix 1). Ten fishermen and 5 distributors (drivers) were interviewed during this
study. Interviews indicated little agreement among fishermen on trends in the fishery.
Most boats fish the same general areas as they did years ago, although some areas were
cited as having declined in recent years (most notably the Featherbed Bank area in
winter). The area south of Black Point was noted by a number of bait shrimp fishermen as
having declined recently. Water quality and/or fresh water discharge from Black Creek
and Gould's Canal is hypothesized by the fishermen as the cause.

Because the two commercially fished shrimp species in Biscayne Bay, Penaeus
duorarum and P. brasiliensis, are an annual crop and are almost certainly recruited from
adult populations originating elsewhere, it is doubtful that total catch will decline in
response to increased effort.

Fluctuations in annual mean CPUE probably largely reflect fluctuations in
recruitment to the bay which results from the variability of wind, current and other
environmental factors affecting larval transport and/or survival. The relatively stable
CPUE's from 1971-1983 must be considered in this context. Since 1971, the lowest mean
CPUE was only 10% less than the 13 year grand mean suggesting that there have been no
major recruitment failures during this period. It also suggests that there have been no
major perturbations to the system that were reflected in declining shrimp densities.

Percentage of bay bottom trawled by the bait shrimp fleet was estimated by
extrapolating information gleaned from a fisheries assessment program recently
completed (Berkeley, 1984). In this study, trawl sampling was conducted aboard the
University of Miami research vessel R/V Gale using roller-frame trawls differing only in
size from commercial bait shrimp gear. Trawls used in this study were 8 feet wide, while
the mean width of commercial shrimp trawls is 12.5 feet (3.8 m) (n = 10). The mean linear
distance traveled during trawling operations by R/V Gale in 5 minutes was 287.3 m. Thus,
if bait shrimp boats tow at this sa e speed, then, in 5 minutes towing, the mean area
covered = (287.3 m) (3.8 m) = 1100 m /5 min. net.



Catches were expressed per 5-minute tow for standardization. Actual towing time
varies between 15 and 40 minutes. Because two nets are fished simultaneously, a 5-
minute tow results in two 5-minute net tows.








The mean catch of shrimp per boat night (1982 and 1983 combined) calculated from
log book records was 5,702. The mean catch from 72 sampled commercial tows was 47.8
shrimp per net per 5 minutes. Thus,

5,702 shrimp/night = 119 5-min. net tows/night
48 shrimp/5 minutes


and area covered per boat per night =


(1100 m2/5 min. net) (119 5-min. net/night) =


130,900 m2


Mean number of boats fishing per night is approximately 18. Thus, area covered by
the entire fleet per night =


(130,900 m2/boat) (18 boats) =


2.36 km2 (0.91 sq. miles)


In one year, the area covered by all boats = 861.4 km2 (332.3 sq. nmles). The general
fishing area in which the vessels operate is approximately 207.4 km (80.1 sq. miles)
(Berkeley, 1984). Thus, 1.1% of the fishing area is trawled per day and on average, the
entire bottom is swept by trawlers about 4 times per year.

Although this project did not attempt to document directly the physical impact of
roller-frame trawls on the habitat, some inferences can be made. In one year, each m2 of
bay bottom within the present fishing area is trawled four times on average. If the gear
destroyed or uprooted sea grass or was otherwise destructive to the habitat, a decline in
the abundance of organisms, including shrimp, or a change in community structure might
be expected. Since no such decline in shrimp abundance was apparent, it appears that the
impact is not severe. Likewise, the results of several studies dating back from the mid-
1960's to the present (Roessler, 1964; Low, 1973; Sogard, 1982; Campos, 1985), show that
the species composition and patterns of spatial and seasonal abundance of fish in the Bay
have remained essentially unchanged. This does not mean that the impact is non-existent,
however. Some physical damage could certainly occur and not be detectable with CPUE
or species composition data. Certain communities could be severely impacted but go
undetected if they constituted a small fraction of the total bay bottom community.


