Where is Rivers Inlet?Rivers
Inlet is a fjord located on the central coast of British Columbia
(BC), Canada. It is in the heart of one of the world's largest
remaining tracts of temperate rainforest, and it is the
traditional territory of the Wuikinuxv (Oweekeno) First Nations. Rivers Inlet epitomises a unique coastal environment, with rich and diverse
marine resources that have sustained First Nations people for
thousands of years, and that continues to sustain high value commercial and
recreational fisheries, aquaculture, forestry, transportation and
tourism into the 21st century (1,2).
The Rivers Inlet ecosystem
Rivers Inlet is approximately
40km long and 3km wide. Together with two major side branches
(Moses and Drainey inlets), it represents a significant area of coastal
marine habitat. Deeply scoured during glacial periods, the fjord
is generally uniformly deep (200-300m) and has a relatively deep
sill at its mouth, before opening into Queen Charlotte Sound.
The head of the inlet is formed by an upper sill above which the
U shaped glacial valley continues eastwards as Owikeno Lake,
equal in size to the inlet itself. Numerous rivers and streams
flow into the lake, draining an extensive glacial fed watershed
of ~4100 km2. The lake feeds into the inlet proper via the short Wannock River.
Map of the Rivers Inlet system
quantities of glacial silt entering the lake, clearly evident in
satellite photographs, and low nutrient levels, make Owikeno Lake quite
unproductive (oligotrophic). Despite this low productivity the
Owikeno watershed has provided excellent spawning (river) and
rearing (lake) habitat for
sockeye salmon [life cycle video / text]
and historically Rivers Inlet had the third largest
sockeye salmon fishery in British Columbia. The Rivers Inlet ecosystem
also supports coho, chum, chinook and pink salmon.
However, the annual return of sockeye salmon is now a shadow of what it used to be [see below], and this decline has had significant repercussions further up the food web.
Although the annual salmon runs still draw many top marine predators to the inlet (e.g.,
orcas and seals), and support large populations of grizzly and black
bears, evidence suggests that bear populations are in decline.
Increased encounters between humans and bears in recent years,
particularly in the fall, are a strong indication that bears are
struggling to meet their pre-winter energy requirements.
inlet itself is highly productive, with a significant spring and summer
phytoplankton bloom supporting large quantities of zooplankton. Forage
fish, such as sand lance and herring, feed on the plankton stocks and
these species in turn attract higher order predators, including dolphins and humpback whales.
Forage fish and benthic invertebrates support other commercially important fish such as halibut,
lingcod and rockfish, although stocks of these species are currently depleted.
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The coast-wide decline of British Columbia sockeye
Rivers Inlet has experienced one of the most
dramatic sockeye salmon fishery collapses witnessed on the coast of British Columbia,
epitomises an alarming province wide trend for this species. Approximately 75% of
northern and central BC coast sockeye salmon stocks are listed as depressed, declining,
or of unknown status (2). This is of major concern as sockeye salmon is a keystone
species in the ecology of many BC watersheds, a major component of the
commercial fishery, and a focal point of the economy, sustenance, and culture
of First Nation’s communities. Therefore, urgency is required in efforts
to understand and manage the cause of these declines.
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The collapse of the Rivers Inlet sockeye salmon fishery
Rivers Inlet was one of the most productive sockeye salmon based ecosystems in British Columbia, vying with the Skeena River
for position as the second largest commercial fishery for this species
Population highs of more than 3 million fish have been recorded and for
the 20th century an annual average fishery catch of greater than 750
was maintained. However, in the 1970's the Rivers Inlet sockeye
population began to decline. Despite reduced harvest rates in the
part of an adaptive management strategy, stocks continued to decline
and the commercial fishery was closed in
1996. In 1999 the stock reached a record low of ~ 3600 fish, just 0.1%
historic levels. Although the commercial fishery has remained closed
1996, with only a small amount of fishing permitted by the
Wuikinuxv First Nations for cultural purposes, the stock has not
recovered to harvestable
levels (a minimum of 200 000 spawners).
caption: The decline in
returns of Rivers Inlet sockeye salmon. Catch has been estimated from
of the commercial fishery in the late 1800’s. To this, escapement
(the numbers of fish escaping the fishery and observed on the
estimates have been added from just before 1950 to the present (figure courtesy of Rick Routledge).
