Winter Predation by Largemouth Bass

It wasn't that long ago, relatively speaking, that you could read an article or talk to other bass anglers and hear how largemouth don't feed through the winter, or how rarely they bite with water temps under 40 degrees. One thing I've learned over the past 5 or 6 years is just how many bass you can catch during the coldest water temps. I've now been on enough trips through the winter in Indiana to realize that if you can get a reasonable presentation to a bass regardless of water temps, you stand a realistic chance of catching fish. I've specifically ice fished for them, broken lots of ice to get a boat to them, and fished immediately after ice thawing, and have had success in all scenarios. Now scientific studies are starting to support what we have anecdotally reasoned.  

The Effect of Largemouth Bass Predation on Overwinter Survival of Two Size-Classes of Age-0 Bluegills by Shoup and Wahl in the soon to be published July issue of Transactions of the American Fisheries Society studied overwinter mortality of bluegill in ponds, some that contained largemouth and some that didn't. Results indicated that ponds with bass resulted in a 16-49% increase in bluegill mortality above what was seen in ponds without bass, the two most plausible explanations being direct consumption of and behavioral modification in bluegill. Increased condition of both bluegill and bass through the testing period suggested direct consumption to play at least some key role.

Additionally, the study also supported the hypothesis of overwinter mortality of age-0 fishes, most likely due to energetics–food limitation and physiological mechanisms. It has been a frequently studied issue (see Causes and consequences of winter mortality in fishes). Authors Shoup and Wahl in this study ultimately conclude that "Size-structured interactions are very complex, involving a suite of trade-offs that are optimized differently in different environments. Our results suggest that winter not only selects for maximization of energy reserves but also enhances the importance of prey body size relative to predator size structure. Additional research examining these evolutionary trade-offs, including winter predation risk, will add to our understanding of the complex set of interactions that influence size-structured survival of age-0 fishes."

Comments

[Paul Roberts]

Very nice.