### Tampa Bay National Estuary Program Technical Publication#05-92



# DISTRIBUTION

# OF SELECTED FISH SPECIES INTAMPA BAY

FINAL REPORT

MAY 1992#05-92



### DISTRIBUTION 

### OFSELECTED FISH 

### SPECIES IN

### TAMPA BAY

Prepared for:
Tampa Bay National Estuary Program 111 7th Ave. South St. Petersburg, FL 33701

Prepared by: Coastal Environmental Services, Inc. 1099 Winterson Rd., Suite 130 Linthicum, MD 21090

Final Report

May 1992

Printed on Recycled PaperFOREWORD This report dated May 

### 1992 and titled "Distributionof Selected Fish Species in Tampa Bay" was prepared by Coastal Environmental Services, Inc. for the Tampa Bay National Estuary Program. All work was prepared under a contract entered into on 

### 16 September 

### 1991 by and betweenTampa Bay Regional Planning Council on behalf ofTampa Bay National Estuary Program and Coastal Environmental Services, Inc. The final products of the project reflect adjustments tothe original scope of workthat were required by the availability of data and time and effort considerations. These adjustments have been made 

### in consultation with the Tampa Bay National Estuary Program, and are described 

### in a detailed work plan submitted on 

### 21 September 

### 1991, and in a revisiontothe work plan submitted on 

### 17 January 

### 1992. This isTechnical Publication

### #05-92 of the Tampa Bay National Estuary Program.

IACKNOWLEDGEMENTS This project has benefitted from the work of many people, and particularlyfrom the willingness of researchers and data managers in the Tampa Bay area to share information ontheir studies. In particular: Dick Eckenrod and Holly Greening of the Tampa Bay National Estuary Program provided excellent advice, guidance, and assistance throughout the project. Bob McMichael and Tim MacDonald of the Marine Research Institute provided data and extensive background information for the Fisheries
-Independent Monitoring Program, while Ken Haddad provided advice and referrals. Thomas 

### Lo of SWFWMD provided the GIS shoreline and hydrographic data we used in generating GIS maps.

ii This report was written by Sara Cairns of Coastal, based on work performed bythe author and Bob Berardo, Peggy Derrick, Doug Heimbuch, Tony Janicki, Susan Janicki, John Seibel, and Dave Wade. Special thanks to those whose contributions went above and beyond the call of duty.ABSTRACT Three reports have been generated as products of the Synthesis of Historical Biological Data projectof the Tampa Bay National Estuary Program (TBNEP):

"Oligohaline Areas 

### in Tampa Bay Tributaries: Spatial Extent and Species Lists", "Database of Benthic Sampling Locations in Tampa Bay", andthe current report,
"Distribution of Selected Fish Species in Tampa Bay"

. The ten fish species chosen for distribution analysis (bay anchovy, silver perch, snook, spotted seatrout, spot, tarpon, striped mullet, red drum, hogchoker, and clown goby) were those identified byTBNEP as potential living resource targets. The analyses were based on extensive spring and fall sampling conducted for the Florida Departmentof Natural Resources' Fisheries
-Independent Monitoring Program. An index of relative abundance was developed that classified one-minute (latitude by longitude) grids within the Bay as having zero catch
-per-unit
-effort (CPUE), low
-to
-medium CPUE, 

### or high CPUE. Maps based onthese analyses were prepared for each combination ofspecies, length class, gear, and season for which adequate data were available. Several species were shownto concentrate primarily 

### intributaries during one 

### or more seasons, especially small snook and red drum, and hogchokers of all lengths. Species with a wide
-spread distribution in the Bay with little evidence of seasonal change 

### in distribution include bay anchovy and silver perch.



### ... IllTABLE OF CONTENTS Page FOREWORD 

## ................................................ i ACKNOWLEDGEMENTS 

# ....................................... ii ABSTRACT 

# ............................................... iii LIST OF TABLES 

# ............................................. v LIST OF FIGURES


## ........................................... vi

INTRODUCTION 

## ............................................ 1

METHODS


## ................................................ 2

RESULTS


## ................................................ 4

DISCUSSION 

# .............................................. 5 Tarpon 

# .............................................. 5 Bayanchovy 

# .......................................... 5 Striped mullet 

## ......................................... 6 Silver perch 

## .......................................... 6 Hogchoker 

## ........................................... 7 Clowngoby


## .......................................... 7 Red drum 

## ............................................ 7 Spotted seatrout 

# ....................................... 8 Spot


## ............................................... 6

Snook 

## .............................................. 9

SUMMARY


## ............................................... 9

REFERENCES 

## .............................................. 49

IV

...LIST OF TABLES Page Table 1. Fish species selected for distribution analyses 

# ...............10 Table 

### 2. Gear types used inthe Fisheries
-Independent Monitoring Program, andthe water depth and bottom type suitable for each gear (FMRI 

