Tiny tagged tuna reveals remarkable journey and growth!
WELL known Australian marine bioligist and author, Julian Pepperell, has revealed a remarkable long term tuna recapture.
On 5 September, a longliner owned by Walker Seafoods Australia caught a hefty northern Pacific bluefin tuna 200 nautical miles east of Mooloolaba. Skipper Bo Lloyd noticed an old tag at the base of the dorsal fin – a tag with a Japanese address. The fish weighed 158 kilograms gilled and gutted and measured 223 centimetres from snout to tail fork.
Pepperell was contacted by Walker Seafoods owner Pavo Walker with the details. A Japanese researcher involved in the tagging program, Dr Ko Fujioka informed Pepperell the fish had been tagged just over 9 years earlier off Kochi Province, on the southern coast of Honshu, Japan. When tagged, it measured just 23.5 centimetres long and weighed around 200 grams – a size estimated to be three months of age.
Pepperell also revealed that over 12,000 tiny Pacific bluefin have been tagged since 2011 and results have shown that they mainly travel across the Pacific to the US coast and back as they grow in their first few years of life. However, this is the first ever recaptured in the Southern Hemisphere and by far the longest time between tagging and recapture.
The otoliths (earbones) of this fish were extracted and knowing that it is almost exactly 9 years old, they will act as "Rosetta stones" for verifying the ages of many other Pacific bluefin tuna.
In final twist, according to Pepperell, the tag had been manufactured in Australia by South Australian fish tag company, Hallprint.