PROGRESS ON THE DEVELOPMENT OF YELLOWTAIL FLOUNDER (PLEURONECTES FERRUGINEUS) FOR AQUACULTURE
J. A. Brown L.W. Crim-1998
Bulletin of the Aquaculture Association of Canada, Edition 98-1: 16-17
Excerpts:
Over the past four years we have been working on developing the yellowtail flounder for commercial aquaculture production in Newfoundland.
Egg incubation has proven to be rather straightforward and not problematic. Standard, 300-L, conical, upwelling tanks have bee used to incubate eggs with good success. Hatching success has varied from 20 to 80% over the years, with some of the variability being due to egg quality problems.
The success of larval culture has improved over the years. Early research focused on determining the best feeding conditions for larvae: prey density and type, loading density, light intensity and photoperiod protocols. Using the "green water" technique and feeding enriched rotifers and Artemia under high light intensity and 24-hour photoperiod, a success rate of over 40% has been achieved from hatch through metamorphosis. Optimal temperature requirements are still to be determined.
One area of larval production which needs to be addressed is the size variability which appears during the larval stage. Size differences among larvae from the same batch of eggs become apparent prior to metamorphosis. Research on the first batch of juveniles produced in 1994 indicated that the "small" metamorphs never reach the size of the "large" metamorphs. This was determined by separating the juveniles at metamorphosis into small and large groups. After two years there was no overlap in size between the two groups and the large juveniles were significantly larger than the small juveniles. Research aimed at determining the size at which these size differences first become apparent will be conducted, so that slow-growing, small larvae can be culled early in the production process.
It appears that pigmentation problems occur during the larval stage, but when and how this happens is still not known. Problems with the nutritional value of the cultured feed as well as stress during rearing likely contribute to the pigmentation problem. Work on improving pigmentation will be carried out as required.
(the Oceans Sciences Centre, Memorial University of Newfoundland, St. John's, NF, A1C 5S7, Canada)