Physiological stress response and recovery of an important estuarine fishery species, dusky kob Argyrosomus japonicus, after a simulated catch-and-release event

Abstract

Catch and release (C&R) angling is a popular pastime the world over; however, studies have found that fish can experience considerable stress during a C&R event. To determine the effect of a C&R event on angled fishes, the physiological stress response (PSR) is often assessed. However, the peak PSR only occurs after a delay and is species-specific. The dusky kob Argyrosomus japonicus is a threatened species that is heavily exploited in South African estuarine fisheries. Given its collapsed-stock status, it is critical to understand the effects of C&R angling on the PSR of this species. The aim of this study was to plot the time-course of the PSR of A. japonicus to determine when the peak PSR occurs. Time had a significant effect on blood lactate (p < 0.05) and glucose (p < 0.05) levels, with both peaking 30–40 minutes after a stressor, but time did not have a significant effect on plasma cortisol levels (p > 0.05). Blood lactate and glucose levels reached recovery by 150 minutes. The results suggest that blood sampling should be done 30–40 minutes after a stressor, and although A. japonicus is able to recover quickly from a C&R event, its delayed PSR may render it vulnerable to post-release predation.

Keywords:

• angling
• blood lactate
• blood glucose
• cortisol
• physiology
• recreational fisheries
• South Africa

Notes

§ This article is based on a paper presented at the 5th Southern African Marine Linefish Symposium, held 8–11 July 2019, at Mpekweni Beach Resort, Eastern Cape, South Africa, and is part of the special issue ‘Linefish resilience in the Anthropocene,’ edited by WM Potts, CG Attwood and PD Cowley