Biologists at Vancouver Aquarium try to boost wild population of endangered frogs

Some of the to-be-released Northern leopard frog tadpoles swim in a tank inside the lab at Vancouver Aquarium in Vancouver, Canada, June 18, 2019. Over 1,000 Northern leopard frog tadpoles raised by biologists at Vancouver Aquarium are prepared to be released to the nature in an effort to boost the wild population of the Northern leopard frog. (Xinhua/Liang Sen)