Marine Harvest further increases its efforts towards sea lice. The company has started up ballan wrasse farming in Øygarden outside Bergen, Norway.
Ballan wrasse is a type of wrasse which naturally baits parasites from other fish. Wrasse has proven to be an efficient tool to reduce the number of lice on farmed salmon.
Wrasse reduces the need for medicinal tools and therefore also the risk of resistant lice. Marine Harvest wishes to extend the use of wrasse on its farming sites. However, it is uncertain how much ballan wrasse can be caught in the wild without negatively affecting the population. In addition the access to ballan wrasse varies depending the time of the year and geographic location. This is why Marine Harvest decided to start up ballan wrasse farming in 2009.
Years of experience
Sea lice are naturally occurring parasites of salmonids. A normal wild salmon can harbour several sea lice. A high number of lice per salmon can affect the salmon’s health condition, though this rarely represents a problem for farmed salmon. However, as the number of salmon on each site is high, a small number of lice on each fish can cause a significant number of lice around the site. In some areas and at certain times of the year lice from salmon farming can represent a threat towards migrating wild smolt and local sea trout populations.
Over the years Marine Harvest has built up experience in using wrasse as a biological tool to control sea lice. Ballan wrasse has in fact been the company’s main tool against sea lice in Agder during the last few years. The results have been very good. When using wrasse, medicines can be avoided. Wrasse has also been introduced at an increasing number of sites in the Hardangerfjord during the last couple of years, with promising results.
Investing NOK 8 million
Different scientific research institutes have done research on wrasse farming, e.g. the aquaculture centre of Institute of Marine Research at Austevoll. Important biological knowledge has been generated, but until now no one have so far committed to ballan wrasse farming on a larger scale.
Marine Harvest has invested NOK 8 million in this project in 2009, and the plan is to invest further NOK 10 million annually over the next 3 years.
Starting up wrasse farming is challenging, but results so far have been promising. Juveniles from the first production cycle have grown into big and strong fish, counting 25 000 juveniles measuring 2-5 cm. Taken into account some challenges along the way, the prospects of delivering farmed ballan wrasse in 2011 look good.
Facts ballan wrasse
- Up to 60 cm long, stout and very colourful body, one long dorsal fin, thick lips, small mouth with conical formed teeth
- Sex changes according to age – young ones are females, while after 10-14 years all are men
- Looks a bit similar to corkwing wrasse and rock cock, but these are much smaller
- Source: Aschehougs small books about nature, ”Fish”
Facts sea lice
- 8-12 mm (adult female included three egg strings). The male is half the length
- Lifestages divided into three motile, four attached and three mobile stages. The lice starts baiting on salmon in the third stage
- Sea lice naturally occur in Norwegian waters
- Reproduces itself throughout the year, though at a higher speed when the temperature increases during spring
- Source: Institute of Marine Research