As many as 20,000 dead fish and other sea animals have washed on the western shores of Nova Scotia, leaving Canadian authorities worried about the cause of such a massive fish kill.

Officials from the Department of Fisheries and Oceans (DFO) investigated reports on Wednesday, Dec. 28, of thousands of dead sea creatures ending up on the beaches of Annapolis and Digby counties.

Among those that washed up along the coast were carcasses of crabs, lobsters, scallops, starfish, and various species of fish.

Authorities have begun testing for low oxygen levels or potential pesticide contamination in the water. They've also issued a warning to the public to buy their seafood only from authorized vendors as a precaution.

In a post on Twitter, the DFO advised residents of affected areas not to collect any of the dead fish and sea creatures that wash up on the shore.

A Series Of Marine Animal Die-offs

While authorities have yet to determine the exact cause of the fish kill, the event appears to be connected to a recent spate of marine animal die-offs along the Bay of Fundy in Nova Scotia over the past few weeks.

Earlier this month, thousands of herring were found dead on shores along the Annapolis Basin. This came just a few weeks after masses of the same fish species ended up on St. Marys Bay.

The latest die-offs were discovered on the beach near Savary Provincial Park in Plympton on Boxing Day, Dec. 26. Residents found thousands of crabs, lobster, bar clams, scallops, starfish, herring carcasses lining up the coast.

DFO regional director general Doug Wentzell said they have asked the help of the Canadian Food Inspection Agency and Environment as well as the Climate Change Canada to get to the bottom of the mysterious fish kills.

The agencies, however, haven't determined the cause of the mass die-offs as of yet. Wentzell said they weren't able to detect any evidence of infections or deadly agents in the water.

The DFO are now planning to test some of the other species that have turned up dead on the shores in recent weeks.

Tests on possible viral outbreaks in the water are still ongoing. These could take a longer time to finish since it involves the cultivation of specimens in the laboratory.

The U.S. Geological Survey (USGS) said a number of factors could trigger a mass fish kill. One of the most common causes is low levels of dissolved oxygen in the water.

This is believed to be the cause of similar mass die-offs of fish in the Indian River Lagoon in Florida and the Hongcheng Lake in China.