Research on Sahtu (Great Bear Lake) fisheries and the aquatic ecosystem: 2000-2015 K.L. Howland, C.P. Gallagher, L. Chavarie, Y. Janjua, M. LeClaire D. Leonard, C. Podemski, D. Simmons, W. Bayha, R.F. Tallman, and W.M. Tonn
Field Work 2000-2014 Jane Baptiste Isreal Neyelle Doug Baton Lyle Neyelle Moise Beyonnie Zoya Pawlychyn Morris Betsidea Aaron Swietzer Gloria Gaudette Clyde Takazo Les Harris Lucy Ann Takazo Bruce Kenny Freddie Vital Greg Kenny Cameron Yukon Hughie Kenny Cyre Yukon Jonas Kenny Tyrone Yukon Mike Legge Charity Yukon Morris Lennie Chris Yukon Mike Low Jean-Guy Chavarie George Menacho Archie Vital Morris Modeste John Betsidea Nathan Modeste Barbara Yukon Melissa Lindsay
DEASE ARM PLUMMERS GREAT (TAH – 2000) BEAR LAKE LODGE ARCTIC CIRCLE LODGE SMITH ARM (TAH – 2500) BRANSON’S LODGE GREAT BEAR TROPHY LODGE PLUMMER’S GREAT BEAR LAKE LODGE GREAT BEAR (Original location LODGE closed 1968) KEITH ARM KEITH ARM McVICAR ARM (TAH – 1500) DELINE (FORT FRANKLIN) GREY GOOSE LODGE Subsistence use only Areas fished by lodges Management zone boundaries
1) Fisheries independent monitoring of relative abundance, catch rates and biological indicators of harvested and unharvested large bodied fish species in all areas of GBL Track changes that may occur with changing harvest levels, development and the environment (cumulative impacts) Stock assessment - model sustainable harvest levels
Tugacho (Dease Arm) 2005, 2010, 2015 Tirato Sahtu (Smith Arm) Kwit la (Great Bear 2006, 2011, 2016 (McTavish Arm) Lake) 2004, 2009, 2014 Tirato Turili (Keith Arm) McVicar Arm 2000-2007, 2012 2003, 2008, 2013
Methods multi-mesh and large (5 inch) mesh gillnets (for consistency with previous studies) Sample fish for biological characteristics (length, weight, age, sex, maturity, etc.) dryfish from sampled fish in remote camps, for community distribution Collect environmental information: temperature, depth, pH, clarity, weather conditions Local sampling technicians (2-5) from the community of Deline hired to assist with the field component each year.
Biological Sampling for Fish muscle muscle Length Weight otoliths Diet Diet Life-history gonads gonads pectoral fin Genetics + Life-history (age) gill rakers Morphology stomach stomach Life-history (fecundity, maturity) Diet Diet
Trout Mean Age – Lake-wide comparison Mean (+1 std) 1984-85 Mean (+1 std) 2000-2006 Mean (+ 1 std) 2007-2011 Mean (+ 1 std) 2012-2016 40 30 Age (years) 20 10 0 Keith McVicar McTavish Dease Smith Area of Great Bear Lake
Females Lake Trout Maturity Spawner % Spawners in adult component of population: Smith Arm: Female 29%, Male 53% Resting Dease Arm: Female 48%, Male 77% McTavish Arm: Female 18%, Male 52% Keith Arm: Female 30%, Male 55% McVicar Arm: Female 43%, Male 82% Males Spawner Minimum age at maturity: Female Male Smith 10 13 Dease 12 12 Resting McTavish 15 14 McVicar 14 13 Keith 16 13
• Annual reporting to SRRB and DRRC, meetings • Contributions to associated follow-on studies • Need for formal science review (DFO Regional Advisory Process (RAP) meeting) and publishing through DFO Canadian Science Advisory Secretariat. • Recommend continued monitoring to allow for detection of change
2) Compare genetic relationships among fish from different arms of GBL to determine stock structure as it relates to current management zones within GBL Lake trout Harvested stocks (fin clips from lodges): • Lack of differentiation among arms due to low levels of gene flow (12/596 = first generation migrants), recent colonization and large founding populations Harris, L., K. Howland, M. Kowalchuk, R. Bajno, M. Lindsay and E. B. Taylor. 2013. Microsatellite and mtDNA Analysis of Lake Trout, Salvelinus namaycush , From Great Bear Lake, Northwest Territories: impacts of historical and contemporary evolutionary forces on Arctic ecosystems. Ecology and Evolution 3:145-161.
