Assessment of Largemouth Bass Growth in Northern Idaho Lakes: Spatiotemporal Patterns and Extrinsic Associations

Abstract

AbstractWe examined patterns in the somatic growth of populations of Largemouth Bass Micropterus salmoides in northern Idaho lakes and modeled its variation to understand how spatiotemporal differences in climate regulate growth in lentic systems. Age was estimated from 768 Largemouth Bass from six distinct populations. Largemouth Bass growth and longevity in northern Idaho was typical to populations at similar latitudes; however, growth was substantially slower than average compared with other populations throughout North America. Mean relative growth estimates of Largemouth Bass for ages 1–8 never exceeded the 25th percentile of the North American average, and relative growth was either stable or slightly increasing as a function of age for most study populations. Annual incremental growth was more variable across years than among populations. Growth tended to be positively related to precipitation during the growing season or mean minimum annual temperature, but the importance of either covariate was dependent on lake surface area. Approximately 50% of the variation in growth of Largemouth Bass was explained by precipitation during the growing season in lakes with a surface area ≤70 ha. In the largest study lakes (i.e., ≥600 ha), over 50% of the variability in incremental growth was attributable to mean minimum annual temperature. Similarity in lake surface area resulted in the most interannual growth synchrony, whereas less synchrony was observed as a function of proximity. We hypothesize that annual climate patterns are not spatially variable enough in northern Idaho to elucidate measurable effects on growth but that local geography may be more important for regulating how climate interacts with Largemouth Bass growth on a regional basis. We interpret our results to mean that the ecology and conservation of Largemouth Bass may benefit from a more complete understanding of the climate–growth relationships on a region‐by‐region basis, with particular consideration for ecosystem characteristics.