Hundreds of dead fish have washed up on the shores of the Ottawa River, sparking an investigation by the province and warnings from area health officials.

"I've never seen this kind of kill," said Pat Tait, who has lived on the riverfront near Fitzroy Harbour, just west of Ottawa, for the past 22 years.

Some of the hundreds of dead fish that have washed up on the shores of the Ottawa River.
(CBC)

Last week, dozens of dead catfish, bass and even turtles washed up along the shore of her property. On Saturday alone, they cleaned up 30 dead fish from the 30-metre stretch of beach near their home.

Most of the dead fish are catfish, but there have also been reports of walleye, perch and sunfish.

Lack of oxygen possible cause of death

'I've never seen this kind of kill,' said Pat Tait, who has lived in the Fitzroy Harbour area for 22 years.
(CBC)

Government officials said it's possible the fish died from natural causes relating to temperature and oxygen levels.

An investigation by the Ministry of Natural Resources and the Ministry of the Environment is underway, with the focus on a 25-kilometre stretch of river between Braeside and the Chats Falls Dam.

"Just because of the numbers we're seeing, that's why we're working with the Ministry of the Environment to undertake some additional investigation," said Paul Moreau, who manages the natural resources office in Pembroke.

He said the last time he saw anything like this was on the Rideau River, when several dozen fish died from lack of oxygen.

Environmentalist Meredith Brown refuses to accept that theory, saying last year the river had high water temperatures and low water levels without this number of fish killed.

Avoid using water, swimming: health officials

Brown, who is the executive director for the Ottawa Riverkeeper citizens group, believes it's caused by pollution or perhaps some kind of virus attacking bottom-feeding fish.

She's heard from about 60 worried residents who reported dead fish along a nearly 100-kilometre stretch of the river west of Ottawa from Fitzroy Harbour to Pembroke, and estimates the number killed may be well over 1,000.
 
Until more is known, the Renfrew County District Health Unit is advising residents to avoid using the water and swimming in affected areas.

Government field staff have collected dead fish and sent them to the University of Guelph for testing. Results are expected to be available later in the week.