In my experience and those opinions of some fishery pros with yellow perch and with a few other fish species such as LMB, I am not sure that the feeding consumption for all ages of fish keeps increasing when temperatures are close to the reported lethal temperatures. Lusk contends that big LMB slow feeding levels when in water that is near the reported lethal range. ....
When reading the published articles ....I think one has to pay close attention to the methods used in that specific research work so as to not to conclude all the results presented to be universal gospel for all ages or sizes of that specie or all fish species. Variations of species sizes and ages I think are natural features of all species.
My experiences are younger fish are able to feed and grow very well in warmer temperatures compared to the older or oldest individuals. Those younger fish are more temperature tolerant and remain more active during the high ends of temperature tolerance. This physiological feature allows optimum grow of young fish. ...
Let's consider fish feeding activity at the other end of the temerature spectrum - cold or colder water. It is commonly known that fish (as cold blooded, warm and cool water species) significantly slow down their feeding activity during winter conditions as water temperature drops below 50F, then 40F or 39F. Optimum Metabolism is less thus feeding is less. My premise is why would this similar colder water feeding activity slow down or gradually decrease when big or old fish especially older larger fish with higher biomass are in water temperatures that are increasing toward or approaching above their optimum preferred upper warm water temperatures toward the lethal limits?. I contend too warmth can be uncomfortable or a stressor for that aged near end of life individual. One does not eat normally or the best when it is under some form of stress. When you are feeding pellets to fish and they quit eating there is almost always a stressor that is causing the lack of eating.
Excellent Bill !!!
All fish eat less when under stress , including less in cold water or very hot water. Being cold blooded they have an optimum temperature range which directly effects metabolism. This is common sense and validated science. It applies to both old and young fish but may affect one more than others. All animals I am aware of have a faster initial growth rate when young and it slows as they age. There are plenty of studies that show growth and feeding slow outside of the normal temp range.
The study in the article I posted was all about LMB feeding and growth in Tenn waters slowing in very hot temps and then when temps fell back into optimum growth range feeding exploded while metabolism steadied (thus adding needed reserves) before feeding and metabolism dramatically slowed as the waters got cold.
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