Thousands of menhaden fish washed up dead in a New Jersey river over the weekend.
In the Shrewsbury River, the small fish completely covered the surface of the water after running out of oxygen.
Experts say that often, predatory fish will chase schools of prey fish into shallow waters, where the large quantity of fish quickly dissolves the oxygen in the water — and results in these mass deaths.
Low oxygen levels in the water following the incident, tested by officials, confirmed this narrative.
Menhaden fish are important in the production of fish oil. They’re also an important prey species for many fish in the Atlantic, in part due to their abundance.