Superchill Kills Scores of Fish at Cooke Aquaculture

This past Tuesday the Department of Fisheries and Aquaculture released a statement stating that they suspect a superchill is responsible for killing fish at three separate Nova Scotia aquaculture sites. Mortalities have been reported at Shelburne Harbour, Jordan Bay, and Annapolis Basin.

Minister of Fisheries and Aquaculture Keith Colwell stated that a fish veterinarian has already been out to visit the Shelburne and Annapolis Basin and they will be out to visit the Jordan Bay site soon to help get to the bottom of the death of the fish species. He explained that fish health veterinarians look into fish mortalities to rule out disease.

The investigation is still ongoing, but the department has conducted a preliminary investigation and said that they believe a superchill is responsible for the death of the fish. A superchill occurs when continual cold temperatures cause the water to drop below the level that causes the blood of fish to freeze. Fish blood freezes when the temperature of the water reaches about -.7 Celsius.

The temperatures were further lowered by high tides that brought in cold water towards the end of February and start of March. The high tide causes flooding in the sea cages. This combined with low air temperatures have caused the cages of the shallow water to be filled with super chilled water.

While they may be deadly to the fish, according to the Department of Fisheries and Aquaculture conditions only occur that form a superchill every five to seven years. They also said that the deaths will not harm the environment as the fish should continue to thrive now that the harm is past.

Spokesperson for Cooke Aquaculture, Nell Halse, stated that the company is still trying to get a firm grip on the loss, but that most of the fish are still in good health and will be harvested soon.

http://www.thecoastguard.ca/News/Local/2015-03-03/article-4063974/Superchill-kills-fish-at-Cooke-Aquaculture-sites-in-Nova-Scotia/1