Sado Wildlife in Focus | The Great Cormorant: Master Fisher Once Pushed to the Brink

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In his 25th essay on Sado Island wildlife, photojournalist Fumie Oyama turns his attention to the great cormorant.

Long criticized for its droppings yet admired as a skilled hunter, the bird carries a complex reputation. Oyama's lens offers a quiet look at the life behind the label.

In recent years, the great cormorant has gained a reputation as a nuisance, blamed for its mess and raucous calls. Yet not long ago, it was on the verge of extinction. Today, along the shores of Sado, its presence feels almost routine. This time, I chose to focus on this often-overlooked bird.

Masters of the Hunt

With a swift dive, the cormorant plunges into the water. Moments later, it bursts back to the surface in a spray — its catch already swallowed. Some birds remain submerged for over a minute.

The great cormorant is a fisherman of the skies. Nearly its entire diet consists of fish. A skilled diver that mostly hunts in the early morning, it can reach depths of one to nine meters. With a heavy appetite, it's said to consume around 262 grams of fish per kilogram of body weight.

These birds tend to move in groups. At times, they line up neatly along power lines like oversized sparrows, resting their wings. The wires sag under their collective weight. Watching them, I couldn't help but wonder — will the lines hold?

Once at the Brink of Extinction

The great cormorant belongs to the cormorant family within the order Pelecaniformes. Found across most of the world — Europe, Asia, Africa, Australia, and Oceania — it inhabits every continent except South America. Of the roughly 40 cormorant species worldwide, four are found in Japan.

It closely resembles the Japanese cormorant (umiu), though the umiu is slightly larger. One subtle difference lies in the beak: the umiu's forms a sharp triangle at the mouth's corner, while the great cormorant's does not. A white patch on the cheek that runs straight behind the eye also helps distinguish the two (as seen in the top photo).

According to Japan's Ministry of the Environment, great cormorants were once widespread across the country. But beginning in the 1960s, their numbers declined sharply. River development, land reclamation, and pollution from substances like dioxins took a toll. Colonies vanished. An estimated 7,000 birds once lived in the Kanto region alone. By 1971, the national count had dropped to just 3,000 — low enough to qualify for endangered status in Japan's Red Data Book.

From the 1980s onward, however, stricter chemical regulations and improved water quality led to a slow recovery. Colonies gradually returned and spread across Japan. Today, their presence is nearly too visible — droppings that damage trees and loud calls that draw complaints have once again cast the bird in an unfavorable light.

Now Part of the Everyday Landscape

Masaoki Tsuchiya, head of the Sado branch of the Wild Bird Society of Japan, notes that cormorants have only become a familiar sight on the island in the past decade. Today, an estimated 2,000 birds inhabit Lake Kamo, Niigata Prefecture's largest lake, spanning roughly five square kilometers.

On Japan's mainland, cormorants have become a serious threat to river fisheries, particularly due to the damage they cause to ayu (sweetfish) stocks. For many fishermen, it has become a critical issue. Lake Kamo, by contrast, is home to a different kind of fishery—one focused on oysters, clams, and sea cucumbers—and has reported no such damage so far.

"For now, we haven't seen any problems," says Tsuchiya. "But with numbers on the rise, it's important to keep a close watch."

Cormorants also occupy a celebrated place in Japan's cultural heritage. Each summer, the ancient tradition of cormorant fishing on the Nagara River in Gifu Prefecture draws crowds with its flickering torchlight and rhythmic coordination. Handlers guide the birds to catch fish and then retrieve the still-whole catch from their throats. Though once performed with great cormorants, the practice now uses the Japanese cormorant (umiu). With a history stretching back over 1,300 years, this fishing method is officially recognized as an Important Intangible Folk Cultural Property.

Branded a nuisance for its droppings and long compelled to surrender its catch to humans, the great cormorant might well be called a bird of misfortune. Fortunately, here on Sado, it has been spared serious conflict with people.

There's something quietly endearing about a cormorant lingering by the riverbank, wings outstretched in the sun after a dive. I can't help but hope we'll continue to look after them with care.

This report was first published on Japan 2 Earth, a JAPAN Forward website featuring Japan's SDGs initiatives. 

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Author: Fumie Oyama

Fumie Oyama is a two-time winner of the Japan Newspaper Publishers & Editors Association Award as a photographer for The Sankei Shimbun. After covering the reintroduction of the crested ibis to the wild for 11 years, Oyama left the company in 2020 to move to Sado Island. There, he continues to photograph the ibis and other wildlife while engaging in farming. He currently promotes the charms of Sado Island as a photojournalist. Follow Fumie Oyama on Instagram.

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