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Successful fertilisation of Amberjack and Blue-fin Tuna eggs from captive broodstock

by the Fish Site Editor
27 July 2005, at 1:00am

By The Malta Centre for Fisheries Sciences - The Malta Centre for Fisheries Sciences (MCFS) successfully obtained fertilised eggs from amberjack (accjol) broodstock reared in captivity. The broodstock is the property of Malta Fish Farming Ltd who supported and collaborated throughout the project, a Department of Information statement said.

Successful fertilisation of amberjack and blue-fin tuna eggs from captive broodstock - By The Malta Centre for Fisheries Sciences - The Malta Centre for Fisheries Sciences (MCFS) successfully obtained fertilised eggs from amberjack (accjol) broodstock reared in captivity. The broodstock is the property of Malta Fish Farming Ltd who supported and collaborated throughout the project, a Department of Information statement said.

This is the first significant step towards the complete control of the life cycle of amberjack and emulates research done at the Hellenic Centre for Marine Research in Greece during 2003, indicating that reproductive maturation and spontaneous spawning can be achieved in captive amberjack in the Mediterranean Sea. The present broodstock were caught as juveniles from the wild and reared in cages for four years.

This was the first year of sexual maturity for this group of 23 fish and 100 per cent of the fish were mature and ready for spawning as the spawning period approached. During the first half of the spawning period in June, spawning behaviour was observed but it was very difficult to collect eggs from the floating cages in Marsaxlokk Bay. However once various problems and obstacles for egg collection were solved, some fertilised eggs were collected during the final stages of the spawning season, and after hatching, a few larvae survived until the start of feeding.

At present, amberjack culture throughout the Mediterranean area depends on wild caught juveniles. The progress achieved by this research is significant towards closing the life cycle of the amberjack in captivity, the DOI said. This will mean that amberjack culture will not remain dependent on wild stocks. It will also increase the diversification of species cultured with more possibility of investment in the industry.

Similar results were obtained for bluefin tuna (tonn) at the beginning of July, where members of a European Union funded research team from France, Germany, Greece, Israel, Italy, Malta (Malta Centre for Fisheries Sciences) and Spain together with the commercial tuna farm, Tuna Graso S.A. based at Puerto de Mazarron in Spain have for the first time successfully used hormonal induction in captive broodstock of the Atlantic bluefin tuna to obtain eggs and sperm. In vitro fertilisation was carried out successfully and viable tuna larvae have been produced. These are developing at the Instituto Espaol de Oceanografa (IEO), Centro Oceanogrfico de Murcia at Puerto de Mazarron in Spain.

This is a very important achievement in controlling the reproduction of the bluefin tuna as it proves that even bluefin tuna is able to mature in captivity and produce viable eggs and sperm. Successful fertilisation is the first step at controlling the whole life cycle of the fish in captivity, the DOI added.

Bluefin tuna fishing stocks are at a very critical level. This must be the first answer to the tremendous political, social and environmental pressure to save the tuna from extinction as it gives substantial hope for the eventual cultivation of the species using larvae produced in captivity, similarly to other well-known fish species.

All members of the reproduction and domestication of Thunnus thynnus (REPRODOTT) consortium are convinced that this project represents one of the last chances to save the species by establishing the possibility of raising domesticated fish in captivity which in turn allows the regulation of tuna fishing intensity to manage the endangered wild stock for the shared benefits of future generations, be they fishermen /fish farmers, consumers and conservationists and at the same time provide viable larvae for the understanding of the biology of the bluefin tuna.

Commenting on these positive developments the parliamentary secretary responsible for Agriculture and Fisheries Francis Agius said that the government always supported this industry in Malta. The financial investment to fisheries guidance issued last June provides for aquaculture and operators in this field can apply to benefit from funds to upgrade techniques to improve the production of organisms beyond the natural capacity of the environment.

Dr Agius added that it is vital for the industry to continue investing in diversification of species that will be under culture with possibbilities both to replenish the wild stocks and with obvious economic potential for the fisheries sector.

Source: Malta Centre for Fisheries Sciences - July 2005

the Fish Site Editor