Mike wrote:
Temperature related trout kills rarely occur all at once; they generally occur incrementally. As a result, a common theme among anglers and their lore is that they never see any dead fish. I only knew of one large(nearly all at once) stocked trout kill related to temperature in 42 yrs. It occurred at the mouth of a cool trib to the Little Schuylkill DH area. What I have witnessed is stocked trout congregated at a trib and the outside members of the pod or school trying to maintain their position either in swifter current or in the warm water/cool water interface. That does not work for long and one by one the fish eventually run out or energy or become overwhelmed by the warmth, lose the ability to stay upright, drift into the warmest water, and are carried downstream as they die. It is likely that as flows diminish and days grow warmer some initially cool tribs even warm to the extent that they no longer adequately serve the needs of congregated trout.
If you place your hand in the mouth of a trib where trout are congregated, at some point across the width of the cooler water you will detect a zone of rapidly varying temperatures as warm water from the main stream swirls in an incomplete mixture of warm and cold currents. What you may also find is that early in the summer 300 stocked trout may be congregated (jammed in) at the mouth of a small, cool trib during the day when the receiving stream is 80 deg F. If the receiving stream temp drops to 71-72 deg F at night or possibly due to a thunderstorm the vast majority of the fish may disperse into the main stream until the next day or next warming period. But recall that even those temp is stressful and are part of the countdown to temperature related mortality (number of 15 min periods per month over 68 deg F).
From competition for cool water and forage standpoints, harvesting some, many, or most of these stocked fish is probably doing the rest a favor.