3. Fisheries

Fisheries image
Photo: G.F. Pinto

3.1. Introduction

3.1.1. General Description

The LSJRB supports a diverse finfish and invertebrate community that has significant commercial and recreational value. Blue crabs account for the majority of landings comprising 65% (1,049,312 lbs) of the total landings for 2016 (FWRI 2017a). Commercial finfish accounted for about 33% (536,166 lbs) of the total catch, which were predominantly striped (black) mullet (27%), flounders and sheepshead (1-4%), followed by menhaden, croakers, seatrout, and catfish (<1%). In 2013, Clay, Duval, Flagler, Putnam, and St. Johns Counties reported a total commercial crab harvest of 1,615,232 lbs (73%); and a fish harvest of some 570,509 lbs (FWRI 2017a). The oyster harvest represented about 2% of the total weight harvested in 2016 occurring in St. Johns County (Figure 3.1). Recreationally, the St. Johns River area supports high numbers of red drum, spotted seatrout, croaker, sheepshead, flounder, largemouth bass, and bluegill that are sought by both local and visiting anglers.

3.1.2. Data Sources & Limitations

All available literature was used to examine potential long-term trends (1955-2016) in fish communities via the presence or absence of species encountered in the particular study. Although, such comparisons can give insight into whether the overall fish community was the same for the time periods compared, a major weakness of this comparison is that it gives no information on how the numbers of a given species may change with time. Also, the collection methods in these studies were not the same, thus making it difficult to draw valid conclusions.

Two data sources were provided by the Florida Fish and Wildlife Research Institute (FWRI) as follows: 1) Commercial fisheries landings reports (1994-2016); and 2) data from the Fisheries Independent Monitoring (FIM) program (FWRI 2002; FWRI 2003; FWRI 2004; FWRI 2005; FWRI 2006; FWRI 2007; FWRI 2008b; FWRI 2009; FWRI 2010; FWRI 2011; FWRI 2012b; FWRI 2013b; FWRI 2014; FWRI 2016a; FWRI 2017b). For commercial landings data, there are uncertainties associated with either the exact location of where a fish was caught and/or the method of estimating total number of landings for a given area. In particular, these data do not differentiate between fish and invertebrates caught in the LSJR or the ICW. In addition, changes in fishery regulations over time limit what can be said of landings between certain time periods. For the most part, the total landings have been graphed. To best standardize comparisons of the total landings over time, we calculated landings per trip, and trends were investigated using a Kendal tau correlation analysis.

The most statistically reliable data used in this report comes from ongoing research conducted by the FWRI-FIM program. Data are presented in two forms. The first form displays for each species yearly Indices Of Abundance (IOA) for relevant age classes (young of the year, adults; or pre-fishery and slot size limits) encountered within the lower basin of the river. The second form displays the monthly length frequency diagrams for each species for the 15-years sampling period (Appendix 3.1.1). Both forms of display allow for more specific insight into temporal trends, recruitment, and the fishery (slot size limits available to fishermen). Potential trends in all these data are investigated using Kendall tau correlation analysis. Finally, scientific literature was used where appropriate to supplement these data and form conclusions about trends and status.

Figure 3.1
Figure 3.1 Percent comparison of commercially important fish and invertebrates caught by fisherman of five counties associated with the lower basin of the St. Johns River in 2016. These data do not differentiate between fish and invertebrates caught in the St. Johns River or the Intracoastal Waterway (ICW).
Figure 3.2
Figure 3.2 Map of areas of St. Johns River sampled by Fish and Wildlife Institute from July 2005 to December 2016 (FWC-FWRI, 2005). In this study, the north, middle, and southern river sections are FWRI areas C, D and E, F respectively.

3.1.3. Health of Fish and Invertebrates

There is not much information on the health of fish and invertebrates from the LSJRB. In the mid-1980s, there were concerns with fish health in the St. Johns River when high numbers of fish with external lesions (called Ulcerative Disease Syndrome (UDS)) were reported by local fishermen. A comprehensive 1987 study (CSA 1988) from Clapboard Creek to Lake George revealed only 73 lesioned fish out of 69,510 (0.11%). However, this study also observed a higher percentage (5%) of lesioned fish in the Talleyrand area with the main affected fish being southern flounder, weakfish, yellowfin, menhaden, southern stingray and Atlantic croaker. FWRI has data for the LSJR and the Aphanomyces fungus – published in part in Sosa, et al. 2007. The latter study comprised of a statewide and historical survey of Aphanomyces and associated ulcerative lesions in fish. In the SJR, a number of species were confirmed with ulcerative lesions from Aphanomyces between 1980-2003 (time of study and retrospective analyses), including striped mullet (Mugil cephalus), Gulf flounder (Paralichthys albigutta), menhaden (Brevoortia sp.), weakfish (Cynoscion regalis), southern flounder (Paralichthys lethostigma), gray snapper (Lutjanus griseus), Atlantic croaker (Micropogonias undulatus), hickory shad (Alosa mediocris), American shad (Alosa sapidissima), brown bullhead (Ameiurus nebulosus), silver perch (Bairdiella chrysoura), pinfish (Lagodon rhomboides), sand seatrout (Cynoscion arenarius), and sheepshead (Archosargus probatocephalus). FWRI research suggested that a major cause of the lesions is a water mold (Aphanomyces invadans) that is more likely to infect stressed fish. Fish can be stressed when exposed to unusual changes in salinity, temperature, and water quality.

