By Véronique Dubos
Photos courtesy of Véronique Dubos
At the end of summer, numerous Arctic char enter the large lake Tasirjuarusik (Virgin Lake), located close to the community of Kangirsuk. However, over the winter Inuit fishers barely found them once they reached the lake. The char reappear in late spring. To understand Arctic char overwintering habits, eight fish entering the Tasirjuarusik system were tagged in August 2021.
The fish were caught using dip nets in a pool, located downstream from a waterfall. At each high tide, an arrival of fish was observed. When no more fish could be seen in the pool, they were pushed towards the pool, by agitating the water surface with rocks attached on a rope crossing the river.
Once caught, each fish was placed in a bin filled with an anesthetic solution (clove oil mixed in water) for a few minutes, until they fell asleep. It was necessary to do surgery to implant the acoustic tag. The surgery was conducted within two to four minutes, by implanting the acoustic tag and administering two stitches. During the surgery, the fish gills were constantly provided with liquid (anesthetic or water). Once the surgery was completed, the tagged fish was released in a recovery basin, located upstream from the waterfall. It was monitored regularly for about an hour or until it was ready to swim back in the river.
Information was transmitted to the local fishers not to fish in the area during the tagging activity to avoid catching one of the tagged fish and give them more chance to reach their overwintering lake.
Acoustic receiver installation
To record the fish location in the Tasirjuarusik system, 11 acoustic receivers were installed in the main lake. Two other receivers will be installed next winter, while access to the upstream lakes will be easier. Each receiver was fixed on a rope, anchored on the bottom of the lake, and attached to a buoy. The GPS location was recorded to be able to find them again. The receivers will be retrieved at the end of the summer 2022 to download the potential detection of a tagged fish.
Noah Eetook, Saomie Thomassie, Véronique Dubos, Carole-Anne Gillis, Aina Igiyok, Silasie Alaku, Jaiku Airo, William Eetook, Victoria Airo, Tommy Kudluk, and with the help and participation of Jaani Nassak, Leo Nassak and Zebedee Annahatak. This project is funded by the Inuit Nunangat Research Program, supported by ArcticNet/Inuit Tapiriit Kanatami.