Bluefin tuna cage. (Photo: Luis Eustaquio)

Genetic research can help tuna stocks recover: expert

The Organisation for the Promotion of Responsible Tuna Fisheries (OPRT) has interviewed a bluefin tuna expert on the research being conducted on the species. In the article “Genetic research on bluefin tuna is in steady progress,”  Dr Motohiko Sano, Director of the Research Centre for Aquatic Genomics, National Research Institute of Fisheries Science, Fisheries Research Agency, discusses how genetic research can help reduce pressure on wild tuna stocks.

He referred to wild Pacific bluefin tuna migrating in the near-shore area of Japan as being in “stable stock condition.”

“Stock management of this species have been launched with the aim to conserve and use them sustainably. Genetic research is useful in supplementing such efforts to manage the stock,” he noted.

Sano contrasted current tuna farming practices, which consist of taking wild fish and fattening them up in cages, with closed cycle breeding, which consists of growing adult tunas from the eggs which were spawned by captured tuna.

He explained that while closed cycle breeding has been achieved in the limited institutions, it has not yet become a practical and affordable practice that can be adopted by the aquaculture industry.

“In the wild, a tuna grows into a parent fish in three years at the earliest, but in farms it takes as long as five years. The efficiency of breeding will improve drastically if the period to maturity is shortened. It is in this respect that the use of genetic information will contribute to tuna farming,” Sano explained.

Success in this arena will also allow for reducing fishing pressures on the wild tuna populations and thus for enhancing the conservation of natural resources.

Since the fiscal year 2011, he said, the government has launched a new research project commissioned by the Fisheries Agency. The objective of the genetic studies is to find genes that may determine the period of first maturation and faster growth rate of the fish, as well as resistance to diseases from the genome; this research is now attracting attention from scientists all over the world.

Sano pointed out that regardless of what the research accomplishes, the importance of using wild tunas will remain firm.

“In order to use the natural stocks on a sustainable basis, I think it is important to establish closed cycle breeding system as soon as possible by using genetic information positively so that there may be no catch of juvenile tuna for farming to the extent that it would adversely affect the stock itself,” he added.

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- Kick-off symposium scheduled for unprecedented tuna research agreement

By Natalia Real
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