NOAA Technical Memorandum

NMFS - SEFC - 238

REVIEW OF THE TORTUGAS PINK

SHRIMP FISHERY FROM MAY

1987 TO JANUARY 1989

GULF OF MEXICO

D2Y r02rUGAJI

IEYVE8r STRAITS

OF

FLORIDA

OCTOBER 1989

GALVESTON LABORATORY

SOUTHEAST FISHERIES CENTER

NATIONAL MARINE FISHERIES SERVICE

NATIONAL OCEANIC AND ATMOSPHERIC

ADMINISTRATION

DEPARTMENT OF COMMERCE
NOAA TECHNICAL MEMORANDUM

SEFC-NMFS-238

REVIEW OF THE TORTUGAS PINK

SHRIMP FISHERY FROM MAY

1987 TO JANUARY 1989

BY

JAMES M.NANCE AND FRANK J. PATELLA

u.s. DEPARTMENT OF COMMERCE

Robert Mosbacher, Secretary

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

John A. Knauss, Administrator

NATIONAL MARINE FISHER1ES SERVICE

James E. Douglas, Jr., Acting Assistant Administrator for Fisheries

OCTOBER 1989

This Technical Memorandum series is used for documentation and timely communication

of preliminary results, interim reports, or similar special-purpose information. Although

the memoranda are not subject to complete formal review, editorial control, or detailed

editing, they are expected to reflect sound professional work.
NOTICE:

The National Marine Fisheries Serice (NMFS) does not approve, recommend

or endorse any proprietary or material mentioned in this publication. No

reference shall be made to NMFS, or to this publication furnished by NMFS,

in any advertising or sales promotion which would indicate or imply that NMFS

approves, recommends, or endorses any proprietary product or proprietary

material mentioned herein or which has as its purpose any intent to cause

directly or indirectly the advertised product to be used or purchased because

of this NMFS publication.

This report should be cited as follows:

Nance, James M. and Frank J. Patella. 1989. Review of

the Tortugas Pink Shrimp Fishery from May 1987 to

January 1989. NOAA Technical Memorandum

NMFS-SEFC-238, 23p.

Copies may be obtained by writing:

National Marine Fisheries Service

Galveston Laboratory

4700 Ave. U

Galveston, TX 77551

or

National Technical Information Service

5258 Port Royal Road

Springfield, VA 22161
INTRODUCTION

The Gulf of Mexico Shrimp Fishery Management Plan

established an area commonly known as the Tortugas Shrimp

Sanctuary off south Florida in May 1981 (Fig. 1). The goal of

the Gulf of Mexico Fishery Management Council in establishing

this no shrimping zone was to avoid the removal of small shrimp,

with the objective of increasing yield from the fishery. This

decision was based on scientific evidence that showed the

Sanctuary area to be the nursery ground for the Tortugas stock of

the pink shrimp Penaeus duorarum, and that the yield of offshore

pink shrimp would be greater if harvest was delayed until shrimp

were larger than minimum legal size in Florida (69 tails per

pound) (Linder, 1965; Berry, 1970). since May 1981, the whole

Sanctuary has been closed to trawling, with the exception of a

small region locally known as the "toe area", which has been

reopened during two brief periods. The purpose of the initial

opening (April 1983 through August 1984) was to evaluate the

effects of trawling in this area (Klima and Patella, 1986). The

recent opening (November 1988 through January 1989) allowed

fishermen more access to a reduced pink shrimp stock (Nance and

Patella, 1988) •

.

This paper reviews the characteristics of the Tortugas

fishery from May 1987 to January 1989 (biological year 1987 and

part of 1988) and compares results with historical data.

Deviations from historical averages are discussed in light of the

established sanctuary. Current trends with regards to the

.Tortugas fishery also are discussed.

