19. The Physiological Status of the Spiny Dogfish Subsequent to Capture by Otter Trawl
John W. Mandelman and Marianne A. Farrington
Abstract.—To provide a synthesis of the physiological responses to otter-trawl capture in spiny dogfish Squalus acanthias, blood values from trawled individuals were evaluated against values from minimally stressed dogfish caught rapidly by hook and line (control). Values and analyses from published studies are considered along with those from the most expansive set of blood samples taken from dogfish captured by both methods to date. Significant impacts of trawling on dogfish blood physiology were reflected in all parameters excluding log plasma protein. Parameters for whole-blood acid–base status (pH, significant decrease; pO2, 45% decrease; pCO2, 82% increase), and the metabolite lactate anion (125% increase) were most perturbed relative to differences induced by the capture methods in other parameters. The concentrations of sera monovalent electrolytes (Na+, K+, Cl–) and glucose were significantly elevated by trawling, but not to the magnitude seen in other studies related to capture stress in fish. Significant elevations in hematocrit and reductions in blood urea nitrogen (BUN) concentrations were also observed subsequent to trawling. Overall, this capture method incited marked changes in blood physiology relative to values in minimally stressed dogfish. However, previous studies demonstrating high rates of posttrawl dogfish survival indicate that such changes are resolvable in this species prior to lethal consequences.