Tuesday, May 29, 2018

30/05/2018: Salmon, one of the most important species of fish in aquaculture

by Zasha Whiteway-Wilkinson, Production Editor, International Aquafeed

Salmon (salmonids) are one of the most important species of fish in aquaculture

In the US, Chinook salmon and rainbow trout also are most commonly farmed salmonids for recreational and subsistence fishing. In 2007, the aquaculture of salmonids was worth US$10.7 billion globally. The production has grown 10-fold during the 25 years from 1982-2007 and has continued to rise exponentially ever since. 


 
Salmon
Image credit: Scazon on Flickr
(CC BY 2.0)
A challenge that the industry is working together to overcome at the moment is the problem of sea lice. This month’s ‘Expert topic’ examines the relationship between the most commonly farmed fish and the parasite that is threatening to decimate entire stocks of the fish from farms all over the world from Norway to Chile to Scotland.

The lice attach themselves to the fish and feed on them, similarly to ticks or nits on humans, this action however kills the stock or renders them unsuitable for sale to consumers. The lice can grow to roughly the size of a pea and lay thousands of eggs in their brief lifetime.

When in the wild, diseases and parasites are normally at low levels and kept in check by natural predation. However, in crowed pens they can easily become epidemics. These diseases and parasites also are known to transfer from farmed to wild salmon. According to “It’s all about salmon – Salmon Aquaculture”, by the Seafood Choices Alliance, Spring 2005, described links between the spread of parasitic sea lice from river salmon to wild pink salmon in the same river, the study was performed in British Columbia.

In 2002 the European Commission (2002) concluded, “The reduction of wild salmonid abundance is also linked to other factors but there is more and more scientific evidence establishing a direct link between the number of lice-infested wild fish and the presence of cages in the same estuary. Finally, it has also been reported that wild salmon on the west coast of Canada are being driven to extinction by sea lice from nearby salmon farms (“Declining Wild Salmon Populations in Relation to Parasites from Farm Salmon”). These predictions however were disputed by other scientists and recent harvests have indicated that the predictions were in error. In 2011, Scottish salmon farming introduced the use of farmed wrasse for the purpose of cleaning aquacultured salmon of the ectoparasites.


Read the full article, HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

For additional daily news from aquaculture around the world: aquaculture-news

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