Category Archives: Notes from the Field

Assessing temporal and spatial trends in fish assemblages within spring runs of the St Johns River basin

By Phillip Parsley

Springs in the middle St. Johns River basin are known for their clear water, intrinsic beauty and unique wildlife viewing opportunities.  Every year tourists and residents spend countless hours swimming in headspring pools or paddling down spring runs enjoying the breathtaking scenery of wild Florida.  However, recent natural events as well as anthropogenic influences have altered our perceptions regarding the health and vulnerability of some of these springs. Researchers and stakeholders have started to notice that lush aquatic vegetation has been replaced by dense algal mats and fish abundances have drastically reduced and been replaced by exotic fish species as habitat and water quality deteriorates.

While numerous studies exist that describe water quality of springs in the St. Johns River basin and include information on plant and invertebrate communities, information describing the fish communities of these springs is lacking.  In order to better understand the complexities of these fish assemblages, primary goals of this project were to determine an efficient sampling protocol for eight springs and their associated spring runs in the St. Johns River basin that will provide baseline data on community fish assemblages; and to document the presence of exotic fish species utilizing springs and how their abundances may change seasonally.

Figure 1. Locations of study springs within the St. John’s River Basin.

The springs and their associated runs in this study are Alexander Springs, Gemini Springs, Juniper Creek, Rock Springs, Salt Springs, Silver Glen Springs, Spring Garden (also known as DeLeon Springs), and Wekiva Springs (Figure 1). 

FWC standardized river sampling protocols were followed as closely as possible. However, some of the spring runs contained areas of dense aquatic macrophytes and a standard electrofisher boat was not practical.  An airboat electrofisher was used instead in these types of areas to avoid the unnecessary destruction of critical vegetation.  Also, a smaller boat we called the “mini-shocker” (Figure 2) was used in Rock Springs Run due to the narrow nature of the run and shallow areas where an electrofishing boat could not access.

A total of 406 sites spread across the eight study springs have been sampled since this project began in March 2019.  204 sites were sampled during the first round of sampling in summer 2019 collecting a total of 21,933 fish comprising 59 different species.  202 sites were sampled in winter 2019-20 and this netted 15,705 fish and 56 different species.  As one may expect, Bluegill (14.9% of total combined catch), Redbreast Sunfish (13.7%), Spotted Sunfish (12.6%), and Largemouth Bass (6.3%) were the most common sportfish encountered as far as total abundance.  Largemouth bass also comprised over one-fourth (25.3%) of the total percent biomass across all samples, with Bowfin (19.3%), Florida Gar (8.8%), and Lake Chubsuckers (8.7%) the next highest contributors.

Figure 2. “Mini-shocker” boat used to sample Rock Springs Run.

Five exotic fish species were collected during both rounds of sampling.  Blue Tilapia (n=153), Brown Hoplo (n=23), Dimerus Cichlid/Chanchita (n=4), Vermiculated Sailfin Catfish (n=62), and Walking Catfish (n=6) were all found to occur in multiple spring runs, however, they only represented 0.7% of the total catch and 4.3% of total biomass, both very miniscule portions of the entire sample.  Standard electrofishing procedures do not appear to be the best method for capturing an accurate representation of the numbers of exotic fish species occurring in the springs so in the future utilizing alternative methods could provide us with better information. 

The Bluenose Shiner (Figure 3), a state listed threatened species, was collected in Rock Springs Run and the Wekiva River.  Isolated populations of this species occur in the St. Johns River Basin and this fragmentation makes it vulnerable to extirpation from this region.  Finding this species in some of our study waterbodies was a positive and brainstorming is already underway as far as future research projects that could contribute to better understanding how best to conserve this species.

Figure 3. Bluenose shiner collected from Rock Springs Run.