### 1990) 

# ............................... 11 Table 3. Length limits used to classify four species of fish as juveniles (less than one year of age) 

# ........................ 12 Table 4. Total number offish caught by gear and season, all years 

### (1989-1991) ....................................... 13LIST OF FIGURES Page Figure 1

## . Sites sampled bythe Fisheries
-Independent Monitoring Program in 

### 1991, not includingfixed stations. 

# ................15 Figure 

### 2. Sampling zones (A

-F) and fixed stations (0) used 

### in the Fisheries
-Independent Monitoring Program. 

# .................1 

### 6 Figure 

### 3. One

-minute grids used bythe Fisheries
-Independent Monitoring Program, labelled by zone (A

-F).


## ................. 17 Figure

### 4. Bay anchovy relative abundance maps: fish of all lengths collected bytrawls in the fall and spring seasons. 

# .............18 Figure 

### 5. Bay anchovy relative abundance maps: fish of all lengths collected by seines in the fall and spring seasons. 

# ............. 19 Figure 

### 6. Bay anchovy relative abundance maps: fish of all lengths collected by drop nets 

### in the fall and spring seasons. 

# .......... 20 Figure 

### 7. Striped mullet relative abundance maps: fish 

## < = 

### 178 mm in lengthcollected byseines in the fall and spring seasons 

# ........ 21 Figure 

### 8. Striped mullet relative abundance maps: fish 

## > 178 mm in length collected by seines inthe fall and spring seasons 

# ........ 22 Figure 

### 9. Striped mullet relative abundance maps: fish 

## > 178 

### mm in lengthcollected by gill nets 

### inthe fall and spring seasons 

# ....... 23 Figure 10. Silver perch relative abundance maps: fish of all lengths collected bytrawls 

### inthe fall and spring seasons 

# ............. 24 Figure 

### 11. Silver perch relative abundance maps: fish of all lengths collected byseines inthe fall and spring seasons 

# ............. 25 Figure 

### 12. Silver perch relative abundance maps: fish of all lengths collected bydrop nets 

### in the fall and spring seasons 

# ........... 26 Figure 

### 13. Spot relative abundance maps: fish of all lengths collected by trawls 

### in the fall and spring seasons 

# ................... .27

viLIST OF FIGURES (continued) Page Figure 14. Spot relative abundance maps: fish of all lengths collected by seines 

### in the fall and spring seasons 

# ..................... 28 Figure 15. Spot relative abundance maps: fish of all lengths collected by gill nets 

### in the fall and spring seasons 

# .................. .29 Figure 16. Hogchoker relative abundance maps: fish of all lengths collected bytrawls in the fall and spring seasons 

# .................... 30 Figure 17. Hogchoker relative abundance maps: fish of all lengths collected byseines in the fall and spring seasons 

## .................... 31 Figure 

### 18. Clown goby relative abundance maps: fish of all lengths collected bytrawls in the fall and spring seasons 

## ....................32 Figure 

### 19. Clown goby relative abundance maps: fish of all lengths collected by seines 

### in the fall and spring seasons 

# ....................33 Figure 

### 20. Clown goby relative abundance maps: fish of all lengths collected by drop nets in the fall and spring seasons 

# .................34 Figure 

### 21. Red 

### drum relative abundance maps: fish 

## < = 77 mm in length collected byseines 

### in the fall and spring seasons 

# ............. 35 Figure 

### 22. Red drum relative abundance maps: fish 

## <= 77 mm 

### in length collected by trawls 

### in the fall and spring seasons 

# ............. 36 Figure 

### 23. Red drum relative abundance maps: fish 

## < = 

### 77 

### mm in length collected by drop nets in the fall and spring seasons 

# ........... 37 Figure 

### 24. Red drum relative abundance maps: fish 

## > 77 

### mm in length collected by seines in the fall and spring seasons 

## ............. 38 Figure 25. Red drum relative abundance maps: fish 

## > 77 mm in length collected by 

### gill nets 

### in the fall and spring seasons 

# ............ 39 Figure 

### 26. Spotted seatrout relative abundance maps: fish < = 

### 170 mm (fall) or 

### 230 mm (spring) in length collected bytrawls 

### in the fall and spring seasons 

# ................................. 40

viiLIST OF FIGURES (continued) Page Figure 27. Spotted seatrout relative abundance maps: fish 

