Biodiversity

Number of Alien Species, by Group, in Coastal B.C..

Coastal British Columbia No. of established introductions Vertebrates   Freshwater Fish 12 Amphibians 2 Reptiles 2 Birds 14 Mammals 11 Total Vertebrates 41   Vascular Plants   Species occurring frequently 406 Species occurring rarely 223 Total Vascular Plants 629

Strait of Georgia (marine & estuary ecosystems only) No. of recorded introductions Seaweed 5 Plants 18 Hydroids, Anemones (Cnidaria) 2 Worms (Polychaeta) 7 Snails, Slugs (Gastropoda) 8 Shellfish (Bivalvia) 11 Amphipods, Isopods (Crustacea) 6 Sea squirts (Tunicata) 4 Sponges (Porifera) 2 Finfish 5 Birds 2 Mammals 1 Other (Kamptozoa, Foraminifera, Platyhelminthes) 2 Total Species 73

Plants are the most common group of alien species in coastal British Columbia.

Alien species (also known as exotic species) are organisms that have been deliberately or accidentally introduced from elsewhere. About 10% of all alien species become invasive, often resulting in high economic and environmental costs.

In coastal B.C.:

• The most common alien species are plants. About 65% of them are widely established. Some deliberately introduced plants, such as purple loosestrife and cordgrasses have become severe problems. Scotch broom, which is considered one of the most destructive alien plants in Canada, was introduced as an ornamental in 1850 on southern Vancouver Island.

• At least 35 of the 41 alien vertebrates were likely released intentionally. These include animals introduced for hunting and fishing, and those released from zoos or by pet-owners.

• Marine invertebrates account for 58% of the alien species in the Strait of Georgia. These include commercially valuable shellfish.

The table above does not include species native to other parts of B.C. that have been moved to new areas. Such movement of animals has caused severe problems in the Queen Charlotte Islands where raccoons and Sitka black-tailed deer from the mainland have been intentionally released.

For detailed information, including graph data, see In-Depth report [pdf].

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