Nori Prices Surge in Japan Due to Poor Seaweed Production Amid Rising Sea Temps; Price of Onigiri Rice Balls Also Impacted

By Rintaro Kaizuka / Yomiuri Shimbun staff writer

7:00 JST, March 25, 2026

Poor seaweed harvests due to rising sea temperatures and damage from fish have led to a drastic fall in nori production. Sales prices have also soared, leaving industry officials at their wits’ end.

“Purchasing costs have doubled in the last four or five years,” said an official in charge at Yamamotoyama Co., a Tokyo-based company that sells domestic nori meant as gifts. “Such price increases have never been seen before.”

The company has raised its prices for roasted nori and nori-based processed products by about 20% in March.

“We can’t lower the quality of our products, so there is nothing we can do about it,” he said.

Long-established Tokyo-based nori manufacturer Shirako Co. also raised the prices of its nori products by 20%-36% last June.

Another major nori seller reportedly changed its labels, which previously read, “Grown in Ariake, Saga Prefecture,” to “Domestically produced,” as the company has had to use nori from various areas in order to secure a sufficient amount.

The poor harvests have been primarily the result of rising sea temperatures, according to the Fisheries Agency and other such entities.

Nori cultivation generally begins around October when the sea temperature falls. However, in recent years, seaweed farmers have been starting around one month later, thus shortening the growing period.

The rising sea temperatures have also led to black sea bream and other fish becoming more active, resulting in them eating the seaweed.

Seeking government support

According to the National Federation of Fisheries Cooperative Associations’ nori business promotion council, the domestic production of nori for fiscal 2024 — between November 2024 and October 2025 — was 5.94 billion sheets, about half the fiscal 2001 figure of 10.68 billion sheets. One sheet is 21 centimeters long and 19 centimeters wide.

The average business-to-business wholesale price reached a record high of ¥24.1 per sheet in fiscal 2024, more than double the fiscal 2020 figure.

“Prices are unlikely to fall in the days ahead,” said Hiroshi Shiraha, president of Koasa Corp., a trading company based in Nagoya that specializes in nori. He added that it has become difficult even for industry officials to predict what will happen to nori production.

“The future is full of uncertainty,” Shiraha said. “We want government support, such as help in securing new production sites.”

The Fisheries Agency is working on developing different varieties of nori that are more resistant to high water temperatures, but it is expected to take time before they can become commercially available.

“Since it is due to environmental changes, it is difficult to drastically improve the harvest,” said Prof. Masahiko Ariji of Kindai University, an expert on aquaculture. “But currently available measures should be implemented, such as setting up barriers to prevent damage from fish.”

Onigiri prices surge

The surge in nori prices is also causing the price of onigiri rice balls sold at convenience stores to increase.

Seven-Eleven Japan Co. has successively raised the prices of 13 types of onigiri by ¥11 to ¥43 since Feb. 10. Soaring costs for rice, distribution and packaging have led to the price increases.

The company also raised the prices of onigiri last April, citing the surge in nori prices as the primary reason.

FamilyMart Co. and Lawson Inc. have also announced successive price hikes for onigiri since last spring.

To keep customers purchasing onigiri, Seven-Eleven has started selling soba-meshi omusubi, which are onigiri made with rice and noodles, while FamilyMart and Lawson have increased their onigiri varieties that do not use nori.

Omusubi Gonbei, a chain store that specializes in selling onigiri, also raised the prices of its Kishu Nankoume, which is onigiri with umeboshi pickled plum, and its Japanese-style Tuna from ¥160 to ¥200 in 2024 and 2025.

Omusubi Gonbei only uses domestic nori for its onigiri due to its color, flavor and crispy texture.

“Costs for ingredients have been gradually rising over the past few years,” said an official of Iwai Corp., a Tokyo-based company that operates the chain. “We worry about consumers drifting away from onigiri.”