James A. Colvocoresses, Florida Department of Environmental Protection, Florida Marine Research Institute, South Florida Regional Lab, 2796 Overseas Highway, Suite 119, Marathon, Florida 33050; Robert H. McMichael, Jr., Florida Department of Environmental Protection, Florida Marine Research Institute, 100 Eighth Ave. SE, St. Petersburg, Florida 33701.

During the past two years the Florida Department of Environmental Protection has prioritized the implementation of its statewide marine Fisheries-Independent Monitoring (FIM) Program in Florida Bay. This program, which has been under development since 1988, uses extensive systematic scientific field surveys to assess the pre-fishery recruitment of resource species which utilize Florida's estuarine and near-coastal areas as nursery zones, as well as to generate other fishery-independent information concerning these stocks. These surveys also serve to achieve a secondary but very important objective of providing a large scale, long-term biological and ecological monitoring program in this critical area of Florida's marine environment. The program is intended to be sustained on a continuing basis and to be eventually expanded to monitor all major estuarine areas in the state.

Initial efforts in Florida Bay have focused on the development of a network of fixed sampling sites, which are being sampled monthly with beach seines and bottom trawls. Preliminary sampling began in September of 1993, with the present network of 31 permanent stations having been established as of August of 1994. Stations have been selected with the multiple objectives of meeting the fishery-monitoring goals of the overall program, providing a framework for comparing the results of present and historical sampling efforts, and for evaluating the effects of alterations of freshwater delivery schedules to Florida Bay. Sixteen sites are sampled with seines, while fifteen are sampled with trawls (Fig. 1, Table 1). The seining gear is a 70' long by 6' deep nylon-mesh, center-bag drag seine made from 1/8" #35 Delta mesh. The net is deployed over shallow flats facing into the current with brails spaced 50' apart. The net is then manually pulled a distance of 30', after which the net is closed and pursed by pulling it around a pole. The bag is then lifted and slowly inverted and the catch transferred to buckets. Deeper waters ( >1.5 m) are sampled using a 20' otter trawl made of 1-1/2" str. mesh nylon, with the bag lined with 1/8" knotless #35 Delta mesh. The trawl is towed behind a 24' mullet skiff at a speed of approx. 1.5 knots for 5 minutes. Bottom distance covered is recorded using GPS set and haul back points, and is generally about 163 m. Three spatially discreet replicate sets are made at each visit to a sampling site.

All fishes and selected macroinvertebrates are identified, enumerated, and representative length frequencies taken. Hydrographic data, atmospheric and sea conditions, and observations relative to bottom type are recorded for each collection. Temperature, salinity, pH, dissolved oxygen and conductivity are recorded at each sampling site, including both surface and bottom when depth permits discrete observations. Quantitative observations of bycatch are recorded. Direct observations of bottom type are made during seining operations, including species composition and estimated percent cover of any vegetation.

Although it is too early to draw definitive quantitative conclusions, on a bay-wide level overall initial results have shown very similar species compositions to those observed during similar studies conducted over the past thirty years, with approximately a 70% overlap in the percent species composition of the finfishes taken. On a local level, in areas where extensive seagrass loss has occurred, there appear to have been dramatic changes in community structure, with a seagrass-based community overwhelmingly dominated by rainwater killifish being replaced by a more diverse benthic fish community composed of toadfishes, gobies, pipefishes and some juvenile gamefishes such as spotted seatrout. Although undoubtedly affected by the recent ecological perturbations in Florida Bay, the finfish community may be more resilient to these changes than other, more immobile organisms.

