Performance of nine external tags on hatchery-reared rainbow trout
We evaluated nine commercially available tags to determine their suitability for marking yearling rainbow trout Oncorhynchus mykiss reared in raceways and circular tanks. The tags tested were Floy vinyl tubing tags FD‐67 anchor, FT‐2 dart, FT‐4 cinch‐up, and FT‐4 lock‐on; modified Carlin; modified Petersen disk; Monel strap 4‐1005; Monel butt end 4‐1242; and Stoffel fish seal. After 9 months, tag losses from raceway fish were lowest (8%) for the FT‐4 lock‐on tag; in tanks, none of the FT‐2 dart, FT‐4 cinch‐up, FT‐4 lock‐on, or the Monel butt end tags were lost. At 90 d after tagging, raceway fish marked with the Monel strap or the modified Carlin tags showed significantly less growth than did fish marked with the FD‐67 anchor tag; the converse was true for fish in tanks. After 9 months, raceway fish marked with the Monel butt end tag and tank fish marked with the FD‐67 anchor tag were least injured. Injury was greater in raceways than in tanks for all tag types. Judged by overall performance, the FD‐67 anchor was the most effective tag for fish maintained in raceways and the FT‐4 cinch‐up was a suitable alternative; the FT‐2 dart, FT‐4 cinch‐up, and Monel butt end tags were equally suitable for fish in tank culture.