Decreasing Capture Vulnerability of Florida Bass (Micropterus floridanus) with Exposure to Catch and Release Angling: Implications for Effort-Based Management

Angler catch rates are often assumed to be linearly related to fish abundance, and thus increasing abundance will improve angler catch rates. However, caught and released fish could modify their behavior post-capture, resulting in lower vulnerability, such that catch rates would not relate directly with abundance. We evaluated declines in angler CPUE of Florida bass Micropterus floridanus with exposure to angling, and whether rates of decline differed between lures. We then constructed an empirical simulation of the vulnerable pool dynamics. We used mark-recapture to estimate population size and how angler catchability changed. The finesse lure exhibited a linear decline from initial 1.77 fish per angler hour to 0.83 fish per angler hour at 144 cumulative hours. The active lure showed an exponential decline from 2.33 fish per angler hour to 0.25 fish per angler hour. Released fish modified their behavior to avoid capture, but different lure types caused angler CPUE to change at different rates. Predicting based on experimental catches, we showed that incremental limitations of effort would increase long-term angler CPUE.  This means that normative management to improve overall population abundance may not have the same effect on angler catch rates without effort-based management.