Effects of the 36-year closure and opening of Joe Bay on fishes and recreational fisheries

By Kerry Flaherty-Walia and John Davis

Major portions of the coastal embayments in northeastern Florida Bay have been closed to public access, and thus to recreational fishing, since the creation of the Crocodile Sanctuary in 1980. The 2015 Everglades National Park (ENP) General Management Plan called for the opening of Joe Bay, which is part of the Crocodile Sanctuary, to public, non-motorized access and catch-and-release fishing. The Fish and Wildlife’s Research Institute’s Fisheries Biology and Fisheries-Independent Monitoring (FIM) programs are involved in a cooperative study with Florida International University, the Snook and Gamefish Foundation, the Audubon Society, and the National Park Service to examine the effects of the 36-year closure and subsequent opening of Joe Bay to catch-and-release fishing.

Locations of Little Madeira Bay, Joe Bay and Long Sound in Florida Bay.

To examine the effects of the closure on fish and macroinvertebrate (nekton) community metrics and recreationally important fish species, fisheries-independent and -dependent sampling methods are being employed across three embayments from 2016-2019 (Figure 1). Two of the embayments are in the Crocodile Sanctuary; Little Madeira Bay has been and will remain closed to fishing while Joe Bay was opened to fishing in November 2016. A third embayment, Long Sound, is not in the sanctuary and has been open to fishing the entire time.  Although the three coastal embayments appear similar in size and function, there are substantial environmental differences among the basins. Freshwater inflow into Joe Bay is much greater than the other two basins, and sediment depth and the amount of submerged aquatic vegetation (SAV) are quite low. Long Sound also has a very thin sediment layer but typically had the highest salinity, and in recent years, has experienced an increase in SAV cover. Little Madeira Bay has both a thick sediment layer and a consistently high percentage of SAV cover that includes Thalassia, indicative of a climax seagrass community. These existing spatial and habitat relationships will affect the prey base and recreational fishes and will be considered in assessing the effectiveness of the new management strategy.

Fisheries-independent surveys are being conducted during wet and dry seasons by FWC using small (21.3-m) and large (183-m) seines and by FIU using baited remote underwater video systems (BRUVs) using GoPro technology (Figure 2). In the first year of seine sampling, nekton communities differed significantly among basins; relative abundance of nekton was greatest in Little Madeira Bay, and the most numerous species were small-bodied fish that serve as the prey base, such as killifishes, mojarras, gobies, and schooling fish (silversides and anchovies), collected by the small seine. Unfortunately, the large seine technique (which collected the majority of recreationally important species) was only used in Long Sound and Little Madeira Bay because the depths and substrate in Joe Bay are not suitable to this sampling gear. The BRUVs, however, were deployed in all basins, and in contrast to the seine sampling, indicated that community composition was similar across basins.  Recreationally important species were most frequently observed in Little Madeira Bay in seines, but in Joe Bay on BRUVs. Sharks were seen frequently on video in Little Madeira Bay and may be affecting BRUV observations there. Trophic groups (small prey, large prey, mesoconsumers, and top predators) appeared stable over time as compared to previously collected seine data using the same methodology from 2006-2009, but there was preliminary evidence of species-specific differences within basins and over time.

Three methods are used to determine the effects of the fishing closure: A. BRUVs, B. Seines, C. Angler Reporting System.

Fisheries-dependent information is being obtained through an angler reporting system developed in conjunction with FIU, the Snook and Gamefish Association, and the Audubon Society (Figure 2, paper surveys and a mobile application). So far, the angler reporting system has a good response rate, but visitation to the recently opened no-motor zone in Joe Bay was low.

Two more years of sampling are ahead for this project, so more comprehensive data analyses incorporating hydrological and habitat dependencies are planned.  Seine and BRUV nekton community data will be compared between gears and across estuaries, and the long-term trends in visitation and angler experiences documented by the angler reporting system will be examined. This project will provide useful data for developing a long-term protocol for fisheries monitoring in these embayments into the future and demonstrates the advantage of collaborative research to reach a common goal.