It's a staple lunch-choice for city-workers all over the country and you're never far from a restaurant or supermarket selling the traditional Japanese delicacy.

寿司现在是英国大小城市上班族的主要午餐选择，附近随便哪家餐厅或超市都在卖这种传统日本美食。

But it turns out sushi may not be as wholesome a choice as we previously thought - leading biologists have warned that it is in fact harming both the environment and our health.

The UK sushi market is worth £69m a year, but because we're eating so much of it, tuna supplies in the oceans are dwindling.

According to Professor Daniel Pauly and Dr Dirk Zeller, the leaders of the Sea Around Us project at the University of British Columbia, bluefin and yellowfin tuna populations have reached “crisis” levels.

Bluefin tuna tends to be served in high-end, luxury sushi restaurants, whereas yellowfin is more common in high-street sushi bars and supermarkets.

Increasing global demand means sushi populations are being overfished. Most of the UK's sushi comes from the Indian Ocean, but according to Professor Pauly we now only have 2-3 percent of what we had 200 years ago.

"We are in permanent crisis if you look at it in historic terms," he warned.

Professor Pauly and Dr Zeller believe it is our love of healthy tuna that's causing the problems in our oceans.