Skip to main content

Two male Oregon Spotted frogs mount a female frog of the same species as they engage in amplexus at the Vancouver Aquarium April 27, 2015 in Vancouver, BC. The aquarium has had success with the program and will be releasing tadpoles near Agassiz.

Jeff Vinnick/The Globe and Mail

This week, hundreds of tadpoles will be released into the Fraser River in hopes that a precious fraction of them will mature into a more stable population of Oregon spotted frogs.

The frogs once lived in the river, its streams and tributaries by the hundreds of thousands, but the species is now endangered in Canada, the likely victim of habitat loss and the invasive bullfrog, said Dennis Thoney, director of animal operations at the Vancouver Aquarium Marine Science Centre.

Because this frog spends most of its time in the water, it is particularly affected by changes in the floodplain.

Story continues below advertisement

"One of the reasons they're endangered – the main reason – is habitat change or modification involved with taking the floodplain out there in the Fraser River and changing how it flows – creating areas for agriculture, changing areas for cities, that kind of thing," Dr. Thoney said.

This is the northern edge of their range, said Christopher Stinson, curatorial assistant of the Beaty Biodiversity Museum in Vancouver.

"And it just happens to fall in the most heavily populated area of British Columbia lower mainland," he said adding that amphibians are a good indicator of ecosystem health. "They have permeable skin, so they're the first to absorb toxins. If there's a healthy amphibian population, [it] is usually indicative of a healthy ecology all around, a healthy environment."

As well, frogs are an important part of the food web, controlling insect populations and serving as food for larger carnivores, such as birds and fish, Dr. Thoney said.

To combat the rapidly declining population, the aquarium began breeding the species in captivity as part of B.C.'S Oregon Spotted Frog Recovery Team.

Between 2010 and 2014, more than 16,000 tadpoles and juvenile frogs produced in human care were released into suitable habitats to increase small existing populations in the wild.

Their efforts are paying off.

Story continues below advertisement

For the first time since the program began, the recovery team has discovered juvenile frogs in the wild, indicating the tadpoles released in recent years are growing and healthy. The juveniles were found near Chilliwack, where they are released.

"We've found metamorphs, or froglets, in the area where we introduced the tadpoles last year, so that shows that actually some of them are surviving to that size," Dr. Thoney said.

"Also, where we released some metamorphs – because we had some surplus froglets that we released – they actually produced eggs, so it looks like we're being somewhat successful in regards to this program."

Mr. Stinson said it is a positive sign that the introduction site is producing juvenile frogs and eggs.

"It is great news for the recovery of the species," he said.

Even though just half a dozen froglets were spotted, Dr. Thoney said: "If you saw half a dozen, there's a lot more out there."

Story continues below advertisement

He said that when they mate, the Oregon spotted frog's call sounds a bit like knocking on wood.

Report an error Editorial code of conduct
Comments

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

If you would like to write a letter to the editor, please forward it to letters@globeandmail.com. Readers can also interact with The Globe on Facebook and Twitter .

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

If you would like to write a letter to the editor, please forward it to letters@globeandmail.com. Readers can also interact with The Globe on Facebook and Twitter .

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff.

We aim to create a safe and valuable space for discussion and debate. That means:

  • All comments will be reviewed by one or more moderators before being posted to the site. This should only take a few moments.
  • Treat others as you wish to be treated
  • Criticize ideas, not people
  • Stay on topic
  • Avoid the use of toxic and offensive language
  • Flag bad behaviour

Comments that violate our community guidelines will be removed. Commenters who repeatedly violate community guidelines may be suspended, causing them to temporarily lose their ability to engage with comments.

Read our community guidelines here

Discussion loading ...

Due to technical reasons, we have temporarily removed commenting from our articles. We hope to have this fixed soon. Thank you for your patience. If you are looking to give feedback on our new site, please send it along to feedback@globeandmail.com. If you want to write a letter to the editor, please forward to letters@globeandmail.com.
Cannabis pro newsletter