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Devin Flawd PhD Student Centre for Fisheries Ecosystems Research, - - PowerPoint PPT Presentation
Devin Flawd PhD Student Centre for Fisheries Ecosystems Research, - - PowerPoint PPT Presentation
Devin Flawd PhD Student Centre for Fisheries Ecosystems Research, Marine Institute of Memorial University of Newfoundland 1 Problem and Background Groundfish stock collapse Flatfish stock declines in the Grand Banks Collapse in the
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Problem and Background
´Groundfish stock collapse ´Flatfish stock declines in the Grand Banks ´Collapse in the late 1980’s, early 1990’s ´Moratorium enacted in 1995 ´Differential recovery rates post-collapse
Yellowtail flounder American plaice
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(Parsons et al. 2015) (Dwyer et al. 2014) Yellowtail flounder American plaice
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Problem and Background
´Flatfish stock declines in the Grand Banks
´Commercially important species - exploitation with bycatch ´Collapse in the late 1980’s, early 1990’s ´Differential recovery rates post-collapse (moratorium enacted in 1995) ´Role of life history characteristics
Yellowtail flounder American plaice
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Fisheries/Species Overview
´ Overfished in NAFO Divisions 3LNO ´ 30+ years, no recovery ´ Bycatch in yellowtail fishery ´ 15-20 years, 1000 mm TL ´ Depth: 100-500, up to 1000 m ´ Temperature: -1 – 4°C ´ Overfished in NAFO Divisions 3NO ´ Rapid recovery after 5 years ´ MSC certified since 2011 ´ 10-12 years, 500 mm TL ´ Depth: 25 – 200 m ´ Temperature: 3 – 5°C
Yellowtail flounder American plaice
Spatial response in recovery?
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Spatial Dynamics
´Spatial response to population change
´Density-Range relationships
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Key Concepts
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From Shepherd and Litvak (2004)
High abundance Low abundance
Core area Total area
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Research Questions
´For each species:
´Biomass associations: Depth and Bottom Temperature ´Species geographic range ´Spatial scale
´Total area vs. Core areas
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Methods
´Canada Department of Fisheries and Oceans
´Long-term bottom trawl multispecies survey ´1985-2015 ´NAFO divisions 3LNO
´Geographic Range
´Area of occupancy (trawl area)
´Spatial Scales
´Kernel density estimation (biomass)
´Biomass associations: Depth and Bottom Temperature
´Generalized additive modeling ´Deviance explained
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Species
Yellowtail Flounder
Time Scale (Years)
1985-1992 1993-2000 2001-2008 2009-2015 American Plaice
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(Parsons et al. 2015) (Dwyer et al. 2014) Yellowtail flounder American plaice
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Spatial Scale
Total Top 50% Top 25% Top 10%
Time Scale (Years)
1985-1992 1993-2000 2001-2008 2009-2015
Species
Yellowtail Flounder American Plaice
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Spatial Scales
25% 10% 50%
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Seasonality
Combined Fall Spring
Spatial Scale
Total Top 50% Top 25% Top 10%
Time Scale (Years)
1985-1992 1993-2000 2001-2008 2009-2015
Species
Yellowtail Flounder American Plaice
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Spatial Scale Maps
25% 10% 50%
1985-1992 (Fall) 1985-1992 (Spring) 2009-2015 (Fall) 2009-2015 (Spring)
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25% 10% 50%
1985-1992 (Fall) 1985-1992 (Spring) 2009-2015 (Fall) 2009-2015 (Spring)
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Geographic Range
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Generalized Additive Models
Canadian Conference for Fisheries Research 2017
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21 Canadian Conference for Fisheries Research 2017
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Time
Core Area Total Area Depth Temp
Deviance Explained
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Time
Core Area Total Area Depth Temp
Deviance Explained
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Key Concepts
From Shepherd and Litvak (2004)
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Bottom.Temp
- 1.6 – -0.4
- 0.4 – 0.8
0.8 – 2 2 – 3.2 3.2 – 4.4 4.4 – 5.6 5.6 – 6.8 6.8 – 8
1985-1992 (Fall) 1985-1992 (Spring) 2009-2015 (Fall) 2009-2015 (Spring)
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Why is this important?
´Fisheries management
´Stock spatial structures
´Temperature/depth associations ´Contingent sub-populations
´Cumulative effects (F, diet, traits) ´Consider mixed fisheries
´Further Research Questions
´Age/length dependencies ´Reproduction/spawning
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Advisor
- Dr. Jonathan Fisher – MUN
Collaborators
- Dr. Noel Cadigan – MUN
- Dr. Dominique Robert – UQAR
- Dr. Rick Rideout - DFO
Thank You!
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Methods
´ Area of occupancy ´ Kernel density estimation
´Bandwidth = ~20 km²
´ Generalized additive modeling
´ (ℎC) 𝑍
F = 𝛾H
´ (ℎI) 𝑍
F = 𝛾H + 𝑡 𝐸𝑓𝑞𝑢ℎ + 𝑡 𝐶𝑝𝑢𝑢𝑝𝑛 𝑈𝑓𝑛𝑞 + 𝑀𝑏𝑢𝑗𝑢𝑣𝑒𝑓 +
𝑀𝑝𝑜𝑗𝑢𝑣𝑒𝑓 + 𝑡(𝑍𝑓𝑏𝑠) ´ (ℎ\]) 𝑍
F = 𝛾H + 𝑡 𝐸𝑓𝑞𝑢ℎ
´ ℎ\^ 𝑍
F = 𝛾H + 𝑡 𝐶𝑝𝑢𝑢𝑝𝑛 𝑈𝑓𝑛𝑞
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𝐸 = 𝐸𝑓𝑤 ℎ\ − 𝐸𝑓𝑤(ℎI) 𝐸𝑓𝑤(ℎC)
From Wood (2006)
𝐵𝑝𝑃 = c c 𝑏F 𝑜F ∗ 𝐽
f g f F
𝑥ℎ𝑓𝑠𝑓 𝐽 = 1 𝑗𝑔 𝑧g ≥ 1 0 𝑝𝑢ℎ𝑓𝑠𝑥𝑗𝑡𝑓
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1985-1992 2009-2015 Bottom Temperature Depth
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1985-1992 2009-2015 Bottom Temperature Depth
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Chapter 2: Spatiotemporal changes in yellowtail flounder and American plaice populations on the Grand Bank using comparative spatial analysis techniques
´ Results
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AP YF
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Results
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1985-1992 2009-2015 3L 3N 3O 3L 3N 3O Bottom Temperature