A view from above and below: Hatchery chinook salmon are self-sorting in tanks

Phys Org –

Hatchery-raised chinook salmon sort themselves into surface- and bottom-oriented groups in their rearing tanks. This behavior might be due in part to the fish’s genes, according to an Oregon State University study.

The finding, published in the journal Environmental Biology of Fishes, could change a commonly held view that hatchery-raised fish are generally expected to behave in the same manner, said Julia Unrein, who led the study as a master’s degree student in the Oregon Cooperative Fish and Wildlife Research Unit in OSU’s College of Agricultural Sciences.

“What we found is hatchery juvenile chinook salmon are not made from the same mold,” Unrein said. “Perhaps by trying to force them to fit our model of what a ‘hatchery fish’ is and constrain them to specific release times, we may be overlooking the variation among individuals that we know is important for the survival of their wild counterparts.”

Carl Schreck, professor in OSU’s Department of Fisheries and Wildlife, said, “The implications relative to Endangered Species Act-listed fish may be profound if they serve to allow the creation of test fish for researchers to use when studying how to successfully get juvenile chinook to safely migrate through Willamette system reservoirs and dams. There are fish culture and habitat restoration implications, as well.”

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