Since 2012, scientists in the four territories where the Japanese eel is most commonly found have worked together on conservation, setting aquaculture quotas in 2015.īut restrictions, including an EU ban on exports in 2010, have created a flourishing black market, with poaching and international trafficking. The deterioration of their freshwater habitats, including by river development, also plays a significant role, along with pollution.ĭams can block migratory routes and eels are sometimes caught in hydroelectric turbines, a leading cause of death for the species. They swim into estuaries and rivers in Japan, Taiwan, China and South Korea, and live in freshwater habitats for between five and 15 years before swimming back out to sea to spawn, and then die.Įels are vulnerable to a wide range of catastrophic human behaviours, and climate change-linked phenomenon like El Nino have affected the ocean currents that carry them, as well as their spawning sites. Once they hatch into larvae, the creatures drift towards coastlines, growing on the way into glass eels. It is now present in every ocean except the Antarctic.īut despite their ubiquity, it wasn't until the early 20th century that European scientists discovered that European and American eels are born somewhere in the Sargasso Sea near Cuba, with their larvae then carried by currents to different regions.Īnd the precise location of eel spawning sites remained an enigma until 2009, when a scientific mission pinpointed the breeding grounds of the Japanese eel, west of the Mariana Islands, some 2,000-3,000 kilometres from Japan's coasts.Įvidence suggests the species mates and lays its eggs at the spot, but the process has still never been observed. "As continental drift affected marine currents and the distance grew between the areas where eels lived and laid eggs, the creature has adapted," she told AFP. "We think that the eel emerged approximately 60 million years ago, near the island of Borneo," explains Mari Kuroki, assistant professor at Tokyo University's aquatic biosciences department.
He theorised eels must simply emerge spontaneously in mud because he could find no traces of their larvae. The mystery of eel reproduction has fascinated scientists for thousands of years, with even ancient Greek philosopher and naturalist Aristotle puzzling over it. Protecting the animal is complicated by their complex life cycle, which unfolds over a vast area, and the many unknowns about how they reproduce. In 2014, the Japanese eel was listed as endangered by the International Union for Conservation of Nature, which cited factors including habitat loss, overfishing, pollution and migration barriers. There are 19 species and subspecies of eel, many of them now threatened. "A dish of unaju (eel on rice) is today nearly three times more expensive than when I started," said Hachisuka. That has driven prices sky-high, even in a country that has battled for years to achieve inflation. The annual catch in Japan of young known as glass eels has fallen to 10 percent of 1960 levels. It mustn't be too sweet or too salty," he told AFP.īut while his recipe has stayed the same, his product has not. In central Japan's Shizuoka, 66-year-old Hachisuka's restaurant in Hamamatsu city has used the same basting sauce base for four decades. While the writhing snake-like creature is repellent to some, it is a mainstay of Japanese cuisine, and since the 17th century has most often been prepared "kabayaki"-style: skewered, grilled and basted in a mixture of soy sauce and mirin rice wine. Pressures on wild stocks ranging from pollution to overfishing mean supplies have dwindled dramatically in recent decades. Precisely how it reproduces is unclear, and coaxing it to do so in captivity without intervention has proved unsuccessful so far. Tsuyoshi Hachisuka gently places skewered eel on a grill, preparing a much-loved Japanese delicacy that is now so endangered it commands eyewatering prices and the attention of international traffickers.Ĭonsumed worldwide, eel is particularly popular in Asia, and perhaps nowhere more so than Japan, where remains found in tombs show it has been eaten on the archipelago for thousands of years.ĭespite its enduring popularity, much about the eel remains a mystery.
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