Exploring Population-Level Effects of Fishery Closures during Spawning: An Example Using Largemouth Bass.

We used an age-structured model to evaluate the impacts of recreational angling during spawning on populations of largemouth bass and the potential benefits of seasonal fishing closures. We simulated fisheries with average and high capture rates (i.e., fractions of the stock caught by anglers). We manipulated mortality rates to mimic the effects of various regulations, including (1) an open fishery with no closures, (2) a full fishery closure during the spawning season, (3) a catch-and-release fishery during the spawning season, and (4) a year-round catch-and-release fishery. We simulated two hypothetical populations: a high-productivity, low-latitude population and a low-productivity, high-latitude population. Spawning season closures produced the largest relative increases in adult abundance when applied to low-productivity populations and when capture rates were high (e.g., 70%) and harvest rates were relatively low (20%). This resulted because very high capture rates imply that most spawning fish will be caught by anglers and potentially lose their broods to nest predators. The existing evidence suggests that these conditions (very high capture rates combined with low harvest rates) are the exception rather than the rule across largemouth bass fisheries. Understanding capture and harvest rates is critical to the use of seasonal closures in recreational fisheries. [ABSTRACT FROM AUTHOR]