Friday, November 18, 2011

Tracking migrating narwhals

Many news outlets have reported this month about a study in northern Canada aimed at tracking narwhal migrations by attaching satellite tracking devices to the whales and monitoring their movements.  It’s a great project that will hopefully shed new light on population dynamics, migratory corridors, and how declining sea ice is affecting the species.
Some news reports suggested that this project is new, but that’s not true.  The effort has been underway for about a decade, and I spent two weeks with the researchers in the summer of 2010 in the same location they worked this year in a challenging effort to capture narwhals for study.
Narwhal research camp in Tremblay Sound
Based in Tremblay Sound, a fjord in northern Baffin Island in the province of Nunavut, the 13-man research team started out by spending more than a day just setting up camp – which included 1,800 pounds of food, three gas grills, two zodiacs and outboard motors and drums of fuel, giants nets, high-tech scientific equipment, and a 25-foot tall radio antenna.  As we finished preparing camp, we all glanced up in unison as our first massive movement of narwhals swam by. 
Like a child’s bath, at first we just heard gentle splashing noises in the distance from the narwhals’ repeated surfacing for air and an occasional whooshing sound as they exhaled.  Then the whales came into view, swimming in groups of threes and fours and sixes, most appearing quite dark like they were not yet very old, some with pinkish gray calves that looked like tiny swimming sausages, and all porpoising at the same speed in the same direction with little concern for the crowd of onlookers standing on the shore less than 50 yards away.  As we watched, our mouths hung open and I could barely catch my breath, so pleased were we with their seeming tameness and abundance.  There must have been 200 of them, and they took more than 10 minutes to pass our camp.  If the scientists had worried about whether narwhals were going to be in the area, those worries quickly disappeared.  Little did we know then that what we believed were the same animals would swim by us repeatedly two or three times a day for the next several weeks.  Watch my video of the narwhals parading by.
Researchers capture a narwhal for tagging.
Unfortunately, we didn’t catch any narwhals while I was in camp.  Day after day, the whales approached the nets numerous times, and every time they must have detected the nets and swam under or around them.  After I left, however, the researchers acquired a different net that apparently was more difficult for the whales to detect, and just 30 minutes after the new net was deployed, they captured their first narwhal.  In the next four days they caught five more.
“You can count whales from the air, you can count them from land, you can see what the herd is doing, but you don’t really get an idea of what an individual does on a daily basis [without tagging them],” said Jack Orr, the chief scientist in charge of the project and a biologist with the Canada Department of Fisheries and Oceans.  “These tags provide us information on where they are geographically on the Earth, but we also get an idea of how they use the water column.  Tags will tell us how long a whale is at a certain depth, and then we can set up dive profiles…Coupling this with information on water depths and what animals use these depths – we know, for instance, that turbot (Greenland halibut) and crustaceans live on the bottom, we know that squid are pelagic so they’re in the water column – and working with other data on ice and other environmental parameters, we can determine what these animals are doing over the course of a year.  It gives us insights into not only its movements but also its behavior.”
By late November, all of the narwhals the team tagged the previous August were in the middle of Baffin Bay at the edge of the pack ice, exactly where it is known that most narwhals spend the winter.  But the scientists were intrigued to see that some of the tagged whales traveled together the entire route while others took widely varying routes to the same destination, including one who went all the way to West Greenland before returning to Baffin Bay.
It will be exciting to see what route this year’s tagged narwhals take to their wintering location, and if they return to Tremblay Sound next summer.