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Sockeye Salmon with Sea Lice Eat Less, says New Study

Alice Mitchell
06 May 2015, at 1:00am

US - Sockeye salmon highly infected with sea lice are much less successful at consuming food than lightly infected fish, according to new research from Simon Fraser University (SFU) and the University of Toronto.

The research indicates that juvenile Fraser River sockeye salmon that are highly infected with sea lice are 20 per cent less successful at foraging than their lightly infected counterparts.

Sean Godwin, from SFU, is the lead author of the study. He said that given how little is known about what affects sockeye survival in the ocean and how uncertain federal fisheries' predictions are as a result, this study's findings deserve serious attention.

"We need to get a better understanding of whether the effect of sea louse infection in our study scales up to the population level," explained Mr Godwin.

"This is the first concrete evidence to suggest that sea lice may indirectly affect the survival of juvenile sockeye, not directly through disease but instead through reduced foraging success.

"More research is needed to determine whether sea lice influence adult sockeye returns."

Mr Godwin noted research suggests that the early marine life of these sockeye is a gauntlet of survival challenges, particularly in Johnstone Strait.

"This is where they have to cope with challenges such as increased predation, lack of food and pathogens such as sea lice," said Mr Godwin.

"They have to have sufficient energy reserves and be able to capitalise on whatever food they can find. If their ability to compete for limited food is impaired, say by sea louse infection, starvation risk could be increased."

Mr Godwin said that fish farms have previously been linked to infection of wild juvenile sockeye by sea lice and that Pacific herring might also be a second reservoir for the parasites.

The fish farms that would be affecting Fraser River sockeye hold Atlantic salmon, are Norwegian-owned and are mainly located in the Discovery Islands, between the Mainland and northern Vancouver Island.

Further Reading

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