The lack of oxygen created by environmental conditions, such as a red tide, is usually the cause when a massive fish-kill occurs in our oceans. But when hundreds of thousands of dead fish washed ashore along Cornwall in England, Mother Nature was not the culprit this time, humans were.

On Sunday, for the second time in a month, dead fish were seen littered along the beach as far as the eye could see at Marazion at St. Michael's Mount.

"The first thing I came across was a dolphin already decomposing and as I approached the shoreline, I was astonished," beach-goer Katrina Slack told the Plymouth Herald. "It was almost as if the waves were made up of thousands of shimmering fish.

“The closer I got I realized the beach was just covered in dead fish and more and more were coming in with every wave. It was a horrible but breathtaking scene."

Speculation for the fish-kill centered on bad weather, attempts by the fish to escape large predators and trawlers dumping the fish because they exceeded their quotas.

As it turned out, the culprit was a trawler, but it had nothing to do with its quota.

Gus Caslake, the chairman of the Cornish Sardine Management Association, told The Guardian that one of the member vessels was forced to release large numbers of sardines after it caught too many to safely pull aboard.

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Caslake said the trawler had been following schools of fish that were closer to shore than normal this winter.

Simon Cadman, an enforcement officer for the Cornwall Inshore Fisheries and Conservation Authority, said several fishing boats were operating in the area, adding that both fish-kills were "likely" caused by the fishermen.

The proper authorities are investigating both incidents.

"If they are discarding that amount of sardines then [the Marine Management Organization] should be looking into that, because that is a ridiculous amount to be throwing back into the sea," Debbie Crockard, a Marine Conservation Society's fisheries policy officer, told The Guardian.

"If this is happening on a regular basis then the law should be looked at."

One commenter summed up the public's distaste over the incidents, writing in a comment on The Guardian post, "Sometimes it’s embarrassing being human."