Assessment of T bar anchor tags for marking the blue swimmer crab Portunas pelagicus (L.)

Abstract

Tagging is a critical technique when studying the population dynamics of any organism, in crustaceans the occurance of periodic molting further jepodises the tagging process. When applied as tested during the present study the standard “T” bar anchor tag (Hallprint Australia TBA-1, TBA-2), similar to the Floy anchor tag, is not considered a successful method of marking the Blue Swimmer Crab Portunus pelagicus. When assessed under laboratory conditions the tag resulted in a 100% failure rate during molting. The use of this methodology for population studies on P. pelagicus is not supported by data gathered by these laboratory based observations. A modified “T” Bar anchor tag, with the labelled barrel extended almost the complete length of the tag, has been developed and data is presented which shows this tag to be marginally superior for use with this animal. These results raise serious questions about data gathered by other studies utilising similar tagging methods.