Article by: Nur Hidayahanum Hamid

Source: University of Jyväskylä - Jyväskylän yliopisto

A collaborative study by the University of Jyväskylä and Natural Resources Institute Finland (Luke), published in the Journal of Applied Ecology, found that enriched rearing environments significantly improve the survival of juvenile fish exposed to common bacterial infections in aquaculture. These conditions, which better mimic natural habitats through added structures in rearing tanks, may also enhance the post-release survival of stocked fish in the wild—particularly important for endangered species conservation and sustainable aquaculture.

Traditional rearing environments, which lack environmental complexity, often promote the spread of parasites and diseases, negatively affecting fish survival both before and after release. To address this, Luke’s Kainuu Fisheries Research Station developed an enriched rearing method that increases habitat complexity.

The study specifically tested Atlantic salmon (Salmo salar) and sea-migrating brown trout (Salmo trutta) exposed to Flavobacterium, a common pathogenic bacterium. Results showed that fish in enriched tanks had significantly higher survival rates during infection outbreaks, although slight differences existed between species and populations.

Interestingly, the improved survival was seen regardless of whether the fish were originally reared in standard or enriched environments, highlighting that the conditions during exposure to the disease are critical. The benefits of enrichment appeared rapidly, potentially due to improved stress tolerance in fish, although this mechanism requires further study.

These findings suggest that habitat enrichment in aquaculture could serve as a natural method to reduce disease-related mortality, improving both fish welfare and the success of supportive stocking programs.

Picture 1: In enriched rearing method structures are added to rearing tanks to increase habitat complexity and resemblance to natural conditions. Credit: Natural Resources Institute Finland (Luke)

Date of Input: 16/04/2025 | Updated: 16/04/2025 | hidayahanum