## < = 

### 170 mm (fall)or 

### 230 mm (spring) in length collected by seines in the fall and spring seasons 

# ........................... .41 Figure 

### 28. Spotted seatrout relative abundance maps: fish 

## < = 

### 170 mm (fall)or 

### 230 mm (spring) 

### in length collected by drop nets 

### in the fall and spring seasons 

# ........................... .42 Figure 

### 29. Spotted seatrout relative abundance maps: fish 

## > 170 mm (fall)or 

### 230 mm (spring) in lengthcollected bytrawls in the fall and spring seasons 

# ........................... .43 Figure 

### 30. Spotted seatrout relative abundance maps: fish 

## > 170 mm (fall)or 

### 230 mm (spring) 

### in length collected 

### by gill nets 

### in the fall and spring seasons 

# .......................... .44 Figure 

### 31. Snook relative abundance maps: fish 

## < = 150

### mm (fall)or 

### 300 mm (spring)inlength collected by seines 

### in the fall and spring seasons 

## .................................... .45 Figure 32. Snook relative abundance maps: fish 

## > 150mm (fall) or 

### 300 mm (spring) in lengthcollected bytrawls in the falt and spring seasons 

# .................................... .46 Figure 

### 33. Snook relative abundance maps: fish 

## > 150 

### mm (fall)or 

### 300 mm (spring)

### in lengthcollected byseines in the fall and spring seasons 

# .................................... .47 Figure 

### 34. Snook relative abundance maps: fish 

## > 150mm (fall)or 

### 300 mm (spring)

### in lengthcollected by gill nets 

### inthe fall and spring seasons 

# ................................. .48

viiiINTRODUCTION The Tampa Bay National Estuary Program (TBNEP) conducted two Framework for Characterization workshops in June and July of 1991. One of the conclusions of the workshops was that the distribution and historical trends in abundance of fish species in Tampa Bay should be prioritytopics for further investigation. Coastal Environmental Services, Inc. focused on these topics as one component of the TBNEP's Synthesis of Historical Biological Data project. The other two components of the project were 

### the location of oligohaline areas 

### in Tampa Bay tributaries (Coastal 1992a)and benthic communities inthe Bay (Coastal 1992b). In order to analyze trends in fish abundance, it is necessary to have access to data that provide reasonable estimates of absolute abundance of a population at different points 

### intime. The most extensive data available onTampa Bay fish populations comes from commercial landings statistics collected bythe National Marine Fisheries Service (NMFS). A recent report (Haddad 1985) used these data to analyze trends in two fish populations, butthe author noted that commercial landings data have major limitations as a source of abundance estimates. The specific locationwhere the fish were caught (e.g., within the Bay or offshore) is not known, and there is no reliable estimate of the amount of fishing effort. 

### A rise or decline intotal landings can easily reflect changes inthe number of fishermen targeting that species, rather than the abundance of the population. The NMFS data analyzed by Haddad (1985) indicatethat bait shrimp (Penaeus 

### duorarum) and spotted seatrout (Cynoscion nebulosus) have declined markedly over the period from 1951

-1955 to 1981. When trends in landings data are large and consistent over time, there is good reasonto conclude that populations are declining. Unfortunately, non-catastrophic changes in abundance are difficult to detect with landings data, being likely to be obscured by changes 

### in fishing effort. Historical data on fish populations other than the NMFS commercial landings data are also limited 

### in their ability to provide abundance estimates for use intrends analysis. Extensive sampling is required to estimate abundance while taking into account such factors as shifts in distribution within an area, migration into and out of the area, and (especiallyfor juvenile populations)mortality. In addition, variations in gear efficiency make it difficult or impossibleto combine data from different studies. TBNEP decided soon after the start of the Synthesis of Historical Biological Data that the available data were not adequate to support analyses of long
-term trends in fish populations. The focus of the projecttherefore shifted to analyzing current distribution patterns within the Bay. An extensive sampling program recently begun bythe Florida Department of Natural Resources (FDNR),the Fisheries
-Independent Monitoring Program, provides a source 

### of data on fish distributions that is free of 

### the problems associated with
1commercial landings data. The program is specifically intendedto collect data that will provide baseline trends and assessments of fish stocks. It targetsjuvenile fishes and uses carefully designed sampling methods and techniques. Although not designed specifically for measuring the distribution of fish within the Bay, it provides the best available data for this purposeand was selected as the source of data for the distribution analyses. The ten species of fish identified as potential living resourcetargets byTBNEP were chosen as the subjects for distribution analyses. These are bay anchovy, silver perch, snook, spotted seatrout, spot, tarpon, striped mullet, red drum, hogchoker, and clown goby (see Table 

