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Restocking has not helped salmon stocks

According to Atso Romakkaniemi who wrote his doctoral dissertation on the topic, supplementary stocking of salmon in the northern Baltic region in order to protect the stocks of wild salmon does not seem to have fostered the recovery of Baltic salmon stocks.

Romakkaniemi says that the survival rates of stocked salmon are much lower than of wild salmon. Salmon reared in hatcheries were more vulnerable to predators and fishers and average survival of stocked salmon was 2.8-3.3 times less than that of wild salmon, regardless of what age the salmon were stocked at.

In rivers, stocked salmon still vie for the same grounds as wild salmon. “Salmon are territorial in rivers and they fight for their habitat. Stocked salmon are noticeably more aggressive and might infringe on the habitats of wild salmon,” says Romakkaniemi.

There is also the risk of the gene pool becoming too narrow. Certain genetic types may accidentally be given preference when selecting the brood fish and those characteristics are then heightened in the stocked salmon population.

Romakkaniemi recommends giving up supplementary stocking. Instead he suggests fishing restrictions as a more appropriate conservation management tool. Evidence shows that fishing restrictions have enabled the Baltic salmon stocks to grow tenfold since the end of the 1980s.

Today Romakkaniemi feels that it is particularly important to effectively manage salmon stocks in rivers. “The situation in Finland is quite favourable, but the salmon stocks in Estonia’s rivers are very small. In order to improve the situation we need to implement more appropriate fishing restrictions and also improve the natural habitats of the salmon,” he says.

Romakkaniemi’s dissertation in the field of fish husbandry Conservation of Atlantic salmon by supplementary stocking of juvenile fish was publically examined on 29 August 2008 at the University of Helsinki.

Text: Juha Merimaa
Photo: Sébastien Agullana
www.helsinki.fi/digitalcommunications
Translation: AAC Noodi Oy

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