Shrimp Landings and By-Catch of Juvenile Gamefish

Gamefish, as referred to in this study, includes species of recreational and/or
commercial importance and those used as baitfish. Data on shrimp and by-catch of
juvenile gamefish were collected during a previous 2-year (1982-83) study of the fisheries
of Biscayne Bay. In this study, an observer was placed aboard a commercial bait shrimp







vessel at least once per month for 2 years. Data was collected on shrimp catch, effort
(towing time), and by-catch from a representative sample of tows preserved and returned
to the laboratory for sorting, identification and measurement. All catches were then
standardized to number of a species per 5-minute tow.

Total annual catch of bait shrimp was calculated by multiplying the mean catch per
boat-night by total effort in boat-nights for the year. Total fleet size was estimated from
boat counts made during thrice-monthly aerial overflights of the Bay. Mean daily effort
in boat-nights was estimated from a series of evening boat counts (n = 59 counts) made at
the three commercial bait shrimp docks: Black Point, Dinner Key, and Virginia Key.
Counts were made after dark to insure that all boats fishing that night would be out. The
difference between total fleet count and number of boats in port after dark was used to
estimate number of boats actually fishing. The mean number of boats fishing per night
was 17.5. For one year (365 nights), this translates to a total effort of 6380 boat nights.
The estimated mean catch per boat-night during the years 1982-83 (log book information)
was 5702 shrimp. Thus, the total annual catch of bait shrimp from Biscayne Bay in 1983
was =
(5702 shrimp/boat-night) (6380 boat-nights) =
36,381,312 shrimp
at an average of 125 shrimp per pound, this equates to 291,050 lbs.

Catches of gamefish species per 5-minute tow were multiplied by the number of
tows in a typical boat-night (119; see previous section) to estimate catch per boat-night.
Mean catch per boat-night for each species was then calculated based on 72 samples
(24 months x 3 samples/mo.). Total annual catch for each species was calculated by
multiplying mean catch per boat-night by the total effort in boat-nights (6380). Catch by
species was also expressed as numbers caught per 1000 shrimp. Annual catch in weight
was estimated by multiplying mean individual weight for each species sampled by the
estimated total number caught.

Twenty-seven species of "gamefish" were recorded at least once in 72 sampled
commercial net tows (Table 2). Pinfish (Lagodon rhomboides) was the most abundant
species of fish in the by-catch. This species, while not of recreational or commercial
importance, is included in this table because it is commonly used as live bait. Two species
of grunts, white grunt (Haemulon plumieri) and bluestriped grunt (H. sciurus) were the
next most abundant species. Gray snapper (Lutjanus griseus) was the fourth most
abundant game fish species with 243,612 estimated caught annually. An estimated 45,997
juvenile spotted sea trout (Cynoscion nebulosus) were caught. From the previous Biscayne
Bay fisheries assessment study (Berkeley, 1984), it appeared that spotted sea trout are
most abundant in the shallowest inshore grassbeds. During the present study, the
locations fished by vessels on which sampling was performed showed that these inshore
grassbeds were overrepresented. Because of this, the estimated by-catch of species
abundant in these areas (e.g. spotted sea trout) may likewise be overrepresented.

Expressed relative to the shrimp catch, 131.1 pinfish, 16.1 white grunts, 11.4
bluestriped grunts, 6.7 gray snapper, and 1.3 spotted sea trout were caught per 1,000
shrimp. Summing the 24 species of fish and 3 species of crustaceans considered
recreationally important, a total of 6,350,104 individuals weighing an estimated 73,320 kg
(161,641 Ibs) were caught in 1983 by the bait shrimp fleet. If pinfish are excluded, then
19,237 kg (42,410 Ibs) of food and/or game species were caught. The gamefish by-catch,
excluding pinfish, is 14.6% of the shrimp catch by weight or 55.5% including pinfish.







