Characterization of Dissolved Free Amino Acids in Salmon Hatchery Water

Straying of hatchery-reared salmon is of high concern to numerous agencies tasked with the protection of native salmonid populations. Hatcheries often utilize water for incubation and rearing purposes from the river these salmon return to, so efforts to imprint smolts to hatchery water as a target return location may be futile. Considerable attention has been directed towards dissolved free amino acid’s (DFAA) as a set of odorants salmon use to navigate and identify their natal rivers. Research has shown that salmonids possess the ability to distinguish between certain water sources based on their DFAA compositions and that DFAA compositions often differ significantly between watersheds. If salmon do indeed utilize DFAA for homing to natal spawning sites, alteration of DFAA composition in hatchery system water during key imprinting and homing periods may serve as a possible technique to improve return rates of hatchery reared salmon to their respective hatcheries. Our results show that hatchery and river water DFAA profiles can be highly similar, which might suggest some variability observed in the returns of hatchery-reared salmon to hatchery fishways may be due to an inability to distinguish between hatchery water and river water based on its chemical components.