By Ted Lange
FWC’s Black Bass Management Plan (BBMP) committed FWC to work with stakeholder groups to mitigate negative public perceptions of club-level bass fishing tournaments. Negative perceptions identified included bass mortality, crowding at boat ramps and poor boating and angling ethics by some tournament anglers. Stakeholders also expressed positive perceptions of bass tournaments through the BBMP including promotion of fishing as well as teaching ethics and stewardship. Regardless, bass tournaments can be very high profile with potentially hundreds of club tournaments occurring in Florida waters each week throughout the year. FWRI biologists working with Division of Freshwater Fisheries staff are working to better understand and mitigate bass mortality caused by bass fishing tournaments through several projects.
The Summer Bass Tournament Live-Well Study was initiated to assess live-well water quality conditions during summer tournaments when bass are most susceptible to mortality due to warmer water which holds the least amount of oxygen. Study objectives are to 1) educate bass tournament anglers about live-well water quality conditions during summer tournaments, and 2) further refine FWC’s fish care guidelines for best live-well management practices under conditions specific to Florida.
During year one of a three summer study, FWRI biologists assessed water quality conditions at club-level tournaments (10-30 participating boats) based on anglers preferred practices. In year two, biologists prescribed specific live-well management practices to random tournament boats and evaluated the resultant water quality conditions. In year three, biologists ran controlled experiments with wild caught fish acclimated to hatchery conditions under three varying management practices. Through controlled experiments, blood stress parameters in bass exposed to these management practices were measured, and a post tournament mortality assessment was conducted.
Year one results, focused primarily on temperature and dissolved oxygen (DO), confirmed that competitive anglers manage their live-wells in a variety of ways resulting in a wide range of water quality conditions. During year two, anglers were assigned specific live-well management regimes which included flow through only (near constant exchange of live-well water), fill and recirculate only (no exchange of water once filled), and fill and recirculate with one exchange of water midday along with the use of salt and ice. Year two results, more intensive and including more water quality parameters, suggested that anglers were reasonably able to maintain adequate levels of DO while minimizing the buildup of ammonia and carbon dioxide in live-well water. During the summer months, when lake surface temperature can exceed 30 °C, it is critical that those holding fish in captivity to manage live-wells conditions to maintain or even stimulate the recovery of bass during the period of confinement.
During year three, biologists repeated year two studies with wild-caught bass held in the research tanks at the Florida Bass Conservation Center where they underwent a simulated angling event prior to being placed in controlled condition live-wells representing the three management regimes. Stress parameters of glucose, lactate, cortisol, chloride, and osmolality in blood plasma were sampled both pre and post live-well confinement to assess the effects of the live-well environment on bass physiology. Finally, all bass were assessed for a seven-day period for post tournament mortality.
Blood samples are currently being analyzed by the University of Florida Veterinary Lab and the Ruskin Tropical Aquaculture Laboratory, UF IFAS. Study results will be utilized in coordination with other study components investigating tournament mortality to update FWC fish care guidelines to provide Florida bass anglers with live-well best management practices that they can readily implement during summer months.