Tuesday, June 5, 2012

Environment News

Bullish on Bullfrogs

Invasive species hard to control

Sourced by Voice staff/Photo S. Price

ntroduced Bullfrogs (Rana catesbeiana) have replaced native amphibians from large areas of southeastern Vancouver Island and the lower Fraser Valley.


Bullfrogs are voracious predators that can easily eat our native frogs - the Red-legged Frog (Rana aurora) and the Pacific Chorus Frog (Pseudacris regilla). Bullfrogs are also thought to spread Batrachochytrium dendrobatidis (Bd), a newly discovered frog disease, although they themselves arenít affected.

The Bullfrog range is expanding in our area, thanks mainly to humans, who are not only moving them around but are also creating habitats that are very suitable for Bullfrogs.


Bullfrogs have been widely introduced around the world as the primary species for commercial frog-leg farming. Frog farms were promoted in BC after the Second World War as an employment venture for returning veterans. These ventures were unprofitable and the bullfrogs were released into the wild. They were also imported by aquatic garden supply companies for stocking backyard ponds. They spread from the original release sites and have now established populations on Vancouver Island between Victoria and Campbell River as well as on some Gulf Islands and the Lower Mainland.

Bullfrogs can prey on and out-compete native frogs. They are also thought to spread a newly discovered frog disease, called Bd or chytrid fungus, although they themselves not affected by this disease. It is very important that we try to prevent the further range expansion of Bullfrogs on Vancouver Island in order to preserve native biodiversity in our wetlands. If you see or hear this frog please contact us at bcfrogwatch@victoria1.gov.bc.ca.


About the Bullfrog Project

The Bullfrog Project is the product of years of research by Dr. Purnima Govindarajulu at the University of Victoria. It is a partnership between the School of Environmental Studies at the University of Victoria and the Centre for Coastal Health Nanaimo. Funding for this project was provided in part by the Invasive Alien Species Partnership Program, a Government of Canada initiative. The Project is focused on public outreach, site monitoring and steward training to prevent Bullfrog range expansion. The Project is also researching methods to mitigate the impact of existing Bullfrog populations by restoring habitats to enable the co-existence of native frog populations.

From May to August, Bullfrog Project coordinators will be traveling throughout the Vancouver Island area giving presentations to raise public awareness and conducting workshops to train wetland stewards. If you know of a group that would be interested in a presentation, please contact us at bcfrogwatch@victoria1.gov.bc.ca.



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