HAOC TOKYO, March 2 (Xinhua) -- For decades, conservationists have called for urgent action to rescue the bluefin tuna, the largest tuna which has been driven to the brink of extinction due to over-fishing.
Ahead of the 2017 World Wildlife Day on March 3, here are some facts and figures about this most prized fish's current worsening situation.
WHAT ARE THEY?
The bluefin tuna is a long-lived and slow growing species, including mainly three subspecies, namely Southern bluefin tuna, Pacific bluefin tuna and Atlantic bluefin tuna.
These three are all on the Red List of Threatened Species issued by the International Union for Conservation of Nature, with Southern bluefin viewed as critically endangered, Pacific bluefin as vulnerable and Atlantic bluefin as endangered.
WHERE ARE THEY?
Southern bluefin tuna can be found in open southern hemisphere waters of all the world's oceans.
Pacific bluefin tuna lives widely in the northern Pacific Ocean and sometimes migrate to the south.
Atlantic bluefin tuna lives mainly in the North Atlantic pelagic ecosystem and its adjacent seas, especially in the Mediterranean.
WHY ENDANGERED?
Mostly used in Japanese sushis and sashimis, the bluefin tuna is considered one of the most valuable forms of seafood in the world.
John Tanzer, director of the marine program at the World Wide Fund for Nature (WWF) International, said this endangered situation "is mainly a result of the Japanese eating habits."
The breeding population of the Pacific bluefin tuna has fallen to a theoretically estimated 2.6 percent of the pre-fishing level, he said, while between 80 percent and 90 percent of the Atlantic subspecies hunted used to serve Japanese dinner tables.
A recent report released by the U.S. Pew Charitable Trusts, a nongovernmental organization, said bluefin tuna fishing today is three times faster than the sustainable level scientists estimate.
About 70 percent of Pacific bluefin are less than a year old when caught, and 95 percent are caught before they reach three years old, thus damaging the species' ability to reproduce, according to the report.
But, being bigger than other tuna, bluefin tuna is estimated to take between four and eight years to come to sexual maturity, making it more vulnerable to the predations of modern industrialized fishing techniques.
WHAT IMPACTS?
Bluefin tuna is one of nature's most successful ocean inhabitants, a top predator in the marine food chain, maintaining a balance in the ocean environment.
If current trends continue, the species will soon be functionally extinct in the Pacific, warned by some media reports.
With the absence of the bluefin, an overabundance of smaller organisms might affect the entire underwater ecosystem. Some scientists even predicted that such a shift could lead to a total collapse of the oceans.
CHALLENGES REMAIN
The WWF has made it clear that declines in the bluefin tuna population have been "largely driven by the demand for this fish in high-end sushi markets."
Still, Japan refuses to reduce fishing quotas in international commercial negotiations. Its stance led to the abortion of a regional plan to protect Pacific bluefin tuna in 2016.
Food culture has been an excuse for the Japanese government on this fishing issue, regardless of the scientific finding that mercury content is the highest in the endangered whales and tunas at the top of the marine food chain.
According to the Japanese Fisheries Agency's investigation released in early February, of Japan's 39 coastal prefectures, as many as 10 of them have been found to have had extra fishing or false reporting.