METHODS

Fishery Data statistics

Collections of detailed catch statistics describing the Gulf

of Mexico shrimp fishery in United States waters since 1956 are

compiled by and available from the Southeast Fisheries Center

(SEFC/Office of Economics and Statistics-ESO). The procedures

used to collect them have been described by Klima (1980). These

statistics consist of catch, recorded as pounds of shrimp (headoff); fishing effort, recorded as either 24 hours of actual

fishing time or number of trips; and size composition of catch,

expressed in eight "count" or size categories representing number

of shrimp tails per pound «15, 15-20, 21-25, 26-30, 31-40, 41-

50, 51-67 and ~68).

These statistics were grouped and analyzed by biological

year (May through April) and used in this report to determine the

effects of the Tortugas Shrimp Sanctuary on the fishery. These

statistics were also used to calculate other useful values such

as catch per unit effort (CPUE), expressed as pounds per 24 hours

of actual fishing, and average number of shrimp per pound. All

1
statistical tests utilized in the report are described in detail

by Nance et ale (1986).

Pink shrimp recruitment from 1960-1988 for the entire

eastern Gulf of Mexico (statistical subareas 1-9) was estimated

using VPA analysis (Nance and Nichols, 1988).

RESULTS

Landinqs

Annual landings during pre-closure biological years (1960-

1980) in statistical subareas 1 through 3, have averaged

approximately 9.98 million pounds (Fig. 2). Pounds landed have

fluctuated from a high of 13.4 million pounds in 1960 to a low of

8.0 million pounds in 1971. Yet, even with this 5.4 million

pound range, the fishery has remained relatively stable

throughout this 21 year period. The standard deviation around

the historical mean was only ±1.69 million pounds, with a value

of 17% for the coefficient of variation. Only during biological

years 1960, 1965 and 1971 have yearly landings fallen outside one

standard deviation of the mean (two values above the mean and one

value below) •

The annual landings for the post-closure period (1981-1987)

have averaged 8.06 million pounds, with a standard deviation of

±1.95 million pounds. No significant difference was

statistically determined to exist between the pre-closure and

post-closure periods, even though a decreasing trend in catch is

visible from the late 1970's to present. During biological year

1986 (May 86-April 87), only 5.5 million pounds of pink shrimp

were landed from statistical subareas 1-3 (Fig. 2). This value

represented the lowest catch recorded from the area and was the

first year that was significantly below the historical average

(Nance and Patella, 1988).

Pink shrimp landings during biological year 1987 are also

low in comparison to the historical average and all years since

1960, with the exception of 1986. Landings for 1987 (May 1987 -

April 1988) were around 7.0 million pounds. This value is low,

but is not significantly below the historical average.

Estimates of pink shrimp landings during biological year

1988 are low, with only 6.0 to 6.5 million pounds expected from

the area. This value level, if it occurred, would be

significantly below the historical average. Only actual landings

from May 1988-January 1989 are available for analysis, but

tentative figures from February 1989-April 1989 were gathered

from port agents in the area. Only landings were estimated, so

statistics such as effort, CPUE, and size composition will only

be reported for the first nine months of biological year 1988.

2
The monthly pattern of shrimp landings in biological years

1987 and 1988 were compared with historical monthly averages.

This comparison documented a dramatic decrease in pounds landed

(Fig. 3). Even though all months except four were below average,

only two months were significantly below their respective

historical average. The significantly below average months

occurred in the early winter months (October-November) in

biological year 1988. In biological year 1987 the shrimp seemed

to be present on the grounds in the early winter, but at a level

that was quickly reduced by fishing. In biological year 1988 the

shrimp were late in arriving onto the fishing grounds and when

they did arrive they were in greatly reduced numbers.

Fishing Effort

Fishing effort by biological year, May 1960 to April 1986,

in statistical subareas 1 through 3 has averaged 15,900 days per

year with a standard deviation of ±2,400 days per year (Fig. 4).

The coefficient of variation was 15%. The small standard

deviation and low coefficient of variation are good indicators of

the stability of this fishery. Even so, effort has fluctuated

from a high of 22,000 days expended in 1960 to a low of only

11,000 days fished in 1979.

