"The oceans are our largest public domain. The United States’ oceans span nearly 4.5 million square miles1, an area 23 percent larger than the land area of the nation. Their biological riches surpass that of our public lands. The genetic, species, habitat, and ecosystem diversity of the oceans is believed to exceed that of any other Earth system. Yet, incredibly, we are squandering this bounty.
Humanity’s hunger for ocean resources and our vast capacity to exploit them result in unprecedented impact upon the oceans and coasts. The disturbing signs of these impacts can be found nearly everywhere we look. Yet, our laws, government institutions, and governance practices have not kept pace with these changes." (excerpt from America's Living Oceans: Charting a Course for Sea Change, summary report, PEW Ocean Trust).
The most famous case is the collapse of the New England Cod fishery due to overfishing and adverse habitat changes. Canadian catches of Atlantic Cod peaked at 775,000 tons in 1980's and declined to 50,000 tons in 1995, a drop of 90%. Even now, the New England cod population is not recovering, but even declining. Yet, the Atlantic cod are still being fished.
Atlantic swordfish populations are also in severe decline. In the early 1800's, swordfish were caught using hand lines and rod and reel, and averaged 300-400 pounds. Now most swordfish are caught before the have a chance to spawn, at below 100 pounds. Other Atlantic billfish populations are also in severe decline.
Along the West Coast of the US, catches of rockfish or groundfish have declined by 70% during the last two decades. Bocaccio (marketed ad Red Snapper,left) catches have declined by 98% since 1969).In 2002, emergency closures of the rockfish fishery were instituted.
Overfished species also include the Bluefin tuna, Alaskan Halibut, and Salmon. According to the Food and Agriculture Organization of the United Nations, 52% of the world's fisheries are fully exploited (fished at maximum level) and 16% are over exploited, and 7% are depleted. Seven of the top ten marine species, which account for 30% of the catch, are fully exploited or over exploited.
One of the "dirty secrets" of commercial fishing is the quantity of other creatures that are caught with the target species and discarded, most of which do not live. In the New England groundfish fishery, 1.8 pounds of bycatch accompany each pound of cod, haddock, and flounder. Shrimpers in the Gulf of Mexico are among the dirtiest, with 4.5 pounds of bycatch for every pound of shrimp. However, Alaska Pollock trawlers have been attempting to reduce bycatch with a system of on-board observers, bycatch limits, and catch share fisheries management policies. They have managed to reduce the bycatch to about 1%. This is still a large bycatch, because the catches are very large. A good discussion of bycatch and policies enacted by the Alaska fisherment can be found at "What's The Catch?"