Meeting Abstract
13.11 Friday, Jan. 4 Comparison of fishing-induced stress response and post-release mortality between sandbar (Carcharhinus plumbeus) and dusky (Carcharhinus obscurus) sharks MARSHALL, H.M.*; BRILL, R.; BUSHNELL, P.; SKOMAL, G.; BERNAL, D.; University of Massachusetts Dartmouth; Virginia Institute of Marine Science/NOAA; Indiana University South Bend; Massachusetts Division of Marine Fisheries; University of Massachusetts Dartmouth hmarshall@umassd.edu
In recent years, exploitation of many shark species has incited management organizations to revise commercial fisheries management plans (FMPs) with the hopes of conserving shark populations. Specifically in the western Atlantic, amendments to the Consolidated Highly Migratory Species FMP demand the post-capture release of several coastal species, including the sandbar (Carcharhinus plumbeus) and dusky (C. obscurus) sharks (Family Carcharhinidae). Although these FMPs are designed to conserve populations, they result in an increased number of sandbar and dusky sharks being released after capture. Research on fishing-related stress indicates that the survival of released fish after capture is not well understood. This study investigates stress response in sandbar and dusky sharks after longline capture, and subsequent post-release mortality. Pop-up Satellite Archival Tags were used to determine post-release survival of sharks after capture on longline gear, and blood stress parameters (electrolytes and metabolites) were collected from each fish. Post-release mortality appears to occur more often, after shorter capture times, in the dusky versus the sandbar shark. In addition, at-vessel mortality occurs after ~3 hours on the longline in the dusky shark. Regression analysis reveals a significant (p<0.05) correlation of increasing levels of sodium, potassium, glucose, and lactate with soak time in the dusky shark, whereas the sandbar shark did not show any correlation. Physiology of the dusky shark seems greatly affected by capture, relative to sandbar sharks, resulting in higher rates of at-vessel and post-release mortality.
