Authors: Jeff W. Higdon and Steven H. Ferguson Presented by: Jeanette M. Rogers

1. Loss of Arctic Sea Ice Causing Punctuated Change in Sightings of Killer Whales (Orcinus Orca) over the Past Century Authors: Jeff W. Higdon and Steven H. Ferguson Presented by: Jeanette M. Rogers

2. Introduction • A. Main Purpose • B. Background Information • C. Methods Used • D. Results found (statistical data explained) • E. Discussion (and possible implications)

3. A. Main Purpose of the Article Higdon and Ferguson “examined correlations between the frequency and distribution of sightings and sea ice concentration to determine if declining sea ice is related to killer whales being seen both more often and farther west into (the) Hudson Bay.”

4. B. Background Information • Killer Whales (Orcinus orca) • Major marine predators and ecosystem modifiers • Typically exist in high densities in temperate waters • Pagophobic • Prey includes fish and marine mammals (i.e. seals) • Three major ecotypes • 1. Transient ~ preys exclusively on marine mammals • 2. Resident ~ preys exclusively on fish • 3. Offshore ~ (no mention)

5. Background Information • Canadian Arctic • Hudson Bay (HB), Hudson Strait (HS), and the Foxe Basin (FB) • Located in eastern Canada Arctic • Hudson Bay – fairly shallow and large estuarine system (≈ 150 m) • Hudson Strait – deeper than the Bay, but smaller (300-900 m) • Foxe Basin – broad, shallow basin (100 m) • Exhibits Arctic oceanographic and sea ice conditions • Farther south than anywhere else along the North American continent

6. B. Background Information • Sea Ice Occurrences • Hudson Bay (HB) – annual complete cryogenic cycle • Freeze-up – late October and November • Break-up – complete usually by first week of August • Significant inter-annual variability dependent on weather and ice thickness • Hudson Strait (HS) – usually persists throughout the year • Probably why killer whales have been prevented from entering the Bay • Foxe Basin (FB) – (no mention made)

7. B. Background Information • Presence of ice-adapted Arctic/Subarctic marine mammals • Five species of seals • Ringed, bearded, harbor, harp, and hooded • Atlantic walrus • Polar bears • Three species of whales (in addition to the killer whales) • Narwhal, beluga, and bowhead

8. B. Background Information • Climate changes • Most pronounced in the higher latitudes • Decrease in the extent of ice (throughout the Northern hemisphere) • Hudson Bay (HB) is predicted to be affected greatest • Recent decades have had sea ice decrease • ay even have complete ice-free conditions by as early as the end of this century • Changes in fish communities • Negative effects on seabirds, ringed seals, and polar bears • Suggested declining sea ice will be reflected first by shifts in the marine mammal range and abundance

9. C. Methods used • Conducted a survey of available literature • Peer-reviewed studies • Consulting reports • Newspapers • Government documents

10. C. Methods used • Spoke with various individuals and groups: • Northern researchers • Tour operators • Conservation officers • Hunters and Trappers Organization (HTO) • Scientists/technicians with Fisheries and Oceans Canada (DFO) in Quebec, Nunavut, and Manitoba • Ontario Ministry of Natural Resources and Makivik Corporation staff

11. C. Methods used • All reports were used regardless of data quality as long as they could be assigned to a region • Sighting reports are of various quality • Some provided estimates of the number of whales, some do not • Group sizes were not used – only number of sightings • Higdon suggested that sighting efforts have remained fairly constant since the 1960s • Increased human population • Greater use of non-traditional methods of travel • Fewer individuals spending longer time on the water

12. C. Methods used Locations of Killer Whale Sightings EHS – Eastern Hudson Strait CHS – Central Hudson Strait WHS – Western Hudson Strait FB – Foxe Basin WHB – Western Hudson Bay CHB – Central Hudson Bay SHB – Southern Hudson Bay JB-EHB – James Bay – Eastern Hudson Bay - Killer Whale Sightings

13. D. Results Found Monthly and Seasonal Distributions

14. D. Results Found • Number of killer whale reports per decade • Subdivided into the four ecoregions (Stewart and Lockhart, 2005)

15. D. Results Found Trends in Median July Sea Ice Concentrations Over Time

16. D. Results Found Five-year Moving Averages of Median Ice Concentrations Change-Point Analyses

17. E. Discussion • A summary of the most extensive collection of sightings of killer whales in Hudson Bay, Hudson Strait, and Foxe Basin and show: • Sightings have increased exponentially • Species occur in Hudson Bay on an annual basis • Increase is significantly related to the decline in sea ice in the Hudson Strait • Suggested killer whale distribution has been influenced

18. E. Discussion • Sample sizes were small due to: • Low numbers of killer whales • Distance travelled • 48 records used – group sizes ranged from 1-20 • Suggested multiple small groups or one large (due to temporary immigration and emigration) • Intuit and hunters believe the same whales return annually

19. E. Discussion • Assumed that sightings have remained largely constant over time • Travel mode may have had an effect • Assumed that growing Inuit populations are balanced out by the decreased number of hunters on the water • If sightings remained constant, can still be effected in the way different communities report

20. E. Discussion • Less-effective reporting occurs in Ontario and Nunavik • Ontario Cree have no word for killer whale • Suggesting occasional observations are recent • Nunavik researchers have heard of occasional sightings only ~ but no systematic data collection

21. E. Discussion

22. E. Discussion • July Sea Ice • 4 Hudson Bay/James Bay subregions • Since 1900 ~ no significant declines • Since 1970s ~ significant trends towards earlier ice breakup and later freeze-ups have been found • Various studies have had different outcomes in other studies • Repulse Bay • Typically has open-water conditions later than other areas • Because it receives ice from Foxe Basin • More sightings of killer whales than any other place • Marine mammal prey species

23. E. Discussion • July Sea Ice (continued) • Hudson Strait • Significant reduction in sea ice • Greatest at CHS • Postulate a “choke point” ~ restricted killer whale access • Another important choke point ~ Fury and Hecla Strait • Few records cover this area

24. E. Discussion • Sightings • Historically none known before the 20th century • All “typical” marine mammals were documented/known before the 19th century • While Intuits believed it was the walrus that turned around the killer whales ~ most likely it was the sea ice

25. E. Discussion Killer Whale Sightings vs. Sea Ice Concentrations

26. E. Discussion • Possible Implications • Sea ice decline = more killer whale sightings • Killer whales could move further into the Canadian Arctic Archipelago ~ from both east and west • Currently, the Hudson Bay region is ice-adapted • Polar bear-seal as predator-prey • Continued changes would result in • Replacement of polar bears as the dominant marine mammal predator

27. E. Discussion • Impacts ~ if Hudson Bay became “ice-free” • Reduction of marine mammal prey populations • Due to killer whale predation • Inuit subsistence culture would be changed

28. Acknowledgements • Gagnon, A. S., and W. A. Gough, 2005. Trends in the dates of ice freeze-up and breakup over Hudson Bay, Canada. Arctic 58: 370-382. • Gough, W. A., A.R. Cornwall, and L.J.S. Tsuji, 2004. Trends in seasonal sea ice duration in southwestern Hudson Bay. Arctic 57: 299-305. • Higdon, J. W. and Ferguson, S.H. 2007. Loss of Arctic sea ice causing punctuated change in sightings of killer whales (Orcinus orca) over the past century. Ecological Applications. 19(5): 1365-1375.

29. Any Questions?