Fishing effort reported for biological year 1987 was around

13,900 days, which is below average, but still within one

standard deviation of the historical mean. Only four years,

1976, 1979, 1981 and 1985 have been below the one standard

deviation from the mean level.

The monthly pattern of fishing effort in biological year

1987 and the first 9 months of biological year 1988 were compared

with historical monthly averages (Fig. 5). Below average fishing

effort values were noted during most of the months of biological

years 1987 and 1988. Only the fall months of biological year

1987 (August-October) and June in 1988 had above average effort

value. No values were significantly different than their

historical counterpart. Effort data is not yet available for the

February 1989-Apri1 1989 period, but since reported catches were

below average during this periOd it is also assumed that effort

levels dropped below their historical values.

Catch per unit Effort

Catch per unit effort (CPUE), is reported as pounds caught

during a 24 hour fishing day (pounds per day). The annual

CPUE at the Tortugas fishing grounds has been a very stable

parameter over the past 27 years. CPUE values have averaged

about 604 pounds per day with a standard deviation of around 91

pounds per day (Fig. 7). This has resulted in a coefficient of

variation value of only 15%. The highest historical CPUE

recorded was close to 800 pounds per day during biological year

3
1981 and the lowest CPUE was 436 pounds per day, which occurred

during biological year 1986. The annual CPUE value during

biological year 1987 was below average at only 507 pounds per

day. This value is one of the lowest CPUE values ever recorded

from this fishery, but it was not significantly different from

the historical mean.

Even though annual CPUE values for the past 27 years have

not varied considerably (with the exception of 1986), large

variations have been noted in monthly CPUE values (Nance and

Patella, 1987). Thus, a large standard deviation value is found

around each monthly historical mean CPUE value. Monthly CPUE

values for biological year 1988 were each compared with their

respective monthly historical mean value (Fig. 7). All months,

except June 1987, May 1988, June 1988 and December 1988 had below

average CPUE values when compared with their historical average.

This was expected, since landings were below average during the

period, while effort levels were near historical levels.

In comparing the monthly CPUE values with the historical

data, we also plotted a ratio of the present monthly CPUE values

from May 1981 through January 1989 over the historical monthly

CPUE values (Fig. 8). These values indicated for the 3 months of

greatest catch (December, January and February) that the

biological year 1987 winter values (December 1987-February 1988)

were very similar to winter values in biological years 1982, 1983

and 1986, but were below winter values in biological years 1981,

1984 and 1985. Biological year 1988 winter values appear

intermediate between the two data sets, with a high value in

December, but a low value in January and probably February.

Biological year 1986 (May 1986-April 1987) was set apart

from all other years by the fact that all months, except one,

were below the equality line (Fig. 8). Similar results were seen

for biological year 1987 (May 1987-April 1988), with only 3

months above the equality line. Biological year 1988 should be

comparable to 1987 with 3 or less months above the equality line.

Recruitment

Total pink shrimp recruitment (statistical subareas 1-9) has

been quite stable over the past 27 years, with a mean value of

1.6 billion shrimp. Recruitment has ranged from a high of 2.5

billion shrimp experienced in biological year 1980 to a low of

1.2 billion shrimp in biological year 1986. The total pink

Shrimp recruitment for the entire eastern Gulf during a given

biological year is highly correlated (0.93) to total eastern Gulf

pink shrimp catch during the same period. Regression analysis,

with catch as the dependent variable and recruitment as the

independent variable, gave an r-squared value of 0.86. Thus, as

one would expect, the amount of catch experienced from the

eastern Gulf pink shrimp fishery in a given year, is a direct

4
result of the strength of the eastern Gulf recruitment of pink

shrimp during the same period. If recruitment is low, catch will

be low. If recruitment is high, catch will be high.

Recruitment of pink shrimp onto the Tortugas grounds usually

occurs during two periods in a biological year. Fall recruitment

is measured from July through December, with the peak of the

season from August through October. The spring season is

measured from January through June, with peak recruitment usually

from March through May. Fall recruitment for the entire eastern

Gulf has averaged 820 million shrimp since 1960, while spring

recruitment has average 790 million shrimp. Both periods have

experienced below average recruitment since the spring of 1986.

Pink shrimp catch on the Tortugas grounds for a given

biological year has a high correlation to fall season recruitment

(0.72), but a low correlation to eastern Gulf spring season

recruitment (0.21). Regression analysis conducted with Tortugas

catch and eastern Gulf fall recruitment gave a r-squared value of

0.59 (Fig. 9).

Biological year 1986 had both the lowest total recruitment

(1.16 billion shrimp) and the lowest fall recruitment (.520

billion shrimp) on record for the eastern Gulf. Thus, it is not

surprising that this year also had the lowest annual Tortugas

catch ever recorded. Fall recruitment for the eastern Gulf

during biological year 1987 (July 87-December 1987) was only .640

billion shrimp.

size

The size of shrimp landed may be used to identify change

that may have occurred due to fishing. If the management measure

of prohibiting trawling in the sanctuary was effective and

restricted the capture of small shrimp, one would expect the size

of shrimp to increase and therefore be different than the

historical average. Many small shrimp were caught when part of

the Tortugas Sanctuary (the toe area) was opened to fishing for

comparative purposes from April 1983 through August 1984, (Table

1). Once this area was closed again, mean number of shrimp per

pound decreased abruptly. Thus, small shrimp (50-60 count) were

caught in great abundance during that open period, while larger

sized shrimp (35-45 count) were caught thereafter with the

exception of the 1987 season (Fig. 10). During the entire

calendar year of 1987, except July and August, smaller than

average shrimp were landed from the fishery. This trend

continued into the 1988 season, but larger shrimp began to be

caught after the July 1988 period. The "toe area" was opened

this last season from November 1988 through January 1989, but

only smaller than average shrimp were caught during December 1988

(Fig. 10).

5
DISCUSSION

In general the Tortugas fishery has been quite stable over

the last 28 year period (1960-1987). Evaluation of annual

historical data showed very low coefficient of variation values

for landings (17%), fishing effort (15%), and CPUE (15%). The

shrimping grounds are bounded by a bottom of loggerhead sponges

and coral reefs where pink shrimp are protected from trawling.

This area of untrawa1b1e bottom surrounding the fishing grounds

may be one reason why this fishery has been so stable since 1960.

Even with this noted stability a reduction in catch and CPUE

has been graphically noticed since the late 1970's with the

exclusion of 1980, 1984 and 1985 (Fig. 2). Biological year 1986

was the lowest year on record. Biological year 1987 was also

below average, but was better than 1986. Even thoguh no

significant differences were found when mean values from preclosure biological years (1960-1980) were statistically compared

to mean values from post-closure biological years (1981-1987),

there appears to be a declining trend in catch from the Tortugas

grounds since the late 1970's. The trend noted in landings from

the Tortugas fishery is very similar to landings from the west

coast of Florida as a whole (Fig. 11).

During biological year 1987, all fishery indices (pounds

landed, effort and CPUE) were below their respective historical

averages. Pounds of shrimp were only 7.0 million pounds, with a

fishing effort value of about 13,900 days. This computed to an

extremely low CPUE vale of only 507 pounds per fishing day. None

of the values were significantly different than their historical

averages.

The offshore pink shrimp fishery discussed thus far is

directly dependent on young shrimp migrating in large numbers

from nursery areas onto the fishing grounds. If these small

shrimp are caught early, maximum yield in the fishery is not

attained (Nance and Nichols, 1988). Yet, if recruitment is

depressed, landings will also be depressed, since the Sanctuary

can_only maximize the yield of the shrimp that are available to

the fishery. Of the two recruitment intervals, the fall

recruitment period seems to be the one that is best correlated to

annual catch on the Tortugas grounds. When eastern Gulf fall

recruitment is above average, annual Tortugas catch is also

usually above average and when fall recruitment is low, annual

catch is usually lower than average. Between 1980 and 1987, fall

recruitment for the eastern Gulf showed a downward slope with the

exceptions of 1984 and 1985 (Nance and Patella, 1988). Thus, the

lower than average landings on the Tortugas grounds during most

of that eight year period seem to be related to a failure of

recruitment of pink shrimp from nursery areas. In 1986 the

eastern Gulf recruitment in both the fall and spring periods was

below average. In 1987 recruitment was still depressed, but not

6
to the extent it was during the 1986 biological year. Periods of

low recruitment were also observed in the late 1960's and early

1970's (Fig. 12). Thus, this present condition is not the first

time low recruitment has been observed in the fishery.

In some fisheries, recruitment over-fishing is a major cause

of the reduced recruitment condition. Yet, there was no apparent

established link between pink shrimp parent stocks and

recruitment in the stock assessment analysis (Nance and Nichols,

1988). Thus, recruitment over-fishing does not appear to be a

likely candidate for the cause of the drop in recruitment.

The permanent closure of the Tortugas Sanctuary was

established in May 1981 to prevent the capture of small shrimp.

As stated earlier, the whole sanctuary has been closed to

trawling since that time, with two exceptions. The "toe area"

was opened to trawling from April 1983 through August 1984 and

again from November 1988 through January 1989 to evaluate the

effects. A report by Klima and Patella (1986) showed an increase

in number of small shrimp caught during the entire initial period

the "toe area" was opened. with the reclosure of the entire

Sanctuary to shrimping activities in August 1984, size ratio

values (average monthly size divided by historical monthly size)

again decreased. During the first opened period, small shrimp

being recruited to the offshore fishery were rapidly harvested

when the "toe area" was opened, but small shrimp were able to

increase in size and then enter the fishery when the "toe area"

was closed (Table 1).

Beginning in January 1987, smaller than average shrimp have

been landed from the fishery even when the entire Sanctuary was

closed. It must be assumed that these smaller than average sized

shrimp were obtained from the fishing grounds and not from

vessels fishing inside the Sanctuary, since violations in the

closed area were at viry low levels during the 1987 season (NMFS

Enforcement Division) • Shrimp distribution patterns may have

shifted during 1987 in response to environmental changes (e.g.,

reduced rainfall, higher water temperature, hurricane Floyd,

etc.), but we have no data to support this theory.

Smaller than average sized shrimp continued to be caught

into the 1988 season, but the trend shifted in July 1988 when

larger than average shrimp again appear to be more abundant on

the fishing grounds. Even when the toe area was again opened to

fishing for a brief 3 month period, smaller than average shrimp

were caught only ~n December 1988.

The major objectives of the Tortugas Sanctuary are to 1)

1personal communication, Southeast Regional Office, Law

Enforcement Group, 9450 Koger Blvd., st. Petersburg, FL 33702.

7
eliminate discarding of undersized shrimp, and 2) increase the

yield per recruit. We have no data to support or reject

discarding of undersized shrimp. Since catch rates were so low

this year, it is assumed that most shrimp caught, no matter the

size, were landed. This may account for the increase in smaller

than average sized shrimp being landed during the 1987 season.

Yield per recruit was enhanced with the presence of the

Tortugas Sanctuary, since it prevents fishing on shrimp as they

migrate from the nursery areas to the offshore fishing grounds.

Yet, yield obtained for each recruit during biological year 1987

was lower than it might have been because of the small size of

the shrimp landed. It is not known why these shrimp were

available on the grounds in 1987, but the trend seems to have

shifted back to normal after July 1988. This deClining trend in

catch seems to have begun in the late 1970's.

