Tagging mortality of Greenland halibut Reinhardtius hippoglossoides (Walbaum)

Tagging mortality for Greenland halibut (Reinhardtius hippoglossoides) was studied under summer and winter conditions. The fish were caught using longlines and tagged with a T-bar tag. The winter experiment was conducted in Cumberland Sound, Canada in May 1997. Air temperatures were below 0degreeC and cold water-masses were present at 0-300 m. Fish were immediately placed in a tub of water after capture and transported by snowmobile to a heated tent for tagging and then placed in cages that were submerged to 300 m depth. The summer experiment was conducted in Upernavik, Greenland in August 1998. Air temperatures were above 0degreeC but intermediate cold water-masses were present at 60-200 m. In the summer experiment, fish were tagged and released in a observation tank to assess immediate tagging mortality (1 to 18 hr). They were then placed in specially designed cages and submerged to 300-500 m to assess short-term tagging mortality (up to 117 hr). A total of 155 Greenland halibut were included in the study. Overall tagging mortality was estimated to be 7%. Immediate handling and tagging mortality in both winter and summer experiments was low (