ulcerative lesions

During the summer and fall of 2010, there was a sequence of unusual events in the LSJR involving extensive fish kills, cyanobacteria blooms, foam formation, and bottlenose dolphin deaths. From late May until July 2010, there were extensive fish kills within the St. Johns River from Lake George to the downtown Jacksonville area. The mortality event lasted much longer than mortality events caused from hypoxia. While multiple species of dead fish were observed, white catfish, red drum, longnose gar, Atlantic stingrays, and menhaden were reported to be most affected by the event. Generally, most observed dead fish did not have lesions or sores. Co-occurring with the fish kill were cyanobacteria blooms of Aphanizomenon cf. flos-aquae followed by blooms of other algal species. Fish histopathology suggested that cyanobacteria-degrading bacteria might have played a role in this fish mortality event. During mid-October, a second, less widespread fish mortality event occurred in the river in which smaller fish, mostly menhaden, were found with lesions near the caudal fin. This later fish kill may have been because of a bloom the fungus Aphanomyces invadans (Sosa, et al. 2007).

FWRI has investigated external abnormalities, such as lesions, in fish since 2000. They surveyed fish and invertebrates for the presence of abnormal growths, colors, and ulcers or gross external abnormalities (GEA). They also sampled mercury levels in muscle tissue from the shoulder area in similar sized (generally larger) spotted seatrout, red drum, southern flounder, southern kingfish (whiting), and blue crabs.

The incidence of GEAs was found to be less than one percent from 2001 to 2010 (FWRI 2002; FWRI 2003; FWRI 2004; FWRI 2005; FWRI 2006; FWRI 2007; FWRI 2008b; FWRI 2009; FWRI 2010; FWRI 2011). During this time period, the percent of fish affected by GEAs has varied between 0.001 to 0.4% (Figure 3.3). While 26 species of fish with GEAs have been encountered by FWRI from 2001 to 2010, the most commonly observed fish with GEAs during this time period are striped mullet, menhaden, sheepshead, and largemouth bass.

Figure 3.3
Figure 3.3 The percent of fish encountered with gross external abnormalities (GEAs) for each year of the ongoing FWRI study. A Kendall tau correlation revealed no significant trend over time (τ= -0.400; not statistically significant) in the percent fish encountered with GEAs from 2001 to 2010.

Mercury has been detected in a number of freshwater, estuarine and marine species in the state of Florida. The Florida Department of Health (FDOH) issues consumption advisories for a number of marine and estuarine fish (FDOH 2016). Generally, these are large, long-lived predatory species, which bioaccumulate high concentrations of mercury, over their lifetimes. Consumption advisories recommend the amount of the affected fish species that can safely be eaten in a given time span. It is recommended that fish that exceed a concentration of 1.5 parts per million (ppm) of mercury not be eaten by anyone. The general population can still eat fish with a 0.3 ppm mercury concentration, although there are more limiting human consumption advisories for children and women of child-bearing age (sensitive populations) when concentrations in fish exceed 0.1 ppm (Goff 2010).

In the LSJR, the FDOH advises limited consumption (1-8 meals per month – depends on the species) of Atlantic croaker, Atlantic thread herring, Atlantic weakfish, black drum, brown bullhead, redbreast sunfish, bluegill, black crappie, gulf and southern flounder, jack crevalle, hardhead catfish, red drum, sand seatrout, sheepshead, spotted seatrout, southern kingfish, striped and white mullet, spot, warmouth, largemouth bass, bowfin, and/or gar. Everyone is advised to eat no king mackerel larger than 31 inches, and no sharks larger than 43 inches (FDOH 2017). Note that more restricted consumption is recommended for children and pregnant/lactating women. For more information about consuming fish, see the FDOH website (FDOH 2017). For more information about mercury in fish and other species, see Section 5.4.4.

Water Quality, Fisheries, Aquatic Life, & Contaminants