List of Endangered Animals in Japan: Why Are Sea Otters Endangered?

Japan stretches from north to south, allowing people to enjoy the changing seasons, from spring flowers and summer greenery to autumn leaves and snowy winter landscapes. The country is home to a diverse range of environments, including forests, satoyama (traditional rural landscapes), wetlands, and oceans, which support approximately 90,000 species of living creatures. Many of these are unique to Japan, but 3,772 species are classified as endangered. Among them are well-known animals like the sea otter and the Iriomote cat. Let's take a look at Japan's endangered species and explore the reasons behind their decline.

What Are Endangered Species?

Endangered species are those at high risk of disappearing from the Earth or those that have already gone extinct. To track the status of endangered species worldwide, the International Union for Conservation of Nature (IUCN) compiles a list known as the Red List. This list identifies wild species that are facing the threat of extinction and serves as an important indicator of their conservation status. In Japan, the Ministry of the Environment creates its own Red List, categorizing species based on their risk of extinction.

Red List Categories: Classification of Species at Risk of Extinction

*Species classified as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU) are considered endangered species.

Reference: Ministry of the Environment Red List 2020 Announcement: https://www.env.go.jp/press/107905.html)

The Red List is reviewed approximately every five years. It helps monitor the status of endangered species, prioritize conservation efforts, and raise public awareness by widely sharing information on species at risk.

Endangered Species in Japan

Japan's endangered animals are classified into eight categories, such as mammals and reptiles. Here, we introduce some species listed in the endangered categories: Critically Endangered & Endangered (CR+EN), Critically Endangered (CR), Endangered (EN), and Vulnerable (VU). This includes well-known animals like the adorable sea otter and the Iriomote cat, which is found only in Japan.

Mammals

Iriomote Cat (CR)

Habitat: Only on Iriomote Island, Yaeyama Islands, Okinawa Prefecture

Characteristics: A member of the feline family, this wild cat has a long body, a thick tail, and a spotted pattern covering its entire body. It features white lines around its eyes and rounded ears. It measures about 50–60 cm in body length and weighs around 4 kg. Unlike domestic cats, it is not afraid of water and even dives to catch fish. Its population has declined due to habitat loss caused by deforestation and development, as well as road accidents.

Sea Otter (CR)

Habitat: North Atlantic coasts; in Japan, limited to certain coastal areas of Hokkaido

Characteristics: Measuring 100–150 cm in length and weighing 22–45 kg, the sea otter is known for its fluffy fur and unique behavior of using rocks to break open shellfish. It primarily feeds on sea urchins and mollusks, often eating while floating on its back. Its habit of holding hands with other otters to avoid drifting away has made it particularly popular. However, sea otters have been heavily hunted for their fur, leading to population declines worldwide, including in Japan, where they are now listed on the Red List. They also face challenges such as marine pollution and habitat loss.

other

Dugong (CR), Japanese Sea Lion (CR), and Tsushima Leopard Cat (CR) etc.

Birds

Oriental Stork (CR)

Habitat: Mainly in Toyooka City, Hyogo Prefecture, Japan

Characteristics: Once commonly seen in rural areas across Japan, this large migratory bird stands about 120 cm tall and has a wingspan of approximately 200 cm. Its body is mostly white, with black wingtips and a long red beak. It prefers wetlands like rice paddies, where it feeds on fish and insects. One of its distinctive traits is building nests up to 2 meters in diameter on treetops.

The Oriental Stork is also famous worldwide for the legend that "storks deliver babies." This belief likely originated from their reputation for being symbols of "parenting" and "family love," as they raise their chicks together as a pair. Additionally, their preference for clean environments may have contributed to their association with bringing babies.

Due to excessive hunting, the decline of rice paddies, and pesticide use, their food sources dwindled, and the species became extinct in the wild in Japan in 1971. However, thanks to conservation efforts such as artificial breeding and reintroduction programs, wild Oriental Storks have now successfully begun breeding again, particularly in Toyooka City, Hyogo Prefecture.

Toki (CR)

Habitat: In Japan, mainly in Sado City, Niigata Prefecture

Characteristics: This bird is about 75 cm long, predominantly white, with a long beak that has a distinctive red tip. It was once widespread across Japan’s rice paddies and wetlands. However, due to overhunting for its feathers, the decline of rice paddies, and the use of pesticides, its food sources diminished. As a result, wild Japanese Crested Ibises became extinct in Japan in 1981, and with the death of the last domestic ibis in 2003, the species was considered extinct in the country. Fortunately, Japan received ibises from China and has since conducted artificial breeding and release programs. Thanks to these conservation efforts, wild populations have begun to recover, particularly in Sado City, Niigata Prefecture.

other

Rock Ptarmigan (EN), Snow Goose (CR), Okinawa Rail (CR), and Japanese Murrelet (CR), etc.