### 1for scientific names).

METHODS Three 

### full years of data were available fromthe Fisheries
-Independent Monitoring Program (FIMP), for 

### 1989 to 

### 1991. The FIMP collects data fromtwotypes 

### of sampling stations: fixed stations and those selected bystratified randomsampling (FMRI 

### 1990). Fixed stations are sampled monthly, andtwotypes of gear have been used consistently across all years: trawls and seines. Random samples are collected during two seasons: spring (March

-June) and fall (September

-December). For the randomsamples, four types of gear have been used consistently across all years: trawls, seines, gill nets and drop nets. Each gear type is used only 

### in areas appropriate for that gear, as defined bywater depth and habitat type (Table 

### 2). Within each season, one bay
-wide set of samples is collected for each gear during the dawn/day time period and one set is collected duringthe dusk/night period. Figure 

### 1 displays the sites actually sampled byeach gear type for one year 

### (1991). Details onsampling methods are described 

### in the 

### 1989 Annual Report (FMRI 1

### 990). The sampling area covered bythe FIMP is divided into six zones that include Boca Ciega Bay, lower Tampa Bay, Old Tampa Bay, Hillsborough Bay, and the lower reaches of the Alafia, Little Manatee, and Manatee Rivers. Random sampling occursthroughoutthese zones, while at least two of the 

### 22 fixed stations are within each zone (Figure 

### 2). The choice of what spatial 

### unit to use 

### in describing fish distributions was an important decision 

### in the analyses. The FIMP uses a latitude/longitude grid drawn at one-minute intervals to define grid cells used 

### in selecting the randomly stratified sampling locations (Figure 3). We decided to use these grid cells as the basic spatial unit for distribution analyses. Technically, due tothe random sample design used 

### in the FIMP, data from individual sampling sites could be used to draw inferences regarding abundancefor all grid cells suitable for that gear within the zone 

### in which the site was located. 

### In practice, we decided (inconsultation 

### with
2Dr. Robert McMichael of DNR) that analyses based onzones would result in misleading apparent differences betweenzones. Since zones were defined for logistical reasons and not based on habitat differences that would affect fish distributions, wedecided notto conduct analyses atthe level of zones. Analyzing the data at the level of grid cells rather than zones had the added advantage of allowing us tocombine data fromthe fixed and randomsampling programs. Since juvenile and adult fish of the same species often have different distributions, it was desirable to performseparate analyses for these two age classes. Dueto naturalvariations 

### in rates of growth within populations, otolith analysis of individual fish isthe only reliable method of aging most fish. The FlMP recorded lengths for upto 

### 20 fish per sample, but did not age individualfish. Wetherefore used length

### to infer age. For four of the species (snook, spotted seatrout, striped mullet, and red drum) we were able tofind length limits to use in classifying individual fish as being less than or greater than one year of age (Table 3). Within
-year variability 

### in growth rates for some species (e.g. snook) meantthat a more accurate division of different ages could be made using different length limits for the fall and spring sampling seasons, For six species we did not have length
-at
-age data based onGulf of Mexico populations, and we combined all catches (regardless of length)to assess distribution patterns. We restricted analyses tothose gears that were deployed in all three years of the study (excludingexperimental gear types). For each species and age class, we also excluded any gear that never caught at least 10 fish in any one year. Samples that collected nofish (zero catches) can be used to infer that few or nofish were present only if that gear is knownto be effective in capturing that size and type of fish. By requiringsome evidencethat a gear type could be effective 

### in collecting a given species and age class we increasedthe probability that observed values of zero catch
-per-unit
-effort (CPUE) reflected 

### low fish abundance rather than poor gear efficiency. Several different methods (parallel beach set, boat set, and offshore circle set) were usedto deploy seines in different habitats. Since measures of sampling effort (area swept) were available for each, we estimated CPUE separately for each deployment method and then treated all seine samples as one gear. For each species, age class, gear, year, and season (springor fall) we calculated the average CPUE for each grid cell. Data from 

### the fixed and randomsampling programs were combined prior to calculating the average CPUE. We used these averagevalues (includingzeros) todetermine the frequency distribution of CPUE across all grid cells sampled. We usedthe 75th percentile of this distribution as a cutoff value in classifying individual grid cells as having a 'medium to