Table 2. Recreationally and/or commercially important species caught by commercial
bait shrimp vessels in Biscayne Bay: Estimated annual catch by the entire fleet in
numbers and weight and mean number caught by entire fleet per 1,000 shrimp.


Estimated
annual catch
Species (numbers)


Estimated
annual catch
(weight in kg)


Haemulon plumieri, White grunt
Haemulon sciurus, Blue striped grunt
Haemulon parrai, Sailor's choice
Haemulon aurolineatum, Tomtate
Haemulon flavolineatum, French grunt
Haemulon spp; unident. grunts
Orthopristis chrysoptera, Pigfish
Lutjanus griseus, Gray Snapper
Lutjanus synagris, Lane snapper
Lutjanus analis, Mutton snapper
Lutjanus spp; unident. snappers
Ocyurus chrysurus, Yellowtail snapper
Diplectrum formosum, Sand perch
Epinephelus striatus, Nassau grouper
Mycteroperca microlepis, Gag grouper
Cynoscion nebulosus, Spotted sea trout
Lachnolaimus maximus, Hogfish
Paralichthys albigutta, Gulf flounder
Caranx bartholomaei, Yellow jack
Caranx ruber, Bar jack
Calamus arctifrons, Grass porgy
Calamus penna, Sheepshead porgy
Lagodon rhomboides, Pinfish
Panulirus argus, Spiny lobster
Menippe mercenaria, Stone crab
Callinectes sapidus, Blue crab


TOTAL


Penaeus spp., Bait shrimp


586,823
415,222
13,003
5,710
10,788
2,855
26,964
243,612
16,178
5,078
5,390
8,884
10,788
952
632
45,997
10,148
2,224
1,903
952
8,245
2,855
4,768,197
84,061
2,855
69,788

6,350,104

36,381,312


Number
caught
per 1,000
shrimp


4,324.9
4,372.3
84.3
31.6
79.0
47.6
1,898.8
2,241.2
175.1
37.6
76.1
102.2
339.9
24.5
66.7
468.7
325.3
165.7
9.9
3.7
185.5
7.0
54,083.0
2,688.2
15.3
1,466.3

73,320.4

132,020.5


16.13
11.41
0.36
0.16
0.30
0.08
0.74
6.70
0.44
0.14
0.15
0.24
0.30
0.03
0.02
1.26
0.28
0.06
0.05
0.03
0.23
0.08
131.06
2.31
0.08
1.92

174.54







The minimum, maximum, and mean size of the species caught by bait shrimp vessels
are presented in Table 3. Even the maximum sizes are generally well below the size
normally caught on hook and line. The largest specimen recorded was a 15 inch (38.0 cm)
gulf flounder, Paralichthys albigutta.

A high percentage of most species is returned to the water alive (Tabb and Kenny,
1969). Thus, estimates of numbers caught are considerably higher than the number killed.
The mortality due to capture and handling of species comprising the incidental catch is
not known, but is believed to vary considerably among species. Crustaceans (stone crab,
blue crab, lobster) appear to suffer little mortality from having been caught. A high
percentage of some fishes such as pinfish, flounder and gray snapper apparently survive.
However, the mortality rate for other species appears to be high. Yellowtail snapper, sea
trout and hogfish are among the more important recreational species in this category.
The significance of this source of mortality is not known.


Summary and Conclusions

The value of the Biscayne Bay bait shrimp fishery is considerable. In 1983 the
estimated total commercial bait shrimp harvest from the Bay was 36.4 million shrimp
worth $1.1 million at dock side* or approximately $3.0 million at retail.** The
availability of live bait for sale makes the existence of retail bait and tackle stores
possible and provides a valuable support service for the local tourist industry. However,
while the economic and social value of the fishery is undeniable, the possible detrimental
effects of the fishery on the biota or the environment are potentially of greater
consequence and must be considered in evaluating the future of the fishery.

Annual mean CPUE's from 1971-1983 have remained relatively stable, suggesting
that the fishery has not significantly affected the habitat's ability to function as a shrimp
nursery.

