GAME OF THRONES

As the cli­mate in Canada’s Far North changes, po­lar bears are be­ing af­fected. One im­pact — the in­creas­ing pres­ence of killer whales in Arc­tic wa­ters — may just un­seat the King of the North.

Canadian Geographic - - CONTENTS - By Sharon Oosthoek

ALONE PO­LAR BEAR am­bles along the western shore of Hud­son Bay, just out­side the town of Churchill, Man. Ev­ery few min­utes, she stops on the rocky beach, stands on her rear legs and peers across the bay’s open wa­ters. Some­thing out there has caught her at­ten­tion. It’s late Au­gust. Months will pass be­fore the in­creas­ingly un­pre­dictable sea ice forms, pro­vid­ing a plat­form to hunt seals and fat­ten up af­ter sev­eral lean months on land. It is not ice, how­ever long­ingly an­tic­i­pated, that has her scan­ning the cold, grey wa­ter. About 300 me­tres from shore, seven tri­an­gu­lar dor­sal fins be­tray the po­si­tion of a group of un­usual vis­i­tors to the bay: killer whales. Per­haps the po­lar bear is just as sur­prised to see the whales as the tourists whose Zo­diac idles a stone’s throw from the pod. Cer­tainly the boat’s driver with Sea North Tours — a life­long Churchill res­i­dent — is as­ton­ished. “Oh man, I can’t be­lieve I’m look­ing at or­cas!” Remi Fou­bert-allen shouts over the noise of an out­board mo­tor. “Look at the male’s dor­sal fin. It must be seven feet!” His eyes widen as he ges­tures ex­cit­edly to­ward the pod. Fou­bert-allen knows some­thing most peo­ple don’t: un­til re­cently, killer whales have been a rare sight in Hud­son Bay. Jo­bie At­ti­taq, an Inuit hunter in Arc­tic Bay, Nu­navut, has no­ticed the same thing on the north­west coast of Baf­fin Is­land. “In the late 1990s, we started to no­tice killer whales were com­ing around to Ad­mi­ralty In­let and even into Adam Sound and right here into Arc­tic Bay,” says At­ti­taq, chair of the ham­let’s Hunters and Trap­pers Or­ga­ni­za­tion. “We never ex­pe­ri­enced this be­fore. Now we get them of­ten.” In fact, killer whale sight­ings in Hud­son Bay and the wider east­ern Cana­dian Arc­tic have in­creased since the year 2000, lead­ing Arc­tic sci­en­tists to muse about the rise of a new apex preda­tor in the North. They say dis­ap­pear­ing sea ice is open­ing up new hunt­ing grounds for killer whales. At the same time, they say, it’s nar­row­ing habi­tat for the North’s long-reign­ing monarch: the po­lar bear. Steve Ferguson, a bi­ol­o­gist with Fish­eries and Oceans Canada, is among those try­ing to fig­ure out ex­actly why the whales are there and what their pres­ence means for the Arc­tic ecosys­tem. He be­lieves the whales are mov­ing north as cli­mate change opens up pre­vi­ously in­ac­ces­si­ble hunt­ing ar­eas that are rich in bel­u­gas, bow­heads, nar­whals and seals. Ferguson’s re­search in­di­cates that sea ice in Hud­son Strait was once a choke point, pre­vent­ing or­cas from ac­cess­ing Hud­son Bay. Killer whales gen­er­ally avoid ice be­cause they can in­jure their tall dor­sal fins as they swim un­der­neath. But de­clines in the area cov­ered by sum­mer sea ice in the strait be­gin­ning in the 1960s are likely re­spon­si­ble for killer whales from the north­west At­lantic find­ing their way into the bay. Fig­ures from the Cana­dian Ice Ser­vice sup­port that con­clu­sion. Re­searchers there say that since 1968, sum­mer sea ice con­cen­tra­tions in Hud­son Bay and in Hud­son and Davis straits have de­clined by 15 to 20 per cent per decade. In Baf­fin Bay, they’ve dropped by 10 to 15 per cent per decade. Work­ing with Ferguson, Win­nipeg-based wildlife bi­ol­o­gist Jeff Higdon has pored through old whal­ing logs and in­ter­viewed Inuit hunters to cre­ate a data­base of killer whale sight­ings in the re­gion. He says Euro­pean whalers kept de­tailed records start­ing in the 1600s, with no men­tion of these awe­some preda­tors in Hud­son Bay un­til well into the 1900s. “The first record I know of for Hud­son Bay was in the 1940s,” says Higdon. But sight­ings picked up start­ing in the late 1960s, with seven re­ported that decade. Records for the 1970s show 12. Ditto for the 1980s. Then a slight rise in the 1990s to 16 be­fore sight­ings soared to 84 in the decade from 2000 to 2009. From 2010 to 2014, there were 24. Sci­en­tists with Fish­eries and Oceans started pay­ing closer at­ten­tion in 2005, which prob­a­bly boosted re­cent num­bers, but a trend is clear. A sim­i­lar pat­tern is ev­i­dent in the wider east­ern Cana­dian Arc­tic. Killer whales have been sum­mer­time vis­i­tors to Baf­fin Bay and Davis Strait since at least the late 1800s, but Inuit hunters say

