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Table of Contents
Preface .......................................................................................................................................................... 4
1 Appreciating a Majestic Canadian Ecosystem ........................................................................................... 6
2 Long-Term Climate Change Trends in a Highly Variable System ............................................................... 8
3 Ominous Signals From the Arctic Ocean .................................................................................................. 10
4 Dramatic Changes in the Hudson Bay Complex ....................................................................................... 13
5 Contemplating the Future of the Hudson Bay Marine Ecosystem .......................................................... 21
6 On our Understanding of the Bay: Recognizing Ominous Signs Without Knowing Where We Are Headed
.................................................................................................................................................................... 27
7 Concluding Thoughts................................................................................................................................ 31
Reference List .............................................................................................................................................. 33
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1 Appreciating a Majestic Canadian Ecosystem
Hudson Bay is historically important and played a defining role in the early history of Canada. Hudson Bay,
and the forts and trading posts established around its
margins and in its watershed, played a pivotal role
in the early fur trade, the economic engine that shaped much of the exploration and settlement of the
lands that would eventually become part of Canada. While Hudson Bay continues to occupy a large part
of the map of Canada, it is mostly ignored by Canadians and there is little appreciation of this vast and
unique part of our country. The Arctic Ocean has, comparatively, garnered much more public, political,
scientific and media attention. The warming of the Arctic, sovereignty issues, oil and gas reserves,
decreases in the volume of the polar ice cap and reductions in the extent of the summer ice cover have
all helped to make Canadians more aware of Canada’s interests in the Arctic.
The Hudson Bay Complex consists of Hudson Bay, James Bay, Foxe Basin, and Hudson Strait, including
Ungava Bay. Covering 1,242,000 square kilometers (km²), this complex is the world’s largest seasonally
ice-covered inland sea. It is also relatively shallow. Hudson Bay has a mean depth of 125 to 150 metres
with a maximum depth of 250 metres. James Bay is even shallower. The corresponding values for Foxe
Basin and Hudson Strait are mean depths of 90 and 300 metres with maximum depths of 450 and 900
metres. The Hudson Bay Complex has, since the last ice age, been undergoing isostatic rebound and, while
the rate is declining, the region is still rebounding at approximately 1.2 metres/century.
The Hudson Bay Complex has two direct connections to the world‘s oceans. Fury and Hecla Strait, at the
northwest corner of Foxe Basin, carries Arctic Ocean water (much of it being of Pacific origin) into the
Foxe Basin. Here, a portion of this flow is carried south along the western coast into northwestern Hudson
Bay via Roes Welcome Sound, which lies between Southampton Island and the mainland. A proportion of
the Arctic Ocean input mixes in Foxe Basin with marine waters of Atlantic origin, which are transported
from the Labrador Sea within a coastal current on the north side of Hudson Strait. The waters mixed in
Foxe Basin exit southeastern Foxe Basin where a proportion, likely relatively small, enters northeastern
Hudson Bay. The bulk of this mass of water is joined by less-saline waters from Hudson Bay and James Bay
and transported out of Hudson Bay in a coastal current along the south side of Hudson Strait.
The Hudson Bay Complex is a unique and majestic ecosystem. It may not raise sovereignty issues, but it is
of national and international significance. It is changing rapidly, and the cumulative impact of climate
change/warming together with a range of other important stressors is large and apparently increasing.
Other major drivers of change include hydroelectricity development, increasing international shipping,
atmospheric transport of contaminants and, in all likelihood, the exploration for, and development of,
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mineral and oil and gas reserves. The marine ecosystem and the living resources that have adapted over
millennia within this unique Arctic/subarctic setting are, or will soon be, fundamentally changed.
The aboriginal cultures and economies that have developed around the harvest of marine mammals,
waterfowl, fish and invertebrates from this marine system are most directly affected. The scope and
significance of some of the reasonably foreseeable changes are potentially very large. Reductions in the
volume and duration of the seasonal ice cover and the cumulative impacts of hydroelectricity
development have the potential to fundamentally change the freshwater budget of the complex and, in
turn, the stratification, circulation, availability of nutrients, biological productivity and food webs in this
marine ecosystem. Changes in the amounts and timing of the freshwater components and nutrient
contents of waters leaving Hudson Bay have potentially very important implications for the productivity
and circulation of the Labrador Sea and North Atlantic.
The Hudson Bay Complex is big—indeed, very big! With an area of 1,242,000 km² it is the world’s largest
seasonally ice-covered inland sea and is slightly larger than the Province of Ontario. Each year about 940
km³ of freshwater is discharged into the system via the rivers along its coastline. This volume of freshwater
is comparable to the combined annual discharges of the Mackenzie and St Lawrence Rivers and almost
one quarter of the combined discharges from all the rivers emptying into the Arctic Ocean and its
associated regional seas. The Hudson Bay watershed is correspondingly huge, covering an area in excess
of 4,000,000 km² including all of Manitoba and parts of Quebec, Ontario, Saskatchewan, Alberta and
Nunavut, as well as portions of Minnesota, North Dakota, South Dakota and Montana.
The largest population of beluga whales (in excess of 50,000 individuals) on the planet spends much of
the summer season in southwestern Hudson Bay, primarily in the Nelson, Churchill and Seal River
estuaries where it feeds primarily on capelin (Kelley, Loseto, Stewart & Yurkowski, 2010). There are also
sizeable populations of narwhales and bowhead whales, especially in Foxe Basin and Northern Hudson
Bay (Higdon & Ferguson, 2010). Killer whales are increasingly observed in the Hudson Bay Complex
(Ferguson et al., 2010), possibly as a result of the reduced ice cover in Hudson Strait and elsewhere in the
system that facilitates their movement from the Labrador Sea. The world’s most southerly populations of
polar bears occur along the Manitoba, Ontario and Quebec coastlines (Peacock, Derocher, Lunn, &
Obbard, 2010), where, at least until recently, the seasonal ice cover has enabled them to successfully hunt
the ringed seals that live and reproduce on the sea ice. Enormous numbers of shorebirds and waterfowl
migrate through the region and nesting, feeding and staging areas of national and international
significance occur within the region.