Physiological stress response, reflex impairment, and survival of five sympatric shark species following experimental capture and release

Abstract

In many fisheries, some component of the catch is usually released. Quantifying the effects of capture and release on fish survival is critical for determining which practices are sustainable, particularly for threatened species. Using a standardized fishing technique, we studied sublethal (blood physiology and reflex impairment assessment) and lethal (post-release mortality with satellite tags) outcomes of fishing stress on 5 species of coastal sharks (great hammerhead, bull, blacktip, lemon, and tiger). Species-specific differences were detected in whole blood lactate, partial pressure of carbon dioxide, and pH values, with lactate emerging as the sole parameter to be significantly affected by increasing hooking duration and shark size. Species-specific differences in reflex impairment were also found; however, we did not detect any significant relationships between reflex impairment and hooking duration. Taken together, we ranked each species according to degree of stress response, from most to least disturbed, as follows: hammerhead shark > blacktip shark > bull shark > lemon shark > tiger shark. Satellite tagging data revealed that nearly 100% of all tracked tiger sharks reported for at least 4 wk after release, which was significantly higher than bull (74.1%) and great hammerhead (53.6%) sharks. We discuss which mechanisms may lead to species-specific differences in sensitivity to fishing and suggest that observed variation in responses may be influenced by ecological and evolutionary phenomena. Moreover, our results show that certain species (i.e. hammerhead sharks in this study) are inherently vulnerable to capture stress and mortality resulting from fisheries interactions and should receive additional attention in future conservation strategies.

Risk perceptions and conservation ethics among recreational anglers targeting threatened sharks in the subtropical Atlantic

“…org, (2) at-vessel (AV) and/or post-release (PR) mortality estimates from empirical research, and (3) anglers in the present study. At-vessel mortality rate data obtained from Morgan & Burgess (2007); post-release mortality information obtained from Gallagher et al (2014a); n/a: data not available Fig. 4.…”

Seasonal and life-stage variation in the reproductive ecology of a marine apex predator, the tiger shark Galeocerdo cuvier, at a protected female-dominated site

“…Tiger sharks were captured using standardized circle-hook drumlines, which is a passive fishing technique (as described in Gallagher et al 2014). Briefly, the gear consisted of a submerged weight base tied to a line running to the surface by means of an attached, inflatable buoy float.…”

A new underwater shark capture method used by divers to catch and release nurse sharks (Ginglymostoma cirratum)

“…Ethically, capture methods should aim to minimize animal suffering (Cuthill, 1991;Jenkins et al, 2014), as well as reduce stress responses, which can bias many types of data collected (Sheriff et al, 2011;Gallagher et al, 2014). Ideally, capture methods should be developed and refined by experienced wildlife biologists and technicians who have studied, planned, and tested methods before starting any wildlife research or management program (Schemnitz et al, 2012).…”

“…Over 30% of current studies from all published research on 29 reef shark species have focused on nurse sharks (Osgood and Baum, 2015). Studies that involved capturing nurse sharks have successfully used fishing nets or baited hook-and-line gear, but these methods are not without limitations or problems (Garla et al, 2006;Gallagher et al, 2014). These traditional capture methods can prolong treatment and handling times on account of gear entanglement and recovery delays (Smith, 1992;Mandelman and Farrington, 2007;Morgan and Carlson, 2010) or cause severe hooking injuries that increase morbidity and mortality (Bansemer and Bennett, 2010;Danylchuk et al, 2014).…”