Meeting Abstract

64.9  Wednesday, Jan. 6  Swimming ability and morphological traits in coho salmon reintroduced and subjected to greater migration distances in the Columbia Basin WAGNER, K.A.*; SABINS, A.M.; PHARR, C.M.; HANCOCK, T.V.; Eastern Washington Univ.; Eastern Washington Univ.; Eastern Washington Univ.; Eastern Washington Univ. wagner.katie@hotmail.com

Coho salmon (Oncorhynchus kisutch) were extirpated from upper Columbia Basin tributaries in the 1900s. The Yakama Nation and Nez Perce Tribe are currently reintroducing coho into Mid-Columbia and Snake River tributaries, respectively. These stocks are primarily derived from a basal stock originating from the Clackamas River of the lower Columbia, thus reintroduced stocks must migrate dramatically further than basal runs. Natural runs of Fraser River coho exhibit differences in locomotor ability and morphology over varying migration distances. To determine if selection is acting upon similar traits in reintroduced stocks, we are analyzing critical swimming speed (U_crit), using a Blazka-type swim tunnel and several underlying physiological and morphological traits, juvenile hatchery coho derived from successful returnees of the Mid-Columbia and Snake Rivers were compared to the basal stock. Reintroduced Mid-Columbia stocks have a lower U_crit coupled with an increase in ventricle size, indicating a possible tradeoff of maximal swimming speed for endurance swimming. These reintroduced stocks also demonstrate decreases in fineness ratio, peduncle length and body width and increases in head length, snout-pectoral length, pelvic fin length; median fin areas; and condition factor. Traits of the reintroduced Snake River stock appear less diverged, which may be a result of continued basal stock introduction. Future analyses of muscle enzymes and fiber type, size, and number may further elucidate any potential adaptations.