Adult Returns of Hatchery Steelhead Juveniles Reared in Earthen- and Asphalt-Bottom Ponds

Abstract

For three consecutive years, postrelease survival was compared between tagged juvenile steelhead Oncorhynchus mykiss reared from fall until spring release in an asphalt-bottom pond and those reared in an earthen-bottom pond at a Washington State hatchery. The two groups were fed nearly identical rations. At release, fish from the earthen pond were significantly longer and heavier but had a lower condition factor than fish from the asphalt-bottom pond. Adult recoveries were significantly greater (P = 0.009) for fish reared in the earthen pond (0.163%) than for those reared in the asphalt pond (0.115%). Although the greater fork length and lower condition factor may have increased the adult survival of fish reared in the earthen pond, smolt lengths and condition factors were inherent to the rearing pond environment.