Blue-green algae and botulism threaten waterfowl on Alberta lakes

Government of Alberta Sustainable Resource Development information bulletin

Blue-green algae blooms and avian botulism in lakes across the province may lead to higher-than-normal bird mortalities. These outbreaks are naturally occurring summer events in many Alberta ecosystems.

Increased rainfall in June and July has raised the risk of naturally occurring botulism outbreaks in some lakes. Warmer temperatures in August may also lead to blue-green algae blooms. Toxins from the botulism bacteria and the algae can be taken in by birds, particularly waterfowl, and may result in the bird dying. Bird deaths due to avian botulism have already been seen on Utikuma Lake, north of Lesser Slave Lake, and Pakowki Lake, south of Medicine Hat. Bird deaths due to these naturally occurring conditions typically start in mid-July, increase through August and decline in September with the cooler days and colder nights.

The bird carcasses do not pose a health risk to humans, but people are reminded to leave carcasses where they occur and allow nature to take its course. The Alberta government monitors blue-green algae blooms and will inform the public if toxins in the water pose a human health risk.

An extensive research project conducted in the 1990s across Alberta, Saskatchewan and Manitoba concluded that management agencies could not effectively limit natural mortality on most large lakes experiencing avian botulism and blue-green algae outbreaks. On some lakes with low avian mortality or specific environmental conditions, clean-up of bird carcasses can have a positive effect. The Alberta government will monitor the situation and take steps where they are warranted.

For more information on botulism and blue-green algae blooms, please visit www.srd.alberta.ca