TOKYO, Japan — Sushi, a standard, cheaper option on the menu in Japanese restaurants, is facing a crisis in the country.

The Russia-Ukraine war, rising costs, and declining freshness have sent food prices soaring.

"There's currently a shortage of salmon, and ikura is in real danger," said Yoshinobu Yoshihashi, a "naka-oroshi," or intermediate wholesaler, at Toyosu Market in Tokyo, the country's largest wholesale market.

The salmon found in Japanese sushi is typically farmed salmon. Conveyor-belt sushi restaurant chains — where the food is served on conveyor belts that customers take for themselves — often use salmon from Norway, the world's largest producer of Atlantic salmon.

But since the end of February, Russia has imposed restrictions on its airspace, which means alternative routes had to be found for flights bringing Norwegian salmon to Japan.

Yoshihashi said the salmon is now flown from Norway to Japan via Dubai, United Arab Emirates. 

The longer routes are more expensive and also mean the fish loses its freshness. There are also fewer flights, so supply has dropped.

"It's difficult for us to immediately account for higher import costs in our prices," Yoshihashi said.

Of Japan's imported salmon and trout, about 70% comes from Chile — and most of that is frozen. About 20% comes from Norway and 10% from Russia.

The Ministry of Agriculture, Forestry, and Fisheries' data on imports and exports indicated that Japan imported about 10% less salmon and trout in January to April, compared with the same months in 2021.

But prices have increased by about 15%, the data said.

Statistics on Toyosu Market in Tokyo showed that the average price per kilogram of imported salmon and trout from May 2017 to 2021 was 1,624 yen, which is about $12, while the average price in May 2022 was 2,121 yen, a 30% increase.

Yoshihashi said that while business was "slowly starting to pick up following the relaxing of COVID-19 restrictions," there were still fewer people out drinking late, and selling expensive food was particularly challenging.

Ikura, another common sushi dish, is facing an even bigger crisis than salmon, Yoshihashi said.

Ikura is a processed food made from the roe of wild salmon.

Shio ikura, or salted salmon roe, is the most popular type of salmon roe. 

Salted ikura is available at high-end sushi restaurants. At a common sushi restaurant, ikura can be had for a few hundred yen. In the case of salted salmon roe, the price can be over 1,000 yen.

Yoshihashi said that the price of ikura could even double.

It's become more difficult to import and export it, and there have also been two years of "poor fishing," Yoshihashi said.

Salmon roe, the "raw material" in ikura, has also become increasingly difficult to secure, which also adds to the price, Yoshihashi continued.

The statistics on Toyosu Market showed that the average price per kilogram of ikura was 7,333 yen as of 2021. Between 2016 to 2020, the average price was around 5,500 yen, so prices were already rising before the Russia-Ukraine war.

The declining salmon population also represents a serious issue, said Shunpei Sato, from the Japan Fisheries Research and Educational Agency.

"Originally, there was an abundance of salmon in Russia and Alaska, but numbers were decreasing in Japan and Canada, which are the southern boundaries of salmon distribution. However, in the last two to three years, there appears to have been a decline in Russia and Alaska as well," Sato said.

Since the 1980s, Japan has been promoting a hatching and stocking program with the aim of helping its salmon population to bounce back. 

The annual national catch — which was about 50,000 tons, a little less than 20 million fish, in the 1970s — recovered sharply by the early 1990s. At its peak, the national catch was about 80 million fish.

Then, in the 2000s, it fell again.

"The population has dropped sharply during the latter half of the 2010s. According to the data for 2020, the catch was about 50,000 tons. In other words, it has dropped to the level prior to the start of the 1970s hatching and stocking program. We are currently investigating the cause," Sato said.

The hatching and stocking program has released about 1.6 billion to 1.8 billion juvenile salmon into the rivers each year. Salmon released into rivers travel downstream for a few days to a month and reach maturity in the ocean. They then return to the river where they were born or released a few years later. Only a small percentage are able to return safely.

"It takes about four years for the salmon to return to the river they were born in. In other words, they spend about four years out at sea. I think changes in the marine environment caused by climate change is one thing to think about," Sato said.

While the salmon population remains low, ikura prices are likely to remain high, even if the Russia-Ukraine war were to end.

This story originally appeared on Business Insider Japan and has been translated from Japanese.