Ponds & Tadpoles

Before You Collect Those Tadpoles

Distributing Tadpoles

If you have set up a frog pond properly that is well used by the frogs, you will soon find yourself with more tadpoles than you can handle. Many species of frogs breed in large numbers to compensate for the high mortality of their larvae. In other words, it is a natural process for a certain number of tadpoles not to survive to metamorphosis. However, many more tadpoles could survive if they were distributed over more sites of permanent water, such as new frog ponds or those which haven't attracted any amorous adult users.

On the one hand, tadpole distribution can allow more tadpoles to survive and it can be used to reintroduce species to areas where they once were. On the other hand, distributing tadpoles is an excellent way to quickly spread diseases that can wipe out as many frogs as what were saved in the first place, if not more. A lot of folks are under the impression that if they don't have chytrid fungus in their area, then they don't have any disease problems. WRONG! There are many other diseases besides chytrid and many are being moved around by people and the trade.

In January, 2003, three batches of awful looking tadpoles from three households in the suburb of Redlynch, Cairns were turned into us for evaluation. They were off colour, sluggish, not eating well, and some had bent tails. They were dropping like flies, so to speak, and we had them virus tested by the School of Virology and Immunology at James Cook University. The researcher found a virus using sequencing but he was unable to identify the virus. We originally dubbed this problem the "Redlynch" virus but now refer to it as a malformation caused by chemicals spreading through waterways. From what we've seen since and the rate of spread that is occuring with this aquatic problem, it is obvious that there are two very effective ways that this problem can be carried from place to place: the first is moving tadpoles around and the second is people who do surveying in the field and do not use disinfection procedures.

The presence of an aquatic virus that kills nearly all the tadpoles in a body of water and/or sits dormant in those that metamorph for later activation is a serious issue.  Likewise, the damage caused by a chemical that causes genetic damage and 100% death rate of all offspring in a cluth is incrementally more serious!  This is especially because this problem does not make its presence known until the later stages of tadpole development. Everything seems fine until the back legs are at least halfway grown and then all heck breaks loose!

Viruses have a long dormancy period - up to two years but some are much longer. Psitticine Beak and Feather Disease and Feline Immunodeficiency Virus (both rampant in Australia) have dormancies up to five years - so tadpoles and frogs in your garden can be carrying a virus (or genetic damage) without showing any symptoms. When tadpoles and frogs that have been exposed become stressed, which is the case at metamorphosis or during the dry season/drought, then the virus is triggered and spreads to other frogs. As soon as those sick frogs go to water, they can spread their pathogens into the water where all the tadpoles can pick it up.

Aside from the problem of spreading disease, regulations in QLD changed during 2004 making it illegal to relocate tadpoles without a rescue permit.

We recognise that rescuing and distributing tadpoles is a tool that can assist the restoration of frog populations on a local level, but we are also extremely concerned about the spread of disease, especially a ranavirus or the malformation problem. We would like to find a sensible, middle ground to a complex problem. Until we hear otherwise from the researchers, we are making the following suggestions concerning the movement of tadpoles anywhere, not just where there are regulations. These suggestions are subject to change based on new findings on the spread of disease in FNQ.

1. Do not move tadpoles outside of your own water catchment and suburb

This includes tourists who are visiting Far North Queensland for holidays - do NOT collect tadpoles here to bring home with you. The most serious amphibian diseases we know of so far are aquatic so keeping to your own catchment might help prevent an aquatic pathogen from spreading throughout a new catchment. If you do not know what area makes up your local catchment, contact your local council or Integrated Catchment Management community group.

Receiving tadpoles from another pond or the wild

If you should acquire some tadpoles (best to check the laws in your area first), each batch you receive should be handled separately from any others and be kept at least a metre (3 feet) of space apart between each container. Put labels on each container with the location the tads came from and the date. Do not put them into your pond but rather raise them in aquariums or other containers.

All containers should have been disinfected first with whatever product you choose (not bleach) and then wiped down with 10% povidone iodine (betadine) and rinsed very well before using for the tadpoles.

All tadpoles should be handled as if they are already diseased. They might look good when you acquire them but this could change over time. If you have been handling them properly to start with, then you won't be spreading disease. If you haven't handled them according to disease control methods, then it is likely you will have cross-contaminated all the tadpoles you have by the time you discover there is a problem - and that would be a tragedy.

For each tank of tadpoles, assign items for that tank only such as a net, cup for drainage, etc. and wear disposable gloves when doing water changes. Don't use those items for any other tank.
When you do your water changes, dump that water down the toilet - not your yard or a storm water drain.
Use one bucket for all water coming OUT of the tadpole tanks and do not use that bucket to refill the tanks - use a separate bucket which has been disinfected and is ONLY used for refilling tanks.
Don't switch plants or fish around from tank to tank. If all the tadpoles did well and metamorphed until there are no more left, then you can reuse the plants and fish. If the tadpoles didn't do well and died, then it is best not to reuse the plants and fish from that tank.
Visit our Raising Tadpoles page for lots more information about looking after tadpoles.

Related Topics