Six years ago, research results were published in the journal Nature which concluded that during the previous fifty years, ninety percent of all large fish in the world's oceans had disappeared. There are many threats to the oceans today, including pollution and global warming, but perhaps the most immediate threat, and the primary cause of this massive collapse in global fish stocks, is overfishing and the use of harmful fishing methods.
Since 1950, world population has more than doubled from roughly 2.5 billion people to now close to 7 billion. The demand for seafood has risen dramatically since then, and the number of people fishing commercially rose for several decades. Additionally the use of large scale industrial fishing methods expanded and intensified during this period. In the past 20 years, however, fish catches peaked in many parts of the world, with a collapse usually following soon afterwards. In Newfoundland, for example, the cod fishery completely collapsed in the early nineties. The Canadian government was forced to close the fishery and roughly 40,000 people lost their jobs.
Ironically, one of the main reasons governments have been hesitant to restrict catches or lower quotas in the past, at the recommendation of experts and scientists, has been a concern about the loss of jobs. Yet, by not taking action, even more jobs have been lost with the complete disappearance of this traditional way of life in many places. Along with the loss of jobs has been the destruction of many important sources of food. Fish stocks in many locations may take decades to recover, while others may be gone forever.
To make matters worse, when a fishery begins to collapse and catches drop sharply, rather than immediately reducing or stopping fishing, the reaction of many governments is to increase subsidies, without which commercial fishing would no longer be economically viable. This means that normal market feedback which would tend to discourage fishing in areas of dropping productivity is overridden. Subsidies allow for continued fishing, pushing a fishery further past the breaking point, at taxpayer expense. Clearly this is both economically and ecologically destructive.
As demand for seafood increases and stocks decline, many intensive fishing methods are being used to try to increase catches. One method is bottom trawling, which involves the use of large nets being dragged across the sea floor. The problem with this method is that many non-catch creatures are caught in these nets, which end up being killed and dumped back into the ocean. The disturbance of the sea floor stirs up sediment, which can kill coral and otherwise damage local ecosystems. A relatively small number of the target fish are caught compared to the damage caused to other species.
Trawling at higher depths also causes similar problems for non-catch species. Additionally, the nets kill large numbers of marine mammals such as dolphins and porpoises. One report estimates that 1000 marine mammals are killed every day by fishing nets. Because of declining fish stocks in many areas, fishing vessels often need to travel much further distances in order to catch sufficient fish. This means a lot more fuel needs to be burned, which contributes to global warming.
One way to help solve the problem is to declare some parts of the ocean to be protected and off limits to fishing, pollution, mining or other damaging activity. This is similar to how national parks and reserves are created on land. Currently about 12 percent of the Earth's surface is protected in this way. Some marine sanctuaries are being created, but at a very slow pace. Currently, less than one percent of the world's oceans are protected.
Overfishing is one of the largest problems affecting the oceans today. It is threatening the viability of many marine ecosystems, and eliminating large food supplies. Many species may never recover and could become extinct. Additionally, overfishing destroys jobs, costs taxpayers money and has significant impacts on local economies. This short sighted and self destructive behaviour clearly needs to end. Immediate action is needed to curtail overfishing, ban harmful fishing methods, and increase areas of the ocean under protection.