Species composition and community structure of juvenile fish in Biscayne Bay
appears to have remained unchanged since the mid 1960's. However, it does not follow
that effects of the bait shrimp fishing operations are non-existent. While natural
mortality is undoubtedly quite high among these small juvenile fishes, and the estimated
total catch of these species by the bait'shrimp fleet is relatively small, the effect of the
fishery on subsequent gamefish recruitment cannot be evaluated without knowing the
magnitude of fishing mortality relative to all other sources of natural mortality. In
addition to estimates of natural and fishing mortality, ecological information, such as
habitat and trophic interactions between juvenile fishes and shrimp, would be necessary to
evaluate and quantify the impact of this fishery on the fish populations in the Bay.









*Assuming an average ex-vessel price of $30 per 1,000.

**Assuming an average retail price of $1.00 per dozen.








The mean catch of shrimp per boat night (1982 and 1983 combined) calculated from
log book records was 5,702. The mean catch from 72 sampled commercial tows was 47.8
shrimp per net per 5 minutes. Thus,

5,702 shrimp/night = 119 5-min. net tows/night
48 shrimp/5 minutes


and area covered per boat per night =


(1100 m2/5 min. net) (119 5-min. net/night) =


130,900 m2


Mean number of boats fishing per night is approximately 18. Thus, area covered by
the entire fleet per night =


(130,900 m2/boat) (18 boats) =


2.36 km2 (0.91 sq. miles)


In one year, the area covered by all boats = 861.4 km2 (332.3 sq. nmles). The general
fishing area in which the vessels operate is approximately 207.4 km (80.1 sq. miles)
(Berkeley, 1984). Thus, 1.1% of the fishing area is trawled per day and on average, the
entire bottom is swept by trawlers about 4 times per year.

Although this project did not attempt to document directly the physical impact of
roller-frame trawls on the habitat, some inferences can be made. In one year, each m2 of
bay bottom within the present fishing area is trawled four times on average. If the gear
destroyed or uprooted sea grass or was otherwise destructive to the habitat, a decline in
the abundance of organisms, including shrimp, or a change in community structure might
be expected. Since no such decline in shrimp abundance was apparent, it appears that the
impact is not severe. Likewise, the results of several studies dating back from the mid-
1960's to the present (Roessler, 1964; Low, 1973; Sogard, 1982; Campos, 1985), show that
the species composition and patterns of spatial and seasonal abundance of fish in the Bay
have remained essentially unchanged. This does not mean that the impact is non-existent,
however. Some physical damage could certainly occur and not be detectable with CPUE
or species composition data. Certain communities could be severely impacted but go
undetected if they constituted a small fraction of the total bay bottom community.


Shrimp Landings and By-Catch of Juvenile Gamefish

Gamefish, as referred to in this study, includes species of recreational and/or
commercial importance and those used as baitfish. Data on shrimp and by-catch of
juvenile gamefish were collected during a previous 2-year (1982-83) study of the fisheries
of Biscayne Bay. In this study, an observer was placed aboard a commercial bait shrimp









Table 3. Recreational and/or commercial species caught
minimum-maximum sizes (fork length) recorded.


by commercial bait shrimp vessels in Biscayne Bay: mean and


Mean Size
in cm (in.)


Min/Max Size
in cm (in.)


Haemulon plumieri, White grunt
Haemulon sciurus, Blue striped grunt
Haemulon parrai, Sailor's choice
Haemulon aurolineatum, Tomtate
Haemulon flavolineatum, French grunt
Haemulon spp., unident. grunts
Orthopristis chrysoptera, Pigfish
Lutjanus griseus, Gray snapper
Lutjanus synagris, Lane snapper
Lutjanus analis, Mutton snapper
Lutjanus spp., unident. snappers
Ocyurus chrysurus, Yellowtail snapper
f Diplectrum formosum, Sand perch
Epinephelus striatus, Nassau grouper
Mycteroperca microlepis, Gag grouper
Cynoscion nebulosus, Spotted sea trout
Lachnolaimus maximus, Hogfish
Paralichthys albigutta, Gulf flounder
Caranx bartholomaei, Yellow jack
Caranx ruber, Bar jack
Calamus arctifrons, Grass porgy
Calamus penna, Sheepshead porgy
Lagodon rhomboides, Pinfish
Panulirus argus, Spiny lobster
Menippe mercenaria, Stone crab
Callinectes sapidus, Blue crab


* carapace length


--o-- only one specimen recorded


7.2
8.4
6.1
6.4
6.8
9.4
16.2
8.2
8.6
7.5
8.0
9.0
13.0
12.7
17.2
9.7
11.7
21.9
7.1
6.3
6.2
6.5
8.5
3.2
2.5
6.4


(2.8)
(3.3)
(2.4)
(2.5)
(2.7)
(3.7)
(6.4)
(3.2)
(3.4)
(2.9)
(3.2)
(3.5)
(5.1)
(5.0)
(6.8)
(3.8)
(4.6)
(8.6)
(2.8)
(2.5)
(2.4)
(2.6)
(3.4)
(1.3)*
(1.0)*
(2.5)*


3.7-18.0
3.1-19.2
2.7-12.1
3.3-10.5
4.7-14.5
8.2-10.2
4.0-22.5
3.2-19.4
5.6-16.7
5.9-9.3
4.6-12.2
6.5-12.2
7.0-17.5
----
--0-
5.1-20.0
4.4-14.2
13.3-38.0
--0--
------
2.9-12.3
-o--
2.7-17.5
1.0-6.0
2.2-2.8
3.3-14.3


(1.5-7.1)
(1.2-7.6)
(1.1-4.8)
(1.3-4.1)
(1.8-5.7)
(3.2-4.0)
(1.6-8.9)
(1.3-7.6)
(2.2-6.6)
(2.3-3.7)
(1.8-4.8)
(2.6-4.8)
(2.8-6.9)
--0--
-0-
(2.0-7.9)
(1.7-5.6)
(5.2-15.0)
0
(1.1-4.8)
-0-
...--o--...
(1.1-6.9)
(0.4-2.4)
(0.9-1.1)
(1.3-5.6)







The minimum, maximum, and mean size of the species caught by bait shrimp vessels
are presented in Table 3. Even the maximum sizes are generally well below the size
normally caught on hook and line. The largest specimen recorded was a 15 inch (38.0 cm)
gulf flounder, Paralichthys albigutta.

A high percentage of most species is returned to the water alive (Tabb and Kenny,
1969). Thus, estimates of numbers caught are considerably higher than the number killed.
The mortality due to capture and handling of species comprising the incidental catch is
not known, but is believed to vary considerably among species. Crustaceans (stone crab,
blue crab, lobster) appear to suffer little mortality from having been caught. A high
percentage of some fishes such as pinfish, flounder and gray snapper apparently survive.
However, the mortality rate for other species appears to be high. Yellowtail snapper, sea
trout and hogfish are among the more important recreational species in this category.
The significance of this source of mortality is not known.


Summary and Conclusions

The value of the Biscayne Bay bait shrimp fishery is considerable. In 1983 the
estimated total commercial bait shrimp harvest from the Bay was 36.4 million shrimp
worth $1.1 million at dock side* or approximately $3.0 million at retail.** The
availability of live bait for sale makes the existence of retail bait and tackle stores
possible and provides a valuable support service for the local tourist industry. However,
while the economic and social value of the fishery is undeniable, the possible detrimental
effects of the fishery on the biota or the environment are potentially of greater
consequence and must be considered in evaluating the future of the fishery.

Annual mean CPUE's from 1971-1983 have remained relatively stable, suggesting
that the fishery has not significantly affected the habitat's ability to function as a shrimp
nursery.

Species composition and community structure of juvenile fish in Biscayne Bay
appears to have remained unchanged since the mid 1960's. However, it does not follow
that effects of the bait shrimp fishing operations are non-existent. While natural
mortality is undoubtedly quite high among these small juvenile fishes, and the estimated
total catch of these species by the bait'shrimp fleet is relatively small, the effect of the
fishery on subsequent gamefish recruitment cannot be evaluated without knowing the
magnitude of fishing mortality relative to all other sources of natural mortality. In
addition to estimates of natural and fishing mortality, ecological information, such as
habitat and trophic interactions between juvenile fishes and shrimp, would be necessary to
evaluate and quantify the impact of this fishery on the fish populations in the Bay.









*Assuming an average ex-vessel price of $30 per 1,000.

**Assuming an average retail price of $1.00 per dozen.







Literature Cited

Berkeley, S.A. 1984. Fisheries assessment of Biscayne Bay. Final report to Dade County
Department of Environmental Resources Management.

Campos, W.L. 1985. Distribution patterns of juvenile epibenthic fish in South Biscayne
Bay, Florida. MS Thesis, RSMAS, Univ. Miami, 109 pp.

Low, R.A. 1973. Shoreline grassbed fishes in Biscayne Bay, Florida, with notes on the
availability of clupeid fishes. MS Thesis, RSMAS, Univ. Miami, 145 pp.

Roessler, M.A. 1964. A statistical analysis of fish populations taken by otter trawl in
Biscayne Bay, Florida. MS Thesis, RSMAS, Univ. Miami, 126 pp.

Siebenaler, 3.B. 1953. The Biscayne Bay commercial fishery. Fla. State Bd. of Conserv.
Marine Laboratory, U. of Miami. Technical series No. 6., 20 pp.

Sogard, S.M. 1982. Feeding ecology, population structure, and community relationships
of a grassbed fish, Callionymus pauciradiatus, in Southern Florida. MS thesis,
RSMAS, Univ. Miami, 103 pp.

Tabb, D.C. 1958. Report on the bait shrimp fishery of Biscayne Bay, Miami, Florida.
Fla. State Bd. of Conserv., Marine Laboratory, U. of Miami. 15 pp.

Tabb, D.C. 1961. A contribution to the biology of the spotted seatrout, Cynosicon
nebulosus (Cuvier), of east-central Florida. Fla. State Bd. of Conserv. Tech. Series
No. 35, 22 pp.

Tabb, D.C. and N. Kenny. 1969. A brief history of Florida's live bait shrimp fishery with
description of fishing gear and methods. Prac. World Scient. Conf. Biol. Cult. of
shrimps and prawns, FAO Fish. Rept. No. 57, vol. 3: 1119-1134.

Woodburn, K.D., B. Eldred, E. Clark, R.F. Hutton, R.M. Ingle. 1957. The live bait shrimp
industry of the west coast of Florida. Fla. State Bd. of Conserv. Marine
Laboratory. St. Petersburg, Fla. Technical Series No. 21. 33 pp.








Appendix I
Bait Shrimp Fishery Questionnnaire


1. Boat name, size nets.



2. Dock.



3. Log book available?



4. How many years fished bait shrimp in Biscayne Bay?



5. What general areas do you fish?



6. Is it seasonal?



7. Have these areas changed over the years? Do these change seasonally?



8. What is average catch-by season?



9. How many hours fished/night?



10. Has this changed over the years?



11. How many days/week, days/year do you fish-(seasonal)?



12. Do you fish outside Biscayne Bay?



13. If yes, more or less than previous years?
14. Disposition of the catch name of wholesaler or driver.







15. Price paid seasonally.


16. How has this changed?



17. Any other historical information -- long term trends in catch, effort, gear,
size of shrimp, etc.



Drivers or wholesalers

1. How many boats in Biscayne Bay do you buy shrimp from?



2. Do you have records we can see on number of shrimp handled?



3. How long have you been buying Biscayne Bay shrimp?



4. Where do you deliver to -- how much do you handle per week, per month, per
year?



5. How much is sold outside Dade County?



6. Historical trends in demand, price, % sold outside county, size, number, etc.




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