Overfishing

A large yellow fin tuna being cut up. Yellow fin and big eye tuna may be commercially extinct in 3-5 years if fishing is not controlled, experts warn.

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Many marine ecologists think that the biggest single threat to marine ecosystems today is overfishing. Our appetite for fish is exceeding the oceans' ecological limits with devastating impacts on marine ecosystems. Scientists are warning that overfishing results in profound changes in our oceans, perhaps changing them forever. Not to mention our dinner plates, which in future may only feature fish and chips as a rare and expensive delicacy.

The fish don't stand a chance

More often than not, the fishing industry is given access to fish stocks before the impact of their fishing can be assessed, and regulation of the fishing industry is, in any case, woefully inadequate.

The reality of modern fishing is that the industry is dominated by fishing vessels that far out-match nature's ability to replenish fish. Giant ships using state-of-the-art fish-finding sonar can pinpoint schools of fish quickly and accurately. The ships are fitted out like giant floating factories - containing fish processing and packing plants, huge freezing systems, and powerful engines to drag enormous fishing gear through the ocean. Put simply: the fish don't stand a chance.

Ocean life health check

Populations of top predators, a key indicator of ecosystem health, are disappearing at a frightening rate, and 90 percent of the large fish that many of us love to eat, such as tuna, swordfish, marlin, cod, halibut, skate, and flounder - have been fished out since large scale industrial fishing began in the 1950s. The depletion of these top predator species can cause a shift in entire oceans ecosystems where commercially valuable fish are replaced by smaller, plankton-feeding fish. This century may even see bumper crops of jellyfish replacing the fish consumed by humans.

These changes endanger the structure and functioning of marine ecosystems, and hence threaten the livelihoods of those dependent on the oceans, both now and in the future.

Fisheries collapse

The over-exploitation and mismanagement of fisheries has already led to some spectacular fisheries collapses. The cod fishery off Newfoundland, Canada collapsed in 1992, leading to the loss of some 40,000 jobs in the industry. The cod stocks in the North Sea and Baltic Sea are now heading the same way and are close to complete collapse.

Instead of trying to find a long-term solution to these problems, the fishing industry's eyes are turning towards the Pacific - but this is not the answer. Politicians continue to ignore the advice of scientists about how these fisheries should be managed and the need to fish these threatened species in a sustainable way.