Molly A. H. Webb

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.

Recovery Program Review for Endangered Pallid Sturgeon in the Upper Missouri River Basin

The pallid sturgeon (Scaphirhynchus albus) is one of the most critically endangered species in the United States. Recovery implementation occurs primarily through activities of three workgroups that function in the upper, middle, and lower portions of the Missouri and Mississippi Rivers. The Upper Basin Workgroup (UBW) consists of federal and state agency biologists, state representatives, and university scientists from Montana, North Dakota, South Dakota, and Nebraska. In August 2003, the UBW requested that the Western Division of the American Fisheries Society (WDAFS) review the existing pallid sturgeon recovery effort in the upper basin and make recommendations to improve the efficiency and effectiveness of the Workgroup. The WDAFS assembled a Pallid Sturgeon Recovery Review Committee to assist the UBW in accomplishing this objective. In total, 52 recommendations were offered to the UBW to address recovery needs, organizational problems, funding shortfalls, and technical concerns. Nine critical recommendations concerning broodstock mating protocols, measures to control pallid sturgeon iridovirus, and habitat restoration are considered the minimum necessary to prevent near-term loss of the species from the upper Missouri River. In addition, the Committee concluded that substantial recovery must occur during the next 5 years to prevent extirpation of the species in the upper basin.

Evaluation of Organochlorine Pesticides and Sex Steroids in Lower Niagara River Lake Sturgeon

Abstract As a long-lived, late-maturing species, lake sturgeon Acipenser fulvescens are vulnerable to the bioaccumulation of contaminants, which may impact reproductive physiology. The purpose of this study was to use a nondestructive method to investigate the relationship between endocrine-disrupting contaminants and sex steroids in lake sturgeon from the lower Niagara River. We screened blood plasma samples from lower Niagara River lake sturgeon (n  =  63) during April and May of 2012 for concentrations of 17 organochlorine (OC) contaminants that may affect endocrine function, as well as for abnormal levels of sex steroids testosterone (T) and 17β-estradiol (E2). We found detectable levels of two OC contaminants in the blood plasma of lake sturgeon, DDE (n  =  21) and γ-BHC (n  =  1). In both cases, plasma contaminant concentration was well below levels known to adversely affect sturgeon reproductive physiology. In addition, qualitative analysis of chromatographs from plasma extracts did not show the pr...

Role of Sex Ratio and Density on Fertilization Success of Intensively Cultured Endangered Woundfin

Abstract Woundfin Plagopterus argentissimus are a small, endangered cyprinid found solely in the Virgin River across Utah, Arizona, and Nevada. As of now, only three facilities culture Woundfin for conservation propagation purposes, but there is growing concern that current extensive culture protocols are not meeting the conservation recovery goals outlined in the Virgin River Resource Management and Recovery Program. The development of alternative rearing methodology, like effective intensive culture conditions, could help increase production to more effectively meet the conservation propagation needs for this species. Our goal was to assess the effect of different sex ratios and fish densities on reproductive success at indoor facilities. We measured fertilization success at three different sex ratios (1:1, 1:3, 1:5; female:male) and three different fish densities (0.05, 0.21, and 0.47 fish/L) in a laboratory setting. Sex ratio did not significantly affect fertilization success (P = 0.73). Fertilization...