Main         Home  |  CO's Welcome  |  Sea Cadet Corps  |  Our Unit  |  Junior Section  |  Things we get up to
Menu :     Ship's Company  |  Parents  |  Adult recruitment  |  Find Us  |  FAQ  |  British Navies  |  Site map

TS Royalist
The Sea Cadets
 Woking & District SCC canoeistSCC teamSCC parade

 

Bullet pointBullet pointBullet point   Tags reveal tuna migration routes    Bullet pointBullet pointBullet point

Adapted from a BBC online article and other sources: Tuesday 5 August 2007

The secrets of the bluefin tuna's migration have been unlocked by a detailed study of the giant fish. Researchers believe two separate populations of the fish share feeding sites in the Atlantic before heading to opposite sides of the ocean to breed.

To help reveal the tuna's migratory pattern, an international team has tagged almost a thousand specimens. Two types of device were used: external tags fitted to the back of the fish, and internal ones, which needed minor surgery.

Accessing the data from the internal tags required fishermen to return the devices after the fish had been caught. However, the external tags were programmed to be automatically released after a predetermined time. The tags then floated to the surface of the water before uploading the collected data via the Argos satellite system.

The team also studied historical records that showed how bluefin numbers, once abundant in the North Atlantic, collapsed after the emergence of industrial fishing.

Postscript: Gordon Ramsay took bluefin tuna off the menu of his two most famous restaurants (Restaurant Gordon Ramsay and Claridge's) after criticism from the Government and conservationists.

Bluefin tuna being released from net

"Bluefin tuna are now critically endangered." [Blue Planet Society]

 

tuna ranch

Wild Bluefin Tuna (Thunnus thynnus) behind the net walls of a "tuna ranch" in the Mediterranean Sea. Fishermen attract schools of tuna to the nets with large volumes of smaller bait fish. Once the tuna are corralled, tugboats tow the giant pens closer to shore. Increasing demand for ocean fish has led to overfishing and widespread destruction of marine habitats. Without careful fisheries management and greater consumer eco-consciousness, many ocean ecosystems could collapse. Photo: Greenpeace/Gavin Newman.

tagged whale shark

This photo shows an example of an external tag - though the creature is a whale shark, not a bluefin tuna. Photo: Steven Wilson

 

 

 

SIMPLY THE BEST - THAT'S THE SEA CADETS !