By David Wood
Acoustic and radio tracking of fish is a common tool used by fish scientists. With it you can do some pretty cool studies; range and habitat affinity, large and small scale movement patterns, the possibilities are only restricted by your imagination (and depending on your imagination; technology). While this is all well and good, I have decided that there is an added bonus to the whole process and that is getting to be an ‘honorary’ surgeon.
Upon getting into the world of acoustic tracking, I visited and talked to many people which included watching the process firsthand. I also found and watched a few videos on how to perform surgery and even pulled some fish out of the freezer to have a few trial runs. All was ready.
My first live patient was a small Carp whom we named Pluto. I placed him in the anesthetising solution and monitored him closely. Unfortunately it is somewhat difficult to practice anesthetising dead fish and getting the concentration correct and then knowing when the fish has entered the right state of consciousness is critically important. Eventually Pluto was deemed ready and relocated to the surgery table. As far as I can recall the surgery went smoothly and Pluto was let go in the recovery tub with a brand new V9 acoustic transmitter and a new scar that he could show off to his mates.
Completing surgery on a Carp.
Fifteen minutes later Pluto showed no sign of recovery, an indication that he had spent too long in the anaesthetic. I spent another half an hour nursing him, trying to get water and oxygen moving though his gills. It was a slow process and recovery occurred in monumentally small increments. Many times I lost hope that Pluto was going to recover at all and came close to retrieving our acoustic tag but I didn’t want to see my first attempt as a failure. When I moved Pluto from the oxygenated recovery tub to the lake water he showed a bit more life, so with a few prayers (to whomever would listen), I watched him wobble off. Was this going to work? Had I just wasted my time and a tag worth a few hundred dollars on a fish that was as good as dead?
We had another 47 Carp to tag for the project and things went smoothly after the learning curve that was Pluto. A month later we went out and downloaded some of our receivers to make sure everything was functioning fine and see how many of our fish had retained their tags or survived the operation. Was Pluto there? I found his tag number and matched it up with the downloaded data and bingo! A whole bunch of hits over that first month on different receivers! I had never be so happy to see a Carp survive. I guess this proved a few things, but most of all how tough Carp really are.
Inserting a V9 acoustic tag into a Carp.
Three months after being released I am happy to report that Pluto, as well as of plenty of his mates are still alive and swimming around in the Hattah Lakes providing us with data.
For more information on this project visit:
For more information on fish tagging, surgery and welfare these are worth a look:
Steven J. Cooke , Vivian M. Nguyen , Karen J. Murchie , Jason D. Thiem, Michael R. Donaldson , Scott G. Hinch , Richard S. Brown & Aaron Fisk (2013) To Tag or not to Tag: Animal Welfare, Conservation, and Stakeholder Considerations in Fish Tracking Studies
That Use Electronic Tags, Journal of International Wildlife Law & Policy, 16:4, 352-374, DOI: 10.1080/13880292.2013.805075
Brown, R. S., S. J. Cooke, G. N. Wagner, and M. B. Eppard. 2010. Methods for Surgical Implantation of Acoustic Transmitters in Juvenile Salmonids — A Review of Literature and Guidelines for Technique. U.S. Army Corps of Engineers, Portland District, Portland, Oregon.
Marine and Freshwater Research: Tagging for Telemetry of Freshwater Fauna, 2009, Volume 60, Number 4, CSIRO publishing.
Editor’s note: Thanks Dave for taking the time to write about your successes with telemetry tagging. The Mildura MDFRC lab seems to punch above their weight at the Lair.