8
SUMMARY

1. Commercial pink shrimp landings from the Tortugas fishery

(statistical subareas 1 through 3) have been relatively

stable for the past 27 years (1960-1986). Average catch has

been 9.6 million pounds per year with a standard deviation

of ± 1.9 million pounds per year. Yet, pink shrimp landings

during biological year 1987 were only about 7.0 million

pounds. It is projected that landings will only be around

6.5 million pounds during biological year 1988. This

declining trend in catch seems to have begun in the late

1970's.

2. Fishing effort for pink shrimp on the Tortugas grounds have

averaged 15,900 days annually for the past 27 years with a

standard deviation of ±2400 days. During biological year

1987, 13,900 days of fishing were expended on the Tortugas

fishery. This to below the historical average, but not

significantly different.

3. CPUE (pounds per day fishing) has been the most stable

parameter over the 27 year period, from 1960-1986, at the

Tortugas fishing area. The historical average has been

around 604 pounds per day with a standard deviation of only

± 91 pounds per day. However, the CPUE value for biological

year 1987 was only 507 pounds per day. This value is low,

but not significantly different than the historical mean.

Biological year 1988 values also appear below the historical

average for the area.

4. Recruitment of small pink shrimp from the nursery areas onto

the grounds was very low for biological year 1986 and again

for 1987 for the eastern Gulf of Mexico. It is this

reduction in available shrimp that has reduced the catch

from the Tortugas fishery. Yet, periods of low recruitment

were also observed in the late 1960's and early 1970's, so

this present condition is not the first time low recruitment

has been observed in the fishery.

5. Larger than average shrimp were landed from the Tortugas

grounds during the early part of biological year 1986 (May

1986-December 1986), but smaller than average shrimp have

been taken for most months since January 1987. This trend

continued until July 1988 when larger than average shrimp

again began to be taken from the fishing grounds.

6. The opening of the toe area to fishing for the three month

period in biological year 1988 did not increase CPUE and no

real change was noted in size of shrimp taken from the

grounds.

7. The major objectives of the Tortugas closure are to 1)

9
eliminate discarding of undersized shrimp, and 2) increase

the yield per recruit. We have no data to support or reject

discarding of undersized shrimp. Since catch rates are low

this year, it is assumed that most shrimp caught, no matter

the size, were landed this year. This may account for the

increase in smaller than average sized shrimp being landed

this past year (January 1987-present).

Yield per recruit was enhanced with the presence of the

Tortugas Sanctuary, since it prevents fishing on shrimp as

they migrate from the nursery areas to the offshore fishing

grounds. Yet, yield obtained for each recruit during the

1987 season was certainly lower because of the small size of

the shrimp landed. It is not known why these shrimp were

available on the grounds in 1987, but the trend seems to

have shifted back to normal after July 1988.

10
•

LITERATURE CITED

Berry, R. J. 1970. Shrimp mortality rates derived from fishery

statistics. In: Proc. Gulf Carib. Fish. Inst., 22:66-78.

Klima, E. F. 1980. Catch statistics - data needs of the

southwestern South American shrimp populations. Western

Central Atlantic Fishery Commission Rep. 28:123-130.

Klima, E.

synopsis

Klima, E.

Tortugas

F., G. A. Matthews and F. J. Patella. 1986. A

of the Tortugas Pink Shrimp Fishery, 1960-1983, and the

impact of the Tortugas sanctuary. N. Amer. J. Fish.

Mgt. 6:301-310.

F. and F. J. Patella. 1986. A synopsis of the

Pink Shrimp, Penaeus duorarum, Fishery, 1981-84, and

the impact of the Tortugas Sanctuary. Mar. Fish. Rev.

47:11-18.

Linder, M. J. 1965. What we know about shrimp size and the

Tortugas fishery. Proc. Gulf. Craib. Fish. Inst. 18:18-25.

Nance, J. M., E. F. Klima and F. J. Patella. 1986. Review of

the Tortugas Pink Shrimp Fishery from May 1984 to December 1985.

NOAA Tech. Memo., NMFS-SEFC-177.