they now see them more reg­u­larly and in larger num­bers. This re­gion has gone from 25 re­ported sight­ings in the 1960s to 79 in the decade from 2000 to 2009. From 2010 to 2014, there were 62. The fact killer whales are com­ing back year af­ter year, and in greater num­bers, tells Ferguson the hunt­ing must be good. “They are do­ing well and re­pro­duc­ing,” he says, adding that he wouldn’t be sur­prised to see sight­ings con­tinue to in­crease. Po­lar bears, on the other hand, ap­pear to be fac­ing a less promis­ing fu­ture.

FOR SEV­ERAL HUN­DRED

thou­sand years, po­lar bears have reigned supreme as the Arc­tic’s top preda­tor. They are uniquely suited to a frigid world, ex­pert in us­ing sea ice as a plat­form for hunt­ing ringed and bearded seals. But the Arc­tic is warm­ing at twice the rate of lower lat­i­tudes, and their habi­tat is chang­ing dras­ti­cally. Po­lar bears have sur­vived warm­ing pe­ri­ods in the past — even to the point of cross­breed­ing with bar­ren ground griz­zlies whose ter­ri­tory over­laps theirs in the south­ern Arc­tic. Char­lotte Lindqvist, an evo­lu­tion­ary bi­ol­o­gist at the State Univer­sity of New York, Buf­falo, pub­lished a study in 2012 show­ing griz­zlies and po­lar bears have swapped DNA over the course of five mil­lion years. Lindqvist sus­pects cross­breed­ing was more fre­quent dur­ing warmer pe­ri­ods as po­lar bear pop­u­la­tions plum­meted and griz­zlies moved north. In fact, a hand­ful of po­lar bear-griz­zly hy­brids have been con­firmed in the Arc­tic over the last decade. But this time, even hy­bridiz­ing is un­likely to have much of an im­pact on their sur­vival, says An­drew De­rocher, a po­lar bear re­searcher at the Univer­sity of Al­berta. Sim­ply put, cli­mate change is hap­pen­ing too fast for them to adapt, he says. “The con­cern over po­lar bears stems from the fact the worst is yet to come,” says Gregory Thie­mann, a po­lar bear re­searcher at York Univer­sity. “We haven’t seen cat­a­strophic de­clines yet, but based on a clear un­der­stand­ing of the re­la­tion­ship be­tween green­house gas emis­sions, sea ice and po­lar bears, this is com­ing.” Cur­rent es­ti­mates peg the global pop­u­la­tion of po­lar bears at be­tween 20,000 and 25,000 — a rel­a­tively healthy num­ber. But sci­en­tists gen­er­ally agree the po­lar bear’s fu­ture is not bright. A U.S. Ge­o­log­i­cal Sur­vey study re­leased in July con­firms that the most sig­nif­i­cant threat is de­clin­ing sea ice. It also pre­dicts po­lar bear num­bers will drop whether green­house gas emis­sions are re­duced or not. While the study sug­gests the heav­ily iced Cana­dian Arc­tic Ar­chi­pel­ago could be a last refuge, that’s only if global av­er­age tem­per­a­tures in­crease by just 2 C. Ac­cord­ing to another study pub­lished in the Novem­ber 2014 is­sue of the jour­nal PLOS ONE, busi­ness-as-usual cli­mate pro­jec­tions mean po­lar bears could face mass star­va­tion and re­pro­duc­tive fail­ure across the en­tire Arc­tic Ar­chi­pel­ago by the year 2100. “If we can’t keep them in the Cana­dian High Arc­tic and north­ern Green­land, we are not go­ing to have them in the wild,” says De­rocher, one of the study’s co-au­thors. The is­sue is that po­lar bears are adapted to hunt seals from ice plat­forms: “I’ve seen them try for seals in open wa­ter,” he says. “I’ve never seen them suc­ceed.” They can sup­ple­ment their diet while on land dur­ing the sum­mer with seabirds, eggs and the odd cari­bou car­cass. And even when sum­mer­time pick­ings are slim, po­lar bears are able to tol­er­ate long months with­out food. But here’s the crux: sci­en­tists be­lieve the bear’s sur­vival de­pends on its abil­ity to feed on high­calo­rie seals when the ice re­turns. The PLOS ONE study sug­gests po­lar bears in the ar­chi­pel­ago may have to sur­vive se­ri­ous in­creases in ice-free con­di­tions by the end of 2100. While healthy adult males may make it through up to six months of fast­ing, ju­ve­niles, cubs and lac­tat­ing fe­males will strug­gle. Al­ready, some pop­u­la­tions are ex­pe­ri­enc­ing de­clin­ing weight and in­creased mor­tal­ity linked to dis­ap­pear­ing sea ice.

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