Breeding wrasse raises feed challenges
Hatcheries in Norway, also in Scotland, Ireland and Russia, are starting to breed wrasse to provide a reliable supply of this biological control agent for salmon farmers. One of the initial challenges was to get the right feeds for broodstock and larvae. Skretting worked with several hatcheries to find the answers, reports www.megafishnet.com with reference to Skretting.
The species chosen for these projects is Ballan wrasse (Labrus bergylta), the largest of the family with adults growing to more than 60 cm and around 3.5 kg. It has proved to be the most effective species at eating the sea lice and can withstand low water temperatures. Kathrine Lunde, a Skretting Product Manager in Norway, gives an insight into the feeds, "We found an attractive taste is very important, wrasse are shy feeders and scare easily. The broodstock feeds are based on our Vitalis CAL and Vitalis REPRO feeds, already established for cod and halibut broodstock. For the wrasse we are binding the feed pellets into small blocks, with extra moisture and ingredients to increase the attraction. We tried several feed options for the larvae and our latest range of Gemma marine hatchery feeds with algal ingredients works well, potentially replacing rotifers in the protocol. Their high protein content seems to suit the wrasse, which is a relatively low fat fish. Hatcheries begin with Gemma Micro and progress through the sequence to Gemma Wean then Gemma Diamond after metamorphosis. When the pellet size reaches about 1.5 mm we again add attractants and make a moister version of the feed, as for the broodstock."
The objective of rearing the wrasse is to introduce small numbers into pens with Atlantic salmon as a biological control, contributing to effective management of sea lice. The hatchery projects are receiving financial support from Ecofish, a part of the European Union Northern Periphery Programme to encourage environment-friendly fish farming.