Nance, J. M. and S. Nichols. 1988. Stock Assessments for Brown,

White and Pink Shrimp in the u.S. Gulf of Mexico, 1960-1986.

NOAA Technical Memorandum, NMFS-SEFC-203.

Nance, J. M. and F. J. Patella. 1987. Review of the Tortugas

Pink Shrimp Fishery from May 1985 to December 1986. NOAA

Tech. Memo., NMFS-SEFC-198.

Nance, J. M. and F. J. Patella. 1988. Review of the Tortugas

Pink Shrimp Fishery from May 1986 to December 1987. NOAA

Tech. Memo.,NMFS-SEFC-207.

11
Table 1. Monthly average weighted number of pink shrimp per pound for

1960- 79, 1981, 1982, 1983, 1984, 1985, 1987, and 1988 (+

indicates larger size group and - indicates smaller size

group than historical average: bracketed portion indicate

open fishing in toe of the boot).

1960-1979 1981 1982 1983

Average Standard Average Average Average

Months Number/1b Deviation Number/1b Number/1b Number/1b

May 46.8 5.1 57.4 + 48.4 + 56.8 +

June 45.2 4.5 52.7 + 45.7 + 50.2 +

July 44.0 4.7 44.2 + 36.6 - 58.0 +

August 44.0 7.7 38.9 - 55.0 + 49.6 +

September 48.7 7.9 47.5 - 49.0 + 44.2 -

October 47.9 4.8 41.4 - 43.3 - 44.0 -

November 43.1 3.3 36.4 - 41.3 - 36.6 -

December 40.2 2.8 34.9 - 39.3 - 36.1 -

January 40.2 3.1 35.6 - 43.6 + 49.4 +

February 42.7 3.1 42.1 - 48.0 + 48.1 +

March 47.5 4.4 46.8 - 57.5 + 58.7 +

April 48.3 5.8 49.8 + 154.1 +1 60.5 +

1984 1985 1986 1987 1988

Average Average Average Average Average

Months Number/1b Number/1b Number/1b Number/1b Number/1b

May ~5'9

~

42.4 - 38.9 - 49.4 + 54.5 +

June 53.1 42.1 - 45.3 + 56.8 + 49.4 +

July 55.0 42.1 - 42.0 - 43.1 - 43.8 -

August 46.9 33.5 - 39.4 - 40.1 - 33.6 -

September 36.9 - 55.3 + 40.2 - 51.2 + 32.6 -

October 45.8 - 45.9 - 38.9 - 54.4 + 35.8

D

November

December

41.0

35.2

- 33.0 - 43.0 - 45.4 + GO.9 - 35.6 - 39.0 - 41.8 + 44.2

January 38.0 - 37.3 - 42.9 + 52.6 + '37.9

February 39.8 - 40.1 - 46.3 + 51.6 +

March 40.5 - 51.1 + 54.5 + 54.8 +

April 44.2 - 48.4 + 55.6 + 53.8 +
STRAITS

OF

FLORIDA

EEYVEST

DRY TORTUGAS

GULF OF MEXICO

Figure 1. Map of the Tortugas pink shrimp sancturay off the coast of Florida.
ANNUAL CATCH

15

(/)

0

z

::> 10

0

a.

lJ...

a

(/)

z

a 5

-I

-I.

L

o

o 1 2 3 4 5 6 7 890 1 2 3 4 5 6 7 890 1 2 3 4 5 6 7

1960 YEAR

Figure 2. Annual pink shrimp landings from the Tortugas grounds for biological

years 1960 through 1987.
MONTHLY CATCH

20

II HISTORICAL CATCH

f.d PRESENT CATCH

o

o

o..

o

o

x 10

(f)

o

Z

:J

o

a.

o

M J J A SON D J F M A M J J A SON D J

1987 MONTH 1988

Figure 3. Average monthly historical catch compared to the catch from May 1987 through