Through days of field work over the past year we believe we have developed efficient sampling procedures for our study systems.  By using those protocols, we now have extensive sampling that yielded a total of 37,638 fish and 63 different species.  Calculating similarity indices between sample seasons will help us better analyze how these community assemblages may change in each spring as well.  Hopefully, the data collected in this study can provide future researchers insights and direction on the best way to make decisions regarding the health and viability of these springs as unique ecosystems. 

Gag Grouper: Where Have All The Cowboys Gone? Evaluating Spatio-Temporal Trends in Male Abundance and Reproductive Dynamics in a Sex-Changing Reef Fish

By Sarah Burnsed, Hayden Menendez, and Sue Lowerre-Barbieri

Gag grouper (Mycteroperca microlepis) are an iconic Florida fish that may be in trouble.  All fish begin as females in estuarine nursery grounds, but as they age they move further offshore, with the oldest, largest fish turning into males (Figure 1).  This life history and spatial ecology pattern makes it difficult to decide on the best measure of reproductive potential.  Based on females-only, the last stock assessment found them to not be overfished or undergoing overfishing. But the same assessment predicted only approximately 2-3% of the population was male and since then commercial fishermen have not been meeting quota, leaving fishermen and scientists concerned that this stock may not be as healthy as assumed.

Figure 1: Conceptual model of gag spatial ecology. Seasonal information is in parenthesis, yr = year, mo = month.

 Beginning in 2015, the Movement Ecology and Reproductive Resilience (MERR) Lab at FWRI began a series of gag studies to evaluate factors affecting gag reproductive potential. Empirical data derived from these studies, including estimates of fecundity-at-age, spawning frequency and sex ratios, and spatio—temporal patterns of sex change and sex ratio, will help to refine estimates of long-term biological productivity of the stock and in turn better manage this important fishery. We describe our three major gag program initiatives below.   

Our initial study (December 2015- May 2018) off the Florida Panhandle targeted the best-known gag spawning habitat ~50-100 miles off Panama City Beach.  Three areas were sampled, with varying protection from fishing: (1) Madison Swanson, an MPA (2) The Edges, open half the year to fishing (3) an open area. Twice monthly during gag spawning season (December-May), we departed lab headquarters in St. Petersburg to drive to Panama City and boarded chartered fishing boats for multiple day cruises. We captured gag using hook-and-line and recorded parameters of time landed, location, depth and ventral pigmentation. We collected video data using an unbaited camera array with a ~360° field of view to assess habitat, spawning behavior and abundance. We evaluated all gag for lengths, weight, genetics, mercury, age, sex, hormones and maturity. Data from our collections were integrated with data from FIM surveys, FDM, and a collaborating commercial fisherman to test assumptions about sex change and spatial management in gag. Results indicate overall gag abundance is low, MPAs do not protect all recruiting males (as previously assumed) and current regulations are not sufficient for males to recover to historic levels. To read more on this study, please see: Lowerre-Barbieri S, Menendez H, Bickford J, Switzer TS, Barbieri L, Koenig C (2020) Testing assumptions about sex change and spatial management in the protogynous gag grouper, Mycteroperca microlepis. Mar Ecol Prog Ser 639:199-214. https://doi.org/10.3354/meps13273.

To assess how these results might differ with location, a second study was begun in December 2018 (extending through May 2021).  This study uses similar methods but is focused ~100 miles offshore of Tampa Bay at (1) Steamboat Lumps, an MPA and (2) the Sticky Grounds, an open area south of Steamboat Lumps, originally brought to our attention by fishermen and confirmed as a spawning site by preliminary sampling. Both habitats are quite different from those in the Panhandle with Steamboat Lumps having considerably less relief than Madison Swanson and the Sticky Grounds characterized by patchy high relief in depths greater than sites sampled before.  Because gag spawn at these offshore sites in the windy winter months, it is not surprising previous sampling in this area has been limited due to uncooperative seas and day trips requiring 18 hour runs from shore. We are fortunate to again work with an impressive group of captains willing to safely execute these trips and share their knowledge of the gag fishery to increase our success.  By expanding the area of collection, we’ll be able to identify and quantify gag spawning aggregations, sex ratios, and reproductive potential off the West Central Florida Shelf and compare these parameters to those collected in the initial study to determine spatial and temporal differences within and between study areas.

