The 4 narwhals still with working satellite transmitters are now spending most of their time towards the edge of the Canadian continental shelf, at the edge of Davis Strait, not far from the international boundary with Greenland. They are likely feeding in relatively nutrient rich areas, probably mainly on Greenland Halibut.
At this time of year there’s often some satellite errors in the position fixes. But with multiple fixes, one can readily derive the most reliable positions over a 10-day period. Indeed, these whales are now either just at the edge of the 9-10/10ths coverage annual sea ice, or in the case of narwhal #115957 and probably #115959, breathing at leads and cracks among the ice sheets. Remember that the counter-clockwise currents in this productive Baffin Bay system maintain mobility of sea ice offshore, even though maximum surface air temperatures are often -20C now. And narwhal can probably detect such gaps quite readily as they surface, using their echo-location click mechanisms.