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Tag a Giant: Bluefin tuna

The Tag-a-Giant research project has recently attached a satellite tag to its 1000th Bluefin tuna. The project has been underway since 1996 so the Tag-a-Giant scientists have been gathering data on these fish for 12 years.

Atlantic Giant Bluefin tuna are one of the ocean's greatest travellers, capable of covering distances of 5,000 miles in just a few months. But the distances they travel are not the only massive thing about them. The biggest Bluefin tuna weigh up to 700 kg, around 10 times the weight of an adult man, and can measure over 3 metres in length. They have two swimming speeds: cruise and "burst". When pursuing prey or escaping predators, these huge fish can shift at a top speed of over 30 miles per hour.

A 10 foot Bluefin tuna receiving the 1000th tag

Bluefin tuna

The “Tag-a-Giant” project has recently put an electronic tag on its 1000th Bluefin Tuna.

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Tag-a-Giant are discovering lots of new things about the tuna's previously hidden lives. Firstly they have found that the fish are as faithful to their spawning grounds as salmon are to theirs. Over 90 percent of Bluefin tuna spawned in the Gulf of Mexico return there to spawn. And the same is true for the population of Bluefin tuna which spawn in the Mediterranean sea.

Scientists have also found that there is far more mixing between these two populations of fish than previously thought. Although the Western ones are faithful to the Gulf of Mexico for spawning - and the Eastern ones show site fidelity to the Mediterranean - in between times, when the fish are out foraging for food, they mix a great deal. It seems that each Bluefin is potentially using the whole of the Atlantic ocean as its feeding ground.

The reason this is so significant is because of fish quotas and trying to set them correctly. Counting Bluefin tuna off the east coast of the States and setting a fishing quota for that number of adults could be nothing short of disastrous: a good proportion of those fish may be of Mediterranean origin, so the numbers could seem artificially high. At a time when Bluefin tuna population numbers have dropped dramatically and they are of the utmost conservation concern, this research on where the fish go could be the key to securing their future.

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User comments

Yasmin Adely
I think it'z rly cool :) ( im only 12 tho :s) LOCATION: 25.2720,55.2695 DATE: Mon, 15 Dec 2008 13:49:24 UTC

Has there been any evidence of blue fin tuna in the north sea? As in the thirties it was a pleasure fishing for large tuna based at Scaborough, Yorkshire. LOCATION: 52.466702,-1.916700 DATE: Tue, 2 Dec 2008 16:36:16 UTC

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