A bigeye tuna has been re-captured, nearly 13 years after it was originally caught, tagged and released as part of a scientific experiment.
The 100 kg tuna was caught 1000 km east of Fiji and the tag returned to fisheries scientists in Noumea.
The monitoring program is organised by the Fisheries Division of Secretariat of the Pacific Community (SPC) as part of a research effort to maintain the health and sustainability of the tuna fishery in the Pacific.
Scientists say that 13 years on the run is close to a record period of freedom, in a tuna-tagging programme SPC began in the 1970s.
Bruno Leroy, a fisheries scientist with SPC, says trained teams catch and release thousands of tuna after fitting them with a numbered plastic tag and recording its species, size, condition, tagging date and location.
“This fish is a great find,” he says. “Recovering the tags is crucial to the success of our programme because they provide information on the growth, movements, natural mortality and fishing mortality of tuna, and help us estimate the status of tuna stocks and the impact of fishing.
“The fish was an old fellow, at least 15 years old, and its recapture is of great value for us as an indication of the longevity of bigeye tuna.”
The tag, a conventional yellow plastic dart tag, was fitted to the back of the fish in October 2000. Scientists were surprised that it was retrieved very close to its release position (see map).
The tag was found by Samuela Ratini, a crew member of Taiwanese vessel San Sai FA No 12, and recorded by the ship’s observer, Sitakio Semisi from Tonga. SPC helps train observers who are stationed on foreign tuna fishing vessels in the Pacific, where their job is to count, measure and identify all tuna taken by the vessel.
Tuna fishing is the biggest industry in the Pacific, worth $5 billion per year. It provides food, employment and income to the 10 million people living in the region.
“Monitoring fish populations is a big part of keeping a check on tuna,” Bruno Leroy says. “This is the world’s biggest tuna fishery and Pacific countries have to manage the fisheries to keep them sustainable. In 2006 we launched the biggest tuna tagging program in the world.
“Since then we have tagged close to 400,000 fish and over 60,000 of these have been recaptured. Recovering tags gives us information that is critical for estimating the status of tuna stocks and the impact of fishing.”
Tuna can be fitted with different sorts of tags: conventional plastic tags or electronic tags that record information about the tuna and the environment in which a tagged fish lives.
With funding and operational support from Papua New Guinea, the French Global Environment Facility, Australia, the European Union, France, New Zealand, the United States, Korea, the Western and Central Pacific Fisheries Commission and Heinz Australia, the programme has tagged fish from Indonesian waters in the west right across to French Polynesia in the central Pacific.
Australia is one of the major supporters of SPC, which has a mission to provide scientific advice to the 22 countries and territories of the Pacific. SPC assists these countries on issues such as development, health and the environment.