January 1989 taken on the Tortugas grounds.
ANNUAL EFFORT

25

Cl

UJ

:r: 20 en

-

I..Len

>- 15 «

Cl

I..L0

10 en

Cl

z

«

en 5

:::>

0

:r:

Jo

o 1 2 3 456 7 8 901 2 3 456 789 0 1 2 3 4 5 6 7

1960 YEAR

Figure 4. Pink shrimp fishery effort on the Tortugas grounds for biological years

1960 through 1987.
30

o

I..LJ

:r:

(f)

u. 20

(f)

>

-«

o

u.

o

(f)

~ 10

a:

o

z

::>

:r:

o

MONTHLY EFFORT

II HISTORICAL EFFORT

o PRESENT EFFORT

M J J A SON D J F M A M J J A SON D J

1987 MONTH 1988

Figure 5. Average monthly historical effort compared to the monthly efforts for May 1987

through January 1989 from the Tortugas grounds.
400

200

ANNUAL CPUE

800

>-

-< 600 o

a:

UJ

a.

(/)

o

z

::>

o

a.

o

o 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 45 67

1960 YEAR

Figure 6. Catch per unit effort (CPUE) for biological years 1960 through 1987.
1000

800

>-

«

Cl

0: 600

UJ

a..

en

Cl

Z 400 ::>

o

a..

200

o

MONTHLY CPUE

11III HI STOR ICAL CPUE

EJ PRESENT CPUE

M J J A SON D J F M A M J J A SON D J

1987 MONTH 1988

Figure 7. Average monthly historical CPUE values compared to the monthly CPUE

values for May 1987 through January 1989 from the Tortugas grounds.
CPUE RATIO ANALYSIS

3 MAY 81

"

0

FISHING ALLOWED IN TOE AREA

-

/ ~

~

-«

a:

-'

JAN 82 -« 2

/

u

-

a:

0

~

(f)

-

:c

.••....

~

Z

w

(f)

w

a: JAN 86

a.

JAN 83

0

0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96

MONTHS

Figure 8. Ratios of monthly CPUE from May 1981 through January 1989 compared with

monthly historical CPUE values (1960 through 1979).
FALL RECRUITMENT VS CATCH

14

•

• •

(/) 12

0

Z

:::>

a

0-

I..L. 10 • •

a

(/)

•

z

a • • -.-J

•

8

.-J •

L

z y = 2.9265 + 7.9990x RI\2 = 0.592

:r:

u 6

~

« •

u

4

0.4 0.6 0.8 1.0 1.2 1.4

RECRUITMENT IN BILLIONS OF SHRIMP

Figure 9. Regression analysis of eastern Gulf of Mexico fall recruitment estimates and

biological year catch from the Tortugas fishing grounds.
JAN 85

JAN 89

JAN 86

SIZE RATIO ANALYSIS

k'" FISHING ALLOWED IN TOE AREA ":t.

JAN88 -

JAN 82

1.4

o

I--

-«

a: 1.2

....J

-«

u

a:

o

I-- 1.0

(/)

I

"

I--

Z

~ 0.8

w

a:

a.

0.6

o 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96

MONTHS

Figure 10. Ratio of monthly mean numbers of pink shrimp per pound from May 1981

through January 1989 to monthly historical mean numbers of pink shrimp

per pound values (1960 through 1979).
PINK SHRIMP CATCH

20

en

£:)

z

~

0

0-

I.J.. 10

0

en

z

0

-'-'

:r:

o

11II FLORIDA

l?J TORTUGAS

80 81 82 83 84 85 86 87 88

CALENDAR YEAR

Figure 11. Comparison of annual catch from Florida (subareas 1-9) and annual

catch from the Tortugas grounds (subareas 1-3).
FALL RECRU ITMENT

1.4

1.2

~ 1.0

o

-.J

-.J

In 0.8

0.6

0.4

60 65 70

YEAR

75 80 85 90

Figure 12. Estimates of fall recruitment of pink shrimp from the eastern Gulf of Mexico.