The biggest challenge facing researchers is to find the optimal first feed. (Photo: Jan Ove Evjemo, SINTEF)
New methods discovered to help lobster larvae flourish
Thursday, December 06, 2012, 00:10 (GMT + 9)
Lobster farming just got a new boost: researchers have determined how to double the survival rates of lobster larvae, a finding that could also help the endangered Norwegian wild lobster species thrive.
Due to the fragile state of the species, Norwegians today harvest just 5 per cent of the 1,000 tonnes fished in the early 1950s, and also release juvenile lobsters Norsk Hummer AS’ facility at Tjeldbergodden as part of sea-ranching programmes.
Norsk Hummer has been active for over 20 years and work with SINTEF and others to optimize lobster farming.
”In nature, development rates among lobster larvae are determined by water temperature,” said SINTEF researcher Jan Ove Evjemo. “In spite of the fact that a female lobster can produce as many as 10,000 larvae, total production along the Norwegian coast is relatively low. This is due to low water temperatures and high predation rates by other crustaceans and fish.”
Norsk Hummer’s facility thus provides the larvae with extra heat to help as many of them as possible survive before sending them off to the wild.
”We have shown that it is possible to double larval lobster survival and boost their growth rates,” said Evjemo.
But the primary challenge has been to devise the best feed for the animals, which eat each other if there is not enough food. Researchers are currently on the point of a breakthrough.
”Firstly, we have reduced the cannibalism problem by means of experiments with new feed,” explained Evjemo. “At the same time, we keep the lobster larvae in a bath supplied with air bubbles and this prevents them from getting too close to each other.”
Researchers separated 600 newly-hatched lobster larvae into three groups, each with its unique first feed and plenty of space. Two groups were fed either the traditional live feed organism Artemia or a wet feed, and the third group was given live copepods (Acartia tonsa), a small crustacean which SINTEF previously tested as a first feed for problematic farmed species.
After 11 days, lobster larvae fed with live copepods exhibited survival rates 20-40 per cent higher than their counterparts, and their development was also improved.
These encouraging results have led researchers to begin planning the production of live feed species on an industrial scale so that it will become available for the marine aquaculture industry, which currently gives species such as wrasse copepods as first feed.
“Wrasse are currently used as our ‘ecological weapon’ in the fight against salmon lice, since the wrasse graze on the lice which are attached to the salmon,” Evjemo added.
The project received funding from VRI Møre og Romsdal and Norsk Hummer.
By Natalia Real