Estimating Regional Fishing Mortality for Freshwater Systems: a Florida Largemouth Bass Example

Species-specific harvest regulations in recreational fisheries are commonly applied regionally to protect stocks from overharvest and satisfy a diverse set of anglers. While setting regulations is a complex task and may incorporate the best available social and biological information, fisheries managers commonly obtain directed fishing mortality estimates within a single lake and then assume similar rates among other systems when setting regional harvest regulations. Thus, there is a need to assess regional levels of fishing mortality for informed use of regionally applied regulations. We implemented a practical method for assessing catch and harvest for a recreational fishery across a broad spatial region. We used a passive tag-reward study design and a regional management regulation area for Florida Largemouth Bass Micropterus salmoides floridanus in central Florida as our case study. The estimated fishing mortality rate included both harvest and deaths due to catch and release. We found overall regional fishing mortality for Florida Largemouth Bass in central Florida was relatively low. From the 247 dart tags returned, the mean annual instantaneous total fishing mortality rate was 0.11 (95% credible interval = 0.08-0.15). We also found fishing mortality rates did not vary with lake size or fish total length. Our study design did not provide mortality estimates for any specific lake due to a low number of tagged fish per lake, but the method could be used to elucidate the effectiveness of regulations that are applied at a regional scale.