Transcript Using Climate Data in Fisheries Stock Assessments

Using Climate Information in
Fisheries Stock Assessments
(with a focus on Pacific Whiting)
Ian Taylor
SMA 550: Climate Impacts
on the Pacific Northwest
Outline
1.
2.
3.
4.
5.
Stock Assessment Background
Example Species: Pacific Whiting
1999 Pacific Whiting Stock Assessment
Climate Impacts
Incorporating Climate Information into
Stock Assessments
Stock Assessment Background
• Sustainable Fisheries Act mandates the
National Marine Fisheries Service (NMFS) to
provide the best available scientific
information on which to base management
decisions about U.S. fisheries.
• NMFS provides this information in the form of
Stock Assessments
• Assessments are presented to the Pacific
Fisheries Management Council
Stock Assessment Background
• Basis for determining catch limits as well as
evaluating the success of previous
management techniques
• Use increasingly complex models
• Incorporate data from:
–
–
–
–
surveys (trawls, acoustic, etc.)
commercial catches
biological information
climate measurements and predictions?
Stock Assessment Background
• Basis for determining catch limits as well as
evaluating the success of previous
management techniques
• Use increasingly complex models
• Incorporate data from:
–
–
–
–
surveys (trawls, acoustic, etc.)
commercial catches
biological information
climate measurements and predictions?
Stock Assessment Background
• Status of 82 West Coast groundfish species
(relative to target abundance in 1998)
– above
4
– near
6
– below
1
– overfished 5
– ???
66
Stock Assessment Background
• Status of 82 West Coast groundfish species
(relative to target abundance in 1998)
– above
4
– near
6
 Pacific Whiting
– below
1
– overfished 5
– ???
66
Example Species: Pacific Whiting
Example Species: Pacific Whiting
• Mostly made into surimi (Krab)
• Caught in midwater trawls off West Coast of U.S. and
Canada
• Allowable Biological Catch (ABC) was 300,000
metric tons in 1998
• U.S. lands 80% of ABC
• Canada lands 30% of ABC
• Spawns in relatively warm water (California?)
• Adults migrate to colder water (WA/BC)
Example Species: Pacific Whiting
1999 Pacific Whiting Stock Assessment
• Single coastal stock
• Age structured model
• Data included:
–
–
–
–
–
Total catch from US and Canadian fisheries
U.S. acoustic/midwater trawl survey
U.S. bottom trawl survey
Canadian acoustic survey
Larval rockfish survey
1999 Pacific Whiting Stock Assessment
• Single coastal stock
• Age structured model
• Data included:
–
–
–
–
–
Total catch from US and Canadian fisheries
U.S. acoustic/midwater trawl survey
U.S. bottom trawl survey
Canadian acoustic survey
Larval rockfish survey
CV
0.05
0.10
100
100
10
1999 Pacific Whiting Stock Assessment
• Single coastal stock
• Age structured model
• Data included:
–
–
–
–
–
Total catch from US and Canadian fisheries
U.S. acoustic/midwater trawl survey
U.S. bottom trawl survey
Canadian acoustic survey
Larval rockfish survey
All considered to be independent
CV
0.05
0.10
100
100
10
1999 Pacific Whiting Stock Assessment
• Projections are extremely uncertain due to
unpredictable recruitment
• Projections do not include the potential for
spatial changes in the population
0.5
Canadian acoustic survey
U.S. acoustic survey
Estimated biomass from the model
0.0
Relative biomass
1.0
Climate Impacts
1986
1988
1990
1992
1994
1996
1998
Climate Impacts
• “During El Niños a larger proportion of the
stock migrates into Canadian waters.”
– NMFS
• “Large changes in coastal ocean conditions in
the past few years have had big ecosystem
impacts”
– Nate Mantua
• Age 1 and 2 fish were relatively small in 1998
Incorporating Climate Information into Stock Assessments
• Don’t throw away data—use more
– Quantify change in distribution due to ENSO/PDO
– Adjust surveys based on this information
• Improve survey accuracy
– Survey where the fish are
• Include climate data in spawner-recruit
relationships
Incorporating Climate Information into Stock Assessments
• Include climate forecasts in short-term
projections
• Multiple long-term projections based on
alternative climate scenarios
FOR MANAGERS:
• Does it make sense to have constant catch
rates in the U.S. and Canada?