Mortality of fish discarded from commercial fisheries is often estimated by using viability keys to parse fish into different categories with unique estimated survival outcomes. In this study we examined the relationships of environmental and physiological parameters and viability classifications of Pacific halibut (Hippoglossus stenolepis) released from commercial longline gear using three distinct hook-release methods. Our results indicate that the hook release method used strongly influenced viability, with careful shake and gangion cut resulting in minimal injuries leading to discarded fish characterized as having excellent viability. In contrast hook stripping resulted in most released fish having moderate or poor viability. Physiological parameters (lactate, hematocrit) were strong indicators of Pacific halibut assigned to the dead viability category. In addition to being captured at greater depth and lower sea bottom temperature, dead categorized fish were associated with high plasma lactate levels and lower hematocrit, attributed to sand flea intrusion. Reducing the use of hook strippers and limiting soak times in areas of known sand flea activity are likely to improve viability outcomes of Pacific halibut released from commercial longline gear. Discard survival and understanding of the factors affecting it remain critical to successful long-term management of Pacific halibut, as sustainable fishing levels are adjusted yearly for estimated mortality consistent with recent fishing discards.

商业渔业中丢弃的鱼的死亡率通常是通过使用活力键将鱼解析为具有独特的估计生存结果的不同类别来估计的。在这项研究中，我们使用三种不同的释放钩方法，研究了从商业延绳钓具释放的太平洋大比目鱼（ Hippoglossus stenolepis ）的环境和生理参数以及生存能力分类之间的关系。我们的结果表明，所使用的鱼钩释放方法对生存能力有很大的影响，仔细摇晃和剪断线会导致最小的伤害，从而导致丢弃的鱼具有良好的生存能力。相反，脱钩导致大多数释放的鱼具有中等或较差的生存能力。生理参数（乳酸、血细胞比容）是太平洋大比目鱼死亡活力类别的有力指标。除了在更深的深度和更低的海底温度捕获之外，死亡的分类鱼还与高血浆乳酸水平和较低的血细胞比容有关，这归因于沙蚤入侵。减少脱钩器的使用并限制已知沙蚤活动区域的浸泡时间可能会提高商业延绳钓装置释放的太平洋大比目鱼的生存能力。丢弃物的生存和对影响其影响因素的了解对于太平洋大比目鱼的长期成功管理仍然至关重要，因为可持续捕捞水平每年都会根据与最近的捕捞丢弃物一致的估计死亡率进行调整。