### low' CPUE or
3'high' CPUE. For example, if the average CPUE values rangedfrom 0 to 15.2, with 75% of all grid cells havinga CPUE value less than 12.8, then only those grid cells with an averagevalue greater than 12.8were classified as 'high'. Grids with zero CPUE (nofish ever collected) were assigned an index value of 

### 0, grids with low to medium relative CPUE (lessthan the 75th percentile cutoff) were assigned an index value of 

### 1, and grids with high relative CPUE were assigned an indexvalue of 

### 2. Relative abundance index values were calculated for each grid cell sampled in each of the three years. If a grid cell was sampled 

### in more than one year, index values were averaged across years. Any average index greater than 

### 0 but less than 

### 1.5 was given an overall value of 1 (lowto medium relative CPUE). (Values less than 0.5 were not rounded down, so that index values of 0 reflect an absence of catches in all years.) Average values between 1.5 and 2 were given an overall value of 2 (high relative CPUE). It is important to notethat these index values reflect relative, rather than absolute abundance. 

### In any given season, the total population of a given species and age class in the Bay may be either lowor high. 

### In either case, these analyses will identify those areas (grid cells) with the highest CPUE relative to all grid cells sampled that season. In an extreme case, if only 1fish was collected in one season, the grid cell in which it was caught would be classified as having a high relative CPUE. Combining data across a three
-year period decreases the chance that a single sample will determine a grid cell's rank, but due tothe random sampling design many grid cells were only sampled in one or two of the three years.

RESULTS The minute
-by
-minute (latitude and longitude) grid cells defined bythe FlMP were the units of analysis for relative abundance, and are also the units used 

### in presentingthe results. A table of grid cells provides a map of the Bay (see Figure 

### 3),slightly distorted if the ratio of heightto width of a table cell is notthe same as the ratio of a minute of longitudeto a minute of latitude. The results of the relative abundance analyses are presented as tables of grid cells in Figures 

### 4
-34. Each figure presentstwo maps of Tampa Bay. A separate map is shown for each combination of species, length class, gear, and season (withspring and fall presented side
-by
-side onthe same page). Unsampled grid cells are left blank, cells with zero catches are lightly stippled, and increasing relative abundance is indicated by darker shading.

4In addition to grid cell tables for all species, we generated 

### GIS maps of relative abundance for two species: red drum (Sciaenops ocellatus) less than 303 mm in length in the spring, and snook (Centropomus undecimalis) larger than 

### 150 rnm in the fall. These maps have been submitted toTBNEP as one of the final products for this project. 

### In interpretingthe results, greater weight can be attached to maps that are based on relatively large numbers 

### of fish captured. Table 

### 4 presentsthe total number of fish caught for each combination of species, length class, gear, and season. These numbers do not reflect absolute abundance since sampling effort varied with gear, year, and season. They 

### do indicate, for example, that the distribution maps for bay anchovy seine and trawl collections are based on large numbers of fish. On the other hand, the spring map for bay anchovies collected bydrop nets simply reflects an apparent absence of bayanchovies 

### in the habitats sampled by dropnets rather than a strong concentration of the population in Old Tampa Bay.

DISCUSSION
Tarpon (Megalops atlanticus). Tarpon inhabit estuaries and shallow coastal waters, spawning offshore but 

### with inshore development of larvae andjuveniles (Boschunget al. 

### 1983). Their life history within Tampa Bay is notwell known, and only three tarpon were caught bythe FlMP for all gears combined between 

### 1989 and 

### 1991. Tarpon was the only one of the tentarget species for which we could not analyze relative abundance.
Bay anchovy (Anchoa mitchilli). Bay anchovies inhabit shallow bays and estuaries (Robins and Ray 

### 1986). This species appears to spawn twice, and sometimes three times, 

### a year 

### inthe Tampa Bay area (Springerand Woodburn 

### 1960). The highest abundance of bay anchovies encountered by Springer and Woodburn 

### (1960)was 

### in the late summer and fall. The distribution of this species does not appear to be salinity dependent, with specimens collected over a wide range of salinities (Springer and Woodburn 

### 1960). The wide salinity tolerance of bay anchovies was confirmed by our analyses of relative abundance. Bay anchovy were distributed widely throughoutthe bay in both seasons of the year, both 

### in the deep water sampled by trawls (Figure 4) and the shallow habitats sampled by seines (Figure

### 5). The only exception was a possible low relative abundance 

### in deep waters near 

### the mouthof the bay during spring (Figure

### 4). Drop nets in seagrass beds (Figure 

### 6) collected few total bay anchovies, and those only 

### in Old Tampa Bay.


### 5Striped mullet (Mugi/ cephalus). Striped mullet spawn from October through May on Florida’s west coast (Collins 1985). Juveniles frequent coastal waters, salt marshes, and estuaries, during both spring and fall, although some juveniles may move offshore in the fall when adults migrateto deeper water to spawn. Small striped mullet were collected by the FlMP 

