Growth of Marked Silver Salmon (Oncorhynchus kisutch) of the 1950 Brood in Puget Sound

Abstract

Silver salmon (Oncorhynchus kisutch) of two different stocks were marked by excision of fins and released during the spring of 1952 into Minter Creek and Lake Washington drainages of Puget Sound, Washington. Over 800 of the marked salmon were recovered during 1952 and 1953 from the sport and commercial fisheries of Puget Sound, the Pacific Ocean, and closely adjoining waters. Mature adults returning to spawn were recovered at traps and weirs at the hatcheries where they were originally released. The growth over the entire 3-year life cycle of the salmon released into the Lake Washington drainage when plotted graphically showed variation in length at maturity from less than 40 to over 80 centimeters in fork length. Salmon from the Lake Washington drainage taken in salt water at the same time and place were larger than salmon from Minter Creek. The average relative lengths of salmon from Minter Creek and Lake Washington recovered in the Pacific Ocean were the same as recorded for the mature salmon recovered at the hatcheries. Salmon migrating to different areas in salt water attained different average lengths at maturity. The average lengths of marked salmon recovered from the Pacific Ocean were always larger than fish recovered at the same time from Puget Sound, and salmon of intermediate size were taken in the Strait of Juan de Fuca and in the Pacific Ocean immediately adjacent. Difference in average size between the Lake Washington salmon (Green River, Soos Creek, stock) and Minter Creek salmon is considered to be a racial characteristic. Exact reasons for differences in length attained by the salmon taken from different areas are not known.