Figure 2: MERR biologist Hayden Menendez sampling blood from the gills of a gag grouper during a directed offshore charter trip. Blood is drawn immediately after capture and processed as part of a companion study to assess if hormones can help indicate transitional fish, which are difficult to determine even with histology.

These studies, and the integration of their results with the larger sampling efforts of the FIM reef fish survey and FDM, changed our understanding of where and when gag change sex.  Previously, it was believed that this occurred only on the spawning grounds and that spawning ground MPAs would protect males.  However, we found fish transitioning from females to males not only on the spawning grounds but also in pre-spawning female-only aggregations. Thus, there is a need to better understand pre-spawning aggregations, their seasonal cues, and spatial consistency, as well as sex-specific movement ecology.  Research on these questions was started in December 2017 when the same fisherman who provided samples from a gag pre-spawning aggregation site for our first study began working with us to dart tag and release gag at his nearshore site. 

 In 2019 and 2020 we increased this effort to include scientific sampling of pre-spawning gag aggregations, dart tagging a larger number of fish, and beginning a program to acoustically tag females (Figure 3 and cover image). Our recaptures so far suggest very high site fidelity of females to pre-spawning aggregation sites, as well as much higher catch per unit effort at these sites than on the spawning grounds. We expect recapture rates at these sites to decrease as fish begin moving offshore. In addition, acoustic tag detections will help us understand where these females move to once they leave these sites. Our ability to detect them throughout the Gulf is made possible because of the iTAG (Integrated Tracking of Aquatic Animals in the Gulf of Mexico) network, which enables researchers to share detections on their receivers that are not their study species.  This network and the data exchange are FWRI initiatives, with the digital exchange developed and maintained by the FWRI Information Science and Management section. These telemetry detections along with dart tag recaptures and reproductive  data will collectively enable us to better understand how this species’ spatial ecology affects vulnerability to fishing and the measures needed to allow more males to recruit to the population, hopefully in turn keeping this valuable fish on dinner plates across the state.

Figure 3: The incision used to insert the acoustic tag is stitched up with one stitch and a series of three knots.

Monitoring and Assessment of Eastern Oyster Growth on Created Oyster Reefs in Tampa Bay

By Dr. Ryan P. Moyer

Oyster reefs, constructed primarily by the eastern oyster (Crassostrea virginica), provide critical ecosystem services to nearly all of coastal Florida. Over many years, multiple generations of oysters settle upon one another, constructing a large reef structure that stabilizes sediment and provides a hard substrate that is utilized as habitat by other species. Oyster reef habitats are crucial components to coastal ecosystems and provide substrate, habitat, and/or food sources to numerous species of gastropods, crustaceans, sponges, worms, fish and birds. Thus, their ability to support recreational and commercial fish species, improve water quality through filtration, and reduce shoreline erosion highlights their significance as critical species within estuarine ecosystems.

In Tampa Bay, continued coastal development, dredging, and historical harvests have led to a reduction in suitable hard substrate for oyster recruitment. Beginning in the early 2000s, several public and private organizations initiated the installation of artificial oyster reefs to mimic the natural substrate oysters need for settlement and growth. These reefs were constructed from shell, concrete domes and mesh shell bags, and were placed throughout Tampa Bay to increase available oyster habitat and oyster populations. In collaboration with Tampa Bay Watch and the Tampa Bay Estuary Program, the Florida Fish and Wildlife Research Institute (FWRI) Coastal Wetlands Research Program implemented a study to assess and monitor oyster growth on old (>5 years), moderate-age (2-5 years), and young (<2 years) constructed oyster reefs.

