Japanese restaurant owners in Hong Kong are grappling with a looming ban on seafood imports from 10 Japanese prefectures because of Tokyo's plan to release treated water from the crippled Fukushima plant into the sea from Aug. 24.

Japan gave the date on Tuesday for discharging the wastewater after first announcing the move in July. Approved by the U.N. nuclear watchdog, Japan's plan has faced opposition at home and abroad over concerns of food safety. The country says releases will be safe and meet global standards.

Hong Kong is Japan's second largest market, after mainland China, for agricultural and fisheries exports. Japanese restaurants are popular in the special administrative region and Japan is a favourite holiday destination for many residents.

Although the details of Hong Kong's ban remains unclear, Halry Yu, 42, owner of Japanese restaurant Hassun, said more than 90% of seafood sent to Hong Kong is gathered in Tokyo.

“If they ban imports that come via Tokyo, I think all sushi restaurants in Hong Kong will be in trouble. There are some seafood supplies from Osaka, but variety is limited.”

Yu expects a loss of up to 40% for his restaurant from the ban and said he would try to salvage business by adding more meat to the menu.

"Meat will become the main theme of the menu. We will start putting barbecued skewers and fried food on our menu that we never had before, to keep the operation running," Yu said. Hong Kong said the ban would apply to imported aquatic products from Tokyo, Fukushima, Chiba, Tochigi, Ibaraki, Gunma, Miyagi, Niigata, Nagano and Saitama.

It includes live, frozen, refrigerated, dried aquatic products, including sea salt and seaweed.

Many Hong Kong customers dining in Japanese restaurants did not know about the ban.

Advertising executive Hilda Lee, 30, said she enjoys eating Japanese seafood, and dines at Japanese restaurants two to three times each month.

"I am a bit worried. But I will choose to still eat it. The Hong Kong government should have very strict control over the imports of seafood," Lee said. "They will conduct a lot of testing and ban those deemed problematic."

Japan has asked Hong Kong officials not to tighten restrictions on food imports. In 2022, Japan exported 75.5 billion yen ($536 million) of fishery products to Hong Kong, according to government statistics.

Jim Smith, professor of environmental science at the University of Portsmouth, said controlled waste release from nuclear sites is common around the world and there had not been any significant impacts on people or the environment.

"The science has been misunderstood and there's been a very effective lobbying campaign against this release by anti-nuclear groups and also in some countries ... there's been political backlash," Smith said.

Some customers remained cautious. Dino Leung, 30, a lifeguard who was eating at a Japanese restaurant in Hong Kong's Wan Chai district, said he would eat other cuisines instead.

"I'm afraid," Leung said. "I will try to consume less, but Japanese food is really good." (Reporting by Edmond Ng and Joyce Zhou; writing by Farah Master; editing by Gerry Doyle)