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The Effects of Rearing Density on Growth, Fin Erosion, Survival, and Migration Behavior of Hatchery Winter Steelhead
Author(s) -
Kavanagh Maureen,
Olson Douglas E.
Publication year - 2014
Publication title -
north american journal of aquaculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 41
eISSN - 1548-8454
pISSN - 1522-2055
DOI - 10.1080/15222055.2014.920747
Subject(s) - hatchery , biology , brood , fishery , juvenile , zoology , rainbow trout , fish <actinopterygii> , raceway , fish hatchery , dorsal fin , aquaculture , fish farming , ecology , physics , finite element method , thermodynamics
Juvenile winter steelhead Oncorhynchus mykiss at Eagle Creek National Fish Hatchery in Estacada, Oregon, were reared for three brood years (2004–2006) at raceway densities of 7,500 (214 fish/m 3 ), 15,000 (429 fish/m 3 ), and 22,500 fish (643 fish/m 3 ) to determine the effects of rearing density on growth, fin erosion, survival, adult yield, and migration behavior. Coded wire tags were used to evaluate adult survival, and fish were radio‐tagged to monitor migration times from the hatchery to the mouth of Eagle Creek following volitional release from the hatchery. We found rearing density had a significant effect ( P < 0.05) on steelhead growth, fin erosion, and adult survival. Winter steelhead reared in low‐density raceways (13.6 kg/m 3 at release) were significantly larger at release, larger at return, had significantly better dorsal fin condition, and had significantly greater smolt‐to‐adult survival rates than did those reared in medium (23.4 kg/m 3 ) and high (35.2 kg/m 3 ) density raceways. No significant relationship between smolt size at release and migration timing was detected; however, the effect of rearing density on fish migration was noticeable in brood year 2004. In that year (2004), smolts from the medium‐ and high‐density groups took from 6 to15 d longer to out‐migrate than those from the low‐density group.