Understanding the stress responses of sharks to recreational catch and release fishing has important management and conservation implications. The blacktip shark Carcharhinus limbatus is a popular recreational species targeted throughout the western, central and eastern Gulf of Mexico (Gulf) yet it is unclear what levels of physiological stress result from catch-release fishing practices with hook and line gear and if the stress levels result in post-release mortality. This study correlates physiological response to stress through blood chemistry analysis and examines post-release behaviour of adult blacktip sharks caught to determine post-release mortality rates. Release behaviour was determined by pop-up satellite archival transmitting (PSAT) tags that record temperature, depth and light level data. To quantify physiological stress levels, blood samples were collected from 52 blacktip sharks and a suite of metabolic and osmotic markers were measured. Thirty-six of those blacktip sharks were also outfitted with a PSAT tag yielding time-at-large from 3 to 180 days. Of the 36 tags, 22 (61%) provided sufficient data to confirm post-release fate and 11 (31%) were recovered providing high-resolution data. Tag data suggests a post-release morality rate of 22.7% (95% confidence interval 7.8-45.4%), with mortality occurring within minutes (immediate mortality) to over 12 h post-release (delayed mortality). Compared to survivors, immediate mortalities exhibited significantly higher lactate (median 2.8 mmol/Lsurvivor vs 5.9 mmol/Limmediate mortality) and significantly lower hematocrit (median 24.4% survivor vs 14% immediate mortality) levels, but no difference was detected between survivors and delayed mortalities. Higher mortality in the western (30%) compared to the central (20%) Gulf may be due to shark handling. All PSATs from mortalities (N = 5) were recovered, and archived data revealed evidence of tag ingestion by predators. Results suggest reduced fight time, decreased handling time and limited air exposure provide blacktip sharks the best survival chances after release by recreational anglers.

中文翻译：

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在墨西哥湾的休闲宪章渔业中捕获黑鳍鲨的压力和释放后的死亡率。

了解鲨鱼对休闲捕捞和释放捕鱼的压力反应具有重要的管理和保护意义。黑鳍鲨（Carcharhinus limbatus）是针对墨西哥西部，中部和东部墨西哥湾（海湾）的一种流行休闲物种，但目前尚不清楚钩和钓具的捕捞释放方式会导致什么生理压力水平，以及压力水平是否导致释放后的死亡率。这项研究通过血液化学分析将对应激的生理反应相关联，并检查捕获的成年黑鳍鲨的释放后行为，以确定释放后的死亡率。释放行为由记录温度，深度和光照水平数据的弹出式卫星档案传输（PSAT）标签确定。为了量化生理压力水平，从52条黑鳍鲨收集血液样本，并测量一组代谢和渗透标记。这些黑鳍鲨中有36个还配备了PSAT标签，产生的时间从3天到180天不等。在这36个标签中，有22个（61％）提供了足够的数据来确认释放后的命运，并回收了11个（31％）提供了高分辨率的数据。标签数据表明，释放后的道德率为22.7％（95％置信区间为7.8-45.4％），死亡率发生在几分钟（即时死亡率）至释放后12小时内（延迟死亡率）。与幸存者相比，即时死亡率显示出较高的乳酸水平（中位2.8 mmol / L生存者vs. 5.9 mmol /中度死亡率）和显着较低的血细胞比容（中位24.4％生存者vs 14％立即死亡）水平，但幸存者与延迟死亡之间未发现差异。西部地区（30％）比中部地区（20％）的死亡率更高，这可能是由于鲨鱼的处理所致。所有来自死亡的PSAT（N = 5）均已恢复，存档数据揭示了掠食者吞食标签的证据。结果表明，减少的战斗时间，减少的处理时间以及有限的空气暴露为黑鳍鲨提供了休闲垂钓者释放后的最佳生存机会。