# NOAA Technical Memorandum NMFS

-SEFC

-238
REVIEWOFTHETORTUGAS PINK SHRIMP FISHERYFROMMAY 1987TOJANUARY 1989

GULF OFMEXICO

D2Y r02rUGAJI

IEYVE8r STRAITS OF FLORIDA



### OCTOBER 1989 GALVESTON LABORATORY SOUTHEAST FISHERIES CENTER NATIONAL MARINE FISHERIES SERVICE NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION DEPARTMENT OF COMMERCENOAA TECHNICAL MEMORANDUM SEFC-NMFS-238


# REVIEWOFTHETORTUGASPINK SHRIMPFISHERYFROMMAY 1987TOJANUARY 1989

BY


### JAMES M.NANCE ANDFRANKJ. PATELLA



### u.s. DEPARTMENT OF COMMERCE Robert Mosbacher, Secretary

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

JohnA.Knauss, Administrator

NATIONAL MARINE FISHER1ESSERVICE James E.Douglas,Jr.,ActingAssistant Administratorfor Fisheries

OCTOBER 1989

ThisTechnicalMemorandumseriesisusedfordocumentationandtimelycommunication ofpreliminaryresults,interimreports,orsimilarspecial-purposeinformation. Although thememorandaarenotsubjecttocompleteformalreview, editorialcontrol,ordetailed editing,theyareexpectedtoreflectsoundprofessionalwork.NOTICE:

The National Marine Fisheries Serice (NMFS) does notapprove, recommend orendorse anyproprietary ormaterial mentioned inthispublication. No reference shall bemadetoNMFS, ortothis publication furnished byNMFS, inanyadvertising orsales promotion which would indicate orimplythat NMFS approves, recommends, orendorses anyproprietary product orproprietary material mentioned herein orwhich hasasitspurpose anyintenttocause directly orindirectly theadvertised producttobeusedorpurchased because ofthis NMFS publication.

This reportshould becitedasfollows:


## Nance,JamesM.andFrankJ.Patella. 1989. Reviewof theTortugasPinkShrimpFisheryfromMay1987to January 1989. NOAATechnicalMemorandum NMFS-SEFC-238, 23p.

Copies maybeobtained bywriting:


### National Marine Fisheries Service Galveston Laboratory 4700Ave. U Galveston, TX 77551

or National Technical Information Service 5258 PortRoyal Road Springfield, VA 22161INTRODUCTION

The Gulf of Mexico Shrimp Fishery Management Plan established an area commonly known as the Tortugas Shrimp Sanctuary off south Florida inMay 1981 (Fig. 1). The goal of the Gulf of Mexico FisheryManagement Council in establishing this no shrimping zonewas 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 inFlorida (69tails 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 inthis area (Klimaand Patella, 1986). The recent opening (November 1988 through January 1989) allowed fishermen more access to a reduced pink shrimp stock (Nanceand Patella, 1988)•



# . This paper reviews the characteristics of the Tortugas fishery fromMay 1987 to January 1989 (biological year 1987 and part of 1988) and compares results with historical data. Deviations fromhistorical 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 inUnited 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 (Maythrough April) andused 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 1statistical tests utilized in the report are described indetail

byNance 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 (NanceandNichols, 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 landedhave fluctuated from ahigh of 13.4million pounds in 1960 to a low of 8.0million pounds in 1971. Yet, evenwith this 5.4million pound range, the fisheryhas remained relatively stable throughout this 21year period. The standard deviation around the historical mean was only ±1.69 million pounds, with avalue of 17% for the coefficient ofvariation. Only during biological years 1960, 1965 and 1971 have yearly landings fallen outside one standard deviation of themean (twovalues above themean 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 adecreasing trend in catch is visible from the late 1970's topresent. During biological year 1986 (May86-April 87), only 5.5million pounds of pink shrimp were landed from statistical subareas 1-3 (Fig. 2). This value represented the lowest catch recorded fromthe area andwas the first year that was significantly below the historical average (Nanceand 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 (May1987

- 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 6.5million pounds expected from the area. This value level, if it occurred, would be significantly below the historical average. Only actual landings fromMay 1988-January 1989 are available for analysis, but tentative figures fromFebruary 1989-April 1989 were gathered fromport agents inthe 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.