### in large numbers only byseines (shallow waters). They were distributed throughout the margins of the bay, particularly 

### in the eastern tributaries and Boca Ciega Bay in spring (Figure 7). A few larger striped mullet were collected by seines (Figure

### 8), but gill nets (Figure 

### 9) were more effective. They were distributed throughoutthe bay in the spring, but none were collected south of Cockroach Bay duringthe fall season. These results are consistent with those of Springer and Woodburn 

### (1960)who reportedthat striped mullet in theTampa Bay area occur in all habitats throughout the year, but who also reported anecdotal evidence of spawning migrations of larger fish along the northshore in the fall.

Silver perch (Bairdiella chrysoura). The spawning activity of silver perch inTampa Bay begins 

### in June and continues through August. Springer and Woodburn (1960) reported that young silver perchappeared in Tampa Bay duringthe month of June, and that the silver perch population in the Bay increased markedly duringJuly, then declined 

### until by November very few individuals were being caught. The FlMP collected large numbers of silver perch using bothtrawls and seines. As with bay anchovies, there were no apparent concentrationsof silver perch in particular areas of the Bay (Figures 10 and 11). Drop nets deployed invegetated areas collected very few silver perchduring the spring, compared to reasonable numbers, distributed throughout the bay, in the fall (Figure 12).
Spot 

### (Leiostomus xanthurus). Spot spawn from late December through March 

### in the Tampa Bay area (Springer and Woodburn 1960). Spawning usually occurs offshore either close to bay entrances (Pearson 1929, cited by Springer 

### & Woodburn 

### 1960) or in deeper offshore waters (Dawson 1958, cited by Springer 

### & Woodburn 

### 1960). Trawl and seine data from previous studies indicate a widely distributed population 

### in the spring months (Springer 

### & Woodburn 

### 1960). Stomach contents indicate that large spot are bottomfeeders (Springer and Woodburn 

### 1960). Spot were collected 

### in large numbers bytrawls and seines, and 

### in moderate numbers by gill nets. The deep
-water trawl data suggest a possible southern and eastern concentrationof spot in the fall (Figure 13). Fall seine samples also suggest a concentration in the tributaries and the south of the Bay (Figure 14), but very few total numbers were captured by seines. Bothtrawl and seine data
6indicate a widely distributed population in the spring, agreeing with data reported in Springer and Woodburn (1960). Gill nets, however, (which probably tend to capture larger, older fish than either of the other gears) suggest a concentrationof fish near the mouthof the Bay 

### in spring (Figure 15).
Hogchoker (Trinectes maculatus). Hogchokersare a bottom
-dwellingspecies commonly inhabiting shallow estuarine areas. In freshwater, they oftentravel hundreds of miles upstream (Robins and Ray 

### 1986). The sizes of the few specimens collected 

### by Springer and Woodburn 

### (1 

### 960) suggested that larger individuals may be found 

### in more saline waters. Hogchokers appeared in large numbers in both trawl and seine collections of the FIMP. Both gears indicatethat these fish are concentrated 

### in the eastern tributaries duringthe fall (Figures 16 and 17). For the shallow
-water habitats sampled by seines the eastern tributaries also had high relative abundances in the spring (Figure 

### 17),while the deep
-water trawls show grid cells with high relative abundance throughout the bay in both seasons.


### Clown goby

### (Microgobius gulosus). Clown gobies inhabit protected, vegetated areas with muddy bottoms (Robins and Ray 

### 1986). Springer and Woodburn (1 

### 960) documented spawning activity in July and November. Duringthe FIMP clown gobies were collected in large numbers by seines, in moderate numbers by trawls, and in low numbers by drop nets. Trawls generally found low relative abundance 

### in the central part of the bay (Figure 

### 18), while seines found patches of high relative abundancethroughout the shoreline (Figure 

### 19). Drop nets also indicated high relative numbers bay
-wide (Figure 

### 20). None of the three gears suggested any seasonal changes in distribution.



### Red drum (Sciaenops ocellatus). The peak spawning season for red drum in Tampa Bay normally occurs from September through October, but has been knownto occur as early as mid
-August (MurphyandTaylor 1990). Pearson 

### (1 

### 929, cited by Murphy and Taylor 

### 1990)concludedthat spawning typically occurred 

### in nearshore waters close to channels and passageways; McMichael and Peters 

### (1 987) recorded nearshore spawning as well as spawning in areas atthe mouthofTampa Bay. The same authors reportedthat the majority of red drum larvae exist 

