Tagging Project Gives Insight Into Tuna Growth Ratesff

Kenya and Tanzania are included in a five-year $16.8m survey to determine whether the tuna is becoming an endangered fish species.

The research, funded by the European Union, involves tagging 80,000 tuna in the Indian Ocean and releasing them into the sea to see how many will be caught in the next five years. The tags are yellow, spaghetti-shaped and made of plastic.

Besides catch rates, the Seychelles-based survey will also monitor the fish growth rates and migration trends. Tuna factory workers as well as artisanal fishermen in the Seychelles have been handing in tags to the project’s officials and claiming the 50 rupee ($10) reward on offer. “Last week, a 51-centimetre tuna that was tagged in the Maldives on August 20 last year was received measuring 104 centimeters,” she said.

“Over one million tons of tuna are caught and sold annually, compared with the 50,000 tons that were exported 50 years ago, and the graph has risen sharply over the past six years,” said Teresa Athayde of the project.

She said that although only 12,000 tuna have been tagged in the entire region, fishermen have so far recovered over 400 off the Seychelles and nearly 100 off other countries within a year.

Although pilot studies had been carried out before, the main project, which is being carried out under the supervision of the Indian Ocean Tuna Commission, commenced in June.

The survey is being conducted by two research ships, Aita Faxku and Kermantxo which are currently in Dar es Salaam, from where they will proceed to Mombasa. The project will also cover the Middle East.

”We recently carried out a tagging operation in Dar-es-Salaam, where only one tag has been found and reported, but in Kenya where no tagging or publicity have been done, 38 tags have been surrendered,” she said.

”We are hoping not to receive back too many of the tags because heavy recovery would mean the tuna we put back into the water are being fished up again,” Ms Athayde said, noting that this is the first major study on tuna stocks in the region. “We hope to receive back only 15 per cent of all the tags we are using, 50 per cent of them in the Seychelles,” she said. “Most of the vessels that catch tuna in the region land it in the Seychelles and that's why we are based here.”