1 Offshore seine 25 14.25 80 25.38 Manatee Bay at ENP hydro station

2 Offshore seine 25 13.38 80 25.82 Manatee Bay by U.S.1

3 Offshore seine 24 54.70 80 56.31 Sprigger Bank - just S of marker '5'

4 Offshore seine 25 7.70 80 56.90 Bradley Key - W side cove

5 Trawl (6-7ft.) 25 7.12 80 56.07 MurrayKey - 1/2mi. N of key

6 Offshore seine 25 2.30 81 1.12 Sandy Key - off NW corner of key

7 Offshore seine 25 13.00 80 27.80 Shell Key - NW corner of L. Blackwater Sound

8 Offshore seine 24 55.08 80 45.25 Buchanan Bank - 1/2 mi. W of N Peterson Key

9 Offshore seine 25 5.06 80 47.30 Roscoe Key - N side of first cut S of key

10 Trawl (6-7 ft.) 25 1.15 80 33.45 Cross Bank Basin - 3/4 mi. N of marker '73'

11 Trawl (5-6 ft.) 25 4.50 80 45.15 Whipray Basin - 2 mi. N of Whipray Channel

12 Trawl (6-7 ft.) 25 8.10 80 36.12 Eagle Key Basin - 2 mi. S of Eagle Key

13 Trawl (6-7 ft.) 24 57.03 80 47.52 Twin Key Basin - 1/2 mi. N of Barnes Key

14 Trawl (3-4 ft.) 25 6.00 80 52.50 Palm Key Basin - 1/2 mi. S of Palm Key

15 Trawl (3-4 ft.) 25 2.90 80 55.00 Johnson Key Basin - 1/2 mi. SW of Johnson Key

16 Offshore seine 24 58.95 80 39.00 West Key - Off beach on SE shore

17 Offshore seine 25 9.12 80 30.70 Nest Key - Off beach at campground

18 Trawl (3-4 ft.) 25 8.00 80 43.20 Crocodile Pt. - 1/2 mi. S of Pt.

19 Trawl (3-4 ft.) 25 7.50 80 48.51 Rankin Lake - 3/4 mi. W of Rankin Key

20 Trawl (4-5 ft.) 25 10.60 80 29.70 Duck Key - 1/4 mi. SE of key

21 Trawl (7-8 ft.) 24 54.65 80 39.70 Shell Key Channel - S end

22 Trawl (6-7ft.) 25 7.00 80 27.80 Buttonwood Sound - 1 mi. W of Grouper Creek

23 Offshore seine 25 4.35 80 33.30 Bottle Key - W side of N point

24 Offshore seine 25 4.45 80 38.70 Russell Key - SW shore

25 Offshore seine 24 58.10 80 51.15 Ninemile Bank opposite Rabbit Key Pass

26 Trawl (4-5 ft.) 25 0.12 80 53.80 Rabbit Key Basin at mouth of Iron Pipe Channel

27 Trawl (9-10 ft.) 24 56.70 80 57.20 Schooner Bank - 1 mi. SE by NPS marker

28 Offshore seine 24 49.10 80 52.05 Old Sweat Bank - N side

29 Offshore seine 25 11.85 80 37.15 Little Madiera Bay - mouth of E. Creek

30 Offshore seine 25 0.40 80 47.68 Sid Key Bank - bank tip 1 mi. S of SW pt. of Sid Key

Dana M. Elledge, Everglades National Park, Florida Bay District, 98701 Overseas Highway, Key Largo, FL. 33037; Robert J. Brock, Everglades National Park, South Florida Natural Resources Center, 40001 State Road 9336, Homestead, FL. 33034-7633.

Spotted seatrout (Cynoscion nebulosus) are currently being collected throughout Florida Bay to ascertain age, growth, mortality, and fecundity estimates along with samples being preserved for future RNA-DNA analysis. Because of the propensity of this species to spend their entire life cycle within the Florida Bay estuary, the physiological fitness of spotted seatrout may be an excellent bioindicator of changing physiochemical conditions brought about by planned changes in upstream water management practices. The goal of this research is to compare the current physiological condition of spotted seatrout with previous Florida Bay studies as well as those from other Florida estuaries.

It was estimated in 1980 that increasing demands for water in south Florida by many user groups would threaten to significantly reduce the amount of water flowing into Everglades National Park, thereby leading to the reduction of spotted seatrout populations. It was found by previous researchers that growth rates varied among spotted seatrout depending upon their location in the bay. This variation in growth rates was attributed to differences in water quality. For example, lower growth rates among spotted seatrout were found in the hypersaline areas such as western Florida Bay than in the more brackish eastern bay. The overall objectives of this project are:

Objective 1. Determine growth rates of Florida Bay spotted seatrout for contrast with other

Florida estuarine waters as well as past growth rates of this species in Florida Bay. Estimates of age, growth, and mortality of spotted seatrout will be made using samples from the recreational harvest and samples obtained by the hook-and-line method. An age regression will be constructed using otoliths to estimate growth of spotted seatrout in Florida Bay. Results will be analyzed in order to correlate a change in growth rate with recent physiochemical changes within the bay. These growth rates will also be compared to similar studies done in the past before the bay experienced the significant ecological perturbations that now exist.

Objective 2. Total weight of the ovary will be used to construct the gonadosomatic index while subsamples (0.05g - 0.10g) of the ovaries will be used to calculate fecundity. As hypersalinity becomes less common with the increase in the amount of freshwater being delivered to Florida Bay, an "improvement" in water quality will be indirectly correlated to length-weight and length-ovarian weight ratios. Fecundity estimates will be related to an age regression of spotted seatrout.