### in the lower Bay areas, and thatjuveniles migratetoward lowsalinity backwater areas (tributaries) of the Bay inthe spring months. During sampling from September 

### 1981through November 

### 1983, McMichael and Peters 

### (1987)reported that 

### 98 percent of all juveniles caught were collected in tributary areas, with 85 percent coming fromthe Alafia River.
7Duringthe FIMP small red drumwere captured in highest numbers by seines, though trawls were apparently effective in capturingthe smaller fish that occur in the fall. Seines recordedareas of high relative abundance in the tributaries in both seasons, with scattered high
-abundanceareas occurringthroughout the rest of the shoreline (Figure 

### 21). In both seasons, the only areas of high relative abundance for the deep
-water trawl samples occurred in or near the mouths of the major tributaries (Figure 

### 22). Drop nets (fished 

### invegetated areas) caught no small red drum 

### invegetated areas 

### in the spring, and only a few 

### in the east of the Bay during the fall (Figure

### 23). These results agree with those of McMichaeland Peters 

### (1987)regardingthe concentration ofjuvenile red drum 

### intributaries tothe Bay. Larger red drum were only occasionally captured duringthe FIMP, byseines and gill nets. The fall seine data hint at a concentration in the tributaries (Figure 

### 24), but gill net collections in the same season found high relative abundance grid cells along the western shore (Figure 

### 25). Gill nets data indicatedthat larger red drum were widely distributed throughout the nearshore areas ofthe Bay in the spring.
Spotted seatrout (Cynoscion nebulosus). Spotted seatrout appear to have a spawning season that extends from Marchand April through September and October (Mercer 

### 1984, cited by McMichael 

### & Peters 

### 1989). McMichaeland Peters 

### (1989) concludedthat spotted seatrout spawn in middle and lower Tampa Bay, with specific spawningareas changing fromyear toyear (depending uponsalinity and temperature). Juvenile spotted seatrout were commonly found in both vegetated seagrass habitats and backwater areas, and appear to be very adaptable to different habitat types. McMichael and Peters 

### (1989) suggested that seagrass is the primary habitat for juveniles, with 

### 78% of all capturedjuveniles having been collected over seagrass areas. A major long
-term decline 

### in commercial catches of spotted seatrout may be due 

### in part

### to loss of seagrass habitat 

### within the Bay (Haddad 

### 1985). Duringthe FIMP, small spotted seatrout were caught 

### in large numbers by seines, moderate numbers bytrawls, and low numbers by drop nets. Data fromtrawls showed a scattered distribution in the fall, with low relativeabundance 

### in the main stem of the Bay in spring (Figure 

### 26). The more abundant seine catches indicated possible concentrations near the mouths (saline portions)oftributaries 

### in the fall (Figure 

### 27). Distribution inthe spring appeared similar tothat in the fall, except for lower concentrations in the mouthofthe Bay andthe Manatee River. 

### In general these results are consistent with the conclusions of McMichaeland Peters 

### (1989). Ifyoung spotted seatrout are concentrated 

### in seagrass areas, however, the drop nets used by FIMP were notvery effective at capturingthem (Figure 

### 28). Larger spotted seatrout were captured duringthe FIMP in moderate numbers by gill nets, and occasionally bytrawls. Total captures were too few to put
-much


### 8emphasis onthe trawl data (Figure 29). The gear that capturedthe most fish, gill nets, indicates a possible concentration in the lower portionof the main stem of the Bay inthe fall, with a more scattered distribution in the spring (Figure 

### 30). Unlike many of the other species, no high relative abundance of spotted seatrout was found inside the tributaries tothe Bay.


### Snook (Centropomus undecimalis). Snook spawn betweenApril and December. Juvenile snook prefer shallow, protected bodies of water with a small surface area (Springer and Woodburn 

### 1960). According to Gilmore et al. 

### (1983, cited in McMichael et al. 

### 1989),juvenile snook move from shallow, riverine areas to deeper waters of the Bay as they grow. Movements of snook between habitats has also been attributedtotemperature change (Springer and Woodburn 

### 1960). Duringthe FlMP small snook were effectively captured only byseines. These data showthe best evidence for a very localized distribution among any of the species. Relatively large numbers were caught, but almost exclusively within just two ofthe tributaries (theAlafia and Little Manatee Rivers), 

