In the News....
United States approves controversial satellite tagging of southern resident killer whales
The endangered southern resident killer whale population are some of the most intensely studied marine mammal species in the world, but their winter distribution and winter feeding habits still remain somewhat of a mystery. They have been spotted as far north as Haida Gwaii and as far south as Monterey, California. In order to better understand where these whales go in the cold winter months when salmon runs are not as plentiful in the Salish Sea, the American government has approved wildlife biologist Brad Hanson at the National Ocean and Atmospheric Administration (NOAA) to attach satellite tags to the dorsal fins of six southern resident killer whales per season.
The chance to gain information about the whales during the winter is something all researchers strive for; however, the problem is that researchers have mixed feelings about the use of satellite tagging. The satellite tags are about the size of a nine-volt battery with two spikes and barbs that hold onto the whale’s flesh. The tags are shot from a cross bow or pneumatic gun into the dorsal fin and remain on the whale anywhere from three to nine weeks until they fall out, leaving the wound to heal on its own. But when the tag falls out, it tears away flesh and the wound can easily become infected. Adding to the concern is that the southern resident whales are a very vulnerable group - the number of individuals sits at a precarious 88 and each animal is important to the survival of the population. Southern residents also live in an urban environment with a lot of toxins proven to interfere with their immune and reproductive systems, making them susceptible to further injury and infection from a satellite tag.
However, Mr Hanson has tagged more that 250 whales from 15 different species and says there have been no adverse impacts connected to their survival. While it is a valid concern, he feels that the damage from a satellite tag is within the naturally occurring range of tissue impact. And indeed, no one can dispute that killer whales often have many cuts, scars, and scrapes on their skin.
None of the resident whales have been tagged yet, and unless the weather cooperates, Hanson’s team may not be able to tag the animals. Yet if they manage a successful tag, the researcher team hopes to follow the whales and collect both prey and fecal samples to help determine their winter food source. Mr Hanson hopes that his tags will help shed light on winter dietary needs and identify specific areas of winter habitat to help refine critical habitat. Scientists can then target those areas in the future to find out if the usage pattern of the southern residents continues.
News article: Vancouver Sun
Photo: Susanne Davies
When it comes to dinner, Eastern Arctic killer whales aren't picky!
Studying killer whales in the Arctic can be tricky, the field season is short, the whales are widely dispersed, and boats are not always readily available. So Steven Ferguson of the Department of Fisheries and Oceans Canada and a colleague turned to local Inuit hunters in order to find out the secrets behind what these Arctic whales are eating. Using an Inuktitut-speaking interpreter they interviewed 105 hunters ranging in age from 30-90 from 11 different communities in coastal Nunavut. This collaboration turned out to be extremely successful. The researchers were able to gather decade’s worth of field notes through interviews, information that essentially that wouldn’t have been available otherwise.
Killer whales are one of the most widely-dispersed mammals in the world and have adapted their hunting strategies to prey on specific food sources available in their given environment. Here in BC we have killer whales that specialize on Chinook salmon and others that eat only marine mammals. In Alaska a population of transients prey on migrating gray whale calves and in Norway another population that feeds on herring. In Antarctica five different types of killer whales have been identified, each with different prey preference. However, there was a large knowledge gap in the ecology of whales living in Arctic Canada, until this study that is. Since the Arctic sea ice is melting, killer whales are moving into new regions, where even the Inuit have not seen them before, and scientists want to know more about their prey preferences and hunting behaviors. According to the Inuit knowledge, the Arctic killer whales eat primarily other mammals and none of the hunters who were interviewed had seen them eating fish. Seventy-three of the hunters had observed killer whales hunting ringed seals; 24 had witnessed them hunting and feasting on narwhal; and 17 had watched them ramming and drowning adult bowhead whales – animals that are more than twice their size.
The killer whales seem to time their visit to the eastern Canadian Arctic as the ice begins to recede in July, which also happens to correspond with when other marine mammals give birth to their young. According to the Inuit hunters, the killer whales work in highly coordinated groups similar to wolves, sometimes herding narwhals and belugas into deep water and circling them to keep them from escaping. Their prey may also try to escape by fleeing into shallower water where the killer whales are not as comfortable. The Inuit even have a word for this phenomenon: "aalirijuk," which translates to “the fear of killer whales”. However from time to time it is the prey with the upper hand; in fact the Inuit have seen narwhal skewering killer whales with their tusks, sometimes killing their tormentors.
Although the data in this study are anecdotes, the information provided by the Inuit is still valuable and very interesting. Not only does this study shed light on the ecological adaptations of Eastern Arctic killer whales, but it also demonstrates the role that traditional knowledge can play in informing traditional science and contributing to marine conservation and management. New Article: Science Magazine
Photo: Gretchen Freund