Objective 3. RNA-DNA analysis will examine the presence/absence of genetic subdivisions within the Florida Bay seatrout population. Previous mark and recapture studies indicated little inter-estuary movement. Gill arches and subsamples of the caudal fin are being frozen for future RNA-DNA analysis. Results from three distinct physiographic areas within Everglades National Park (Ten Thousand Islands, western Florida Bay, eastern Florida Bay) will be compared. Results will also be compared and contrasted with similar work being done in other Florida estuarine waters.

Fishery-dependent and fishery-independent samples are being collected monthly all over Florida Bay. Data recorded for all samples include date of capture, area captured, total length, total weight, sex, gonad weight, and physiochemical parameters such as water temperature and salinity. 534 otoliths have currently been extracted for future age and growth analysis. 350 gonads have been weighed in order to construct a gonadosomatic index. 100 ovaries have been subsampled to estimate fecundity and 65 gill arches have been frozen for future RNA-DNA analysis.

Collection of samples will continue until approximately September, 1996.

Donald E. Hoss, Gordon W. Thayer, NOAA/NMFS Beaufort Laboratory, Beaufort, North Carolina 28516-9722.

Investigators at the NMFS Beaufort Laboratory are conducting research to address the interagency Florida Bay Science Plan. Our objectives deal with changes in the distribution and abundance of living resources that have occurred in the Bay, including changes in trophic structure and effects of toxic pollutants on target organisms. Research efforts include sampling with various gear types for phytoplankton, zooplankton, ichthyoplankton and juvenile fish. Sampling was initiated on a monthly to bimonthly basis beginning in September 1994. Ichthyoplankton and zooplankton data, once analyzed, will be compared with data collected by us in 1984-1985 using similar sampling protocols and stations. Benthic habitat, and the resident fish community structure are being analyzed from data collected on a bimonthly bases, beginning in July 1994, using the same stratified random-sampling stations employed during 1984-1985. Mercury/methylmercury analyses will be made on target carnivore fishes (e.g., red drum, spotted seatrout, and gray snapper) and their food sources beginning in fall 1995. This study is being funded by the NOAA Florida Bay Restoration Program, and we project continued field sampling, laboratory analyses, and data syntheses throughout calendar years 1996 and 1997, with expansion of efforts in future years.

Data analyses are progressing on all aspects of the project. Presently, our ichthyoplankton samples are being sorted with an emphasis placed on spotted seatrout larvae, a species that we regularly collected in 1984-1985. Analyses of water samples for enumeration of phytoplankton indicate a minimum of 27 common genera including centric and pennate diatoms, monads, dinoflagellates and flagellates. There are both geographic and seasonal signals in the phytoplankton with spatial influences dominating temporal ones. The eastern region of Florida Bay is characterized by low phytoplankton biomass; the central region, and especially the north-central, is a seasonally influenced productive area; and the western portion of the Bay is also productive, but less influenced by seasonal changes.

Assessments of the fishery habitat and fishery community demonstrated consistent decreases in both plant and fishery species abundances relative to 1984/85. Thalassia, Syringodium, and Halodule short shoot densities have decreased extensively in each of the four strata that were sampled in 1984/85. Fish densities have decreased dramatically in Johnson Key Basin and in areas adjacent to Gulf of Mexico waters and channels within Florida Bay, but show little numerical change in areas adjacent to the Atlantic Ocean and an actual increase in the central portion of our sampling area. In the central portion, there has been a shift in the dominance of resident fishes from mojarra and rainwater killifish during 1984/85 to bay anchovy during July 1994 - May 1995, and the increases observed in the Central stratum were due to increases in bay anchovy at those stations where seagrass habitats were impacted. Since anchovy are an important food resource for spotted seatrout, any increases in anchovy numbers may have a positive influence on spotted seatrout abundances. This shift in resident fish dominance also suggests a shift in trophic feeding levels. Mojarra are benthic feeders and rainwater killifish feed on crustaceans associated with the seagrass canopy while anchovy are water column particle/zooplankton feeders.

Jerry Lorenz, Chris Harrington, National Audubon Society.

The mangrove-dominated zone that forms the interface of the Everglades with Biscayne and Florida Bays is an important area for wildlife in south Florida. This polyhaline dwarf red mangrove (Rhizophora mangle) swamp provides a primary nursery ground for sport fish, is the primary habitat of the endangered American Crocodile and West Indian Manatee and is heavily used as a feeding ground by wading birds. Historically freshwater from the Everglades reached the Florida Bay mangroves via Taylor Slough. In recent decades, the hydrology of the mangrove zone has been altered by the construction and operation of a system of canals and levees. Outstanding among these is the C-111 canal, which diverts water from Taylor Slough to an area just east of US Highway 1, thereby disrupting the natural processes in both areas. Further complicating the freshwater flow pattern is the US Highway 1 levee which has blocked all surface water flow from the Everglades to Biscayne Bay.

