Taking the next step: Examining recruitment and population variation in largemouth bass when catch and release angling disrupts parental care

Largemouth bass are a popular sport fish throughout North America, supporting an economically important recreational fishery. Changes in recruitment driven by decreases in reproductive success during catch and release angling events potentially affect population size and may disrupt the sustainability of an important resource.

We conducted field experiments on largemouth bass nests in a shallow, oligotrophic lake in eastern Ontario.  Nesting male bass were angled from their nest site and the magnitude and rate of naturally occurring brood predation was quantified.  We found that in multiple cases, half of a single brood could be consumed by predators in as little as five minutes, resulting in a significant reduction in reproductive output.  In a second experiment, we tested for changes in largemouth bass recruitment in response to simulated brood predation in eight small ponds.  In four treatment ponds, swimmers manually reduced eggs in each nest by a target 50%. Treated ponds showed a notable reduction in number of YOY produced and total biomass when compared to control ponds. These studies indicate that brood predation of largemouth bass eggs during the absence of a nest guarding parental male (e.g., during an angling event) may have important implications to largemouth bass recruitment dynamics.