Aqua: DHA improves survival and development of halibut larvae

New research from Norway shows the levels of DHA that ensure better growth, survival and normal pigmentation in Atlantic halibut larvae.

The bottleneck in halibut farming is related to insufficient supply of important nutrients. Two feeding trials at NIFES, in collaboration with the Norwegian Institute of Marine Research, suggest for the first time minimum levels of the marine fatty acid DHA needed for good survival and normal pigmentation.

In a feeding trial, a group of Atlantic halibut larvae was fed the crustacean Artemia, which was enriched with a high content of the marine fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), provided as an emulsion. Another group was given Artemia that was enriched with fish oil. Enriched artemia from the first group contained 7.5% DHA of total fatty acids, while the other group contained 4.1% DHA of total fatty acids.

The Atlantic halibut larvae that were fed artemia which contained about 8% DHA had an increased survival rate of 39%, compared to 12% survival rate of the other group. Also, growth was better in the first group.

“This tells us that Atlantic halibut larvae need at least 8% DHA for a good survival rate and growth”, says Kristin Hamre at the Aquaculture Nutrition Research Programme at the National Institute of Nutrition and Seafood Research (NIFES).

In another feeding trial, two groups of Atlantic halibut larvae were fed artemia, which was enriched with either 9.4% DHA or 12.5% DHA provided as emulsions.

46% of the Atlantic halibut larvae which were fed Artemia from the first group showed normal pigmentation, while a total of 77% of the Atlantic halibut larvae from the second group had normal pigmentation, says Hamre.

DHA improves survival and development of Atlantic halibut larvae. These results suggest that Atlantic halibut larvae may need as much as 15% DHA for normal pigmentation, says Hamre, adding that the EPA and ARA (aracidonic acid) ratio in the Artemia was 3.5% in both groups. The relationship between EPA and ARA also affects pigmentation. In this trial survival rate was similar in the two groups, and at the same level as the first trial.

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Aqua: DHA improves survival and development of halibut larvae