2) Compare genetic relationships among fish from different arms of GBL to determine stock structure as it relates to current management zones within GBL Lake trout Different morphotypes (assessment samples): • morphotypes of Lake Trout from GBL are genetically differentiated • but…they are still genetically more similar to one another than to outside populations • colonized GBL from a single glacial refugium – intra-lake divergence Harris,L., L. Chavarie, R. Bajno, K. Howland, S. Wiley, W. Tonn, and E. Taylor. 2014. Evolution and origin of sympatric shallow-water morphotypes of Lake Trout, Salvelinus namaycush , in Canada's Great Bear Lake. Heredity (avail. online, accepted July 14, 2014 )
2) Compare genetic relationships among fish from different arms of GBL to determine stock structure as it relates to current management zones within GBL Cisco Different morphotypes (assessment samples): • similar to trout, morphotypes of cisco from GBL are genetically differentiated • morphs within a lake genetically more similar to one another than to outside populations • similar pattern in lakes across North America • only 2 areas of GBL analysed Turgeon, J., S.M. Reid, A. Bourret, T.C. Pratt, K.L. Howland, A.M. Muir, J.D. Reist. Morphological and genetic variation in Cisco ( Coregonus artedi ) and Shortjaw Cisco ( C. zenithicus ): Evidence for repeated sympatric origin of Shortjaw Cisco in deep inland lakes. Conservation ( submitted )
2) Compare genetic relationships among fish from different arms of GBL to determine stock structure as it relates to current management zones within GBL Further work • Lake wide analysis of cisco • Analysis of whitefish
3) Documentation of morphological variation and ecological roles of zls major fish species: Lake Trout Growth 1000 2002 Fork length (mm) 1000 mm 800 600 600 mm 400 200 0 0 5 10 15 20 25 30 35 40 45 Age (years)
N=555 adults 3 morphs identified UPGMA cluster Body Shape Head Shape Fin and Body Lengths 88-93% classification success Discrimination Analysis: 4 th morph: rare; difficult to identify as a distinct cluster, but distinguished using MANOVA Chavarie, L., K. Howland and W. Tonn. 2013. An exceptional case study of Lake Trout, Salvelinus namaycush , diversity: the coexistence of multiple shallow-water morphotypes in Great Bear Lake, NT. Transactions of the American Fisheries Society 142:814-823.
Dease Smith Significant body shape variation McTavish within a morph across arms Suggests parallel evolution among arms or several colonization events Keith McVicar ƛ = 0.24 ƛ = 0.075 ƛ = 0.078 ƛ = 0.086 ƛ = 0.17 ƛ = 0.094 p≤ 0.01 (59 %) p≤ 0.01 (81 %) p≤ 0.01 (74 %) p≤0.01 (73%) p≤ 0.01 (88 %) p≤ 0.01 (72 %) DF2 CV2 Morph 1 Morph 3 Morph 2 DF1 CV1 Chavarie, L., K. Howland, L. Harris and W.Tonn. 2014. Polymorphism in Lake Trout in Great Bear Lake: intra-lake morphological diversification at two spatial scales. Biological Journal of the Linnaean Society , (avail. online, accepted July 24, 2014 )
Sahba forms in shallow water ( Tahdǝ gosahba ́ ) Dáré lı̨ GoSahba ́ (named for outflow of Great Bear Lake) Sahba that will grow large – scientists identify this type as having a longer head and smaller fins. Sahba k’áht’a (fin) – scientist identify this type as having a shorter head and intermediary fins. Sahba k’áht’a Nedǝ́ * ( with long fın) Also lives ın deep water – scientists identify this type as having a deeper caudal peduncle and longer fins Sahba Yéhkw’ e̩nę́ Hı ̨ zégǝ * (curved jaw) A newcomer (~20 yrs.) – scientists identify this type by the large lower jaw; it is rare and mostly in one area of Great Bear Lake S̨ ahba Dek’odze (red) Only seen in the spring and in fall in the shore – not identified as a distinct type by scientists; known as a spawner *New term developed as cross-cultural tool for dialogue about morphology ; forms known but no Dene name existed
Diet- Fatty acids Morph 1 Morph 2 Significant distinction among morphs, especially Morph 3 Morphs 2 and 4 DF2 Some overlap among Juvenile Morphs 1, 3 and juveniles Morph 4 Discriminant analysis: λ = 0.031 p≤ 0.01 DF1 Chavarie, L., K. Howland C. Gallagher and W. Tonn. 2014. Fatty acid signatures and stomach contents of four sympatric Lake Trout: assessment of trophic patterns among morphotypes in Great Bear Lake. Ecology of Freshwater Fish ( avail. online, accepted September 17, 2014 )
Diet: Stomach contents 100 100 100 Morph 1 Morph 2 90 90 90 100 80 80 90 80 70 70 80 70 60 60 70 60 50 50 60 50 50 40 40 40 40 30 30 30 30 20 20 20 20 10 10 Relative index 10 10 0 0 0 0 Fish Invertebrate Benthic Pelagic Surface Fish Invertebrate Benthic Pelagic Surface Fish Invertebrate Benthic Pelagic Surface Fish Invertebrate Benthic Pelagic Surface 100 100 Morph 3 Morph 4 100 100 90 90 90 90 80 80 80 80 70 70 70 70 60 60 60 60 50 50 50 50 40 40 40 40 30 30 30 30 20 20 20 20 10 10 10 10 0 0 0 Fish Invertebrate Benthic Pelagic Surface Fish Invertebrate Benthic Pelagic Surface 0 Fish Invertebrate Benthic Pelagic Surface Fish Invertebrate Benthic Pelagic Surface
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