Retention of intra-peritoneal transmitters and post-operative recovery of four Australian native fish species

Regulation of the world's rivers has permanently altered the natural flow regime in many systems. Australia's rivers have also been subject to extensive modification; however, little is known of the effect altered flows have on many native fish species. Active transmitters offer an effective method of monitoring fish movement but there is little information on tag retention and post-tagging survival for most Australian species. Four fish species from the north-eastern rivers of New South Wales were surgically implanted with dummy transmitters to determine retention and incision healing rates. Eel-tailed catfish (Tandanus tandanus) were implanted with three types of dummy radio transmitters and the transmitter with the shortest externally exited antenna is recommended. In Australian bass (Macquaria novemaculeata), low water temperature, abdominal distention in females and the breakdown of dissolvable sutures contributed to the expulsion of dummy acoustic transmitters. Freshwater mullet (Myxus petardi) and sea mullet (Mugil cephalus) were implanted with dummy acoustic transmitters and healing rates were different between the two species. The present study demonstrated species specificity in tag suitability and recovery rates, the advantages of quarantining fish before release following the surgical implantation of transmitters and the value of controlled experiments to determine optimal transmitter design and post-operative conditions.