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Bluefin Tuna

Longlining, Overfishing & Atlantic Bluefin Tuna

Case Study

Longlining was developed after World War II by Japanese fishermen.

An international fleet of thousands of longliners now fish the world's oceans, landing millions of tons of tuna and swordfish every year. Longlining, an ultra-efficient practice developed after World War II by Japanese fishermen, deploys up to 60 miles of baited hooks across vast expanses of the Atlantic ocean where bluefin tuna migrate. In addition to catching swordfish and tuna, longlining tends to catch other, untargeted species like sharks and sea turtles. Fishermen try to keep this bycatch to a minimum but this is often difficult to do, and attempts at making the gear more selective have had only limited success.

Men haul giant bluefin tuna aboard during the mattanza.

Longlining fleets of several European and Asian nations, having fully exploited their own fishing grounds, are now fishing in African waters. Vessels go to the port of Las Palmas, in the Canary Islands, to offload their catch, most of which is shipped back to Europe, Japan and the United States. Longliners deploy up to 60 miles of baited hooks to catch highly migratory species such as tuna and swordfish.

The impacts of overfishing are being felt by many centuries-old European fisheries. Each summer blue-fin tuna migrate into the warmer waters of the Mediterranean to breed and spawn. An ancient and very proud fishing tradition known as the tonnara is still practiced on the western coast of Sicily, during which men haul giant bluefin tuna aboard in an event called the mattanza. The tonnara consists of a long fence-like net that forces migrating bluefin tuna to become entrapped in a series of netted chambers. The nets are raised and the tuna are slaughtered. Although once practiced in at least 200 locations throughout the Mediterranean, there are now barely enough tuna to support two tonnaras.