WWF tagging threatened tuna to track numbers
Workers cut the head of an Atlantic bluefin tuna on a fishing vessel on the Mediterranean sea (Reuters)
Across Mediterranean ports, bluefin tuna has been one of the pillars upon which civilisations have depended over the centuries.
But in past decades fishing has increased so dramatically that according to the WWF the adult population of bluefin tuna has decreased by 80 percent in the past 20 years.
Bluefin tuna is a large predatory fish, found in the western and eastern Atlantic and its surrounding seas.
Most of the catch is taken from the Mediterranean Seam, which stands as the world's most important bluefin tuna fishery.
The demand for bluefin tuna continues to rise, largely due to demand from Japan for sushi and sashimi.
The price of a kilogram of bluefin tuna can reach in Tokyo as much as US$33.
According to the WWF a 342kg fish fetched a record price of US$370,000 in January, 2011 - with prices for tuna rising even higher following the tsunami.
In response, the EU has set a maximum fishing quota of bluefin tuna in the Mediterranean and eastern Atlantic to 11,400 tons in 2011; down from 13,500 tons in 2010. Spain was set an annual limit in 2010 of 2,523 tons, according to the country's Environment Ministry.
In January 2008 the WWF began a bluefin tuna tagging project funded by Prince Albert II of Monaco Foundation.
The project aims to gather information on the migratory patterns of juvenile and adult bluefin tuna, as well as to test whether populations of this fish in some specific part of the Mediterranean are isolated from the rest of the species' migratory routes.
This project involves catching live specimens of bluefin tuna and inserting inside them two kinds of tags that will record depth, temperature and additional data.
Susana Saenz Trapaga, the WWF fisheries official, says: "Fishing has been very intensive in the Mediterranean Sea. Especially since the 1990's. The situation of overfishing has been brutal particularly because of the development of red tuna farms and I would say that since 2006 the management measures have restricted a little - overfishing - the situation is critical and we need to re strengthen these measures."
Archival tags will remain inside the fish until it gets caught by fishermen in the coming years.
The tag has a label that offers a €500 reward to any person bringing the tag to WWF offices in the Spanish city of Barcelona.
Holding one of the tags Gemma Aquiles, another WWF fisheries official, explains: "These two models register all sorts of parameters. This one is put in the belly of the fish and we need to recuperate the fish to be able to download the data that has been registered."
Pop-up tags are designed to release themselves from the fish when it reaches maturity and once it reaches the surface of the water it sends information via satellite.
Aquiles adds: "This one is put on the dorsal fin of the fish it registers all the data and we prepare it so that a certain day it is released and when it released it goes onto the surface and from the surface it begins to transmit data via satellite."
Archival tags cost US$2,200 whereas the pop up variety are valued at US$3,000.
The procedure of attaching the tag to the fish involves hauling the fish onboard, cutting a small incision on the underside of the fish, inserting the tag, and stitching up the wound.
The entire procedure from capture to release should take no more than one-and-a-half minutes.
The tagging process is carried out by two scientists from WWF.
From the moment the fish is taken out of the sea a race against the clock takes place on board the Columbus.
Because of the small size of the fish in this instance the scientists use an archival tag.
Since 2008 a total of 66 bluefin tuna have been tagged. None of them have ever left the Mediterranean Sea.
The WWF has asked the European Union, whose member nations do most of the fishing, to close bluefin tuna fisheries as an interim measure.
It estimates that quotas are being violated by about 50 percent and that real catches of bluefin tuna are around 50,000 tons.
Catalonia, as well as the rest of Spain, conducts a very strict policy towards controlling the total amount of blue fin tuna fished in the Mediterranean.
All bluefin tuna fishing boats go out to the sea carrying an official inspector on board who controls the number of fish catch by that boat.
Manel Noguera owns a trawling fishing boat in the port of Roses.
He says that ever since restrictions on bluefin tuna fishing were established its number has increased and as this species is a voracious predator stock of smaller fish has decreased, resulting in less profit for trawler fishermen like himself.
He says: "We notice that as time goes by we spot more and more of them. Now they jump a lot on the surface and before it was a rare sight. And after all these years of fishing bans we notice the increase. For us who use trawlers to fish this is very bad because tuna eats all of our fish. It is a predator and eats all the fish we usually catch."
Restaurant Mar y Sol is one of Roses' most popular seafood restaurants and depends on the quality of its catch.
Its chef Juan Ayaht is preparing bluefin tuna tataki, one of the restaurant's signature dishes.
But the raw material - tuna - is expensive and the restaurant has seen the rising prices and quotas reduce.
Ayaht says: "They also say it so they can charge more for it. Because it is a highly demanded favourite fish. It is world popular dish. They say this isn't fished a lot and so they don't sell it to you so they can charge more for it."
These hungry diners enjoy bluefin tuna today but for how much longer?
The WWF believes if tuna stocks are not managed more responsibly, it could soon be a dish only the super-rich can afford to indulge in.