Reptiles

Miyako Grass Lizard (CR)

Habitat: Miyakojima, Ikema, Irabu, and Ogami Islands, Miyakojima City, Okinawa Prefecture

Characteristics: This species is endemic to Japan, measuring around 20–30 cm in length. It has a slender body and striking green coloration. It inhabits grasslands and forests, feeding on insects. Due to habitat destruction from development, pesticide use, predation by invasive species, and over-collection for the pet trade, sightings of this species have become increasingly rare.

Loggerhead Sea Turtle (EN)

Habitat: Along Japan’s Pacific coast

Characteristics: The loggerhead sea turtle is distinguished by its reddish-brown shell and relatively large head compared to other sea turtles. It spends most of its life in the ocean, coming ashore only to lay eggs on sandy beaches. Overhunting for food and crafts, coastal development reducing nesting sites, and marine pollution have severely impacted its survival, pushing it toward extinction.

other

Green Sea Turtle (VU), etc.

Amphibians

Japanese Giant Salamander (VU)

Habitat: Rivers in Honshu, Shikoku, and parts of Kyushu

Characteristics: This species is endemic to Japan and is one of the largest amphibians in the world. It has remained almost unchanged for 30 million years, earning it the title of a "living fossil." It can grow up to 1.5 meters long, although large individuals have become increasingly rare. It has dark brown skin with black mottling, a wide mouth, and small eyes. Nocturnal by nature, it inhabits upstream river areas. It is also known to have a lifespan similar to that of humans.

Due to river development and water pollution, its habitat has been significantly damaged, leading to a decline in its population. It was designated a Special Natural Monument of Japan in 1952, meaning that all individuals found in Japan are protected under law.

other

Abu Salamander (CR), etc.

Brackish and Freshwater Fish

Tanago (Bitterling) (EN)

Habitat: Various regions across Japan

Characteristics: Tanago is a freshwater fish native to Japan, admired for its beauty and unique reproductive behavior. Just a few decades ago, it was commonly found in rivers and lakes throughout Japan. It measures approximately 5–10 cm in length, with different species displaying variations in color and patterns. During the breeding season, males develop a vibrant coloration known as nuptial coloration. One of the most distinctive aspects of this fish is its spawning method: it lays eggs inside freshwater mussels, which provide protection from predators and a continuous supply of fresh water.

The decline of Tanago populations is attributed to habitat loss due to river modifications and agricultural development, predation by invasive species, and water pollution. Additionally, the decrease in freshwater mussels—essential for their reproduction—has further endangered many Tanago species.

Japanese Eel (EN)

Habitat: East Asia, including Japan. In Japan, it is found in rivers along the Pacific side of Honshu (west of Kanto), the Seto Inland Sea, and the western coast of Kyushu.

Characteristics: The Japanese eel can grow up to 1.3 meters long and has an elongated, slippery body. It has been a vital part of Japanese cuisine and culture for centuries, particularly associated with the custom of eating eel on "Doyo no Ushi no Hi" (the midsummer Day of the Ox).

The population decline of the Japanese eel is attributed to changes in ocean temperature and currents caused by global warming, which disrupts its migration routes. Overfishing, illegal poaching and smuggling of young eels, and habitat destruction due to dam construction and river development have also contributed to its endangered status. In 2014, the International Union for Conservation of Nature (IUCN) classified it as an endangered species (EN), and in 2013, Japan’s Ministry of the Environment also designated it as an endangered species (EN). The extinction of the Japanese eel could mean the loss of a significant aspect of Japanese culinary tradition. Protecting this species is closely linked to preserving Japan’s cultural heritage.

other

Sockeye Salmon (Himemasu) (CR), Japanese Spined Loach (Teppouo) (CR), etc.

Insects

Japanese Stag Beetle (VU)

Habitat: Deciduous forests from Hokkaido to Kyushu

Characteristics: Known as the "King of Stag Beetles" due to its majestic appearance, the Japanese Stag Beetle is one of the most popular and iconic beetles in Japan. Males can grow up to 80 mm, while females reach about 50 mm. They have a glossy black body and powerful, thick mandibles that give them a strong and imposing look. They are nocturnal and feed on the sap of trees such as sawtooth oak and konara oak.

