Measuring cortisol, the major stress hormone in fishes

Abstract

Stress in teleosts is an increasingly studied topic because of its interaction with growth, reproduction, immune system and ultimately fitness of the animal. Whether it is for evaluating welfare in aquaculture, adaptive capacities in fish ecology, or to investigate effects of human‐induced rapid environmental change, new experimental methods to describe stress physiology in captive or wild fish have flourished. Cortisol has proven to be a reliable indicator of stress and is considered the major stress hormone. Initially principally measured in blood, cortisol measurement methods are now evolving towards lower invasiveness and to allow repeated measurements over time. We present an overview of recent achievements in the field of cortisol measurement in fishes, discussing new alternatives to blood, whole body and eggs as matrices for cortisol measurement, notably mucus, faeces, water, scales and fins. In parallel, new analytical tools are being developed to increase specificity, sensitivity and automation of the measure. The review provides the founding principles of these techniques and introduces their potential as continuous monitoring tools. Finally, we consider promising avenues of research that could be prioritised in the field of stress physiology of fishes.

Fish biomarkers from a different perspective: evidence of adaptive strategy of Abramis brama (L.) to chemical stress

“…Cortisol level in plasma is a well-accepted acute stress indicator, and has been successfully applied to assess a level of stress both in the controlled environments and in the wild (reviewed by Sadoul and Geffroy [52]). Expression of cr in A. brama from the exposed population in our study is not significantly different from the reference population, indicating low level of acute stress in the fish.…”

Effects of prophylactic antibiotic-treatment on post-surgical recovery following intraperitoneal bio-logger implantation in rainbow trout

“…Traditionally, measurements of circulating levels of plasma cortisol from whole body-or blood sampling have been used as a proxy for measuring stress in fish, but this method requires the invasive collection of blood or tissue 29 . Novel alternative techniques are available and have been shown to provide robust data on cortisol levels, ranging from non-invasive sampling of faeces, urine or water-borne cortisol to more invasive sampling of fin tissue, mucous or scales 30,31 . However, all of these techniques require the collection of blood, water or tissue and will consequently only provide a "snapshot" of the recovery period or level of stress.…”

Effects of passive integrated transponder tagging on cortisol release, aerobic metabolism and growth of the Gulf killifish Fundulus grandis

“…With respect to SPE format, the original report of this technique employed Sep Pak C18 cartridges (Ellis et al, 2004) and this format remains widely used Ellis et al, 2013;Fanouraki et al, 2008;Newman et al, 2015;Sadoul & Geffroy, 2019;Wong et al, 2008). We found that the recoveries of known amounts of cortisol from acidified water samples were reasonably high using this SPE format.…”

“…As the principal glucocorticoid in teleosts, cortisol is a marker of the primary stress response (Barton, 2002;Sopinka et al, 2016;Sadoul & Geffroy, 2019). In order to obtain multiple measurements on the same fish with minimal disturbance, we monitored cortisol noninvasively by measuring its release from the fish into the surrounding water (Ellis et al, 2013;.…”