FWRI Coastal Wetlands staff perform oyster density counts as part of monitoring on a young created oyster reefs (foreground). At the same time ecological surveys are conducted, high-precision elevation surveys are conducted to assess elevation change in newly constructed oyster reefs (background)

Physical assessments of oyster growth (e.g., oyster density, shell height, associated fauna) are coupled with real-time kinematic (RTK) Global Positioning System (GPS) surveys resulting in high-resolution (cm) elevation control of both the reefs and associated shorefaces being sheltered by the reefs. To date, 16 constructed oyster reefs in Tampa Bay with variable substrates (shell bags, concrete domes and loose shell) and ages (old, moderate and young) have been assessed, with young-age reefs being monitored bi-annually. In addition, three nearby natural reefs have been identified to serve as controls, and the same metrics used on created reefs are measured there. Physical oyster growth and faunal information at the 16 sites will be correlated to elevation (depth below mean tide level) and age (young, moderate, old) to further understand how these reefs mature over time.

Oysters are tolerant to prolonged areal exposure, however in order to release toxins and feed they must be submerged; therefore, it is imperative to maintain tight elevation controls during reef construction to ensure proper placement of substrate within the water column. As a result, reef sections situated above, or below suitable oyster settlement depths may experience reduced settlement, increased predation and reduced growth. The conclusions from this study will be used to maximize oyster growth potential and inform adaptive improvement in the planning and design phase of future oyster restoration projects to ensure maximum recovery of healthy oyster populations in Tampa Bay and around Florida.

Spatio-temporal Distribution of Endocrine-Disrupting Compounds in the Florida Keys

By Renee Duffey and Luke McEachron

Water quality throughout the Florida Keys remains a principal management concern because pollutants can have significant impacts on fish, wildlife and sensitive reef systems. In recent years there has been increasing concern regarding environmental effects of endocrine disruptors (EDCs). EDCs are commonly found in pharmaceuticals and personal care products (PPCP), pesticides and other household products. Endocrine disruptors mimic hormones and can cause a wide range of health problems in humans, fish, and wildlife even at small doses.

EDC occurrence has been documented by several studies throughout Florida, however, no single spatial database or map has organized historic and current EDC sampling throughout the FKNMS, or the Florida Reef Tract, despite widespread recognition that EDCs are a threat to biological and economic resources.  To address this need, the Information Science and Management section initiated a one-year project to summarize the type, concentrations, sampling gaps and distribution of endocrine-disrupting compounds (EDC) primarily in the Florida Keys.

We compiled 15 datasets representing approximately 951 unique sampling locations and 621 chemicals. Of the over 600 chemicals included in the database, only 91 chemicals were federally listed by EPA as known endocrine disruptors (2009, 2013). While not federally listed, numerous chemicals have potential endocrine disrupting properties documented in the scientific literature and by non-federal authorities (e.g., World Health Organization (WHO), United Nations (UN)). Consequently, we expanded the scope of the project to include potential EDCs and also chemicals that either indicate human by-products (e.g., caffeine, sucralose, cholesterol and other human waste indicators).

Unlike other routine water quality monitoring programs, EDC sampling was generally isolated to one or two sampling events and/or targeted specific locations. Lack of long-term, consistent sampling presents challenges when assessing spatial or temporal patterns in EDC concentrations. Additionally, very few chemicals of the 621 we identified in this study were sampled by more than one data provider. Differences in laboratory detection limits between data providers also makes comparisons difficult, particularly for EDC concentrations which are often at or below detection limits.

Data compiled by this project are available online via the Endocrine-disrupting compounds (EDCs) in the Florida Keys Story Map. A Story Map combines maps with narrative text, images, and multimedia content to create compelling, user-friendly web apps.

