For centuries, the seas have been viewed as a limitless bounty, a continuous source of food and resources. However, decades of fishing, pollution and destruction of habitat have taken their toll. Scientists now estimate that some 90% of the oceans have been overfished. With over 80 species of fish teetering on the verge of extinction, experts liken the continued human consumption of ocean life to the last buffalo hunt.
This paper focuses on the effects of overfishing on one of the most widely-consumed fish species - the tuna. The first part of the paper is an overview of the various tuna species. The next part then examines the reasons behind the depletion of the tuna population. In the last part, the paper details the consequences of this depletion, and the various proposals put forth to help the tuna population recover.
Overview of the tuna population
Commercially speaking, tuna is the most profitable and important fish species. Because of their popularity, at least six species of tuna fish are either on the verge of the endangered list or nearing extinction altogether.
The tropical skipjack, for example, is the species most commonly used in canned tuna. Albacore, another light-skinned tuna, is also often canned (Hailes).
Nearly 35% of all tuna harvested from the oceans are yellowfin, the main species used in making sushi. Because of their popularity, scientists say that the yellowfin population has declined by over 30% over the past decade (Hailes).
The Northern bluefin and Southern bluefin are the most endangered tuna species. The Southern bluefin is found in the southern oceans. This species has a high fat content and is highly valued by the Japanese market for making sashimi ("What are Southern Bluefin Tuna").
Their Atlantic counterparts, the Northern Bluefin, used to populate the Mediterrenean seas. However, experts estimate that the critically endangered Northern bluefin is in danger of becoming extinct. The Northern bluefin population has declined by an estimated 98% over the past four decades of commercial shipping (ECES News Articles).
Despite the dire figures, however, the Northern bluefin continues to be harvested for the Japanese sushi market. Making matters worse, bluefin tuna is also becoming popular in the Mediterranean market. Left unchecked, the World Wildlife Foundation (WWF) warns that wild bluefin stock can completely disappear from the oceans in a few years (ECES News Articles).
The critical situation of the bluefin and yellowfin have placed a strain on other tuna species as well. The Bigeye tuna, for example, is currently found in the Pacific and Atlantic Oceans.
Because it is being eyed as a replacement for the popular bluefins, the bigeye tuna now faces the same dangers that decimated other tuna populations ("The Trouble With Tuna").
Causes of depletion
In a healthy ecosystem, tuna populations would be spawned in schools, grow to adulthood and be able to spawn the next generation of tuna. However, factors have disrupted this cycle, interfering with the tuna's ability to spawn and resulting in severely depleted populations.
Most of these disrupting factors are human made. Since the 1960s, traditional pole and line fishing has given way to commercial tactics, which have greatly increased the catch and placed stress on tuna populations.
One commercial fishing technique involves the use of long-lines. Instead of single hooks, long-liner boats string out 3,000 baited hooked lines for miles across the ocean. Fleets of these boats then trawl across the ocean for hours at a time, hooking more tuna than could be caught with a traditional, human-controlled pole (Greenpeace).
Critics contend that long-line fishing also hooks juvenile salmon, thus disrupting the school's ability to spawn and keeping the population from recovering. In addition to tuna, these long-lines also kill other wildlife, including endangered species of shark and turtles. To release trapped dolphin, many fishers simply cut the line and leave the hook inside the mammal (Greenpeace).
In the oceans around Australia, the Southern bluefin is often caught using the purse-seine method. Instead of hooks, fishers use fine nets to enclose the fish. ("What are Southern Bluefin Tuna"). Currently, there are an estimated 3.5 million such fishing vessels scouring the ocean for edible fish. Many are equipped with sonar equipment and satellite navigation. These nets can snare up to 120,000 pounds of…