The effect of catch-and-release angling on the parental care behavior of male smallmouth bass

Parental investment theory predicts that parents should adjust the level of care given to offspring relative to brood size and stage of brood development. This variation in parental care results from a trade-off between the reproductive value of the current brood and the reproductive return that the parent can expect to receive from future broods. Our study, carried out in Charleston Lake, Ontario, Canada, examined how handling stress and brood predation associated with catch-and-release angling influenced parental care behaviors and, ultimately, nest abandonment decisions of male smallmouth bass Micropterus dolomieu. Individuals were divided into six treatment groups: two different controls (n = 10 and 11) and four test groups that were either angled and then released (n = 11), had broods reduced manually to simulate predation (n = 12), received a combination of angling and brood reduction (n = 10), or had their brood size augmented through the manual addition of larvae (n = 10). Exposing the fish to a model brood predator revealed that, after catch-and-release events, angled males were less willing or less able to defend their broods than were control fish. In addition, with or without angling, males subject to simulated brood predation were the least aggressive in defending their remaining broods. Moreover, the only treatment groups that showed substantially greater rates of nest abandonment were those that included simulated predation.