The phenomenon is suspected to be related to warmer-than-usual water temperatures amid this summer’s intense heat wave, suggesting a link to climate change. The die-off is expected to affect supplies – and prices – of uni and ikura, or salmon roe, for the next few years, on top of the economic disruption already wrought by the pandemic.
Fishing cooperatives around the city of Kushiro in eastern Hokkaido, a region known for high-quality Ezo-bafun uni, reported that more than 90% of sea urchins in their respective areas had died as of Oct 1.
The Chirippu cooperative in nearby Hamanaka said about half of its sea urchins were killed.
This not only hit supply near the peak New Year’s demand season, but also wiped-out masses of young shellfish ahead of the next fishing season.
Newly stocked juvenile sea urchins are off-limits for four years until they mature.
The Akkeshi cooperative, known for its eponymous oysters, has reported the death of around 80% of its sea urchins. In a normal year, its sea urchin catch is worth ¥200 million to ¥300 million (US$1.8 million to US$2.7 million). Given the likely hit to future catches, the cooperative estimates the overall impact at around ¥1 billion.
“The effects will last three to four years,” a representative from the Chirippu cooperative said. “This is the first time we’ve had a red tide in this area. We don’t know what the impact will be.”
The damage goes beyond sea urchins. Four fishing areas saw a total of 11,960 salmon die, with even those already caught in nets needing to be destroyed. One Kushiro-area cooperative lost 85 tonnes of kombu kelp.
Red tides – algae blooms that produce harmful toxins – are not uncommon on Japan’s main island of Honshu in the spring and summer.
But they almost never occur around Hokkaido, where water temperatures are typically low year-round, and had not been confirmed in eastern Hokkaido before now.
This year’s record-breaking heat, along with periods of extremely low rainfall, may have played a role. Water surface temperatures were 5℃ above average near Kushiro and the coastal area of Tokachi in July and August.
“The water surface was unusually calm, and there were no big low-pressure systems passing through,” according to a senior researcher at the Sapporo branch of the Japan Meteorological Agency.
“It’s possible that without the water being disturbed, the temperature couldn’t fall.”
Other factors may be involved in the die-off, such as bouts of intense rain that diluted salinity levels in nearby waters.
“It’s hard to conclude that the red tide caused the sudden deaths, though there’s suspicion because they were confirmed at the same time,” said a representative of the Central Fisheries Research Institute of the Hokkaido Research Organization’s fisheries branch.
Seafood wholesaler Kaneshime Takahashi Suisan says sea urchin prices are already higher than usual at around ¥60,000 per kg.
“There’s been a huge impact” just as “we’ve been getting more inquiries as interest has picked up in dining out” after the recent lifting of the emergency declaration, a senior executive said.
Uni and roe experience strong demand toward the end of the year as people order osechi, or traditional New Year’s platters. The impact of the mass deaths is immediately surfacing at department stores.
At the Isetan Shinjuku store in Tokyo, the price of Hokkaido urchin is as much as twice the usual charge, depending on the producing area, according to operator Isetan Mitsukoshi Holdings.
“The price of roe used for osechi had risen each year” before the recent disaster, a communications officer at a major department store said. “Even given that there are frozen products, I can’t tell what is going happen from next year.”
Because osechi and year-end gifts are sold months in advance through catalogs, it will be impractical to pass on the extra costs to consumers.