### in bothspring and fall (Figure 31). These results are consistent with Springer and Woodburn's 

### (1 960) description of juvenile habitats. Larger snook were captured duringthe FlMP 

### in lowto moderate numbers by each of three gears (trawls, seines, and gill nets). The data are relatively scant buttend to show a distribution similar tothejuveniles, concentrated in the tributaries (Figures32and 

### 33). The exception is gill net captures 

### in the spring (only 22 fish total), which were scattered throughout the nearshore areas of the Bay (Figure 34).

SUMMARY

Coastal prepared maps of distribution within Tampa Bay for nine of the 

### 10 species idenfified as potential TBNEP living resource targets. The results were typically consistent with reported distribution patternsfor those species described 

### in the literature, while providing an overview for all nine species based onconsistent sampling methods and effort. A strong pattern of concentration in tributaries was found for small snook, indicatingthe probable importanceof habitats within freshwater tributaries as nursery areas for juvenile snook. The highest observed relative abundance of small red drumalso tended to occur within tributaries, as did that for hogchokers of all lengths. 

### In contrast, some species had high relative abundances scattered throughout the Bay in both the fall and spring seasons. This was particularly true of bay anchovy and silver perch, with the analyses indicating no strong habitat preferences or seasonal movements.
9Table 1. Fish species selected for distributionanalyses.

Scientific Name Common Name
Anchoa mitchilli Bairdiella chrysoura Centropomus undecimalis Snook Cynoscion nebulosus Spotted seatrout Bay anchovy Silver perch

Leiostomus xanthurus

Megalops a tlanticus spot Tarpon

Trinectesmaculatus Hogchoker
I Mugil cephalus Sciaenops ocellatus 

# I I Microgobius gulosus Clown goby 

# I Striped mullet Red drum

10REFERENCES
Boschung, H.T., J.D. Williams, D.W. Gotshall, D.K. Caldwell, and M.C. Caldwell. 

### 1983. The Audubon Society Field Guide to North American Fishes, Whales, and Dolphins. Alfred A. Knopf, NY. Coastal Environmental Services, Inc. 1992a. Oligohaline Areas 

### in Tampa Bay Tributaries: Spatial Extent and Species Lists. Tampa Bay National Estuary Program Technical Report #04-92. Coastal Environmental Services, Inc. 1992b. Database of Benthic Sampling Locations in Tampa Bay. Tampa Bay National Estuary Program Technical Report #06-92. Collins, M.R. 1985. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (South Florida)

-- striped mullet. U.S. Fish and Wildlife Service Biological Report 82(11.34). U.S. Army Corps of Engineers, TR EL

-82

-r. FMRl (Florida Marine Research Institute, Juvenile Fish Group). 

### 1990. Fisheries

Independent Monitoring Program. 1989 Annual Report (Preliminary data). Haddad, K. 1985. Habitat trends and fisheries in Tampa and Sarasota Bays. In: Treat, S.F., J.L. Simon, R.R. Lewis III, and R.L. Whitman, Jr. (Eds.). Proceedings, Tampa Bay Area Scientific Information Symposium (May 1982). Burgess Publishing Co., Inc., Minneapolis, MN. McMichael, 

### R.H. and K.M. Peters. 

### 1987. Early life history of the red drum, Sciaenops ocellatus (Pisces: Sciaenidae), in Tampa Bay, Florida. Estuaries 

### 10 (2): 92

-107. McMichael, R.H., Jr. and K.M. Peters. 1989. Early life history of spotted seatrout, Cynoscion nebulosus (Pisces: Sciaenidae), in Tampa Bay, Florida. Estuaries. 12(2):98-110. McMichael, R.H., Jr., K.M. Peters, and G.R. Parsons. 1989. Early life history of the snook, Centropomus undecimalis, 

### in Tampa Bay, Florida. Northeast Gulf Science. 10(2):113-125. Murphy, M.D. and R.G. Taylor. 1990. Reproduction, growth, and mortality of red drum, Sciaenops ocellatus, in Florida waters. Fishery Bulletin 

### 88: 531

-542.

49Peters, K

.M

. and R.H. McMichael, Jr

. 1987. Early life history of the red drum Sciaenops

### ocellatus (Pisces: Sciaenidae), in Tampa Bay, Florida. Estuaries. 10:2:92-107 Robins, C.R. and G.C. Ray. 1986. A Field Guide to Atlantic Coast Fishes of North America. Houghton Mifflin Company, Boston. Springer V.G. and K.D. Woodburn. 

### 1960. An ecological study of the fishes of the Tampa Bay area. Professional papers series: number one. Florida Board of Conservation Marine Laboratory, St. Petersburg, FL.



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