Largemouth Bass in a Warming World

Rypel (2009) applied tree-ring techniques to incremental growth patterns in largemouth bass (Micropterus salmoides Lacepede) otoliths -- i.e., the aragonite (CaCO₃) structures in fish that are used for acoustic perception and balance -- in order to explore potential relationships between annual bass growth and various climate metrics in the southeastern USA, as manifest in six rivers and seven reservoirs distributed across Georgia, Alabama and Mississippi that were sampled during the summers and autumns of 2005-2008 and from which 397 largemouth bass were collected and analyzed.

Rypel reports that "results from multiple regressions suggested that on average roughly 50% of the annual variability in largemouth bass growth was attributable to climatic variations," with annual growth indices typically being found to be "above-average during the warmest, driest years, and below-average during the coldest, wettest years," due to the facts that "annual bass growth was significantly negatively correlated with annual precipitation metrics, and significantly positively correlated with annual temperature metrics."

Considering the above findings, the warming and drying that is predicted by models to occur in many places would appear to be good news for largemouth bass, as well as for the people who love to fish for them and for many other types of fish, since an increase in temperature generally "stimulates metabolism, and enhances growth rates of fishes," according to Rypel, who cites in this regard the studies of Beitinger and Fitzpatrick (1979) and Brander (1995).

Additional References
Beitinger, T.L. and Fitzpatrick, L.C. 1979. Physiological and ecological correlates of preferred temperature in fish. Integrative and Comparative Biology 19: 319-329.

Brander, K. 1995. The effect of temperature on growth of Atlantic cod (Gadus morhua L.). ICES Journal of Marine Science 52: 1-10.