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Thursday
Apr092015

How the Sushi Industry is Rolling the Dice on the Future of the Marine Ecosystem

Image Courtesy of Alpha

It would have been impossible to fathom back in 718- the year sushi was first ever recorded- the heights of popularity that this Japanese delicacy would reach, and the associated ecological repercussions to fish stocks that would occur as a result.

Recent rise in demand for sushi

Sushi- for the very few individuals out there who are unaware of this dish- is a meal consisting of cooked vinegared rice, combined with a range of other ingredients such as seafood and vegetables. It has become tremendously chic as of late and restaurants serving sushi can now be found in almost every city across North America, Europe and Australia. A couple of statistics to put the scale of the demand into perspective are that global sushi consumption has increased by 40% from the late 1990s, and in London in 2007 there were more than 300 Japanese restaurants serving sushi with a worth of more than £500 million a year.

Wider implications

It is easy when at a sushi restaurant to focus solely on the rolls in front of oneself and not to consider the wider implications of what such a lucrative industry means to the overall health of these fish stocks. However, a few heads were turned on January 6th, 2013 when a single Bluefin tuna was sold for £1.09 million at the Tsukiji fish market. Although the price tag can be misleading as this was the first fish purchased at the market, which is held as a prestigious honour and therefore prices are often excessively inflated, it still highlights the fact that a stock that once use to be in abundance has declined to a point where each fish now fetches top dollar. An astounding change over a relatively short period of time considering the fact that in the United States in the 1960s Bluefin tin was used for cat food.

Image Courtesy of Dennis Tang

Impact of sushi demand:  Directly targeted fish stocks

The question therefore arises how depleted are current stocks of not only Bluefin tuna but of the other highly desirable fish species one would find on a sushi menu, such as Bigeye tuna, Yellowfin Tuna, Red snapper, Japanese yellowtail and salmon? Unfortunately, the answer is extremely discouraging with the majority of these species having suffered population declines in excess of 90% since 1950 levels with the Bluefin tuna stock having declined by 94.6%.  Declines attributed to a rate of overexploitation exceeding the rate at which the species can successfully reproduce. Such substantial population reductions mean that these populations linger on the edge of extinction, evident with the WWF predicting that the Atlantic Bluefin tuna will not have a breeding population in three years time unless immediate action is taken to drastically decrease the current catch limit.

Impact of sushi demand:  Wider marine ecosystem

The impact however does not end with the species that are directly targeted, but rather affects a whole range of organisms that have an ecosystem link with those previously mentioned. Most of the species that are important to the sushi industry coincide with also being top predators within their respective food web, which means that they stabilise the marine environment through regulating prey populations. Their absence destabilises the food web and results in a trophic cascade, a series of irreversible complex knock-on effects that move from the higher down through to the lower levels of the food web. The result is an ecosystem dominated by lower trophic level species such as herring, mackerel and jellyfish. Jellyfish in particular are undergoing substantial population increases due to the loss of the top predators such as Bluefin tuna. This is extremely problematic as jellyfish are ferocious competitors that outcompete smaller fish for food and even eat those competing species’ eggs, contributing to a greater loss of fish abundance in the world’s oceans.

Image Courtesy of Jason Pratt

Bleak future

It’s unfair to point the finger entirely at the sushi industry as the reason that the world’s oceans have suffered cataclysmic declines in fish stocks. However, it is also ignorant to assume that this surge in demand for this Japanese delicacy has not had a part to play, particularly for the massive declines that have been witnessed over the last 50 years to species such as the Bluefin tuna. The concern is furthered by the fact that despite stocks hovering on the edge of commercial viability the industry continues to grow in popularity, evident in France where sushi consumption has increased by 30% every year for the past few years. It therefore seems as though the fundamental economic principle of supply and demand will prevail until the supply is no longer viable.

It might be time for society to start adapting its palate to the jellyfish roll, as it seems more likely to become a reality the longer we continue to overfish the last of these dwindling predatory fish stocks. If you care about the conservation of our marine life, why not contribute to extensive marine research projects as a volunteer?

By Robin Denson

Frontier runs conservationdevelopmentteaching and adventure travel projects in over 50 countries worldwide - so join us and explore the world!

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