Let’s do it again: Closing the book on a pilot in situ redfish tagging experiment with Underwater Tagging Equipment

No abstracts are to be cited without prior reference to the author.

In 2003-2008 2,777 beaked redfish (Sebastes mentella) were tagged in situ with remotely operated Underwater Tagging Equipment (UTE) developed in collaboration between Marine Research Institute in Iceland and marine-device manufacturer Star-Oddi. Tagging redfish in their own environment avoiding the hazardous trip to the surface is made possible by attaching the UTE in front of the codend of a pelagic or demersal trawl and tagging with a remotely operated robot. The main objective of the research has been studying both vertical and horizontal migration patterns of beaked redfish stocks in the Irminger Sea and adjacent waters. Of the tagged fish, 62 (2.3%) have been recaptured. The experiment included tagging 105 redfish with electronic data-storage tags (DST) of type 'micro', recording pressure and temperature but, none have been recaptured to date. The distribution of days at liberty is wide with the longest time at liberty almost 7 years and the longest distance travelled over 300 nautical miles, with few individuals migrating between defined stock units. Despite the UTE being the only known successful tool for tagging redfish at great depths only Iceland has used it. We, therefore, believe the experiment ‘deserves to be repeated’ with further development of UTE.