Meeting Abstract
P1.164 Tuesday, Jan. 4 Post-capture blood chemistry of sharks in the family Lamnidae indicates a potentially higher vulnerability to fishing pressure MARSHALL, H.*; FIELD, L.; SEPULVEDA, C.; BERNAL, D.; University of Massachusetts Dartmouth; University of Massachusetts Dartmouth; Pfleger Institute of Environmental Research; University of Massachusetts Dartmouth hmmarshall@gmail.com
Sharks in the Family Lamnidae posses morphological and physiological specializations that support high performance swimming. Lamnids have vascular specializations that allow for metabolic heat retention, have a cardiovascular morphology and physiology capable of producing greater cardiac outputs, and have elevated metabolic capacities. Research has shown that relative to species in the Family Carcharhinidae, the shortfin mako shark (Isurus oxyrinchus) has higher (p<0.05) enzymatic biochemical metabolic capacities within the heart. I. oxyrinchus also has higher (p = 0.0005) myoglobin content per gram of cardiac tissue relative to carcharhinids. Such morphological and physiological adaptations may allow lamnids to undergo relatively faster burst swimming speeds and quick recovery. When lamnid sharks are captured in fishing gear, they undergo unnatural bouts of exhaustive exercise that, coupled with improper ventilation, lead to an impaired recovery. This would result in a higher physiological perturbation leading to higher at-vessel mortality rates when compared to other sharks. Indeed, published at-vessel mortality rates and recent stress-related research suggests that species belonging to the Family Lamnidae may be particularly vulnerable to fishing pressure. Our research shows that lamnid sharks (e.g., porbeagle, Lamna nasus, and shortfin mako) have different lactate (up to 9X higher; p<0.05) and glucose (up to 2x higher; p<0.05) values relative to carcharhinids. Our preliminary results indicate that lamnid sharks appear to be more vulnerable to capture and that this is a product of the enhanced metabolic capacities within these species.
