The goal of conservation breeding is to breed animals in controlled environments for the purpose of releasing them back into the wild. When it comes to breeding animals in captivity, there are usually difficulties and issues. These challenges can be the result of many factors, such as lack of knowledge of their breeding behaviour, enclosure requirements, and special dietary needs.

Solving the conservation breeding issues  are critical, especially when dealing with species that are not commonly bred in captivity, such as endangered amphibians. Amphibians in captivity can face many reproductive dysfunctions. These dysfunctions in frogs and toads depend on multiple factors, including gamete (sperm and egg) quality in both sexes, genetics, husbandry and missing environmental stimuli that trigger reproduction. Either alone or in combination, these are the root causes often cited for the total or partial inhibition of reproduction currently observed in the majority of captive amphibian populations. For this reason, much research is required to determine and fix these dysfunctions.

 

WPC’s breeding program for Canada’s most endangered amphibian, the Oregon spotted frog (Rana pretiosa), OSF for short, certainly presents its challenges. Fortunately, with the help of our partners at Toronto Zoo, we are working to better understand and solve these challenges. Part of this project is analyzing OSF’s sperm quality and factors that are affecting its quality.

The key question that might come to mind is – how do we collect sperm from a frog?

Well, it is an interesting process. Firstly, most frogs are external fertilizers; hence they do not have an external organ dedicated to breeding. Secondly, frogs usually release sperm while they urinate, so in order to collect sperm, we need to gather a sample of the frog’s urine. Usually, biologists collect urine with a pipet from outside the cloaca or in our case, we insert catheters and collect urine directly from the cloaca. These methods may differ from one species to another.

However in OSF sperm is not present in the urine when collected by this means. To make sure we have enough sperm for analysis, we use hormones that trigger the frogs to release sperm. The two hormones biologists mostly use in breeding programs are Human Chorionic Gonadotropin (HCG) and luteinizing hormone-releasing hormone (LHRH), also known as Gonadotropin-releasing hormone (GnRH). Biologists usually use either one or a combination of the two hormones. The dosage of hormones may differ between species, and for most species such as the OSF, the effect of different dosages of hormones is currently unknown.

Pourya Sardari sampling sperm from an Oregon spotted frog

This breeding season we are completing research into this process. The purpose of the current project, which is still in its early stages, is to determine what will happen to OSF’s sperm at different hormone dosages.

Conservation breeding can be quite challenging, especially with species that are not very common. Fortunately, with the help of science and technologies, we can improve the captive breeding programs’ outcomes, producing more and healthier individuals to release back into the wild.

Andrea Gielens

Lead Biologist – Fraser Valley Wetlands Recovery Program

Andrea manages WPC’s captive breeding and release programs for the Oregon spotted frog and the coastal western painted turtle. Andrea has studied at-risk reptiles and amphibians in Canada and abroad, including a term at the Durrell Wildlife Conservation Trust in Jersey. Andrea also manages the Taylor’s checkerspot butterfly recovery program in BC.

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