Feeding strategies to achieve correct metamorphosis of Atlantic halibut, Hippoglossus hippoglossus L., using enriched Artemia |
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| Authors: | B Gara R J Shields L McEvoy |
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| Institution: | Seafish Aquaculture, Marine Farming Unit, Ardtoe, UK;2NERC Unit of Aquatic Biochemistry, University of Stirling, Stirling, UK |
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| Abstract: | Atlantic halibut, Hippoglossus hippoglossus L., larvae were reared under four different Artemia feeding regimes for 40 days from day 20 post first feeding. Three Artemia enrichments were used: Super Selco? (SS), AlgaMac 2000? (AM) and a particulate mix of AlgaMac 2000? with tuna orbital oil (TOO/AM). The SS and AM Artemia were tested in three different combinations: (1) a 1:1 ratio continuously to day 60 (AM/SS); (2) a 1:1 ratio to day 41, then AM only (AM/SS-41): and (3) AM only to day 41, then a 1:1 ratio (AM-41). The fourth treatment comprised TOO/AM Artemia, which was fed continuously. At day 60 post first feeding, measurements were made of survival and growth rates, postmetamorphic characteristics (i.e. eye migration and pigment distribution), and lipid composition. The mean survival rates ranged from 65.1% to 84.5%. Specific growth rates varied from 7.64 to 8.13. The eye migration indices were between 2.3 and 2.6. These parameters did not differ significantly among treatments (P 0.05). A significantly greater proportion of fry (P<0.05) exhibited‘perfect metamorphosis’(correct pigment distribution and complete eye migration) in the AM/ SS-41 and AM-41 treatments (59.8 ± 3.03% and 54.6 ± 1.08%, respectively) compared to the AM/SS and TOO/AM treatments (35.9 ± 4.02% and 39.9 ± 6.43%, respectively). The fatty acid compositions of livers and eyes varied according to feeding regime, but did not correspond to the metamorphosis characteristics of the fry. |
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