Field Notes

Killer whales are mak­ing their way into Hud­son Bay in ever-in­creas­ing num­bers. That’s bad news for the species that call the bay home.

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In Jan­uary 2013, res­i­dents of Inukjuak, an Inuit set­tle­ment in Arc­tic Que­bec, were met with an un­usual sight: a dozen or so killer whales trapped by sea ice cov­er­ing the waters of Hud­son Bay. For two pan­icked days, the whales — once seen only rarely in the bay — took turns breath­ing through a mod­est hole in the ice.

Luck­ily, the ice even­tu­ally opened up and the whales were able to es­cape, al­though it is not known if they were able to make it to more friendly waters be­fore en­coun­ter­ing fur­ther ice cover.

Ei­ther way, their pres­ence of­fered proof of a trend: the num­ber of killer whales fol­low­ing prey into Hud­son Bay is in­creas­ing as sea ice cover di­min­ishes, melt­ing ear­lier in the year and form­ing later. The trend is strong enough that one re­searcher — Steve Fer­gu­son of Fish­eries and Oceans Canada and the Univer­sity of Man­i­toba — goes as far as to sug­gest that killer whales may even­tu­ally re­place po­lar bears at the apex of the re­gion’s food chain.

“They are there to eat,” Fer­gu­son told CBC in a re­cent in­ter­view. “They ap­pear to be eat­ing other whales and seals. I would imag­ine, if we lose our sea ice, they will re­place po­lar bears as the top preda­tor.”

Not sur­pris­ingly, cli­mate change is the driv­ing force be­hind the ex­pan­sion of the killer whales’ range. Ac­cord­ing to a data­base of

whal­ing logs and Inuit testimony com­piled a few years ago by Fer­gu­son and his col­league Jeff Hig­don, the first re­ported sight­ing of a killer whale in Hud­son Bay was in 1940. The whales re­mained al­most un­known un­til the 1960s, when a flurry of seven sight­ings were recorded late in the decade.

That to­tal grew to 84 in the 2000s. There were a fur­ther 24 be­tween 2010 and 2014. And the trend shows no signs of slow­ing. This past June, two killer whale car­casses washed up on the shores of the Belcher Is­lands, just off the east­ern coast of Hud­son Bay. “Killer whales are not nor­mally seen around the is­lands,” Lu­cassie Ar­ragutainaq, head of the lo­cal hunters and trap­pers as­so­ci­a­tion, told CBC in an in­ter­view at the time. “But since win­ter to spring, sev­eral sight­ings have been re­ported.”

The growth in the num­ber of sight­ings cor­re­sponds to an 11 per cent de­crease in sea ice cover in Hud­son Bay — equiv­a­lent to 16,000 square kilo­me­tres— be­tween 1968 and 2010, ac­cord­ing to fed­eral gov­ern­ment records.

In me­dia in­ter­views, Fer­gu­son has said the grow­ing pres­ence of killer whales will sig­nif­i­cantly af­fect other species in the bay. Bel­uga whales, which are prey for killer whales, are of spe­cial con­cern. More than 55,000—about one-third of the world’s pop­u­la­tion—con­cen­trate in river estuaries on the west­ern coast each sum­mer to mate, raise young and feed, pro­vid­ing a mas­sive op­por­tu­nity for pre­da­tion.

Be­yond Hud­son Bay, sight­ings of killer whales are ris­ing in parts of the Arc­tic. Inuit hunters re­port the whales have been seen tar­get­ing species such as nar­whal and bow­head whales, in ad­di­tion to bel­uga, in ar­eas such as Foxe Basin and Lan­caster Sound, be­tween Hud­son Bay and Devon Is­land.

Once th­ese species had lit­tle to fear from killer whales, which avoid ice be­cause it can dam­age their dor­sal fins. The de­cline of their pro­tec­tive cover due to cli­mate change, how­ever, is al­ter­ing their habi­tat. And that will al­most cer­tainly lead to change in the Hud­son Bay ecosys­tem.

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