Health and condition of juvenile chinook and chum salmon near the Chena River Dam, Alaska

Abstract

During May-June, 1995 and 1996, outmigrating chum salmon, Oncorhynchus keta, and chinook salmon, O. tschawytscha, were captured in the Chena River near the Chena River Lakes Flood Control Project. Fish condition was determined through the investigation of physical injury and scale loss. Except for one sample, the proportion of injured fish was never greater than 7% for chum or chinook salmon. Few injuries were severe. The proportion of chinook salmon with scale loss ranged from 1-33%, most of which were only partially descaled. When significant length differences existed, injured, descaled, and partially descaled fish were always larger than non-injured and non-descaled fish. Arctic grayling (Thymallus arcticus) diet by weight consisted of chum salmon (2%), invertebrates (89%), other fish (3%), and miscellaneous material (6%). Plasma cortisol levels were used as an indicator of the primary stress response of chinook salmon and did not indicate any unusual physiological stress level.