Relationship between Habitat and Sport Fish Populations over a 20-YearPeriod at West Lake Tohopekaliga, Florida

摘要

Relationships between environmental variables and sport fish population parameters were investigated for West Lake Tohopekaliga from 1983 to 2002. Through time, the lake has undergone a process of cultural oligotrophication as indicated by reductions in nutrient and chlorophyll-a concentrations because of improvements in wastewater treatment and the establishment of hydrilla Hydrilla verticillata in the system. With this decline in trophic state, angler catch and catch rate increased for largemouth bass Micropterus salmoides, but harvest and harvest rate decreased for black crappie Pomoxis nigromaculatus. Furthermore, the angler base of the lake shifted almost exclusively to those fishing for largemouth bass. Although angling effort for largemouth bass has increased through time with reductions in trophic state, angling effort for black crappies and sunfish species Lepomis spp. has declined. The growth of largemouth bass less than age 5 has also declined since the late 1980s, and the proportion of memorable-sized fish in electrofishing catches decreased with decreases in total phosphorus. Areal coverage of hydrilla varied dramatically throughout this 20-year period, and angler catch rate of largemouth bass as well as angler harvest rate of black crappies were positively correlated with hydrilla coverage. We believe the current level of nutrients and intermediate levels of vegetation (20-40%) should be maintained to balance the needs of both the angling and nonangling communities and to maximize the economic potential of the lake.