News Round-Up

Scales offer insight into chronic stress of fish


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

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