Chinook salmon (Oncorhynchus tshawytscha) display the greatest variability of return times to freshwater of all Pacific salmon. Differential return times to freshwater have segregated populations of Chinook into two broad types or runs, fall and spring, named for the time of year in which they migrate to freshwater. Migration time...
Nearly 3000 juvenile Chinook (Oncorhynchus tshawytscha) and coho (O. kisutch) salmon captured in nearshore waters off the coasts of Washington and Oregon from 1999-2004 were tested for infection by Renibacterium salmoninarum, Nanophyetus salmincola, and skin metacercariae. First, three quantitative PCR primer/probe sets were compared for detection of R. salmoninarum; amplification...
Most parasites and their hosts live in a balance within their environment; however a disease outbreak can occur when either the parasite, host, or environment, are perturbed. Myxozoan parasites are associated with a wide variety of cultured and wild fish populations. Most myxozoans are relatively benign to their vertebrate host;...
First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite...
Animals respond to stressful situations with increases in plasma levels of
glucocorticoid stress hormones. These hormones originate from the adrenal cortex
in response to stimulation of the hypothalamic-pituitary-adrenal axis.
Glucocorticoids (corticosterone in reptiles) function to mobilize energy and
suppress unnecessary functions until the stress passes. Among these immediately
unnecessary functions...
Diseases caused by parasites are recognized as significant sources of mortality in wild fish populations. I assessed the impacts of multispecies parasitism on a threatened stock of juvenile coho salmon (Oncorhynchus kisutch). A crucial prerequisite to this research was proper identification of parasites, which can be difficult for species lacking...
This study was conducted to determine the effects of
shipping stress on the immune system in domestic lambs (Ovis
aries) and to determine the potential of the thymic peptide,
thymulin, to reduce those effects of stress on the immune
system. Treatments consisted of no shipping (as unstressed
controls), shipping (as...