There is a great deal of evidence that indicates a change has occurred in the types of plants growing in this region coincident to the changes in water delivery. We believe that prey base fish populations have also been affected by these changes in hydrology and flora. Our current thinking is that water management practices in the Everglades, specifically management of the C-111 canal drainage area, adversely affect the populations of small fishes in the mangrove zone and, as a result, may be implicated in the decline of wildlife throughout the Florida Bay region.

Sampling fishes in this area proved to be somewhat of a challenge. Deep mud, unforgiving climatic conditions and myriad biting insects combined to drive away all but the most determined scientists. Furthermore, accepted techniques for sampling fishes over wetlands all proved flawed in this unique habitat. Eventually, through trial and error, a unique nine square meter drop net that effectively collected mangrove fishes was developed. This method requires little contact with the substrate, does not alter the habitat being sampled, does not alter the distribution of fishes over the wetland surface, and allows for differential sampling of microhabitats within the wetland. Catch efficiencies range from 78% for rainwater killifish Lucania parva to 92% for gulf killifish Fundulus grandis.

To accomplish our goal of linking manmade changes in water delivery to resident species abundance, we sampled fish populations in the mangrove zone of Biscayne and Florida Bays from 1990 through June 1995 at four to six week intervals, in conjunction with a detailed analysis of hydrologic conditions through the use of continuous recorders. Sites were selected based on the proximity and hydrologic influence of Taylor Slough. The three sites north of Florida Bay were selected based on a decreasing west to east gradient of the influence of the Slough, with TR (located in central Taylor Slough) receiving the most fresh water, HC receiving the least and JB intermediate between the two (JB and HC were sampled August 1990 - June 1995 and TR from December 1991 - June 1995) . BS (sampled from February 1992 - June 1995), located on Barnes Sound, historically received some freshwater from the Everglades, but the construction of US-1 and Card Sound Roads had impounded the area, effectively cutting off all surface connection to the Everglades. A site on Cape Sable (BL: sampled from August 1990 - present) was selected as a reference site in that it is probably the area least influenced by direct water management activities. Two sites associated with the freshwater Slough (9M: November 1993 - June 1995 and MD: October 1994 - June 1995)) were not sampled until late in the study and will not be addressed here. Furthermore, space restrictions dictate that data collected at BL, although pertinent, will not be discussed.

Preliminary numerical analysis of the first three years of our data set indicate that prey fish density and biomass are adversely affected by lower rates of fresh water inputs. Categorizing the years based on rainfall data, the first year was a drought year (1990-1991) the second year (1991-1992) had close to "normal" rainfall and the third year (1992-1993) had higher than normal rainfall and can best be described as a flood year. Hydrologic data indicate that the percent of high water days increased yearly from the drought year to the flood year Furthermore the percent of high water days decreased from TR to HC, along the west to east gradient of Taylor Slough influence (an exception was the unexpectedly high water at HC during the drought year). Likewise, the percent of low salinity days increased from the drought year to the flood year and decreased across the west to east gradient.

Resident fish of the mangrove swamp responded to the spatial and temporal changes in water delivery. The periodic sample with the highest estimated biomass increased from the drought year to the flood year and decreased from west to east along the decreasing freshwater gradient. The implications are that decreased flow over the last 30 years may have eroded the food pyramid of the Florida Bay ecosystem from the bottom up, thus culminating in the current decline of top predators such as wading birds and game fishes. However, a complete analysis of the data set must be performed in order to confirm these preliminary results.

Another goal of the study was to examine the effects of introduced fish species on the native fauna. The exotic Mayan cichlid (Cichlasoma urophthalmus) was the most common species collected by weight and made up as much as 90% of the catch by biomass in some samples. Prior to December 1989, this fish was very common throughout the mangrove ecotone. The Christmas freeze of 1989 annihilated the species; no individuals were collected for more than a year and the species as a whole was uncommon in our collections until late in 1991. Since that time, this species has continued to increase in both number and biomass and, where abundant, the increase in the cichlid population has been coincident to a decline in native species. Furthermore, the range of the Mayan cichlid continued to expand. The species was never collected at our BL site, although it was captured incidentally at nearby locations. In June 1995, the last scheduled sample to be collected at BL contained breeding adults and juveniles of this species. BL will continue to be sampled indefinitely so that any changes in community structure will be documented.

