Bioelectrical impedance analysis (BIA) is commonly used in human health and nutrition fields but has only recently been considered as a potential tool for assessing fish condition. Once BIA is calibrated, it estimates fat/moisture levels and energy content without the need to kill fish. Despite the promise held by BIA, published studies have been divided on whether BIA can provide accurate estimates of body composition in fish. In cases where BIA was not successful, the models lacked the range of fat levels or sample sizes we determined were needed for model success (range of dry fat levels of 29%, n = 60, yielding an R² of 0.8). Reduced range of fat levels requires an increased sample size to achieve that benchmark; therefore, standardization of methods is needed. Here we discuss standardized methods based on a decade of research, identify sources of error, discuss where BIA is headed, and suggest areas for future research.

Inland waters provide valuable ecosystem goods and services and are intrinsically linked to downstream coastal areas. Water quality impairments that lead to harmful algal blooms damage valuable commercial and recreational fishing economies, threaten food security, and damage already declining native species. Prymnesium parvum is a brackish water golden alga that can survive in salinities less than 1 ppm and when it blooms it can create toxins that kill aquatic life. Blooms have been documented globally including 23 U.S. states. We report a case study of an aquatic life kill associated with P. parvum in Dunkard Creek (WV-PA, USA), in the Ohio River Drainage. We document the immediate impact to aquatic life and responses of the aquatic community ten years post-kill. Most fish species returned within a year. Excellent connectivity to unimpacted tributaries and a river downstream likely aided the reestablishment of most species, although some had not reached pre-kill abundances after ten years. Mussel taxa did not recover despite significant efforts to relocate adult mussels and stocking of host fish inoculated with glochidia; probably due to other water quality impairments. Given the potential for lateral transport of P. parvum via industry and natural vectors we conducted an ecological risk assessment mapping the spatial extent of U.S. waters that could be threatened by golden algae colonization and blooms using a national water quality database and a state database. Overall, about 4.5% of lotic systems appeared to have some level of risk of harboring P. parvum, making them at risk for potential golden algae blooms in the face of increasing salinization and eutrophication of freshwaters.

Studies have predicted declines in trout habitat of over 50% given projected climate warming scenarios. Therefore, knowledge of the performance of trout strains at elevated temperature is critical for management of trout fisheries and trout strains under climate change. Our objectives were to compare the performance of three strains of Rainbow Trout Onchorynchus mykiss at elevated temperatures. We compared growth, consumption, and feed efficiency at 20°C and 22°C, and critical thermal maxima (CTM) among the strains. The Case Western strain is registered as a warm‐tolerant strain with the National Fish Strain Registry, and it did achieve a significantly higher CTM (31.29°C) than the Kamloops (31.14°C) but not the Wytheville (31.20°C) strain. Such small differences are likely not biologically significant. While the CTM of the Case Western strain was higher than that of the Kamloops, the Case Western strain consistently performed poorer than the other strains in feeding and growth experiments at 20°C and 22°C. Our results add to the growing body of literature suggesting that differences in thermal performance do exist between strains of trout. While there is debate about whether these differences are due to evolutionary adaptation to local environmental conditions or phenotypic plasticity, the differences being found in thermal performance of trout suggests future research aimed at improving thermal performance via thermal testing and selective breeding may yield stock with improved tolerance and growth at warmer temperatures.Received April 17, 2014; accepted June 24, 2014

Pharmaceuticals and personal care products (PPCPs), such as statins and beta-blockers, are commonly used to treat cardiovascular disease in adults. Active versions of these pharmaceuticals and their various metabolites enter surface waters via wastewater treatment plant (WWTP) discharge, as well as from other point sources. Sub-lethal effects of statins and beta-blockers on wild fish at environmental concentrations have been understudied up to this point. The objectives of this study were to use several health condition metrics and determine if there was a relationship between fish condition and environment concentrations of statins and beta-blockers near two West Virginia WWTPs. Water samples were collected from upstream, downstream, and effluent pipe from August to November 2022, and analyzed for atorvastatin, simvastatin, metoprolol, and carvedilol via liquid chromatography with tandem mass spectrometry. Fish were sampled upstream, at the discharge, and downstream of each WWTP in November 2022. Fish health was assessed with three metrics: relative weight (Wr), hepatosomatic index (HSI), and gonadosomatic index (GSI). ANOVAs were used to assess differences among the health metrics based on sex, genus/species, and location relative to WWTPs. Additionally, changes in Wr relative to surface water concentrations of statins and beta-blockers was modeled with a Bayesian linear mixed effects model, with surface water concentrations as fixed effects with a random slope, while the section and genus parameters were treated as random intercepts. Surface concentrations for atorvastatin (0.47–4.36 ng/L), simvastatin (0.27–0.95 ng/L), metoprolol (2.80–21.01 ng/L), and carvedilol (0.43–0.90 ng/L) varied across sampling sections. HSI based on sex and species were nearly significant. GSI was significantly higher in females. Wr differed among genera, as well as the interaction between genus and sample section (p < 0.001). Fixed effects from the linear mixed effects model showed Wr was negatively related to simvastatin (−0.139 [−2.072–1.784]) and carvedilol (−0.262 [−2.164–1.682]) while atorvastatin (0.207 [−1.371–1.845]) and metoprolol (0.052 [−0.533–0.584]) were positively related to Wr. Individual genera responded differently to each pharmaceutical based on location, indicating that it is likely that other factors were also influencing the fish health metrics. Further research targeting individual tissues and controlled experiments with different exposure regimes will be required to further enlighten the long-term effects of cardiovascular PPCPs on fish health.