Hi all,

We have a conservation breeding program for northern leopard frogs for reintroduction. We typically release tadpoles at about Gosner stage 30 and then do follow up monitoring at the release site once individuals have reached metamorphosis.

In order to assess the success of our reintroduction efforts and any experiments we would like some way to batch mark the larvae. The challenge is that the marking method needs to cause minimal mortality, be effective at ~ Gosner stage 30, have high retention rates, last until metamporphosis, and ideally be inexpensive and easy to apply. I doubt that there is a marking method that meets all of these criteria but low mortality is the most important.

From what I have read (some references below) VIE has an unacceptable rate of mortality and not great tag retention in some species (or have had success but using later Gosner stages), calcein fluorochrome dye has low mortality but not great tag retention unless we can mark them later than Gosner stage 37, other fluorochrome dyes have poor retention and deleterious health effects, pit tags are too big, coded wire tags have good retention rate, and low mortality, but don't look like they would be a good field method. Genetic methods are good for identifying individuals that come from our breeding program but not good for experimental design.

I wondered if anyone out there was aware of any other methods that I haven't mentioned or who have success with the methods above?

Thanks in advance for your help!

Lea

References:

Andis A (2018) A new, noninvasive method of batch-marking amphibians across developmental stages. Herpetological Conservation and Biology 13: 423-432.

Fardell L, Stockwell M, Valdez J, Klop-Toker K, Clulow S, Clulow J, et al. (2015) Tagging tadpoles: Retention rates and impacts of visible implant elastomer (VIE) tags from the larval to adult amphibian stages.

Grant, E. 2008. Visual Implant Elastomer Mark Retention through Metamorphosis in Amphibian Larvae. Journal of Wildlife Management 72(5): 1247-1252

Iannella M, Liberatore L, Biondi M (2017) Marking tadpoles with Visible Implant Elastomer (VIE) tags: methods for improving readability and decreasing mortality.

Martin RA (2011) Evaluating a novel technique for individual identification of anuran tadpoles using coded wire tags. Herpetological Conservation and Biology 6: 155-160.

Ringler E, Mangione R, Ringler M (2015) Where have all the tadpoles gone? Individual genetic tracking of amphibian larvae until adulthood. Molecular Ecology Resources 15: 737-746.