Philip V. Haner

A Microassay for Gill Sodium, Potassium-Activated ATPase in Juvenile Pacific Salmonids

Abstract A microassay well-plate method is described for determining Na+,K+-ATPase activities of small gill sections from juvenile Pacific salmon Oncorhynchus spp. The method differs from the established macromethod by detecting inorganic phosphate in nanomole rather than micromole concentrations. This permits the use of much smaller tissue samples, which makes it possible to release fish after sampling. Use of sonication during enzyme extraction and elimination of the need to deproteinize samples before ATPase analysis further simplify the assay. Application of the microwell-plate technique for both Na+,K+-ATPase activity and protein analysis permits rapid processing of many samples. It also produces results equivalent to those of the macroassay; no significant differences occurred between sample duplicates run by the two methods with the same enzyme extract (P > 0.05). The coefficient of variation (100·SD/mean) for microassay samples containing enzyme activities of at least 10 umol inorganic phosphate p...

Incidence of Renibacterium salmoninarum Infections in Juvenile Hatchery Spring Chinook Salmon in the Columbia and Snake Rivers

Abstract From 1988 through 1992, we assessed the prevalence (frequency of occurrence) and severity (degree of infection) of Renibacterium salmoninarum (RS) among fish in marked groups of Columbia River basin and Snake River basin hatchery spring chinook salmon Oncorhynchus tshawytscha before release and during their seaward migration. During the study, prevalence of RS infection decreased (from >90% to 90%) than in the hatchery (mean <70%), but there were no differences in similar comparisons of Columbia River fish. Although prevalence and severity of RS infection were not correlated in the groups studied, it appears that fish from the Snake River were more severely infected than those from the Columbia River. Some groups of Snake River fish had higher seve...

Skin Reflectance as a Nonlethal Measure of Smoltification for Juvenile Salmonids

Abstract Our efforts to find nonlethal methods of assessing the parr-smolt transformation of juvenile steelhead Oncorhynchus mykiss and spring and fall chinook salmon O. tshawytscha led to the development of a video system for quantitatively measuring skin silvering using skin reflectance. Gill Na+, K+-ATPase activity, skin guanine concentration, and skin reflectance were recorded from groups of fish marked with freeze brands at hatcheries and downstream sample sites in the Columbia River basin. Skin reflectance of migrants was significantly higher than that of fish before release; nonmigrants (released fish that did not migrate) had significantly lower skin reflectance than migrants from the same groups. Skin reflectance was significantly correlated with gill ATPase activity and skin guanine concentration. Skin reflectance increased during the parr–smolt transformation and could be used as a nonlethal indicator of smoltification.