It’s that time again — for a sixth year in a row the tadpoles from the endangered Oregon spotted frog, bred on the rooftop at Vancouver Aquarium Marine Science Centre, have been released into the wild.
This year, the frogs produced 2,031 tadpoles which were released in an area near Chilliwack with the Oregon Spotted Frog Recovery Team. Though breeding these frogs is not an easy task (as they require very specific conditions), this year’s number of tadpoles is an improvement from the 600 tadpoles produced last year. The lower yield in the previous year can be attributed in part to an unusually warm winter in the Lower Mainland.
“Last year it warmed up too quickly and then all of a sudden it cooled down,” says senior aquarium biologist, Darren Smy, which is one of the reasons why the number of offspring was much lower. This year they kept the water in the frogs’ habitat one or two degrees cooler in order to prepare for another possible rapid change in temperature. A lot of hard work goes into caring for these endangered amphibians, Smy explains that they even simulate rain in their habitats when it’s raining outside which encourages the males to call.
The Oregon Spotted Frog Recovery Team releases the tadpoles in the same location every year in an separate area to wild populations in order to keep track of the growing population. Last year, the team found juvenile frogs in the wild as well as a few egg masses in that same area, which proves that the tadpoles released in recent years grew into healthy frogs and are now reproducing. This year, 10 egg masses were found at the release site. This is an encouraging discovery that shows the breeding program is having a positive impact on this endangered species.
There used to be hundreds of thousands of Oregon spotted frogs early last century throughout the Fraser Valley but their population has declined by as much as 90 per cent in B.C. This drastic decline in population is largely due to habitat destruction and the introduction of non-native invasive species such as reed canary grass and bullfrogs.
The health of Amphibian species like the Oregon spotted frog serves as a direct indicator of environmental health. They play an important role in our local ecology which is one of the reasons why the conservation of this species is crucial.
Last year we were honoured by the Associations of Zoos and Aquariums with the Edward H. Bean Award for our work with the Oregon spotted frogs. This award recognizes a truly significant captive propagation effort that effectively enhances the conservation for the species. In 2010, Vancouver Aquarium became the first aquarium in the world to breed this species and has successfully bred these animals each year since then for release of tadpoles to establish wild populations.