Young Sea Turtles and Floating Debris in Sargassum Habitat

By Tomo Hirama

Sea turtle hatchlings emerge from sandy beaches, swim offshore, and, in a few days, reach Sargassum-dominated surface-pelagic drift communities (or Sargassum habitat). The Sargassum habitat provides protection and food for these sea turtles during the first few years of their lives. We have found that these turtles are opportunistic omnivores, apparently feeding on anything that fits into their mouths including synthetic materials that can harm them. Sargassum, plastics, and other floating objects gather at surface convergence zones that are typically located at the edges of ocean currents. After exposure to ultraviolet rays and other aspects of the ocean environment, large-size plastics are broken down into smaller fragments that are then bite-sized for the young sea turtles in Sargassum habitat. Alarmingly, we have observed a high prevalence of plastics included in the diets of these turtles.

Sargassum habitat with debris.

Because of late-summer to fall storm events, some post-hatchlings, which are only a few weeks to a few months old and have been living in Sargassum habitat, are washed back on the beaches, mainly along the East Coast of Florida. These wash-backs are often in poor condition. Some are found dead and others die later at rehabilitation facilities. Since the early 2000s, we have been examining the gut contents of wash-backs that died. The percentage that had ingested plastics was about 80 % during the early 2000s but has reached 100 % during recent years. When ingesting plastics, the wash-backs seem to have no preference in color; we see a wide range of colors of plastic in their GI contents, with the majority being translucent and white as these are the most abundant types in the Sargassum habitat. By dry weight, about 30 % of the gut contents from these turtles were plastics.

The gastro-intestinal content of a wash-back that was 7.8 cm straight carapace length.

In addition to our study of wash-backs, we have also been capturing and studying post-hatchlings in the offshore Sargassum habitat. When comparing these two groups, we’ve found that the body condition index of the wash-backs was significantly lower than that of the post-hatchlings that were captured offshore.  Although the relationship between plastic ingestion and cause of death is often not clear, the ingestion of plastic may result in nutritional dilution (non-nutritious material contributing to a feeling of satiation and reducing the urge to continue feeding) or may cause an impaction of the digestive tract.

FIM’s Marine Fish Mercury Program — Indian River Field Lab

By Richard Paperno and Deb Leffler

The Florida Fish and Wildlife Conservation Commission’s Fish and Wildlife Research Institute (FWC-FWRI) Mercury Program conducted by the Fisheries-Independent Monitoring (FIM) Program is one of the most comprehensive efforts in the United States for monitoring mercury concentrations in marine and estuarine fishes. Mercury is a toxic metallic element that has been shown to bioaccumulate in fish tissue. Humans and wildlife that consume fish can potentially ingest significant levels of mercury in their diet. In 1989, the FWC-FWRI began to examine total mercury levels in fish muscle tissue from many economically and ecologically important species to better understand mercury contamination in Florida’s marine fishes. With analytical cooperation from the Florida Department of Environmental Protection, the program’s initial goal was to document mercury levels in Florida’s commercial and recreational fishery species to assist the development of regional Fish Consumption Advisories. In 2006, the FWC-FWRI began analyzing mercury samples in-house at the Indian River Field Laboratory. This addition expanded the program’s analytical capabilities and its focus to now include ecologically important predator and prey species in marine and estuarine habitats.  Currently, the Indian River Field Laboratory is responsible for all analyses of marine fish mercury samples within the waters under Florida’s jurisdiction.  

To date, we have examined the concentration of total mercury in more than 113,000 fish representing over 350 species. These species represented all major trophic groups from primary consumers (e.g., anchovies, herrings, mullets) to apex predators (e.g., mackerels, tunas, billfish, sharks). Most individuals we examined contained low concentrations of mercury, but concentrations in individual fish varied greatly within and among species. Overall, fish concentrations ranged from 0.001 ppm to 32.0 ppm, yet only 10% of all individuals analyzed had tissue concentrations above the U.S. EPA “Choices to Avoid” consumption guideline of approximately 0.47 ppm. Species with very low average mercury concentrations tended to be those that feed on plankton, detritus, invertebrates, or small fishes. Apex predators typically had the highest mercury concentrations. In most species, mercury concentration increased as fish size and age increased.

