For years, aquatic researchers have sought an easy way to determine when wild fish are under stress. Now University of Guelph researchers have shown for the first time that a key stress hormone, cortisol, accumulates in fish scales slowly and remains there for weeks.
The finding means measuring cortisol levels in scales could offer a simple, minimally invasive glimpse into fish well-being, allowing scientists to better understand how they are coping with agricultural, industrial or biodiversity changes.
Cortisol is a well-known stress indicator and appears readily in the blood. But blood tests are invasive and don’t provide a good indication of long-term stress, because levels return to normal soon after a stressful event. MORE