Eye-tagging

The association sometimes eye tags trout parr to monitor upstream/downstream migration of fish. The tag is a type of resin called Elastimer which has fluorecent properties and comes in various colours. We use a yellow Elastimer, which is inserted into the mucus membrane behind the eye using a siringe similar to the one used for diabetes. The tags have a 95% retention rate and by tagging both eyes we decrease the chance of loosing the tag. The fish are measured, tagged then have their adipose fin removed all of which is done under anaesthetic. When the complete batch of fish have been tagged they are taken to a specific point within the river catchment, usually above a barrier and released after being acclimatised to the river.

The fish can be spotted at night by using a special ultraviolet torch, the tags glow in the dark and show the fish as two little yellow dots in the water. Others are sometimes captured by members fishing, members are asked to report any of these fish captured stating location and if possible scale samples are taken. The scales will determine the age of the fish which immediately lets us know when and where it was released. During an electro-fishing survey three years ago we captured a tagged fish which had been released 4km downstream the year before.