Efforts to manage stocks of salmonids in Pacific Northwest stream systems are complicated by the occurrence of several runs of a species thought to represent races rearing sympatrically as juveniles. In order to collect the population statistics needed to properly manage these stocks, managers need a method of identifying juvenile...
Detection of L-serine and D,L-alanine by juvenile coho salmon (Oncorhynchus kisutch) was measured in a two-choice Y-trough. Threshold concentration for olfactory
detection of L-serine was 10-8 M for zero-age parr, 1O-7 M for yearling parr, 10-5 M for smolts in late April-early May, and 10-6 M for smolts in June....
Phenotypic similarities of coho salmon (Oncorhynchus kisutch)
stocks from Oregon, Washington, and California were compared using
agglomerative and divisive cluster analyses. The phenotypic characters
evaluated included the following: 1) the isozyme gene frequencies
of transferrin and phosphoglucose isomerase; 2) the life history
characters time of peak spawning and proportion of...
Periodic determinations of plasma hormone levels suggested that changes in interrenal activity are unrelated to changes in thyroidal or gonadal activity during development (smoltification) of juvenile coho salmon (Oncorhynchus kisutch). Moreover, in an experiment where fish were reared under various conditions of crowding and water inflow rate, it appeared that...
The importance of hormone reservoirs in mature teleost eggs is
unknown. To elucidate the effects of hormones on embryonic development,
steelhead trout eggs, Oncorhynchus mykiss, were immersed in either cortisol,
testosterone, or thyroxine at two different stages of development. Elevated
concentrations of cortisol were detectable in the trout eggs or...
Plasma concentrations of cortisol, a glucocorticoid hormone that
is immunosuppressive in mammals, increase during stress and
smoltification of salmonids. There was a reduction in the ability of
lymphocytes to generate antibody producing cells (APC) in vivo
concurrent with increased plasma cortisol titers during smoltification
of coho salmon (Oncorhvnchus kisutch). Cortisol...
Depleted species of rockfish (Sebastes spp.) from the Northeast Pacific experience high discard mortality due to "barotrauma," induced from the rapid change in pressure during capture. Research suggests rockfish have the potential to survive barotrauma if immediately recompressed, but the potential for long-term recovery is unknown. In this project, we...
Juvenile coho salmon (Oncorhynchus kisutch) of three transferrin
genotypes (AA, AC and CC) were experimentally infected with the
causative agent of bacterial kidney disease (BKD) and mortalities
observed. Six experimental and control groups were used:
(1) bacteria-infected + no Fe⁺³ ; (2) bacteria-infected + low Fe⁺³
levels; (3) bacteria-infected +...
To best manage Eagle Creek National Fish Hatchery and minimize any negative impacts that the current hatchery program may be having on Endangered Species Act-listed salmonids in the Eagle Creek Basin, I determined if wild fish are being displaced from preferred habitats by hatchery salmonids Oncorhynchus spp. This thesis had...