Senior fish health inspector with CEFAS looks at the use of retenone

Gyrodactylus salaris a monogean ectoparasite

Gyrodactylus salaris (GS) is a monogean ectoparasite, that was first reported from Sweden and it is believed to occur naturally in Russia and the Baltic regions of Finland, Latvia and Lithuania. The strains of salmon in the Baltic have a high tolerance to infection, but the Atlantic salmon is very highly susceptible to the parasite. Its believed that GS was introduced into Norway in the 1970's (thought to be via stocking of infected fish imported from a Swedish hatchery) and has caused the complete collapse of the Atlantic salmon populations in over 40 major rivers.

In Norway, rotenone is used to eradicate GS from some rivers. This treatment kills all the fish in the river, which is then restocked with uninfected eggs and juveniles from the local gene bank. Rotenone treatment and restocking is one of a number of options that could be considered if GS were to be introduced into the UK. In 2004, the UK fish health authorities were invited to Norway to observe a rotenone treatment of a major river system. Read more ...

This blog is written by Martin Little, The Aquaculturists, published and supported by the International Aquafeed Magazine from Perendale Publishers. To get your copy of 'PPLAPP' click here.