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This study evaluated the use of electroshock as an alternative to traditional techniques for immobilizing and euthanizing hatchery fish. We used a commercially available electroanesthesia unit at the U.S. Fish and Wildlife Service's Carson National Fish Hatchery (Carson, Washington) to euthanize adult spring Chinook salmon Oncorhynchus tshawytscha and to sort and collect gametes of fish at maturation. During euthanization by electroshock, the response of each fish was observed, muscular and vertebral hemorrhaging was quantified, and electrical settings were optimized accordingly. During gamete collection, fish were either electroshocked or exposed to tricaine methanesulfonate (MS-222); hemorrhaging, egg viability, egg size and quantity, and resultant fry quality were examined for each treatment group. Electroshocked fish had a higher likelihood of injury during gamete collection than did fish exposed to MS-222. On average, each electroshocked fish had less than two hemorrhages on both fillets examined. The size of each hemorrhage was less than 0.10% of the fillet surface. Fecundity and egg and fry quality were not affected by either immobilization method. Electroshock was a viable and efficient means of euthanizing adult spring Chinook salmon or sorting the fish and collecting their gametes. However, equipment settings must be optimized based on site-specific (e.g., water conductivity) and species-specific (e.g., fish size and seasonal state of maturation) factors.

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Declining fish health, fish exhibiting external lesions, incidences of intersex, and death, have been observed recently within the Potomac River basin. The basin receives surface runoff and direct inputs from agricultural, industrial, and other human activities. Two locations on the North Fork of the Shenandoah River were selected for study in an attempt to identify chemicals that may have contributed to the declining fish health. Two passive sampling devices, semipermeable membrane devices (SPMDs) and polar organic chemical integrative samplers (POCIS), were deployed during consecutive two-month periods during the spring and early summer of 2007 to measure select organic contaminants to which fish may have been exposed. This study determined that concentrations of persistent hydrophobic contaminants, such as polycyclic aromatic hydrocarbons (<760 picograms per liter), legacy pesticides (<10 picograms per liter), and polychlorinated biphenyls (<280 picograms per liter) were low and indicative of a largely agricultural area. Atrazine and simazine were the most commonly detected pesticides. Atrazine concentrations ranged from 68 to 170 nanograms per liter for the March to April study period and 320 to 650 nanograms per liter for the April to June study period. Few chemicals characteristic of wastewater treatment plant effluent or septic tank discharges were identified. In contrast, para-cresol, N,N-diethyltoluamide, and caffeine commonly were detected. Prescription pharmaceuticals including carbamazepine, venlafaxine, and 17α-ethynylestradiol were at low concentrations. Extracts from the passive samplers also were screened for the presence of estrogenic chemicals using the yeast estrogen screen. An estrogenic response was observed in POCIS samples from both sites, whereas SPMD samples exhibited little to no estrogenicity. This indicates that the chemicals producing the estrogenic response have a greater water solubility and are, therefore, less likely to bioaccumulate in fatty tissues of organisms.

h n S. H o l m e s , L i -H s i e n Rin, J o a n n e M. T r e m b l a y , a n d R o b e r t K. Zeldin ( C o m p i l e d a n d e d i t e d b y [Barbara S.K. S t a n l e y ) fir at WESTERN MICHIGAN UNIVERSITY on June 5, 2016 gct.sagepub.com Downloaded from