Evaluation of anchor tags for marking the commercial sand crab, Portunus pelagicus (L.) (Portunidae : Decapoda)

Abstract

Laboratory and field trials of a modified Floy FD67 anchor tag were conducted on P. pelagicus in Moreton Bay, Queensland. The tags did not affect short-term survival of the crabs in the laboratory. Only 470 of 1754 crabs tagged and released in the field were returned. Return rates of crabs by size, sex, and area of tagging class were markedly heterogeneous. Poor visibility of the tags on recapture, regardless of their colour, makes this tag unsuitable for any quantitative population studies. Poor return rates were exacerbated by fishermen not examining categories of crabs that are unmarketable.