Thursday November 4, 2010

As explained in our recent post Fisheries Outpatient Center, we are currently conducting a study of trout (Oncorhynchus mykiss) movements in a central valley watershed. We expected that we would be able to track fish throughout the watershed, but recapturing a tagged fish was unexpected. This female O. mykiss was first caught angling on March 23, 2010. It was approximately 20 inches (505 mm) in length and appeared to be post-spawn, due to the eroded caudal fin and lean appearance. We surgically implanted an acoustic transmitter (HTI LX tag) and released the fish in the same location where she was caught. Since her release we have been tracking her location using fixed and mobile hydrophone receivers. During the last 7 months she has remained within one third of a river mile (570 meters) of the site where she was originally captured and released. To our surprise, while out angling this fall for additional O. mykiss to tag, we managed to recapture this same fish (October 20, 2010). The incision was completely healed but, interestingly, a suture remained loosely attached (sutures usually dissolve within 90 days). The fish was measured and released, again.
Video source: FISHBIO

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