2The monthly pattern of shrimp landings inbiological years

1987 and 1988 were compared with historical monthly averages. This comparison documented adramatic decrease inpounds landed (Fig. 3). Even though all months except fourwere 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. Inbiological 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. Inbiological year 1988 the shrimp were late in arriving onto the fishing grounds andwhen they did arrive they were ingreatly reduced numbers. Fishing Effort Fishing effort bybiological year, May 1960 to April 1986, in statistical subareas 1 through 3has 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 ahigh of 22,000 days expended in 1960 to a low of only 11,000 days fished in 1979. Fishing effort reported forbiological 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 inbiological year 1987 and the first 9months 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 (poundsper day). The annual CPUE at the Tortugas fishing grounds has been avery stable parameter over the past 27 years. CPUE values have averaged about 604 pounds per daywith 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 31981 and the lowest CPUEwas 436 pounds per day, which occurred

during biological year 1986. The annual CPUE value during biological year 1987was below average at only 507 pounds per day. This value is one of the lowest CPUE values ever recorded fromthis fishery, but itwas not significantly different from the historical mean. Even though annual CPUEvalues for the past 27 years have not varied considerably (withthe exception of 1986), large variations have been noted inmonthly CPUE values (Nanceand Patella, 1987). Thus, a large standard deviation value is found around eachmonthly historical mean CPUE value. Monthly CPUE values forbiological year 1988were 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 themonthly CPUE values with the historical data, we also plotted a ratio of the present monthly CPUE values fromMay 1981 through January 1989 over the historical monthly CPUE values (Fig. 8). These values indicated for the 3months of greatest catch (December, January and February) that the biological year 1987 winter values (December 1987-February 1988) were very similar towinter values inbiological years 1982, 1983 and 1986, but were belowwinter values inbiological years 1981, 1984 and 1985. Biological year 1988winter values appear intermediate between the two data sets, with ahigh value in December, but a lowvalue inJanuary andprobably February. Biological year 1986 (May1986-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 forbiological year 1987 (May1987-April 1988), with only 3 months above the equality line. Biological year 1988 should be comparable to 1987 with 3 or lessmonths above the equality line. Recruitment Total pink shrimp recruitment (statistical subareas 1-9) has been quite stable over the past 27years, with amean value of 1.6 billion shrimp. Recruitment has ranged from ahigh of 2.5 billion shrimp experienced inbiological year 1980 to a low of 1.2 billion shrimp inbiological year 1986. The total pink Shrimp recruitment for the entire eastern Gulf during a given biological year ishighly correlated (0.93) to total eastern Gulf pink shrimp catch during the sameperiod. Regression analysis, with catch as the dependent variable and recruitment as the independent variable, gave an r-squared value of 0.86. Thus, as onewould expect, the amount of catch experienced fromthe eastern Gulf pink shrimp fishery inagiven year, is adirect 4result 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 ishigh, catch will be high. Recruitment of pink shrimp onto the Tortugas grounds usually occurs during two periods inabiological year. Fall recruitment ismeasured from July through December, with the peak of the season fromAugust through October. The spring season is measured fromJanuary through June, with peak recruitment usually fromMarch 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 ahigh 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 (1.16billion 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 (July87-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 (thetoe area) was opened to fishing for comparative purposes fromApril 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 ingreat 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 andAugust, 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 fromNovember 1988 through January 1989, but only smaller than average shrimp were caught during December 1988 (Fig. 10).

5DISCUSSION

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 abottom 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 frompreclosure biological years (1960-1980) were statistically compared tomean values frompost-closure biological years (1981-1987), there appears to be adeclining trend in catch from the Tortugas grounds since the late 1970's. The trend noted in landings from the Tortugas fishery isvery similar to landings from the west coast of Florida as awhole (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 onyoung 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 andwhen fall recruitment is low, annual catch isusually lower than average. Between 1980 and 1987, fall recruitment for the eastern Gulf showed adownward 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 inboth the fall and spring periods was below average. In 1987 recruitment was still depressed, but not 6to the extent itwas 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 amajor 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 inMay 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 fromApril 1983 through August 1984 and again fromNovember 1988 through January 1989 to evaluate the effects. A report by Klima and Patella (1986) showed an increase innumber of small shrimp caught during the entire initial period the "toe area" was opened. with the reclosure of the entire Sanctuary to shrimping activities inAugust 1984, size ratio values (averagemonthly size divided byhistorical 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 inJanuary 1987, smaller than average shrimp have been landed from the fishery even when the entire Sanctuary was closed. Itmust 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 inJuly 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 abrief 3month 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. 7eliminate 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, nomatter 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 itprevents 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 itmight have been because of the small size of the shrimp landed. It is not knownwhy these shrimpwere 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 inthe late 1970's.