Funding for periodic collections of fishes was terminated as of June 1995. At this time, we have no intention of actively pursuing further funding for continued periodic samples. Recent discussions with ENP raised the potential for including at least some of the sites in a biological monitoring program to assess iterative processes proposed by the COE and the SFWMD concerning modified water deliveries to Taylor Slough. If funding is made available, the collection of samples may be restarted in the future. At present, our research goals are to pursue funding to conduct specific experiments designed to support our findings to date. These experiments will be along two avenues: 1. To more closely examine the relationship of salinity (and possibly nutrient delivery) to primary and secondary productivity, and 2. To elucidate the impact of the exotic Mayan Cichlid on the ecosystem.

R.E. Matheson, Jr. , D.K. Camp, K.A. Bjorgo, Florida Department of Environmental Protection, Florida Marine Research Institute.

The faunal community of seagrass beds in Florida Bay includes, among other elements, large numbers of fish and decapod crustaceans. These animals include juveniles of some species (transients) as well as all or most life­history stages of other species (residents). Populations of transients often have pelagic larval stages whose recruitment to the Bay can be greatly affected by oceanographic processes operating outside of the Bay, and these animals are also often the subject of extensive fisheries (e.g., pink shrimp, Penaeus duorarum; gray snapper, Lutjanus griseus). Residents, on the other hand, may be better indicators of overall ecosystem health because they are less affected by processes operating outside of the system and because they are not harvested by man. They are, however, an important element in the diet of predatory fish and birds that utilize Florida Bay as a feeding ground. The seagrass fauna (both resident and transient) could be greatly affected by seagrass die­off and is also vulnerable to the effects of algal blooms and changes in freshwater input. From 1984 through 1986 (prior to the recent seagrass die­off), Powell et al. (1987) used 1­m2 throw traps to collect quantitative data on the forage fish and decapod community. Throw traps of this type are biased toward the resident portion of the fauna. During 1994 and 1995 we repeated a portion of the work of Powell et al. (1987) with the goals of documenting changes occurring in seagrass­associated fauna since the recent seagrass die­off and providing baseline data for evaluating the effects of planned future ecosystem changes on this fauna. This work addresses Questions 1 and 2 in the "Living Resources" section of the Science Plan for Florida Bay. It is most pertinent to Task i ("Develop baywide faunal monitoring program...Compare results with past studies) of Question 1 and Tasks i and ii ("Collect unbiased information on...indicator species" and "Focus on habitat­based research...pre­ and post­die­off seagrass and mangrove faunal community composition must be quantified") of Question 2. In this presentation we will compare physical, seagrass, fish, and shrimp data collected in these two studies.

We conducted our sampling with one of the throw traps used by Powell et al. This trap is a box with each side 1­m wide by 45­cm deep and without top or bottom. The effective depth of the trap was extended by a floating net of 3­mm mesh attached to the top of the box at one end. To collect a sample, we randomly threw the trap over a seagrass bed, and forced the trap frame into the bottom in order to isolate 1 m2 of seagrass. We then removed animals by using an internal seine. Each trap was seined a minimum of ten times, and seining was continued until three successive passes produced no organisms other than, as in the previous study, mud and hermit crabs. We also collected two 15.3 cm core samples with each throw­trap in order to characterize the seagrass bed in terms of seagrass species, shoot density, leaf surface area, and mean blade length and width. With the exception of two sites in March 1994, six throw­trap samples were collected from each site on each sampling date. To date we have collected samples in March and September of 1994 and June of 1995. This corresponds to the dry season and the early and late wet seasons of the previous study, but we will refer to them by their calendar seasons and call them our winter, autumn, and summer samples, respectively. Physical data and fish data that we present here include all three sampling periods for both studies, while shrimp and seagrass data include only the winter and autumn periods.

Sampling in both studies was conducted on banks representing five different vegetational subenvironments of the bay as defined by Zieman et al. (1989): the Atlantic near the Buchanan Keys (Buchanan), the East Central near Cowpens Key on Cross Bank (Cross), the Northeast near Eagle Key (Eagle), the Interior near Coon Key (Coon) and between Roscoe and Dump Keys (Dump), and the Gulf near Oyster Keys (Oyster). Buchanan is characterized by a moderate tidal range and good exchange with the Atlantic Ocean. Cross has a small tidal range and is isolated by other banks from either freshwater or marine exchange. Eagle has a small tidal range, but is near the Taylor River emptying into Little Madeira Bay and is, therefore, susceptible to freshwater input from the mainland. Coon and Dump both have a small tidal range and are isolated from both freshwater and marine exchange. Oyster has a large tidal range and is open to the Gulf of Mexico. The previous study employed a stratified sampling design with the strata being transects along the top and either side (ca. 50 cm deeper than the top) of a given seagrass­covered mud bank. Our comparisons here include only the leeward transects from the 1984­'86 study.