The data generated by the FWC-FWRI Mercury Program have been used to inform the public and to weigh the potential risks and health benefits of consuming common fishery species in Florida. These data have also advanced scientific research regarding ecological tracers and ecosystem function. Indian River Field Laboratory scientists have shared Florida mercury results through numerous professional presentations at scientific conferences, technical reports, and more than 20 publications in scientific journals. Ongoing cooperative collaborations regarding mercury with researchers within and outside of the FWC-FWRI currently involve stable isotope applications, point- and non-point source identification, ecosystem-wide assessments, and evaluation of mercury effects on marine fishes at the sub-cellular level.  Sampling in Florida waters is continuing, and FWC-FWRI research relating mercury to fish age, feeding ecology, and the trophic structure of Florida’s marine and estuarine ecosystems will help us better understand concentrations of this element in marine fishes and their habitats.

Understanding the Gravidity of the Situation: Developing a Calendar of Freshwater Mussel Reproduction

By Susan Geda and Lauren Patterson

Freshwater mussels within the family Unionidae are one of the most imperiled groups of animals in the world. Of the 61 species that occur in Florida, 60% are endemic to Florida river basins and over 25% are listed under the endangered species act. To aid freshwater mussel management efforts, the FWC Freshwater Mussel Conservation Program (FMCP) implements standardized sampling for the long-term monitoring of mussel populations statewide.

An important aspect of long-term monitoring is understanding reproductive requirements of target populations. Freshwater mussels possess an extremely unique life cycle, requiring a phase of parasitism during larval development that uses freshwater fish as hosts. Glochidia (larvae) are brooded in the female mussel’s gills, undergoing several developmental stages. Once mature, the mussel creates a shockingly accurate lure to mimic prey of host fish. When the fish bites, glochidia burst from the mussel and attach to the fish’s gills. Glochidia then transform into juveniles and drop off into the sediment, hitchhiking into new habitat. This process, as well as the migration of some fishes, is often mediated by water temperature. Therefore, as global temperatures rise, so does the probability that mussel and fish host distributions will not overlap during reproductively active intervals. When the timing of these natural phenomena no longer coincides with historical spawning seasons, species and the ecosystems that they support often fail to withstand the repercussions.

Collaborative efforts between FMCP and the U.S. Geological Survey resulted in publication of a non-lethal protocol for assessing gravidity (reproductive stage) in freshwater mussels. The protocol standardizes field and laboratory methods, a necessity considering previous studies classifying stages of larval development lack consistency. Uniformity of developmental stages allows results to be compared among all occurrences and species, enabling FWC biologists to develop the Freshwater Mussel Gravidity Almanac (FMGA), an online research tool for compiling and visualizing gravidity information collected using the published protocol. Being able to conceptualize when mussel species are brooding mature larvae throughout the year will help managers and biologists identify trends and data gaps, determine when to collect mussel broodstock, monitor impacts of climate change, and inform management decisions regarding fish and invertebrate populations. Thus, FMGA will facilitate future research, conservation and recovery efforts.

In the coming months, the FMCP will publish and integrate over ten thousand gravidity records collected since 2015. Conclusions drawn from the FMGA will become more robust as the dataset expands. Hence, this is where we ask for your help! Records of gravidity observation can be submitted through our desktop webpage or mobile application. Links for both can be found on the FMGA home page where the gravidity calendar and collection data are hosted. Once a submitted record and associated identification are validated, it is incorporated into the interactive gravidity calendar. The protocol includes visuals and character descriptions for differentiating each stage of development, and the phone application is user-friendly. Field surveys, long-term monitoring projects, and museum collections all present opportunities to contribute data and broaden the FMGA for a wider body of interest. Adoption of crowdsourcing projects like the FMGA will provide a more accurate understanding of population dynamics and further the conservation of these highly imperiled and extraordinary organisms.

