Effects of radio-tagging on two-year-old, endangered Macquarie perch (Macquaria australasica: Percichthyidae)

Radio-telemetry provides an effective means of studying the habitat use of threatened fishes where repeated recapture of individuals is undesirable. In these circumstances, it is especially important to ensure that radio-tagging methods are appropriate for the particular species of interest. An aquaria-based evaluation of three methods for radio-tagging two-year-old Macquaria australasica was conducted until 28 days post-surgery. Successful radio-tagging was determined from three indicators: (1) survival; (2) healing of the surgical incision or tag attachment site; and (3) resumption of feeding. Internal-coil radio-tags proved to be the most suitable radio-tag type, with complete survivorship and tag retention for the duration of the trial and fish commonly resuming normal feeding behaviour within two days post-surgery. In contrast, implanting a radio-tag internally and exiting a whip antenna is unsuitable for M. australasica on the basis of poor survivorship, rejection of radio-tags and prolonged alteration of feeding behaviour. No mortality or radio-tag rejection was observed in association with externally attached whip-antenna radio-tags, and post-surgery resumption of feeding was comparable with that of fish with internal-coil radio-tags. However, external radio-tags caused substantial abrasion of the epidermis and loss of scales. Internal-coil tags should be applied in radio-tracking studies of this species.