Due to deforestation and overcollection for the pet trade, their population is declining, increasing their risk of extinction.

Giant Water Bug (VU)

Habitat: Wetlands such as rice paddies across Japan

Characteristics: Measuring about 4–7 cm in length, females are slightly larger than males. Their bodies are large, flat, and oval-shaped, with powerful forelegs adapted for capturing prey. Using their scythe-like forelegs, they hunt frogs, loaches, and other aquatic creatures. In the past, they were commonly found throughout Japan.

However, habitat destruction due to agricultural development, environmental deterioration caused by invasive species (such as American crayfish), and excessive capture for commercial purposes have led to their population decline.

other

Diving Beetle (VU) etc.

Terrestrial and Freshwater Mollusks

Mametanishi (CR)

Habitat: Honshu to Kyushu

Characteristics: A small freshwater snail endemic to Japan. The shell is about 13 mm in length and 7 mm in width, with a dull yellow-brown hue and a subtle sheen. It inhabits water bodies with minimal flow, such as spring water and subterranean streams, where it clings to aquatic plants or gravel. It is highly sensitive to environmental changes and feeds on microalgae.

The decline of this species is primarily due to river modifications, agricultural land development, and water pollution from herbicides and household wastewater.

Japanese Hard Clam (VU)

Habitat: Coastal areas of Japan (notable locations: Ise Bay, Seto Inland Sea, Kujukuri Beach in Chiba Prefecture)

Characteristics: A bivalve shellfish with a rounded triangular shape, usually white or chestnut brown. It thrives in shallow waters and sandy-muddy seabeds where freshwater flows in. This clam is deeply embedded in Japanese culinary traditions, especially during the Hinamatsuri (Doll Festival), where it is used in festive soups. Additionally, it was historically used in the Heian-period game "Kai-awase," a shell-matching game. Due to the perfect fit of its two shells, it has been regarded as a symbol of marital harmony for centuries.

However, land reclamation, degradation of tidal flats, and water pollution have caused a dramatic decline in its population.

other

Karasugai (EN), etc.

Other Invertebrates

Horseshoe Crab (CR+EN)

Habitat: Coastal regions of East Asia, including Japan (notably Seto Inland Sea and northern Kyushu)

Characteristics: With a body length of about 60 cm, it has a hard, helmet-like shell and a sharp, sword-like tail. Horseshoe crabs have existed for over 200 million years, predating the dinosaurs, earning them the title of "living fossils." Despite the "crab" in its name, it is not actually a crab but belongs to the same arthropod group as dragonflies and cicadas. Recent studies even suggest a closer relation to spiders.

Their shallow coastal habitats have been destroyed due to land reclamation for industrial and agricultural purposes, leading to a decline in their numbers.

Japanese Freshwater Crayfish (VU)

Habitat: Streams and spring-fed water sources in Hokkaido, Aomori, Iwate, and Akita Prefectures

Characteristics: Measuring about 5–6 cm in length, it has a brownish body and is smaller than the invasive American crayfish. As a nocturnal scavenger, it feeds on aquatic plants, fallen leaves, and the remains of small animals. Because it thrives only in clean, cold waters below 13–20°C, its presence was once considered an indicator of high water quality.

The decline in population is attributed to rising water temperatures due to climate change, pollution, and habitat destruction. Additionally, invasive species have outcompeted it, leading to further habitat loss.

other

Coconut Crab (VU), etc.

Protecting Endangered Species

This article highlights the current situation of endangered species in Japan and the challenges they face. The causes of their decline vary, including climate change, deforestation, land development, pollution, and the impact of invasive species. No single factor is solely responsible for the crisis.

To ensure biodiversity for future generations, why not start taking action today?

Raising Awareness

• Stay informed about environmental issues and endangered species through news, books, and online sources. Observe nature and develop an appreciation for the wildlife around you.

• Participate in conservation events organized by environmental groups.

What You Can Do in Daily Life

• Choose products made from recycled or environmentally friendly materials.

• Save electricity and water to reduce unnecessary consumption.
• Recycle actively and take your trash home when visiting nature.
• Buy locally sourced food to reduce carbon emissions from transportation and minimize food waste.
• Avoid using plastic bags and bottles—carry reusable bags and bottles instead.
• Never release pets or non-native species into the wild.
• Do not touch or feed wild animals.
• Use public transportation or bicycles instead of cars when possible.