Threats

One in five people on this planet depends on fish as the primary source of protein“. —Food and Agriculture Organization

We are in the situation where 40 years down the line we, effectively, are out of fish.” —Pavan Sukhdev, UN Environment Programme

The tuna oceanic highways have turned into gauntlets lined with giant nets and endless lines of fishing boats. Fishermen have resorted to high-tech ways to catch tuna, including devices that draw the fish into bunches so that fishermen can catch more of them at once. Many of the world’s valuable tuna species face a number of urgent yet common threats to their continued existence such as significant population declines, poor international conservation management, and high levels of illegal, unreported, and unregulated illegal fishing.

Global appetites for fish, especially Japanese appetite for sushi, is the predominant threat to Atlantic bluefin. Bluefin aquaculture, which arose in response to declining wild stocks, has yet to achieve a sustainability, in part because it predominantly relies on harvesting and ranching juveniles rather than captive breeding.  Despite some concern, assessments from the 2010 Deep Water Horizon Oil spill estimated that the population loss would not be significant, ranging from 0.4–4% of juveniles, which is within the range of annual variations.

Tuna Decline

Overfishing

Overfishing continues despite repeated warnings of the current precipitous decline. In 2007, researchers from the International Commission for the Conservation of Atlantic Tunas (ICCAT)—the regulators of Atlantic bluefin fishing—recommended a global quota of 15,000 tonnes to maintain current stocks or 10,000 tonnes to allow the fisheries recovery. ICCAT then chose a quota of 36,000 tonnes, however surveys indicated that up to 60,000 tonnes was actually being taken (1/3 of the total remaining stocks) and the limit was reduced to 22,500 tonnes. Their scientists now say that 7500 tonnes is the sustainable limit. In November 2009 ICCAT set the 2010 quota at 13,500 tonnes and said that if stocks were not rebuilt by 2022 it would consider closing some areas.

According to information collected by the International Seafood Sustainability Foundation (ISSF), the Eastern Pacific stock of yellowfin is overfished and some overfishing is occurring in the Indian Ocean. The northern and southern Atlantic Ocean stocks of albacore are also overfished. The skipjack tuna, while quite resilient, could easily slip into a vulnerable state due to overfishing if improperly managed.

Bigeye tuna are prized in Asia for sashimi as well as frozen and fresh in other markets. As bluefin tuna populations shrink around the world, pressure on bigeye fisheries is increasing. According to information collected by the ISSF Scientific Advisory Committee, overfishing is occurring in Eastern and Western Pacific Oceans. Bluefin tuna populations have declined severely from overfishing and illegal fishing over the past few decades –not just Atlantic bluefin tuna, but also Pacific bluefin tuna and Southern bluefin tuna. Population declines have been largely driven by the demand for this fish in high end sushi markets.

What can be done?

The next few years will be pivotal for the oceans. If strong measures are implemented now, much of the damage can still be reversed. In terms of what needs to happen, preventing overfishing is fairly straightforward: first and foremost, scientifically-determined limits on the number of fish caught must be established for individual fisheries, and these limits must be enforced. Second, fishing methods responsible for most bycatch must either be modified to make them less harmful, or made illegal. And third, key parts of the ecosystem, such as vulnerable spawning grounds and coral reefs, must be fully protected.

References: worldwildlife.org
saveourseas.com