The physiological consequences of catch‐and‐release angling: perspectives on experimental design, interpretation, extrapolation and relevance to stakeholders

Abstract

Over the past 20 years, there has been a dramatic increase in the use of physiological tools and experimental approaches for the study of the biological consequences of catch‐and‐release angling practices for fishes. Beyond simply documenting problems, physiological data are also being used to test and refine different strategies for handling fish such that stress is minimised and survival probability maximised, and in some cases, even for assessing and facilitating recovery post‐release. The inherent sensitivity of physiological processes means that nearly every study conducted has found some level of – unavoidable – physiological disturbance arising from recreational capture and subsequent release. An underlying tenet of catch‐and‐release studies that incorporate physiological tools is that a link exists between physiological status and fitness. In reality, finding such relationships has been elusive, with further extensions of individual‐level impacts to fish populations even more dubious. A focus of this article is to describe some of the challenges related to experimental design and interpretation that arise when using physiological tools for the study of the biological consequences of catch‐and‐release angling. Means of overcoming these challenges and the extrapolation of physiological data from individuals to the population level are discussed. The argument is presented that even if it is difficult to demonstrate strong links to mortality or other fitness measures, let alone population‐level impacts of catch‐and‐release, there remains merit in using physiological tools as objective indicators of fish welfare, which is an increasing concern in recreational fisheries. The overarching objective of this paper is to provide a balanced critique of the use of physiological approaches in catch‐and‐release science and of their role in providing meaningful information for anglers and managers.

Effects of Simulated Angler Capture and Live‐Release Tournaments on Walleye Survival

“…Interfacing our measures of survival with similarly designed studies that have measured secondary stress responses supports the conclusion by Cooke et al (2013) that the linkage between physiological stress measures and mortality is not straightforward. For example, our finding that Walleyes survived the stress of capture and tournament procedures better at temperatures below optimum-in particular, that fish acclimated to 18…”

“…Numerous studies have measured changes in secondary stress responses of fish that are subjected to both simulated and actual angler capture and tournament procedures (Cooke et al 2013). Changes in secondary stress measures (e.g., blood glucose, plasma chloride, plasma and tissue lactate, and plasma osmolality) are informative for assessing sublethal effects of angling or tournament processes on fish and may provide insight into mechanisms for mortality; however, for fisheries managers, anglers, and tournament organizations, the foremost concern is fish survival (Cooke and Schramm 2007).…”

Post-tagging behaviour and habitat use in shortnose sturgeon measured with high-frequency accelerometer and PSATs

“…While drawing inferences from captive hatchery-reared fish is problematic (e.g. [64]), if a similar mechanism exists in adults, recovery is expected in less than 6 h for all physiological variable measured (except for glucose) which could potentially explain the duration of the recovery phase observed here (up to 5 h) and suggests that physiological metabolites will normalize within the time period of the study.…”

“…High VeDBA during tag-load-related movements, indicated by high roll angles in the smallest individual, likely contributed to additional energy expenditure. The extended resting period and increased energy expenditure due to postrelease stress could contribute to increased vulnerability to other stressors, fishing recapture or death [30,31,40,41,59,[62][63][64][65].…”

Physiological disturbances and behavioural impairment associated with the incidental capture of freshwater turtles in a commercial fyke-net fishery

“…In particular, physiological (e.g. Davis 2002, Cooke et al 2013b) and reflex (e.g. Davis 2010) endpoints serve as objective indicators of animal welfare in fisheries (Diggles et al 2011, Cooke et al 2013b) and can be used to inform conservation actions (Wikelski & Cooke 2006, Seebacher & Franklin 2012 given their utility in defining cause and effect relationships and elucidating mechanisms of mortality (Cooke & O'Connor 2010, Cooke et al 2013a.…”