Summary
Breeding site fidelity has evolved in many vertebrate taxa, suggesting both that site selection has an important influence on fitness potential and that the decision to reuse a nesting site is related to the individual’s prior nesting success at that location. For a species that provides parental care, such as the Largemouth Bass Micropterus salmoides, catch-and-release angling impacts individual nesting success and fitness through physiological disturbance and by removing the nest-guarding male from its brood, thereby allowing temporary access to eggs and hatchlings by brood predators. To assess the impact of catch-and-release angling on nest site fidelity, we compared the consequences of angling on individually marked (i.e., with passive integrated transponders) nest-guarding male Largemouth Bass in Ontario. An extremely high degree of nest site fidelity in year two was observed for males that were angled only once during year one (87% within 10 m of the previous year’s nest), 96.7% of which remained on the nest and completed parental care activities. There was significantly lower fidelity in year two, however, for males that were angled multiple times during year one (27% within 10m of the previous year’s nest), only 5.6% of which remained on the nest and completed parental care activities. This observed difference suggests that angling nesting bass may cause them to avoid previously used nest sites and instead search for alternative sites during future reproductive seasons. This human-induced impact on nest site choice may impact the future reproductive success of those Largemouth Bass.
Methodology
All manipulations and observations were undertaken in Long Lake, a closed access, natural lake of approximately 70 ha, located on the property of the Queen’s University Biological Station, near Chaffey’s Lock, Ontario (44 deg 30.6 min N, 76 deg 24.3 min W). During 15 years of monitoring Largemouth Bass spawning in Long Lake, we have observed that the entire shoreline of Long Lake is suitable nesting habitat for Largemouth Bass, i.e., shallow, solid substrate with substantial levels of woody debris and other natural structure. The lake is extremely clear, as well as being high sided and heavily wooded, affording it fairly substantial protection from wind effects. In addition, no rain events have ever been observed to cause any kind of noticeable increase in turbidity. Although we have never attempted any type of population estimate, we have never observed even minor fish kills over the last 20 years. For the nine spawning seasons since 1998 in which nesting bass surveys have been conducted in Long Lake, the total number of nesting male Largemouth Bass in the lake ranged from 52–73 with similar size distributions for nesting males across years. This number of nesting males, however, represents some unknown number (but likely a small percentage) of mature males in the lake, only some unknown percentage of which attempt to spawn in any given year. All of these observations suggest that the Long Lake Largemouth Bass population has been stable throughout its recent history. Similarly, we have not observed any obvious changes in the population of brood predators, which is predominantly Bluegill, Lepomis macrochirus, but also contains low numbers of Yellow Perch, Perca flavescens, and Rock Bass, Ambloplites rupestris. Concurrent studies on spawning Bluegill activity indicated no major shifts in population size structure or abundance of this major brood predator across the study periods (DPP personal observations).