Lack of oxygen in water kills thousands of fish in P.E.I.
Wednesday, August 3, 2016, 2:05 PM - Thousands of dead fish in the Southwest River of P.E.I. are the result of a lack of oxygen in the water, according to officials.
Wade MacKinnon, a manager with the province's Public Safety and Justice department, confirmed the cause of the fish kill to CBC News, saying "The Southwest River was anoxic at the time," and confirming that live trout found at the head of the river meant this was "not a pesticide related event."
While it's not possible to estimate exactly how many fish died in the tidal portion of the river, MacKinnon told CBC News the person who reported the incident said there were thousands of dead fish.
The P.E.I. Department of Agriculture and Forestry cites both natural and human causes for fish kills from oxygen-depleted (anoxic) waters. At some times of the year, wind and churning waters can mix oxygen-poor water up from the bottom of coastal ponds, decreasing the oxygenation of the surface water as a result.
Fertilizer and septic run off from farming operations is the chief human cause of oxygen-poor surface water, as nutrient overloading makes fertile territory for algae and sea lettuce growth. As the algae blooms and dies, it consumes the available oxygen in the water, making a dead zone for fish and other marine life.
CBC News reports such a die off in the Southwest River isn't uncommon, with reports coming in every year since 2007.
Fish kill map courtesy P.E.I. Department of Communities, Land and Environment.
CBC News reports there have been 16 such anoxic events this year in P.E.I., affecting 15 waterways and one freshwater pond.
The province has required mandatory 15 m buffer zones along all Island streams to prevent run off chemicals and soil from spilling into waterways during heavy rains for several years.