Estimation of tag loss in marine turtle research

From the results from long-term multiple tagging studies of marine turtles in eastern Australia, the probability of tag loss was estimated for standard monel and titanium turtle tags applied at different tagging positions on Caretta caretta and Chelonia mydas in nesting and feeding-ground studies. Tag loss was variable, being a function of tag design, tagging position, species, study type and tag age. Tag loss was greatest from the more distal tagging positions on the trailing edge of the front flippers. Rear flipper tags were lost at a higher rate than tags in the axillary-tagging position on the front-flipper. Tag loss was greater for turtles tagged in nesting studies than in feeding-ground studies. Monel tags, in general, were lost at a greater rate than titanium tags. There was a species contribution to titanium tag loss but not to monel tag loss. The probabilities of tag loss calculated for this study can be used as correction factors for tag loss in those marine-turtle studies where recapture rates have been measured.