Catch-and-release angling is a popular recreational activity that has been shown to have impacts on fish welfare. Angler behaviour (e.g., choice of gear type, handling time) and environmental conditions (e.g., water temperature) during angling events have been documented to influence fish condition and post-release survival. This is particularly true for air exposure duration and water temperature, which are known as two of the most significant determinants of the fate of released fish. Here, Rainbow Trout (RBT; ) were angled and air exposed for a random duration of time ranging between 0 and 120 seconds across a range of water temperatures (12–26°C). Reflex impairment was assessed on a binary scale using vestibular-ocular response, burst swimming response, and ability to return to equilibrium as indicators. Dehooking time and fight duration of angling events were also recorded. Our results revealed a positive relationship between total reflex impairment and water temperature, air exposure, dehooking time, and body size (total length). At the warmest water temperatures, reflex impairment was consistently high even for fish exposed to air for mere seconds regardless of other angling behaviours. At cooler water temperatures and air exposure times greater than ∼70 seconds, reflex impairment levels were moderately high. When water temperatures were relatively cool and air exposure times were shorter (>70 seconds) reflex impairment was moderate. Based on these results, we suggest anglers targeting RBT during warm-water periods minimize overall handling time and air exposure, or avoid targeting RBT altogether. These best practices should help improve fish welfare and post-release survival.

中文翻译：

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鱼类处理和水温对虹鳟反射损伤的交互影响

捕获后释放钓鱼是一种流行的娱乐活动，已被证明对鱼类福利有影响。据记录，钓鱼活动期间钓鱼者的行为（例如，渔具类型的选择、处理时间）和环境条件（例如，水温）会影响鱼类的状况和放生后的存活率。对于空气暴露时间和水温来说尤其如此，这两个因素被认为是释放鱼类命运的两个最重要的决定因素。在这里，虹鳟鱼 (RBT; ) 在一定的水温 (12–26°C) 范围内以一定角度暴露在空气中，时间范围为 0 到 120 秒。使用前庭眼反应、突发游泳反应和恢复平衡的能力作为指标，对反射损伤进行二元评估。还记录了钓鱼事件的脱钩时间和战斗持续时间。我们的结果显示，总反射损伤与水温、空气暴露、脱钩时间和体型（总长度）之间存在正相关关系。在最温暖的水温下，无论其他钓鱼行为如何，即使鱼暴露在空气中仅几秒钟，反射损伤也始终很高。在较冷的水温和空气暴露时间超过 70 秒的情况下，反射损伤水平中等偏高。当水温相对较低且暴露在空气中的时间较短（>70 秒）时，反射损伤为中度。根据这些结果，我们建议钓鱼者在温水期间以 RBT 为目标，尽量减少总体处理时间和空气暴露，或完全避免以 RBT 为目标。这些最佳实践应有助于改善鱼类福利和放归后的存活率。