Flatwoods Salamander Headstarting in the Apalachicola National Forest

By Pierson Hill

The Apalachicola National Forest (ANF) harbors one of only two remaining population “strongholds” for the critically imperiled frosted flatwoods salamander (Ambystoma cingulatum). Listed as Federally Threatened in 1999, recent annual surveys within the ANF have revealed ongoing and precipitous population declines and extirpations, raising considerable alarm among those concerned about the species’ survival. Dormant season prescribed fire regimes have failed to maintain the wetland plant communities the salamanders need for successful egg laying and larval survival, and woody succession has rendered most breeding sites unsuitable. Habitat restoration is underway, but the few remaining populations are precariously small.  For the past four years, FWRI biologists in the Reptile and Amphibian Subsection have been headstarting flatwoods salamanders to reduce the chance that the species will go extinct in the immediate future.

What is does it mean to headstart a flatwoods salamander? Following salamander breeding migrations in October-November, eggs (which are laid before wetlands fill up with rain) and aquatic larvae are collected from the field and brought into captivity where they are hatched into aquatic “cattle tank” mesocosms. The artificial mesocosm environment replicates the ephemeral pond habitats the larval salamanders normally occupy, but with the benefit of being absent of predators, providing lots of food, and having stable water levels. Once larvae reach large sizes or undergo metamorphosis, they are returned to their breeding ponds in April-May. Drift fences and mark-recapture are being used at a couple of these ponds to monitor population sizes and determine the fate of headstarted salamanders following their release.

The average larval survival rate in mesocosms is 90% — much better than the 10% estimated for wild populations. Our efforts have resulted in a total of 1,735 headstarts being released back onto the ANF between 2017 and 2019. An additional 450 have been sent to a captive assurance colony maintained by The Amphibian Foundation in Atlanta, Georgia. Unfortunately, we have seen few of these headstarts return to their wetlands to breed and the two populations we are monitoring continue to decline each year.

Greatly complicating these efforts, the ANF has been plagued with extreme winter rainfall patterns in each year of the project, and this winter is currently experiencing the third drought in the past four years. Without enough rainfall to fill breeding wetlands, there is little hope for natural salamander reproduction, and we must intervene to salvage as many eggs as possible. Accompanied by a small army of volunteers, we spend thousands of person-hours in December combing through vegetation in dry wetlands trying to locate eggs before they succumb to the harsh conditions. Despite heavy egg losses at some sites, this December we rescued approximately 1,350 live eggs from 13 ponds and hatched them into 95 mesocosms containing nearly 25,000 gallons of water. With a maximum planned capacity of 1,000 larvae, keeping this many mouths fed will be a major challenge, but it’s necessary to keep the species around for at least another year

More information on FWC-FWRI’s Flatwoods Salamander Headstarting Project can be found at myfwc.com and in FWRI’s 2020 Programs Document.

Estimating In-Season Recreational Fishing Effort and Catch in the Gulf of Mexico: A collaboration between FDM and CBM

By Colin Shea, Tiffanie Cross, and Bev Sauls

Florida’s recreational fishery in the Gulf of Mexico is characterized by over one million participants dispersed over a broad geographic area. For a recreational fishery of this size, the most feasible method for monitoring effort (number of angler trips) and catch (landings in pounds) is through off-site sampling. Florida’s Gulf Reef Fish Survey (GRFS) employs an off-site mail survey of registered anglers, in addition to dockside intercept surveys conducted in the field, to estimate annual recreational fishing effort and catch for several reef fish species, including red snapper. Although off-site sampling methods such as the GRFS mail survey enable monitoring of large-scale fisheries at a reasonable cost, estimates derived from these methods are typically not available until after the recreational fishing season has ended. This delay presents a challenge, as management of recreational fisheries under annual catch limits (ACLs) requires the ability to accurately predict when an ACL will be reached. Managers of recreational fisheries would therefore benefit from the availability of in-season estimates of effort and catch.