Temperature and salinity varied somewhat between the two studies, but the differences were not pronounced and were probably of little consequence to the fauna. At three of the six sites we sampled under warmer conditions than were recorded in 1984­'86. At Buchanan and Dump this included both our summer and autumn samples and at Coon this included a portion of our autumn sampling. The overall temperature range for all sites combined in 1994­'95 did not, however, exceed that in 1984­'86. Salinity differences between the two studies are also rather unremarkable. In both studies the lowest salinities were recorded at Eagle. At the two interior sites, Coon and Dump, slightly lower salinities were recorded in winter and summer of 1994­'95, and at Coon slightly higher salinities were recorded in autumn of 1994­'95. Again, the overall range in 1994­'95 did not exceed that in the previous study.

In contrast to the physical data, a marked change occurred in seagrass density over the ten­year period at one of the six sites: there was a large decline in seagrass density at Dump. Otherwise, increases in seagrass density were recorded for the beds at Eagle and Coon, but density at these sites was relatively low in both studies. Seagrass density at Buchanan and Cross was relatively high in both studies, and seagrass density at Oyster was somewhat intermediate between the low values at Eagle and Coon and the high values at Buchanan and Cross.

Among the fish, most sites were numerically dominated in both studies by two species that we term "canopy residents", the rainwater killifish (Lucania parva) and the goldspotted killifish (Floridichthys carpio), and two species that we term "benthic residents", the gulf toadfish (Opsanus beta) and the code goby (Gobiosoma robustum). Canopy residents may live near the substrate but are relatively motile and are often found up in the water column; they may, therefore, be quite reliant upon seagrass for cover. Benthic residents live on or in the substrate, are less motile, and may depend less on seagrass cover. Fish species richness in both the 1984­'86 and 1994­'95 studies was highest at the two stations with free exchange with marine waters, Buchanan (25 and 16 species, respectively, in the two studies) and Oyster (20 and 16 species), and lowest at the two interior sites, Coon (6 and 9 species) and Dump (9 and 10 species).

Among the decapods, the bryozoan shrimp, Thor floridanus, numerically dominated all sites in 1994­'95 and all but Oyster in 1984­'86. Several other grass shrimp in the genera Periclimenes and Hippolyte were prominent at most sites as were alpheids (genus Alpheus). Pink shrimp, Penaeus duorarum, were prominent at Oyster in both studies and at Buchanan and Coon in 1994­'95. As with the fish, the shrimp faunas at Buchanan (12 and 9 species) and Oyster (12 and 11 species) were the most speciose, with richness being much lower at the other sites (only two species were collected at Dump in 1984­'86).

Total fish density in both studies was highest at Dump and lowest at Eagle despite a significant decrease at Dump and increases at both Eagle and Oyster over the ten­year period. Median numbers ranged from 28 and 22.5 fish per m2 (for 1984­'86 and 1994­'95, respectively) at Dump to 3 and 7 fish per m2 at Eagle. Density of benthic resident fishes increased significantly over the ten­year period at both Dump and Oyster but did not change elsewhere. Density of canopy residents was more variable between the two studies, with significant differences at five of the six sites. These differences included declines and Dump, Buchanan, and Cross and increases at Eagle and Oyster. An overall comparison of fish community composition at the six sites revealed that the most marked change was in the increased percentage of the fish community comprised by benthic versus canopy species at Dump. At the species level, this change at Dump was due to a significant density decrease in one canopy resident, rainwater killifish, and significant increases in two benthic residents, code and clown gobies.

We suspected that the increased densities of total fish, benthic residents, and canopy residents at Oyster might be due to a different mix of Halodule­versus Thalassia­dominated samples in the two studies (this site has the most heterogeneous seagrass bed of any of our sites). A closer investigation of this phenomenon, however, revealed that Halodule­dominated samples collected in 1984­'86 produced significantly fewer fish than did Halodule­dominated samples collected in 1994­'95. This situation warrants further investigation.

