Effects of dart tags on the growth and survival of captive snapper, Pagrus auratus (Sparidae)

The effect of dart tags of three different sizes (4.5, 6 and 9 cm streamer length) on the growth and survival of two groups of captive snapper, Pagrus auratus (Sparidae) was examined in a 1 year trial. Both groups were originally sourced as juveniles (0+), from wild stocks. Mean (+/- SD) fork lengths (FL) of the groups at the commencement of the experiment were 176 +/- 13 mm (n = 120) and 131 +/- 13 mm (n = 96). After tagging, the groups were held for 6 months in flow-through tanks, then counted, measured and transferred to net cages in a large Bow-through pool for the remainder of the trial. No initial tagging mortality occurred. For both groups, survival and growth were unaffected by either the presence of a tag or its size. Tag loss was approximated by a single exponential decay function. Average decay constants were 0.0004 day(-1) and 0.0008 day(-1) for the smaller and larger snappers, respectively. Tag loss was independent of tag size.