Higher Trophic Levels

Gamefish Populations in Florida

Florida Bay Project Profile - 52

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Questions: What are the population trends in four of the most popular recreational gamefish in Florida Bay? What are the responses in catches of each species to fishing effort and to factors such as rainfall, water level, and salinity?

Background/Project: Sportfishing in Florida Bay in Everglades National Park (ENP) has been monitored nearly continuously since 1958. The angler catch and fishing effort data collected from 1985 to 1996 as part of this research program was recently analyzed to examine whether any notable changes had taken place in the adult populations of several important game-fish. This decade corresponds to the beginning of microalgal blooms and severe seagrass die-offs in Florida Bay. The study included the four most popular gamefish: gray snapper (Lutjanus gris-eus), spotted seatrout (Cynoscion nebulosus), red drum (Sciaenops oceallatus), and snook (Centropomus undeci-malis). Catch data on non-guided recreational anglers was obtained from interviews conducted at the Flamingo boat launch sites every weekend after the anglers returned with their catches. The residence of the angler, area fished, fish kept and released, number of hours fished per trip, species preference, and lengths were recorded. Similar information about guided fishing trips was obtained from monthly logbooks completed by the permitted fishing guides who operated within ENP boundaries. The study also examined the response of these fish to fishing effort (angler hours fished) and to rainfall, water level, and salinity. Environmental data was collected at the ENP water quality monitoring stations located throughout the bay and the Everglades' wetlands.

Findings to Date: In this project, catch rates were used as an index of relative abundance for the four gamefish species being monitored. Gray snapper and spotted sea trout catches have fluctuated greatly since 1985, with peak catches during 1991 and 1992. Statistical results indicate that rainfall and salinity levels may influence populations of gray snapper and spotted seatrout. Red drum and snook catches declined during the 1985-1988 period, but increased from 1989-1996. Increased size regulations, bag limits, and pressures placed on the fisheries between 1982-1986 partially accounted for the decrease in catches of these two species during the mid 1980's. Catches of red drum in Florida Bay were lowest in 1988, but increased significantly by 1996. Catches were greatest in northern Florida Bay. The total annual snook catches climbed greatly from 1986 to 1994 with lowest catches being reported in southern Florida Bay. Greater catch rates for snook followed high rainfall and high water-level years in upland marshes. The total annual fishing catch was calculated for each of the four fish species and examined in relation to fishing effort. For all four species, fishing effort was closely correlated with annual catches which suggests that fish stocks (populations) were not severely impacted by recreational fishing pressure during the study period.

Status: This ongoing project began in 1958 and is one of the longest continuous marine recreational fishery monitoring programs in the world.

Restoration Impacts: This project will enable ecosystem managers to better predict how bay recreational fish populations will be impacted by the restoration of surface water flows to the Everglades' wetlands.

Funding Source: Everglades National Park

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