Assessing Effects of Gizzard Shad Removal on Nutrient Cycling and Gizzard Shad Population Dynamics Biomanipulation via removal of gizzard shad has been proposed as a management strategy for improving water clarity by reducing internal nutrient loading from the sediments. Preliminary studies at Lake Denham, Florida, suggested that strong biomass reductions of gizzard shad using haul seines may reduce phytoplankton biomass. Recently, biomanipulations have been attempted on several lakes of the Harris Chain of Lakes, Florida using gill nets, but the results of these efforts have yet to be experimentally evaluated. Understanding how fish life history metrics respond to density reductions is critical to understanding the potential impact of biomanipulation on lake food webs. We used a whole-lake gizzard shad reduction experiment (i.e., a biomanipulation) to 1) assess impacts of a commercial gizzard shad removal on their population dynamics (i.e., recruitment, growth, mortality), 2) measure diet contents of gizzard shad to indicate mode of feeding, 3) explore the potential for gizzard shad removal to influence lake water quality, and 4) evaluate the potential for bycatch impacts on black crappie Pomoxis nigromaculatus fisheries. |
Size Selectivity of an Otter Trawl for Black Crappie at Five Florida Lakes |
Fish Community Composition in Tussock Forming Aquatic Macrophytes at Two South Florida Lakes |
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Hatching Duration, Growth, and Survival of Age-0 Largemouth Bass along a Latitudinal Gradient of Florida Lakes Survival of age-0 largemouth bass to age-1 is largely influenced by temperature dependent factors such as: hatching date, growth rate, and over-winter mortality. Florida’s climate changes with latitude from sub-tropical to temperate, thus the influence of temperature driven factors affecting survival may differ across Florida’s latitudinal gradient. Using hatching dates, growth and survival information, we are investigating the mechanisms that influence age-0 largemouth bass survival across Florida and how those mechanisms relate to conventional recruitment hypotheses for this species. This study was funded by the Florida Fish and Wildlife Conservation Commission. |