What Ontario is doing

To prevent these unwanted invaders from coming into the province or spreading further, Ontario has regulated all species in the genus Pacifastacus as prohibited invasive species under the Invasive Species Act. This includes:

  • signal crayfish (and its subspecies)
  • shasta crayfish
  • pilose crayfish
  • snake river pilose crayfish

Learn about the Invasive Species Act and regulations.

Background

Pacifastacus is a genus (closely related group) of crayfish that live in a variety of freshwater environments.

Species like the signal crayfish (Pacifastacus leniusculus) have caused significant disruption in non-native habitats due to their competitive nature and rapid reproduction rates.

Species in the Pacifastacus genus include:

  • signal crayfish (Pacifastacus leniusculus) including 3 subspecies:  
    • Pacifastacus leniusculus leniusculus
    • Pacifastacus leniusculus trowbridgii
    • Pacifastacus leniusculus klamathensis 
  • shasta crayfish (Pacifastacus fortis) 
  • pilose crayfish (Pacifastacus gambelii) 
  • snake river pilose crayfish (Pacifastacus connectens)   

Although no longer allowed in Ontario, species in the genus Pacifastacus may be available for sale online in other jurisdictions where they are sold for food and aquarium use.

The signal crayfish is common in aquaculture, where it is farmed for human consumption. Live signal crayfish are available for sale in the United States and may be intentionally or accidentally released into natural environments.

Pacifastacus species may also be unlawfully used as bait by anglers, leading to accidental releases.

Range

Species in the Pacifastacus genus are native to the Western United States and British Columbia.

They have been introduced widely beyond their native range, with species like the signal crayfish spreading through parts of Europe and Japan.

Pacifastacus species are not known to exist in the Great Lakes Basin or to occur in Ontario waters.

View a distribution map of Pacifasticus species.

Impacts of Pacifastacus species

Species within the Pacifastacus genus, particularly the signal crayfish, can severely alter local ecosystems and reduce biodiversity by:

  • competing with native species for food and space
  • burrowing behaviour, causing bank erosion and reducing water quality, leading to habitat degradation
  • carrying pathogens which may spread to native species

How to identify Pacifastacus species

Pacifastacus species, like the signal crayfish, are usually characterized by their robust claws and the lack of a rostrum (the beak-like structure) between the eyes.

Their body colour can vary, often displaying a reddish-brown hue with distinctive white or bluish patches on their claws.

What you need to know

  • Learn how to identify species in the Pacifastacus genus and how to prevent the introduction or spread of these crayfish to local waterways.
  • It is illegal to import, deposit, release, possess, transport, propagate, buy, sell or trade species in the Pacifastacus genus in Ontario. Only signal crayfish (Pacifastacus leniusculus) which are dead and prepared for human consumption may be imported, transported, bought or sold in Ontario.
  • Never buy or use Pacifastacus species for an aquarium, bait or any other purpose.
  • If you possessed crayfish in the Pacifastacus genus on January 1, 2024, the date the regulation came into force, you may continue to possess and transport them until January 1, 2026. This transition period provides time for you to become aware of the rules and dispose of the crayfish. Before January 1, 2026, you must kill the crayfish and dispose of it in a way that ensures it does not spread (for example, by freezing them and placing into the garbage).
  • If you are in possession of a species in the Pacifastacus genus and would like to learn more about what you need to do, email us at species@ontario.ca.
  • Never release any live organisms into Ontario waterbodies. 

Reporting illegal activity

If you have any information about the illegal importation, distribution or sale of Pacifastacus species, report it immediately to either:

If you’ve seen a Pacifasticus species or another invasive species in the wild: