J.G. Stottrup, R. Sheilds, M. Gillespie, M.B. Gara, J.R. Sargent, J.G. Bell, R.J. Henderson, D.R. Tocher, R. Sutherland, T. Naess, A. Mangor Jensen, K. Naas, T. van der Meeren, T. Harboe, F.J. Sanchez, P. Sorgeloos, P. Dhert, R. Fitzgerald-1998
Summary:
The work in this 2 year Concerted Action was organised into theoretical and practical work. The theoretical work involved discussion meetings and reviews, whereas ongoing research was coordinated between the participants and a sampling scheme was planned for the coordination of the analytical work to supplement present knowledge in the field of larval nutrition. A total of 24 reviews and papers were written as a result of this project and are listed in the EU final project report.
Different rearing strategies are used for the 3 species of marine fish examined; turbot Scophthalmus maximus, cod Gadus morhua and halibut Hippoglossus hippoglossus. The most widespread is the use of rotifers and Artemia nauplii in the case of turbot, whereas for cod and halibut the original copepod-based rearing techniques have only recently been shifted to the use of rotifers and Artemia. Copepods remain unquestionably the better nutritional live prey, but the problems associated with obtaining sufficient numbers of the right size at the right time suggest that the use of rotifers and Artemia nauplii will continue to be dominant in the next century. The provision of copepods for a short duration is the compromise many hatcheries depend on to supply essential nutrients. This is particularly important for obtaining high survival rates of naturally pigmented juvenile halibut. Artemia on the other hand are particularly useful in supplying the necessary energy input in the form of triacylglycerol to ensure high growth rates in the rapidly developing fish larvae.
The rearing strategy employed for halibut has an economic impact, since the type of live prey used influences survival. The inclusion of copepods are required for high survival of normally-pigmented juveniles. Advances in the nutritional value of Artemia would improve the situation and encourage investors in this production. The inclusion of all-female stocks of halibut in the rearing scheme would also improve the economic balance.
(paper sent to the 3rd European Scientific and Technical Conference to be held in Portugal, during May 1998)
(Danish Institute for Fisheries Research, Dept. of Fish Biology, Box 101, DK-9850 Hirtshals, Denmark)