E. P. Foster

Potential Classification of Sex and Stage of Gonadal Maturity of Wild White Sturgeon Using Blood Plasma Indicators

Abstract Because white sturgeon Acipenser transmontanus show no readily discernible external signs of gender, management agencies use surgical biopsies to determine the sex and stage of gonadal maturity of individuals. This procedure is highly invasive and can be difficult under field conditions. Therefore, gonadal tissue and blood were collected from white sturgeon captured in tribal and commercial fisheries (fishery fish) and by fish and wildlife agencies (oversize fish) in the Columbia River basin to develop a method of determining sex and stage of maturity using the blood plasma indicators testosterone (T), 11-ketotestosterone (KT), estradiol (E2), and calcium (Ca2+). The sex and stage of maturity was determined by histology or by visual examination in maturing fish. Plasma sex steroid levels were measured by radioimmunoassay, and plasma Ca2+ was measured spectrophotometrically. White sturgeon showed sex- and maturity-specific levels of steroids and Ca2+. Stepwise discriminant function analysis (DFA) ...

Evidence of Detrimental Effects of Environmental Contaminants on Growth and Reproductive Physiology of White Sturgeon in Impounded Areas of the Columbia River

This study sought to determine whether wild white sturgeon from the Columbia River (Oregon) were exhibiting signs of reproductive endocrine disruption. Fish were sampled in the free-flowing portion of the river (where the population is experiencing reproductive success) and from three reservoirs behind hydroelectric dams (where fish have reduced reproductive success). All of the 18 pesticides and almost all of the 28 polychlorinated biphenyls (PCBs) that were analyzed in livers and gonads were detected in at least some of the tissue samples. Metabolites of p,p′-dichlorodiphenyltrichloroethane (DDT) [p,p′-dichlorodiphenyldichloroethylene (DDE) and p,p′-1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD)] were consistently found at relatively high levels in fish. Some males and immature females showed elevated plasma vitellogenin; however, concentrations were not correlated with any of the pesticides or PCBs analyzed. Negative correlations were found between a number of physiologic parameters and tissue burdens of toxicants. Plasma triglycerides and condition factor were negatively correlated with total DDT (DDD + DDE + DDT), total pesticides (all pesticides detected – total DDT), and PCBs. In males, plasma androgens and gonad size were negatively correlated with total DDT, total pesticides, and PCBs. Fish residing in the reservoir behind the oldest dam had the highest contaminant loads and incidence of gonadal abnormalities, and the lowest triglycerides, condition factor, gonad size, and plasma androgens. These data suggest that endocrine-disrupting chemicals may be accumulating behind dams over time. Overall, results of this study indicate that exposure to environmental contaminants may be affecting both growth and reproductive physiology of sturgeon in some areas of the Columbia River.

Toxic Contaminants in the Urban Aquatic Environment

Management of urban areas to reduce their impact on salmonids requires an understanding of the water quality affecting them, including anthropogenically derived toxic chemicals entering urban waterways used by salmonids. Toxic contaminants create complex problems for aquatic organisms and have important implications for natural resource managers. Toxicity is associated with exposure; therefore, it is important to understand the occurrence and concentration of toxic chemicals, which can range from episodic at high concentrations to chronic exposures at low concentrations. In addition, there are several categories of toxic chemicals with many individual chemicals within each class, which could have similar or very different environmental concentrations, longevity, and toxicity.