Thousands of dead fish seen in New York canal: what killed them?

Video of thousands of dead fish clogging the waterways at Shinnecock Canal in Hampton Bays, New York, went viral earlier this week as people wondered just what did in the aquatic creatures. Now, officials have revealed that their investigation cites suffocation as the likely culprit.

According to Gizmodo and The Verge, the videos show thousands of silver bunker fish (which are also known as menhaden fish) as they struggle for survival in the canal, each one desperately trying to take one final breath in what has been called a “gruesome fishpocalypse.”

Naturally, there was some concern that the fish were done in by exposure to industrial waste, or toxic algae, or perhaps even some yet-known phenomenon linked to climate change. Fortunately, none of those were to blame, so people living nearby have no reason to fear for their health.

So why did the fish die? As the New York State Department of Environmental Conservation told CBS News and Newsday, the fish died of suffocation after they were chased into the canal waters by a school of bluefish (their natural predators) and became trapped there. The overabundance of fish in the canal waters depleted the oxygen in the water, causing them to die off.

Officials monitoring the situation, report no additional deaths

Despite the relatively mundane cause, even locals were stunned by what they saw, according to CBS News. As Valley Stream native Dennis Demarco is said in his video of the event, “even the locals have not seen anything like this before,” adding that it was an “unbelievable scene.”

Conservation Department personnel said that they were continuing to monitor the situation, but noted that “no additional fish kills” were reported after the initial incident. “Some dead bunker are floating in the Shinnecock Bay,” Erica Ringewald, the department’s media relations director, told CBS News, “but most are believed to have sunk to the bottom.”

She added that officials were working to clean up any dead fish that wash up on nearby beaches and that they were working to monitor their movement from the air. The town of Southampton and the County Department of Public Works “worked… to open and close the canal to keep the oxygen levels up while allowing some fish to escape,” Ringewald explained on Tuesday.

As Popular Science noted, this is hardly the first time a mass die-off like this has occurred. In 2014, a similar event took place in Marina de Rey, California, as thousands of anchovies died in the harbor after purportedly attempting to escape predators. Likewise, in August, roughly 4,000 dead whitefish were found floating on Montana’s Yellowstone River, said.

The August incident, however, was not the result of would-be prey swimming for their lives, the website said. Rather, it was caused by a highly-contagious parasite, Tetracalsula bryosalmonae, that can cause kidney disease in affected fish. In addition to the whitefish, the parasite killed off a large number of rainbow trout and Yellowstone cutthroat trout, the website added.


Image credit: JustineAiko