The Mystery of Fish Deaths in a Foul Chartreuse Sea

This story originally was watching hakai and is part of climate desk Cooperation.

Dead fish were everywhere, covering the beach near town and stretching to the surrounding coast. The sheer scale of the October 2021 species extinction, when hundreds if not thousands of herring washed up, stuck in the minds of residents of Kotzebue, Alaska. Fish were “literally all over the beaches,” says Bob Schaeffer, a fisherman and elder of the Qikiqtaġruŋmiut tribe.

Despite the dramatic deaths, there was no identifiable culprit. “We have no idea what caused it,” says Alex Whiting, the environmental program director for the Native Village of Kotzebue. He wonders if the die-off was a symptom of a problem he’s been eyeing for 15 years: blooms of toxic cyanobacteria, sometimes called blue-green algae, that are becoming increasingly visible in the waters around this remote Alaskan town.

Kotzebue is located about 40 kilometers north of the Arctic Circle on the west coast of Alaska. Before the Russian explorer Otto von Kotzebue gave the place his name in the 18th century, the region was called Qikiqtaġruk, which means “place that is almost an island”. The 2 km long settlement is bordered on one side by the Kotzebue Sound, a branch of the Chukchi Sea, and on the other side by a lagoon. Airplanes, boats and four-wheelers are the main means of transport. The only road out of town just goes around the lagoon before heading back in.

Downtown, the Alaska Commercial Company sells groceries popular in the lower 48 — from cereal to apples to two-bite brownies — but for many urbanites, the real grocery store is the ocean. Alaska Natives, who make up about three-quarters of Kotzebue’s population, pull hundreds of pounds of food from the sea every year.

“We’re sea people,” Schaeffer tells me. The two of us are crammed into the tiny cabin of Schaeffer’s fishing boat in the balmy hours of a drizzly September 2022 morning. We’re heading toward a water monitoring device that’s been anchored in Kotzebue Sound all summer. At the bow, Ajit Subramaniam, a microbial oceanographer from Columbia University, New York, Whiting and Schaeffer’s son Vince have their noses tucked into upturned collars to protect themselves from the cold rain. We’re all here for a summer to gather information about cyanobacteria that could be poisoning the fish that Schaeffer and many others depend on.

Huge colonies of Algae are nothing new and are often useful. In spring, for example, increased light and nutrient levels cause phytoplankton to bloom, creating a microbial soup that feeds fish and invertebrates. But unlike many other types of algae, cyanobacteria can be dangerous. Some species can produce cyanotoxins that cause liver or neurological damage and possibly even cancer in humans and other animals.

Many communities are infested with cyanobacteria. Although many cyanobacteria can survive in the marine environment, freshwater blooms tend to attract more attention, and their effects can spread to brackish water environments as streams and rivers carry them out to sea. In East Africa, for example, flowers in Lake Victoria are held responsible for massive fish deaths. People can suffer too: in 1996, in one extreme case, 26 patients died after treatment at a Brazilian hemodialysis center, and an investigation found cyanotoxins in the clinic’s water supply. Fever, headache or vomiting occur more frequently in exposed persons.

Zack Zwiezen

Zack Zwiezen is a USTimesPost U.S. News Reporter based in London. His focus is on U.S. politics and the environment. He has covered climate change extensively, as well as healthcare and crime. Zack Zwiezen joined USTimesPost in 2023 from the Daily Express and previously worked for Chemist and Druggist and the Jewish Chronicle. He is a graduate of Cambridge University. Languages: English. You can get in touch with me by emailing

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