Causes of sockeye declineSalmon
have complex lifecycles,
with both freshwater and marine phases, involving
lengthy migrations [life cycle video / text]. The factors affecting their survival are
and varied. Currently, one of the leading hypotheses for sockeye
declines in British Columbia,
including the Rivers Inlet population, is increased mortality in the
early marine phase of their life cycle (1,2). Juvenile sockeye salmon
feed on plankton and it is therefore expected that changes in the
seasonal timing of plankton blooms, affecting the quality and quantity of
plankton prey available to them, is critical to their growth and
development in coastal waters before migration into the open ocean.
The Rivers Inlet Ecosystem StudyThe Rivers Inlet Ecosystem Study (RIES), funded by the Tula foundation,
was initiated in 2008 to build on the research platform laid by Rick
Routledge’s team at Simon Fraser University (SFU) between 2002
and 2007. A collaboration between SFU and the University of British Columbia, the
RIES developed around the objective to:
"Understand the dynamics of spring productivity and how it affects the growth of juvenile sockeye salmon."
productivity is affected by many factors, including the weather (e.g.,
sunlight available for photosynthesis, wind induced mixing of the sea
surface, freshwater runoff - rain and snow melt - and its
seasonal timing) and ocean conditions. The juvenile sockeye do not use
the spring production directly, but feed on the zooplankton
grazers of phytoplankton. An understanding of the dynamics of spring
production, and how it affects juvenile
sockeye growth therefore, by necessity, requires a
multidisciplinary approach that investigates as many
components as possible of the pelagic ecosystem. In addition
to present day ecology, paleoecogical investigations currently
underway at SFU and Fraser Valley University are being used
to help us understand the historical ecology of this
ecosystem. Working closely
Wuikinuxv First Nations, the RIES objectives are currently being
tackled through multiple
Future work In 2004 the Canadian government formally recongnised the uniqueness and value of the BC central coast when it was
designated one of five Large Ocean Management Areas for coordination of
integrated management policy. The Pacific North Coast Integrated
Management Area (PNCIMA) stretches from northern Vancouver Island to
the British Columbia / Alaska border. However, this region is
facing increasing pressure from many of the uses listed above, and
growing interest in oil and gas exploration and development (1,3).
Vulnerability to these direct human impacts is exacerbated, and
management complicated, by the effects of climate change, including
warming, changing productivity regimes, anoxic bottom waters, shifting
oceanic currents, and more variable weather patterns (1,3,4).
and pressures faced at Rivers Inlet are symptomatic of
those throughout coastal British Columbia, related to resource
climate and natural ecosystem change. Rivers Inlet is an ideal focal
area for researching and understanding these ecological changes, their
social and economic impacts, and developing effective integrated
management strategies. As such the relevance of the RIES reaches
far wider than Rivers Inlet itself. Future research aims to not
only build on our understanding of the Rivers Inlet ecosystem in its
present state, but also to reconstruct its historical ecology and
produce modeling tools to predict future change and inform
ecosytem based management, and to develop its scientific outputs for
social and economic upliftment.
References1. McKinnell S.M. et al., 2001, North American Journal of Fisheries
Management, 21(4): 774-791
2. Levy D., 2006, Sockeye salmon report, The Sierra Club of Canada
– BC Chapter. [PDF].
3. Montenegro A. et al., 2009, Canadian Parks and Wilderness Society, pp. 62
4. State of the Oceans – Pacific Region, 2007, Canadian Science Advisory Secretariat Science Advisory Report 2008/028 [PDF]