FOOD AND FEEDING OF JUVENILE CHINOOK SALMON IN THE CENTRAL COLUMBIA RIVER IN RELATION TO THERMAL DISCHARGES AND OTHER ENVIRONMENTAL FEATURES. Page: 3 of 78
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ABSTRACT
The relationship of thermal discharges from Hanford reactors to
food and feeding of juvenile chinook salmon (Oncorhynchus tshawytscha)
in the central Columbia River, Washington was studied in 1968 and 1969.
The primary objectives were to (1) evaluate the food composition and
feeding activities of the fish and (2) determine if heated effluents
influenced their welfare. Environmental conditions, i.e. seasonal changes
in river temperatures and flow volumes, in relation to thermal require-
ments of young chinook are detailed. Data on food organisms utilized
by the fish are presented for 1968 and 1969, whereas analyses for possible
thermal effects are based on the more extensive 1969 data.
Young chinook at Hanford consumed primarily various stages of aquatic
insects, of which adult and larvae Tendipedidae (Diptera) were of dominant
importance. Other major food organisms were the order Collembola and
the families Notonectidae (Hemiptera) and Hydropsychidae (Trichoptera).
Small fry fed almost exclusively on tendipedids. The food composition
was essentially similar in 1968 and 1969. Over 95 percent of food organ-
isms utilized orginated in the river ecosystem.
Analyses to detect thermal effects were made on parameters dealing
with food, feeding and growth compiled from fish collected at three sites
above ("coldwater stations") and three sites below ("warmwater stations")
the effluent discharges. The following comparisons were made: (1) food
organisms utilized, (2) feeding activity, (3) mean insects per feeding
fish, (4) seasonal increases in fish length, (5) fish length-weight
relationships, (6) coefficients of condition, and (7) dry weight of
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Becker, C.D. FOOD AND FEEDING OF JUVENILE CHINOOK SALMON IN THE CENTRAL COLUMBIA RIVER IN RELATION TO THERMAL DISCHARGES AND OTHER ENVIRONMENTAL FEATURES., report, January 1, 1971; Richland, Washington. (https://digital.library.unt.edu/ark:/67531/metadc863419/m1/3/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.