Observations on the Migration of Salmonoid Fishes in the Upper Columbia River

Abstract

DURING the period of the preliminary investigations into the possible methods of preserving the Columbia River salmon and steelhead at the Grand Coulee Dam certain miscellaneous observations1 were made which have a bearing on the homing tendency of these fishes. In 1937 a rack was built across the Wenatchee River near the town of Monitor, about 6 miles above the junction of that river with the Columbia and about 22 miles above Rock Island Dam. Numbers of fish were transported from Rock Island Dam (on the Columbia River) and placed in the Wenatchee River above the rack, for reasons explained elsewhere (State of Washington Department of Fisheries, 1938). Of the steelhead (Salmo gairdnerii) so transported, 28 were marked with strap tags at the dorsal edge of the base of the caudal fin before liberation. Those tagged were liberated above the rack between August 21 and September 4. The rack, which had been impassable to the downstream movement of fish, was removed on October 2. All the fish passing the Tumwater Dam, about 22 miles upstream from the Monitor rack, were counted and no tagged steelhead were seen at that point. A careful search was made in the Wenatchee River for about 4 miles below the Tumwater Dam without seeing any of these fish. None of the tagged steelhead were subsequently reported from the Wenatchee River. In the spring of 1938, five of these tagged steelhead were recovered by sportsmen in the Columbia River: one at Nespelem (about 15 miles downstream from Grand Coulee Dam) and four at Kettle Falls (about 40 miles from the Canadian border). These fish had remained in the Wenatchee River for a month or more. Then some time subsequent to the removal of the Monitor rack they had moved down the Wenatchee to the Columbia (6 miles) and on up the Columbia to Nespelem (about 120 miles) or Kettle Falls (about 230 miles). The simplest interpretation of these results would be that these were fish which had been reared in the upper Columbia drainage and, obeying the homing tendency, they had not continued up the Wenatchee (which supports a considerable run of steelhead that normally come into the Wenatchee at this season) but, instead, had returned to the Columbia and turned up the latter toward the streams of their nativity. Since no study has ever been made concerning the home river of the runs of fish appearing at Rock Island the proof of such an interpretation is not possible. If this interpretation is correct, these results present a remarkable instance of the strength of the homing tendency. The observations of Dr. H. B. Ward (1939) on the Baker River and elsewhere have led him to conclude that temperature is an important factor in guiding the migration of the sockeye salmon (Oncorhynchus nerka) while in fresh water, and, given similar other conditions, the adult migrants of this species will turn into the tributary having the lower temperature. The Okano-