The Effects Of Heated Water On Warmwater Fish In Earthen Raceways

Two-year studies were conducted in 3 earthen raceways (160 m x 6 m x 2 m). One raceway was maintained at ambient water temperature, I had a heated floating plume over 60% of the surface, and 1 was maintained at near heated water discharge temperature. Average water temperatures ranging up to 36.7 C were not lethal for any fish species tested. With the possible exception of threadfin shad (Dorosoma petenense) 110 difference in long-term survival of any species was detected, but when the entire population was considered as a whole, survival of fishes confined to the highest temperatures was reduced. Growth rates of largemouth (Micropterus salmoides) and spotted basses (M. punctatus), channel catfish (Ictaluras punctatus), redear sunfish (Lepomis microlophus, and gizzard shad (D. cepedianum) in at least 1 of the heated water treatments exceeded growth in the control. Total standing crop and growth rates of bluegill (L. macrochirus) and drum (Aplodinotus grunniens) were lowest in the treatment with highest water temperatures. Little difference was seen between the control and the treatment with a floating heated water plume.

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