Developing methods to evaluate vitality of Pacific salmon bycatch from marine commercial fisheries to improve post-release survival

在以丰富的鱼种为目标的同时，太平洋鲑鱼商业捕捞无意中捕获了必须释放的不太丰富的鱼种（称为兼捕）。 最近，商业太平洋鲑鱼渔业的行业领导者Canadio拥有的不列颠哥伦比亚省北方船队中的船只被ENESCO和其他团体列为目标，因为它们对副渔获物的释放做法很差。这导致了这些渔业的一些对抗和经济不确定性。Canadio希望改进其船队使用的活鱼释放方法，并开发一种可靠的、科学上可辩护的方法来估计捕获时的副渔获物状况，以更好地预测释放鱼的存活率。我们提出了一个简单的技术，观察员或其他船上量化副渔获物的条件下，使用快速反射评估，很少干扰渔民的正常工作，我们的小组在淡水太平洋鲑鱼渔业以前验证的方法。 这一技术可用于查明对释放的鱼造成最大伤害的船只或处理方法，并有助于制定更好的做法。预计2015年粉红鲑鱼将大量出现，这为在现实条件下以鲑鱼作为副渔获物物种对该方法进行测试提供了机会。研究活动将在一艘北方BC商业围网船上进行（行业实物船舶捐助5万美元，为期10天），该船根据科学研究许可证运营。当遇到混捕的鱼饵时，我们会立即评估它们的状况和反应，然后释放大部分。所有的粉红色鲑鱼也将立即释放。一个亚组的鲑鱼副渔获物的生命力将进行评估，并在附近的海岸网围栏附近进行监测，以确定预测死亡率的生命力措施。还将评估一部分鱼的活力和捕获后的血液采样，以了解各种程度的损伤背后的生理压力。这项研究的目标是估计释放后的死亡率以下典型的兼捕处理方法，确定可预测性的反射措施释放后的生存，并使用生理信息来了解损伤和死亡率。

While targeting abundant species, commercial Pacific salmon fisheries inadvertently capture less abundant species that must be released (termed bycatch). Recently, vessels in the northern BC fleet owned by Canfisco, an industry leader in commercial Pacific salmon fisheries, have been targeted by ENGOs and other groups as employing poor release practices for bycatch species. This has led to some confrontation and economic uncertainties for these fisheries. Canfisco wishes to improve on live release approaches used by its fleet and develop a reliable and scientifically defensible method to estimate bycatch condition at capture to better predict survival of released fish. We propose a simple technique for observers or others on-board to quantify bycatch condition using rapid reflex assessments with little interference to the fishers' normal routine, an approach previously validated by our group in freshwater Pacific salmon fisheries. This technique could be used to identify vessels or handling methods that cause the most harm to released fish and enable better practices to be developed. There is a strong run of pink salmon expected in 2015, providing an opportunity for the approach to be tested under realistic conditions with chum salmon as a bycatch species. The research activity would occur aboard a northern BC commercial purse seine vessel (industry in-kind vessel contribution of $50K for 10 days) operating under a scientific research permit. As chum bycatch are encountered, we would immediately evaluate their condition and reflexes, then release most of them. All pink salmon will also be immediately released. A subset of chum salmon bycatch will be assessed for vitality and held captive for monitoring in nearby near shore net pens to determine vitality measures predictive of mortality. A subset of fish will also be assessed for vitality and blood sampled post-capture to understand the physiological stress underlying various levels of impairment. The goals of the study are to estimate post-release mortality following typical bycatch handling approaches, determine the predictability of reflex measures for post-release survival, and use physiological information to understand impairment and mortality.