Spencer Baird had blamed the messy, voracious bluefish for decimating fish populations in New England, but he had the foresight to warn against the trawler as an even more destructive force. Like the bluefish, trawlers are incredibly wasteful predators, destroying everything in their paths. But unlike the bluefish, which create a buffet for the scavengers traveling in their wake, thereby helping to maintain the existing food web, bottom trawlers leave only rubble, making it difficult for the marine environment to recover to its natural state. Bottom trawlers destroy 4 to 16 pounds of marine life for every fish they catch. This waste, known as bycatch, can include other species of fish (including sharks), sea turtles, dolphins, octopuses, corals, and more--anything that has the misfortune to be caught in the path of a rumbling trawl.
Today's trawlers use much the same technology as in Baird's time. But the difference is twofold. First, in scale: The world's largest supertrawler, the Atlantic Dawn, debuted in 2000. It isn't just a fishing ship. It's a huge floating factory. Weighing 14,000 tons unloaded and stretching longer than 11/2 football fields, the Atlantic Dawn can store 18 million servings of frozen fish in its hold. The ship's otter trawl is supersized, at 200 feet wide and 40 feet tall: A 747 jet could fly through the metal doors. The weighted net is so heavy and powerful that it can sink to the bottom and shove aside 25-ton boulders as it chases down fish.
The second difference is the digital technology. It's been a long time since anyone could catch flatfish by hand in shallow waters, as colonists described with such heady enthusiasm. Modern industrial fishing ships are equipped with satellite technology, seabed-mapping software, sonar, radar, GPS devices, and more tools that transform the ships into highly sophisticated fish-seeking missiles.
Most trawlers aren't nearly as massive as the Atlantic Dawn. Just 1 percent of the world's fishing fleet can be called supertrawlers. But these few massive ships catch a huge portion of the world's seafood.
Meanwhile, in coastal regions and in seas like the Mediterranean, you're more likely to see boats hardly bigger than a large speedboat hauling the otter trawl's telltale steel doors. But what these ships lack in tonnage, they make up for in number. Together with the supertrawlers, they rake a seafloor area twice the size of the continental United States every year. Spencer Baird would be loath to visit New England's remaining fishing ports today. The trawler fleet there fishes an area the size of Rhode Island, Massachusetts, Connecticut, New Hampshire, and Maine combined.
Trawlers are the flagships, so to speak, of a global fleet that has expanded exponentially since the end of World War II. The naturalist Walter Garstang reported that fishing effort had more than tripled on England's shores in the decade he studied the nascent trawling industry, and yet catches were dropping. And now we have added to the weaponry other specialist fishing gear like the purse seine, which targets fish at the top and middle of the ocean's water column. The seiners encircle schooling fish with 1,000-yard nets before dragging them into the hold. Without laws to protect marine mammals, it is purse seiners that are the most likely to drown dolphins and porpoises chasing schooling tuna.
This story has repeated itself again and again on a global scale since the early 20th century. Improved technology has allowed fishing fleets to search farther, deeper, and longer for fish. This expansion is not driven by some unspoken desire to conquer the oceans, like summiting Mount Everest or hiking Death Valley. It's because we've already laid waste to the marine wildlife that was easiest to catch. We started with the slowest and most trusting seabirds and marine mammals (sorry, Steller's sea cows!) and are now in pursuit of the most elusive fish in the world's remotest underwater places.
by Andy Sharpless and Suzannah Evans, Scientific American | Read more:
Image: Flickr / sludgegulper
Today's trawlers use much the same technology as in Baird's time. But the difference is twofold. First, in scale: The world's largest supertrawler, the Atlantic Dawn, debuted in 2000. It isn't just a fishing ship. It's a huge floating factory. Weighing 14,000 tons unloaded and stretching longer than 11/2 football fields, the Atlantic Dawn can store 18 million servings of frozen fish in its hold. The ship's otter trawl is supersized, at 200 feet wide and 40 feet tall: A 747 jet could fly through the metal doors. The weighted net is so heavy and powerful that it can sink to the bottom and shove aside 25-ton boulders as it chases down fish.The second difference is the digital technology. It's been a long time since anyone could catch flatfish by hand in shallow waters, as colonists described with such heady enthusiasm. Modern industrial fishing ships are equipped with satellite technology, seabed-mapping software, sonar, radar, GPS devices, and more tools that transform the ships into highly sophisticated fish-seeking missiles.
Most trawlers aren't nearly as massive as the Atlantic Dawn. Just 1 percent of the world's fishing fleet can be called supertrawlers. But these few massive ships catch a huge portion of the world's seafood.
Meanwhile, in coastal regions and in seas like the Mediterranean, you're more likely to see boats hardly bigger than a large speedboat hauling the otter trawl's telltale steel doors. But what these ships lack in tonnage, they make up for in number. Together with the supertrawlers, they rake a seafloor area twice the size of the continental United States every year. Spencer Baird would be loath to visit New England's remaining fishing ports today. The trawler fleet there fishes an area the size of Rhode Island, Massachusetts, Connecticut, New Hampshire, and Maine combined.
Trawlers are the flagships, so to speak, of a global fleet that has expanded exponentially since the end of World War II. The naturalist Walter Garstang reported that fishing effort had more than tripled on England's shores in the decade he studied the nascent trawling industry, and yet catches were dropping. And now we have added to the weaponry other specialist fishing gear like the purse seine, which targets fish at the top and middle of the ocean's water column. The seiners encircle schooling fish with 1,000-yard nets before dragging them into the hold. Without laws to protect marine mammals, it is purse seiners that are the most likely to drown dolphins and porpoises chasing schooling tuna.
This story has repeated itself again and again on a global scale since the early 20th century. Improved technology has allowed fishing fleets to search farther, deeper, and longer for fish. This expansion is not driven by some unspoken desire to conquer the oceans, like summiting Mount Everest or hiking Death Valley. It's because we've already laid waste to the marine wildlife that was easiest to catch. We started with the slowest and most trusting seabirds and marine mammals (sorry, Steller's sea cows!) and are now in pursuit of the most elusive fish in the world's remotest underwater places.
by Andy Sharpless and Suzannah Evans, Scientific American | Read more:
Image: Flickr / sludgegulper
