A small town on the eastern coast of Hokkaido has seen a proliferation of rare wild sea otters, giving it hopes of becoming a tourist hot spot at a time when the endangered marine mammal has been vanishing from Japanese aquariums.

"I would love to come here again," said Satoshi Ishizuka, 53, who was visiting Cape Kiritappu in Hamanaka from Kanagawa Prefecture, south of Tokyo, on an evening in mid-August while he excitedly watched an otter swimming with its head up duck behind some rocks.

Supplied photo taken May 31, 2020 shows wild sea otters witnessed in Hamanaka, Hokkaido. (Photo courtesy of Yoshihiro Kataoka)(Kyodo)

Sea otters can be observed year-round at the cape, even as their numbers dwindle significantly at aquariums due to international trade restrictions and aging populations.

The tourist industry is especially thrilled.

The manager of the Kawamura Ryokan inn in Hamanaka said there has been an increase in people coming with high-end cameras to photograph the otters.

Katsuya Yumoto, head of the sales management department at a travel agency in the city of Kitami in Hokkaido's Okhotsk region, said, "I would like to propose an attractive travel plan for people, such as eating oysters from Akkeshi (in the northern main island's Kushiro region) and stopping by Cape Kiritappu to see the sea otters."

Yoshihiro Kataoka, 72, who published a photobook of sea otters around the cape, speculates that sea otters in the Northern Territories -- as Japan calls four Russian-held islands off Hokkaido that Tokyo claims -- have expanded their habitat and since been witnessed in Hamanaka.

In 2017, two females and one male otter were confirmed there. With the addition of a new male, four babies had been born as of last year. Only one adult was raised, but a fifth otter was born in April this year. Breeding takes time.

"Breeding is not so easy because the pups are sometimes bitten to death by male otters that aren't their father. I hope we can increase the number of offspring somehow," said Kataoka.

Supplied photo taken Feb. 13, 2020 shows wild sea otters witnessed in Hamanaka, Hokkaido. (Photo courtesy of Yoshihiro Kataoka)(Kyodo)

Trade in wild sea otters is restricted as they have seen their populations reduced due to overhunting for their fur, making them rare in domestic aquariums.

According to the Japanese Association of Zoos and Aquariums, based in Tokyo, at their peak in 1994, there were 122 sea otters at 28 facilities around the country.

But currently, only six sea otters are being raised at four aquariums; Adventure World (Wakayama Prefecture), Marine World Uminonakamichi (Fukuoka Prefecture), Toba Aquarium (Mie Prefecture), and Suma Aqua Life Park Kobe (Hyogo Prefecture).

That could change, however, if breeding of sea otters at Cape Kiritappu begins to threaten the local fishing industry, with sea otters eating copious amounts of seafood. In that case, the otters could be captured and sent to aquariums.

Naonori Okada, secretary general of the association, gave an example of the Environment Ministry transferring captured harbor seals to various aquariums in and after 2016 due to damage to the fishing industry at Cape Erimo at the southern tip of Hokkaido.

"If there are more sea otters and they are captured, aquariums might be willing to accept them," said Okada.

While an official of the Hamanaka Fisheries Cooperative admitted to "worry" about wide-scale damage, for the time being, there has been no noticeable impact.

"We would like to explore their utilization as a tourist resource while considering their coexistence with fishermen," said a Hamanaka town official.