Problems with Buying Frogs
and Tadpoles for Wild Release
Watching frogs metamorphose from tadpoles to frogs is an enriching experience for children of any age. Many biological supply companies and pet stores sell frog eggs and tadpoles just for this purpose. However, it is important to understand that releasing tadpoles and frogs purchased online, in a catalogue or in a pet store is a bad idea.
Several frog species available for purchase are not native to Maryland. This includes the popular grass frogs which are typically found in the southern United States. While it is likely that many of these species may not survive in Maryland, those that do may outcompete our native frog species for limited resources (like food) or, even worse, may harbor diseases. For a list of frogs native to Maryland, please check out our frog page.
Purchasing frog species native to Maryland can also cause several problems. For one, any purchased animal can harbor a potentially hazardous disease. In addition, while the bull frog may be native, the genetics makeup of bull frogs which are found in pet stores can be very different from that of bull frogs found around Maryland.
Releasing any frogs into the wild that have been purchased also comes with the possibility of introducing emerging diseases like chytridiomycosis or ranavirus.
Chytridiomycosis is an infectious disease that affects amphibians. It is caused by a chytrid fungus known as Batrachochytrium dendrobatidis. Chytridiomycosis has been linked to dramatic declines in populations of amphibians in the western United States, Central America and South America. It is believed that 30% of global amphibian populations have been affected by the chytrid fungus, with some populations experiencing 100% mortality.
The oldest reports of chytrid fungus have been linked to the African clawed frog, a popular frog found in the international pet trade. It is believed that African clawed frogs as well as other amphibians exported for the pet and scientific trades are responsible for the global transport of chytrid fungus. Many tadpoles sold by biological companies have been found to be infected by the chytrid fungus. So, if any infected tadpoles are released into the wild, then they can spread the disease.
Ranavirus is another serious infectious disease that affects both amphibian and reptile species. Ranaviral disease, infection and mortality have now been reported on every continent except Africa. In Maryland, larval wood frogs, spotted salamanders and marbled salamanders have experienced the most mortality due to ranavirus. In addition, the eastern box turtle has also been found to be affected by this virus. Similar to the chytrid fungus, ranaviruses have been spread by the movement of infected animals through the trade in amphibians for pets, food and research.
Alternatives to Purchasing Tadpoles
One alternative to purchasing tadpoles online is to collect some of your own. Legally, you are allowed to collect and possess 25 tadpoles of any one species at one time. Look for tadpoles in a local stormwater management pond or other small waterbody. Be sure to note where you found the tadpoles, so you can release them back to the same site once they have metamorphosed.
To limit the spread of disease, always remember to sterilize aquaria and dipnets prior to catching tadpoles. This can be accomplished by soaking nets and aquaria in a 10% bleach solution for at least 10 minutes. After sterilizing materials, rinse equipment with clean water. In addition, wash hands thoroughly before and after handling any amphibians or reptile. This precaution helps keep your germs from being passed to the animal or germs from an animal you may have previously held.
While the tadpoles and frogs remain in your care, be sure to isolate them from other animals, particularly any other amphibians or reptiles. Be sure that the animals are healthy and disease-free before releasing them back into the wild.
By collecting your own tadpoles from a local source, you can still enjoy the educational aspects of watching the miracle of metamorphic animals while also protecting local populations from the spread of disease. Additionally, the educational experience can be greatly enhanced by allowing the students to collect and release tadpoles and frogs.
Cope's gray treefrog tadpole by: John White
Tadpole with ranavirus by: Scott Farnsworth
Box turtle with ranavirus by: Scott Farnsworth|
Bullfrog by: John White
- Discover Maryland's Herps
- Maryland Herp History
- Maryland Herp Checklist
- Survey Techniques, Collecting Ethics, Safety and the Law
- Problems with Buying Frogs and Tadpoles for Wild Release
- Technical Guide: A Key to the Reptiles and Amphibians of Maryland - 86.3 MB pdf file
- Maryland Amphibian and Reptile Atlas (MARA) Project
- Natural Heritage Program
- Wildlife & Heritage Home
"A Joint Project of the Natural History Society of Maryland, Inc. and the Maryland Department of Natural Resources"
To see older newsletters, please visit the MARA Resource Page.
The Maryland Herpetology Field Guide is a cooperative effort of the MD Natural Heritage Program and the MD Biological Stream Survey within the Department of Natural Resources and their partners. We wish to thank all who contributed field records, text, and photographs, as well as support throughout its development.