By dividing the shrimp community into three categories (small carideans [with a variety of lifestyles], alpheids [benthic], and penaeids [generally inactive by day]) we found and increased importance (in terms of percent faunal composition) of benthic species at Dump, Coon and Oyster. Overall densities of the numerically dominant shrimp, Thor floridanus, parallel those of fish, with densities at Eagle and Coon being lower and those at Dump, Cross, and Buchanan being higher. In this case, however, the density at Oyster was also low. Significant changes over the ten­year period occurred at Coon and Dump (decreases) and Eagle (increase), but, again, the most dramatic difference was at Dump, with the median value dropping from 978 to 52 T. floridanus per m2. The benthic alpheids increased at Coon, Dump, and Oyster and decreased at Cross. The dramatic increase at Dump is evidenced by a change in the median density value from 0 to 11 alpheids per m2.

In summary, the most dramatic changes among these six banks occurred at the site near the Dump Keys. At most sites salinity, temperature, and benthic fish densities changed little over the ten­year period. Other parameters were more variable, but the greatest changes were at Dump. Species richness of shrimp and fish in both studies was greatest at the sites with the most marine influence and least at the sites most isolated from either marine or freshwater influence. Inter­site fish density patterns were also similar between the two studies, with the low­circulation, freshwater­influenced Eagle site and the low­circulation Coon site producing the fewest fish. Densities of seagrass, total fish, canopy fish, and Thor floridanus all declined significantly at Dump. Benthic fish and alpheid shrimp densities, on the other hand, increased significantly.

At the species level the change in the fish community at Dump was due to a significant decrease in the abundance of rainwater killifish and significant increases in the abundance of code and clown gobies. What does this change translate into in terms of forage fish on this bank? If we take the statistical liberty of averaging our density data over the 922,860 m2 area of bank between the southernmost Dump Key and Roscoe Key, and also turn our numbers into biomass based on the average weight for each species at Dump, we estimate that, on any given day, this bank community contained 1,590 kg less rainwater killifish biomass and 822 kg more code and clown goby biomass during 1994­'95 than during 1984­'86. For the piscivore this means approximately half the forage biomass concentrated in these three numerically dominant species. The ultimate effect of this change, however, may also be influenced by differences in predator efficiency in dense versus sparse seagrass and in capturing canopy versus benthic prey.

In the immediate future we plan to continue sampling at some or all of our sites in order to obtain a database more comparable to the 1984­'86 database, initiate sampling in other areas of interest (based on perceived changes occurring in seagrass beds at these locations, among other factors), and begin (with the collaboration of other researchers) an evaluation of the health of resident animals at different locations in the Bay (e.g., parasitological and histological studies) and conduct further analysis of our decadel comparison.

Thomas W. Schmidt, Everglades National Park, South Florida Natural Resources Center, 40001 State Road 9336, Homestead, Florida 33034-6733.

Fishing activity and harvest of sportfish from Everglades National Park have been monitored nearly continuously since 1958. It is one of the oldest, ongoing marine creel census surveys in the U.S. This monitoring program was orginally initiated because of concern over greatly increased fishing pressure resulting from the construction of a highway, marina facilities and access canal to Whitewater Bay in 1958. The first ten years of the program (1958-69) were conducted through contract with the University of Miami and were directed at evaluating only the sport fishery at Flamingo. Over 75 species of fish have been reported within the recreational catches; however , five species (gray snapper, spotted seatrout, red drum, sheepshead, and black drum) have comprised over 86% of the catch since 1958. In 1965, a permitting system was instituted for commercial (hook and line, netting, trapping and professional guides) fishermen operating in the park. Harvest of three top sportfish; gray snapper, seatrout, and red drum approached maximum sustained yield (MSY in numbers) between 1974 and 1986 when commercial fishing was permitted. Until 1972, these catch data consisted of monthly total harvest, by species, for each fisherman. The harvest reports were voluntary and did not include any measure of fishing effort or specific areas of fishing harvest so it was impossible to monitor populations by ecosystems or management unit, or to evaluate the degreee to which fishermen complied with the reporting requirements of there permits. In 1972, the NPS expanded the harvest monitoring program to include daily trip ticket reports from the commercial permit holders, fishing area classifications, effort data, random field checks by patrol rangers for compliance, and developed censusing techniques to evaluate total parkwide sport fishing and commercial effort. In 1978 a detailed account of the park's fishery database was completed in response to sport fishermen and professional guide complaints of declining stocks. An overall decrease in fish stocks was noted during the mid-1970's, these declines are believed to have been the result of low rainfall and reduced estuary runoff resulting in increased natural mortality and reduced recruitment rather than harvest. In 1980, new regulations were established to create aggregate bag limits for both commercial and sport fishermen, mandatory reporting as a condition of a permit, and to abolish all commercial fishing (except for guides) after 1985.

