A comparative evaluation of three methods used to tag South African linefish

Abstract

Tagging effects and loss rates of 60 Roman Chrysoblephus laticeps tagged with dart tags with barbs (D-tags), T-bar filaments (T-tags) and visible implant fluorescent elastomer (VIFE) tags were investigated. The fish were tagged and monitored in a controlled tank experiment over a period of 198 days. Application technique and underwater visibility of VIFE tags were assessed in a preliminary experiment on Roman and on fransmadam Boobsoidia inornata. The use of 25-gauge needles improved VIFE tag application. Whereas VIFE tagging caused fin rot in fransmadam, it had no negative effect on Roman. VIFE tag codes could be identified underwater from a distance of 3m under ambient light. There was no significant difference in growth rates among groups of Roman with different tags and controls, but rates of tag loss were high for D-tags (53%) and T-tags (73%). Although some of the VIFE marks were incomplete, all VIFE-tagged fish were individually recognised at the end of the study. The results highlight the need to take cognisance of the high tag loss rate of conventional tags during the design of mark and recapture studies.