8SUMMARY

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 catchhas been 9.6 million pounds per year with a standard deviation of ± 1.9million pounds per year. Yet, pink shrimp landings during biological year 1987 were only about 7.0 million pounds. It isprojected that landings will onlybe around 6.5million pounds during biological year 1988. This declining trend in catch seems to have begun in the late 1970's. 2. Fishing effort forpink 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 (poundsper 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 daywith a standard deviation of only ± 91pounds per day. However, the CPUE value forbiological year 1987 was only 507 pounds per day. This value is low, but not significantly different than the historical mean. Biological year 1988values 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 forbiological year 1986 and again for 1987 for the eastern Gulf of Mexico. It is this reduction inavailable shrimp that has reduced the catch from the Tortugas fishery. Yet, periods of low recruitment were also observed inthe late 1960's and early 1970's, so this present condition is not the first time low recruitment has been observed inthe fishery. 5. Larger than average shrimp were landed from the Tortugas grounds during the earlypart of biological year 1986 (May 1986-December 1986), but smaller than average shrimp have been taken formost 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 inbiological year 1988 did not increase CPUE and no real change was noted in size of shrimp taken from the grounds. 7. Themajor objectives of the Tortugas closure are to 1)
9eliminate 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 itprevents fishing on shrimp as theymigrate 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. Shrimpmortality 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 SouthAmerican shrimppopulations. 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 fromMay 1984 to December 1985. NOAA Tech. Memo., NMFS-SEFC-177. Nance, J. M. and S. Nichols. 1988. StockAssessments 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 fromMay 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 fromMay 1986 to December 1987. NOAA

Tech. Memo.,NMFS-SEFC-207.

11Table 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 41.0

- 33.0

- 43.0

- 45.4 + 

# GO.9 December 35.2

# - 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 

# GULFOFMEXICO

Figure1. MapoftheTortugas pinkshrimpsancturayoffthecoastofFlorida.

### 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

Figure2. Annual pinkshrimp landingsfromtheTortugas grounds forbiological

years 1960through 1987.

# MONTHLY CATCH 20 

### II HISTORICAL CATCH 

### f.d PRESENTCATCH



### 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

Figure3. Average monthly historical catchcompared tothecatchfrom May 1987through

January 1989taken ontheTortugas grounds.

### ANNUAL EFFORT 25
Cl UJ :r: 20 en



### -I..Len >- 15 

## « ClI..L0 10 en Cl 

### z 

## « en 5 :::> 0 :r:J

### o 

### o 1 2 3 456 7 8 901 2 3 456 789 0 1 2 3 4 5 6 7 1960 YEAR

Figure4. Pinkshrimpfishery effortontheTortugas grounds forbiological years

1960through 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

Figure5. Average monthly historical effortcompared tothemonthlyeffortsforMay1987

throughJanuary 1989fromtheTortugas 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

Figure6. Catch peruniteffort (CPUE)forbiological years 1960through 1987.1000

800 >- 

## « Cl 

### 0: 600 UJ a.. en Cl Z 400 ::> 

### o a..
200



### o 

# MONTHLY CPUE
11III HISTORICAL CPUE 

### EJ PRESENT CPUE



### M J J 

### A SON D J 

### F M A M J J 

### A SON D J

1987 

### MONTH 1988

Figure7. Average monthlyhistorical CPUEvaluescompared tothemonthlyCPUE

valuesforMay1987throughJanuary 1989fromtheTortugas grounds.

# CPUE RATIO ANALYSIS 3 MAY81 

# " 0 FISHING ALLOWED INTOEAREA



### - 

# /

~ ~ 

## -« a: 

## -' JAN 82 

## -« 2 

# / u



## - a: 0

~ (f)



### - :c .••....

~ Z w (f) w a: JAN 86 a. JAN 83 00 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 MONTHS

Figure8. RatiosofmonthlyCPUEfrom May1981 through January 1989compared with

monthly historical CPUEvalues (1960through 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
40.4 0.6 0.8 1.0 1.2 1.4 RECRUITMENT INBILLIONS OFSHRIMP

Figure9. Regression analysis ofeastern GulfofMexicofall recruitment estimates and

biological yearcatchfromtheTortugas fishing grounds.JAN85

JAN89

JAN86 

# SIZE RATIO ANALYSIS

k'" FISHING ALLOWED INTOE AREA 

## ":t. JAN88
-

JAN82 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. Ratioofmonthly mean numbers ofpinkshrimp perpoundfrom May1981

through January 1989tomonthly historical mean numbers ofpinkshrimp perpoundvalues (1960through 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 ofannual catchfrom Florida (subareas 1-9)and annual

catchfromtheTortugas grounds (subareas 1-3).

# FALL RECRUITMENT 1.4

1.2

~ 1.0 

### o -.J -.J In 0.8

0.6

0.460 65 70 YEAR 75 80 85 90

Figure 12. Estimates offallrecruitment ofpinkshrimpfromtheeastern GulfofMexico.