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Following tagging and marking fish were held in an indoor raceway for four to five days to note initial mortality before being transferred to either the outdoor cement raceway or outdoor pond. The procedures for tagging and marking fish varied among the four systems evaluated. p~T TaQS. The general guidelines and techniques for PIT-tag implantation developed for Pacific salmon (Oncorhvnchus spp.) (Prentice et al. 1987) and those developed and used for Colorado River basin fishes from past performance studies (USFWS 1990) were followed. From these two studies, two anatomical sites were selected for PIT-tag implantation--the body cavity and dorsal musculature. These two sites were determined the best anatomical sites from both a technical and biological standpoint. Juvenile fish were PIT tagged either in the body cavity or dorsal musculature; adult brood fish were PIT tagged only in the body cavity. The procedure for implanting PIT tags in the body cavity of fish less than 175 mm differed slightly from adult fish. These differences were the point of insertion and angle of initial penetration. For fish less than 175 mm, the insertion point was approximately that point where the tip of the pectoral fin lay naturally along the ventral body musculature. The tag was inserted posteriorly through the lateral ventral musculature into the body cavity. The insertion location into the body cavity was about 10 mm posterior to the pelvic girdle for fish greater than 175 mm. The tag was inserted anteriorly through the ventral musculature. The insertion location for fish PIT tagged in the dorsal musculature was about 10 mm anterior from the origin of the dorsal fin on the left side of the fish. The tag was inserted posteriorly along the base of the dorsal fin into the musculature. All PIT tags were implanted manually in test fish with a modified syringe and 12-gauge hypodermic needle. Tags and needles were disinfected with 90go 8