By Shawn Dell Joyce
Ocean fish are the last wild creatures that people hunt on a large scale. We used to think of the ocean’s bounty as endless, but recently we have discovered its limits. Between 1950 and 1994, ocean fishermen increased their catch 400 percent by doubling the number of boats and using more effective fishing gear, according to Seafood Watch, a consumer awareness program at the Monterey Bay (Calif.) Aquarium.
In 1989, the world’s catch leveled off at just over 82 million metric tons of fish per year. We have reached “peak fish” and no amount of boats will help us catch more fish. Today, only 10 percent of all large fish – both open ocean species including tuna, swordfish, marlin and the large ground fish such as cod, halibut, skates and flounder – are left in the sea, according to research published in National Geographic.
“From giant blue marlin to mighty bluefin tuna, and from tropical groupers to Antarctic cod, industrial fishing has scoured the global ocean. There is no blue frontier left,” lead author Ransom Myers told National Geographic. “Since 1950, with the onset of industrialized fisheries, we have rapidly reduced the resource base to less than 10 percent – not just in some areas, not just for some stocks, but for entire communities of these large fish species from the tropics to the poles.”
“The impact we have had on ocean ecosystems has been vastly underestimated,” said co-author Boris Worm. “These are the megafauna, the big predators of the sea, and the species we most value. Their depletion not only threatens the future of these fish and the fishers that depend on them, it could also bring about a complete re-organization of ocean ecosystems, with unknown global consequences.”
Marine biologist Sylvia Earle says, “I don’t blame the fishermen for this. We, the consumers, have done this because we have a taste for fish and ‘delicacies’ such as shark-fin soup. Our demand for seafood appears to be insatiable…driven by high-end appetites. I’ve always believed that even when there is only one bluefin tuna left in the sea someone will pay a million dollars to be able to eat it.”
Earle, who is also an author and sustainability advocate, points out that “Most people also don’t know how bad it is for us to be eating so much fish, not only because of the destruction of an ecosystem vital to survival but also because the big predatory fish are full of the toxins and other pollutants that we cast into the oceans. It’s not as healthy to eat fish as most people believe.”
Three factors are responsible for the depletion of our oceans:
–Coastal wetlands are a fertile habitat for fish and shellfish, but also popular places for people. More than half of the world’s people live near a sea coast, placing most of our large cities next to the ocean. Bay waters are polluted by sewage, oil, chemicals and agricultural fertilizer. Paved surfaces near wetlands and tidal areas increase storm water run-off.
–Trawling and dragging are fishing methods that destroy habitat by dredging up the sea floor. Some trawlers put rockhopper gear, including old tires, along the base of their nets to roll over rocky reefs, giving sea life no place to hide. Dredges drag nets with a chain mesh base through soft sand or mud to catch scallops and sea urchins, crushing other life on the sea floor and damaging places where fish feed and breed. Some scientists believe that fishing with rockhoppers and dredges harms the ocean more than any other human activity.
–According to the United Nations Food and Agriculture Organization, one in four animals caught in fishing gear dies as bycatch (unwanted or unintentional catch). Tons of fish are tossed out because they’re not what the fishing boat was after, have no market value, or are too small to sell. Bycatch often takes young fish that could rebuild depleted populations if they were allowed to grow up and breed. It is estimated that for each pound of shrimp caught in a trawl net, an average of two to ten pounds of other marine life is caught and discarded as bycatch.
Some seafood can be sustainably farmed. Clams are raised in special beds on sandy shores, where their harvest does little to disturb the ecosystem. Oysters and mussels are often raised in bags or cages suspended off the seafloor, doing little damage as they’re harvested. Many farmed fish, such as salmon, are grown in net pens, like cattle in a feed lot. This is as environmentally damaging in the ocean as cattle feed lots are on land.
Additionally, mangrove forests have been cut down and replaced with temporary shrimp farms that supply shrimp to Europe, Japan and America until the water becomes polluted.