Using the 2019 Gulf of Mexico recreational red snapper fishery in Florida as a case study, Fisheries Dependent Monitoring collaborated with the Center for Biostatistics and Modeling to explore the utility of a model-based approach to estimating in-season effort and catch. This approach used an in-season index of fishing effort, derived from interviews conducted at fish landing sites throughout the region, to estimate recreational fishing effort prior to the availability of GRFS mail survey estimates. We then derived mean catch rates (pounds harvested per trip) to estimate total catch (landings in pounds) for the 2019 red snapper recreational fishing season. Ultimately, our goal was to compare the model-based estimates of effort and catch to those derived from the GRFS after the close of the 2019 season. Our case study indicated that a model-based approach provided in-season estimates of effort and catch that were comparable to those derived from the GRFS. The model-based prediction of total red snapper catch in June and July 2019 averaged 1,141,127 pounds, or 67% of the ACL, whereas the GRFS estimate for the same time period was 1,175,920 pounds, or 69% of the ACL.

Reliable in-season estimates of effort and catch are useful to managers because they can help to inform decisions about extending or shortening the recreational fishing season. Indeed, our efforts contributed, in part, to the decision to extend the 2019 red snapper season by six days in October and November. Importantly, the Gulf Reef Fish Survey was credited by officials for contributing to the effective management of Florida’s recreational red snapper fishery in the Gulf of Mexico. As a group, the Center for Biostatistics and Modeling is excited to continue our collaborative effort with Fisheries Dependent Monitoring, and we hope to refine our approach and explore new avenues as we move into the 2020 recreational fishing season and beyond.

Evaluating Eelgrass for Restoration at Lake Apopka

By Jamie Richardson and Maggie Bass

Many of us are familiar with Lake Apopka – once known for its pristine waters and premier fishing, then known for its status among the most polluted lakes in the state. Pesticides and fertilizers from agricultural run-off were pumped into the lake from the 1940s to the 1990s. Over time this sandy bottomed, clear watered system turned into a muck bottomed, algae filled lake that appears green on every satellite image you see. Fish, wildlife, and plants all suffered negative impacts from these decades of dumping. Many efforts have been made over the years to improve and restore Lake Apopka to its former glory with slow and limited success. A recent effort taken on by the University of Florida (UF) in collaboration with the St. John’s River Water Management District (SJRWMD) and FWRI is an initiative to repopulate submerged aquatic vegetation (SAV) in the lake. Our Freshwater Plants Research team began an ongoing monitoring and research project of Lake Apopka’s SAV, with a specific focus on American Eelgrass (Vallisneria spp.) as FWC’s contribution to this initiative.

Maggie Bass takes a sediment core from Lake Apopka near historic pump house.

In November 2018 our team, affectionately known as the “Action Snackers,” began monitoring a thriving patch of eelgrass located on the North Shore of the lake. Each month we note the changes we observe; record water depth, Secchi disk transparency and water chemistry data; and collect sediment cores from in and around the patch for analysis. The sediment cores are then processed and sieved down to very fine sediment components to reduce the sample material to the particle size of eelgrass seeds. Our sieved samples are then housed at the Eckerd College greenhouse in St. Petersburg for monitoring of germination.

Although our crew was oftentimes met with hurdles such as fast-approaching thunderstorms, extreme summer heat on breezeless days, or arriving to our collection site only to realize we were experiencing some equipment malfunction, our dedication and teamwork paid off. The results show that an eelgrass seed bank is present and possibly expanding. Our greenhouse data show an emerging pattern of seasonal highs and lows for eelgrass germination. Understanding this information will be important to restoration efforts, such as deciding which months planting would be most successful. The project is ongoing, and all data and results are being shared with UF and SJRWMD to assist management decisions to repopulate Lake Apopka’s SAV.

Maggie Bass checks an eelgrass specimen for reproductive parts.