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Apr 08, 2023 139 likes •387 views

Sampling approaches for understanding fish community dynamics and environmental associations in the Great Lakes of the Northwest Territories, Canada K.L. Howland, X. Zhu, D. Leonard, T.J. Carmichael, L. Chavarie, C.P. Gallagher, Y. Janjua, C.

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K.L. Howland, X. Zhu, D. Leonard, T.J. Carmichael, L. Chavarie, C.P. Gallagher,

Y. Janjua, C. Podemski, E. Smith, R.F. Tallman, and W.M. Tonn

Sampling approaches for understanding fish community dynamics and environmental associations in the Great Lakes of the Northwest Territories, Canada

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1 3 4 2 ALASKA

CANADA

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Mackenzie River Basin

Uranium Mine Diamond Mine Gold Mine Hydro Dam Pulp Mill Coal Mine Oil Sands Mine Remediation

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High latitude areas have experienced disproportionate levels of climate warming in recent years

Surface temperature anomaly for January 2010 relative to the mean for 1951–1980 (Hoegh-Guldberg & Bruno 2010, NASA GISS)

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Despite their significance and the potential for impacts

to these lakes, there is minimal knowledge of their ecosystems

Limited studies to date have focussed on harvested

fish species

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Objectives

Design surveys that:

Build on existing time series for large-bodied

fish species to address questions regarding stock status & sustainable harvest levels

Address knowledge gaps regarding the lake

ecosystems & the relationships of different ecosystem components to fisheries production

Develop baseline from which to assess

impacts of climate change & other anthropogenic drivers on lake ecosystems & harvested fish

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Considerations in study design

Large surface area (Great Slave

28,930 km2, Great Bear 31,080 km2)

Remote, limited infrastructure
Short navigable season
Small boats
Limited resources (financial and

human)

Minimal backgound information,
esp. habitat; crude bathymetry

Great Bear Lake July 25, 2004

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ARCTIC CIRCLE LODGE KEITH ARM McVICAR ARM (TAH – 1500) GREAT BEAR LODGE BRANSON’S LODGE PLUMMERS GREAT BEAR LAKE LODGE GREAT BEAR TROPHY LODGE DELINE (FORT FRANKLIN) GREY GOOSE LODGE PLUMMER’S GREAT BEAR LAKE LODGE (Original location closed 1968) KEITH ARM

Subsistence use only Areas fished by lodges

DEASE ARM (TAH – 2000) SMITH ARM (TAH – 2500)

Management zone boundaries

Great Bear Lake

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Great Slave Lake management zones

2011

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Methods - Ecosystem Sampling Design

Inshore (0-2 m) Littoral (3-20 m) Pelagic-profundal (21-50 m) Pelagic-profundal (51-100 m) Pelagic-deep profundal (100-150 m)

McVicar Arm (2013)

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5 10 15 20 25 30 35 40 45 Red (0-2 m) Yellow (3-20 m) Green (21-50 m) Purple (51-100 m) Blue (100+ m) Number of taxonomic groups in a sample Sampling strata

Kick Net

Benthic invertebrate diversity Great Bear Lake 2012

Ponar Grab

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10 20 30 40 50 60 70 80 90 100 Red (0-2 m) Yellow (3-20 m) Green (21-50 m) Purple (50-100 m) Blue (>100 m) Average frequency (%) Sampling strata Platyhelminthes Nematoda Annelida Mollusca Malacostraca Copepoda Ostracoda Arachnida Insecta

Benthic invertebrate community composition Great Bear Lake 2012

Kick Net Ponar Grab

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Camp 2 Camp 1 McVicar Arm, Great Bear Lake 2013

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Depth Zone Water quality Zooplankton (plankton net) Benthic Inverts (Kick, Ponar grab) Fish (gill nets) 0-2 m

 

Seine only 3-20 m

  

 21-50 m



Lower/ Upper



Lower/ Upper 51-100 m



Lower/ Mid/ Upper



Lower/ Mid/ Upper 100+ m



Lower/ Mid/ Upper



Lower/ Mid/ Upper

Composition, Abundance, Biomass Composition, Abundance, Biomass

Composition, Abundance, Biomass, Demographics

Temp, Chla, DO, pH, Tubidity, Conductivity

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Temporally intensive community-based monitoring

Off shore (60 m depth) temperature array; zooplankton; benthic invertebrates Nearshore benthic/ terrestrial invertebrates

Deline Great Bear Lake Keith Arm

2011

Annual

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Epilimnion Metalimnion Hypolimnion

Water Temperature – Great Bear Lake

3-20 m 21-50 m 51-100 m 100+ m

Keith Arm (2012) McVicar Arm (2013)

0-2 m

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Great Bear Lake Development of thermocline in 2012 & 2013

(Johnson 1975 JFRBC)

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Epilimnion Metalimnion Metalimnion Hypolimnion

Chlorophylla – Great Bear Lake

3-20 m 21-50 m 51-100 m 100+ m Keith Arm (2012) McVicar Arm (2013) 0-2 m

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Benthic invertebrate abundance Great Bear lake 2012

100 200 300 400 500 600 700 800 900 1000 Red (0-2 m) Yellow (3-20 m) Green (21-50 m) Purple (51-100 m) Blue (100+ m) Number of aquatic invertebrates in a sample Sampling strata

Kick Net Ponar Grab

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Shallow  Deep Low  High productivity

Shallow and warm water

Low productivity Shallow water High productivity Deep and cold water Higher productivity Deep water Low productivity Higher dissolved oxygen

Associations of Fish with Environment (Great Slave Lake 2013)

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Decision Making

Sustainable Harvest Levels
Population dynamics models
Adaptive management
Inform management of species (e.g. salmonids ) where there is high

polymorphism & intraspecific diversity in demographic traits

Predictive ecosystem models
State of ecosystem/fisheries, future impacts, climate change
Trans boundary agreements
Influence decision making in the South
EA processes
Comprehensive baseline, standardized monitoring protocols

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Acknowledgements

NWT Cumulative Impacts Monitoring Program
Sahtu Renewable Resources Board
Deline Renewable Resources Council
Deline Lands and Finance Corporation
GNWT Renewable Resources Deline
DFO Hay River & Yellowknife
Polar Continental Shelf Project
Natural Sciences and Engineering Research Council
Canadian Circumpolar Institute
Field Work 2012: Darren Kenny, Bobby Modeste, Allison Tatti, Gerald Tutcho,

Archie Vitale; DFO Winnipeg - Dave Boguski, Kristin Hynes

Field Work 2013: Chris Yukon, Archie Vitale, Allison Tatti, Morris Betsidea,

Isodore Betsidea; DFO Winnipeg - Kristen Adair