This report presents an analysis of catch/harvest data from Florida Bay ( Areas 1-5) to evaluate current trends in abundance for the top four gamefish species, (red drum, spotted seatrout, gray snapper and snook), based on recreational guide and non-guided catch and harvest per unit of effort data (CPUE, HPUE). These data include: (1) recreational winter quarter ramp data from Flamingo 1980-90 and 1995, (2) annual guide data within the park (1980-1989, and 1994), and (3) 1994 guide data, stratified by fishing area and projected on GIS maps. Monthly guide reports consist of daily trip entries indicating amount of effort (hours fished), resultant catch, number harvested and area fished for each day. All of the recreational non-guided fishermen catch data for Florida Bay has come from weekend day interviews conducted at the Flamingo boat ramps. Monthly guide reports and interview sheet summaries provide estimates of catch and harvest (fish landed) per unit-effort for successful fishermen (those fishermen who caught spotted seatrout, red drum, gray snapper, snook).

For seatrout, during 1980-90 and 1995, a similar general pattern was seen for the average number of spotted seatrout harvested per successful boat and per hour of fishing out of Flamingo, as that shown by guide catch/harvest per hour data for 1980-90, and 1994. The lack of increase in harvest per boat and per hour fished in 1994, may be due to regulations imposed on the fishery in 1989 by the state of Florida and adopted by the park which raised the legal size limit from 12" to 14", For 1995 quarterly data, seatrout reached new highs in numbers released and may reflect a good stock recruitment of small juvenile seatrout. Lower catches were reported in southern Florida Bay (Area 2). During the most recent winter quarterly periods analyzed, 1990 and 1995, snook catch rates abruptly increased over the 1987-89 period and reflect a good stock recruitment of small juvenile snook . The large increase in catch/harvest rate from 1982-86 occurred despite size and bag limits and a five month closure on the fishery. Because of length-limit restrictions and closed seasons on snook and possible changes in fishing behavior, an unknown number of fishermen are releasing their catch to support recent promotions in catch-and-release fishing. Snook catches were highest in the 10,000 Islands and lowest in southern Florida Bay.

For red drum, during 1989-90 and 1995, the average winter harvest per successful boat at Flamingo has followed a pattern similar to that of winter average harvest rate per man-hour. The lack of increase in harvest per boat and per man-hour is probably due to the 1989 bag limits of 1 fish per person following almost two full years of prohibited harvest (1987-88). Increased size limits (12'' to 18") and a closed season imposed on the fishery in September 1985 probably accounted for the large declines in average harvest per boat and per man-hour fishing in 1986, however, the sharp declines in harvest rates during 1985 suggest the possibility of overharvest or poor recruitment. The increase in 1995 average winter catch per boat and per man-hour fishing may be a result of the decline in harvest/catch rates from 1985 to 1990, allowing offshore stocks to rebuild and recruitment to increase in Florida Bay as observed in winter 1995. Guide harvest rates of red drum from 1980 to 1984 have followed catch rates being highest in 1983 and lowest in 1982. The large decline in harvest from 1985 through 1987 is probably due to increased minimum size limits. Slightly higher catch rates were found in areas 2 and 5, the outer reaches of the estuary, than in areas 1, 3, and 4, the more inland portions of the Bay, and is probably due to the fact that red drum recruit to the park's fishery from offshore waters. During the 1990's, the average number of gray snapper harvested per successful trip and per hour of fishing out of Flamingo has dropped as low or lower than anytime during the previous record and the trend may continue downward. For the guides, there was little annual variation in CPUE/HPUE until 1990 when the HPUE dropped lower than anytime during the previous record. One factor that partially explains the lower harvest per boat and per hour fishing may largely be due to the regulations imposed on the fishery in 1988 when the legal minimum size was increased from 6 to 8 inches, and in Feb.1990, which established a minimum legal length of 10" and a bag limit of 5 fish per person. During 1989-90 and 1995, the increase in catch but not harvest may reflect a good stock recruitment of small juvenile fish which are being released because of size regulations. In 1994, the highest catch rates of gray snapper for Florida Bay were found in Area 2. Recent studies of larval and juvenile fish within the park suggest that coral reefs off the middle and lower Florida Keys probably supply much of the recruitment to the park population. Spawning occurs on the reefs and the larva drift to the estuaries via tidal flow. Therefore, management of the park's gray snapper population must consider harvest occurring outside the park particularly in respect to recruitment. Although recent bag and size limits and seasonal closures have reduced harvest, catch rates for seatrout, snook, and red drum have increased in the 1990's.

Last updated: 04/23/98
by: Monika Gurnée
gurnee@aoml.noaa.gov