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Regime Shifts
Anne B. HollowedSenior Scientist
Alaska Fisheries Science Center
2
Definitions (Overland et al. 2008)
• Displacement—Inspection of a time series —Statistical difference in mean given observed variance
• Mechanism—Identification of underlying processes (discrete states)—Non-linear/deterministic
• External—Systematic changes in ecosystems—Climatic or human—Changes in state = phase transitions
3
Climate Indices (Bond & Overland)
4
Mantua et al. 1997
5
1972-76
1977-81
SSTSLP
Bond et al. 2004
99-02
72-76
77-81
2003
6
Mechanistic conceptual framework (Emanuele DiLorenzo, PICES)DiLorenzo et al. 2008 GEOPHYSICAL RESEARCH LETTERS, VOL. 35
Also see Wooster and Hollowed 1995 CJFAS
7
Mechanisms: Dominant modes of North Pacific decadal variability (Emanuele DiLorenzo, 2008 &PICES presentation)
SST – Sea Surface Temperature anomaly, SSSa – Sea Surface Salinity anomaly, SSHa Sea Surface Height anomaly
8
-6-4-202468
1950
1954
1958
1962
1966
1970
1974
1978
1982
1986
1990
1994
1998
2002
Aleutian Low
Jan-
50
Jan-
55
Jan-
60
Jan-
65
Jan-
70
Jan-
75
Jan-
80
Jan-
85
Jan-
90
Jan-
95
Jan-
00
58N, 170W
54N,162W
56N, 138W
44N, 126W
32N, 120W -2 .50-2.00-1.50-1.00-0.500.000.501.001.502.002.50
Date
Lo
cati
on
Temperature Anomalies 1958 -1999
-2.50--2.00 -2.00--1.50 -1.50--1.00 -1.00--0.50 -0.50-0.00
0.00-0.50 0.50-1.00 1.00-1.50 1.50-2.00 2.00-2.50
Nino-NorthHollowed et al 2001
9
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
-3
-2
-1
0
1
2
3Pacific Decadal Oscillation Index, Winter (DJF), 1901-2006
1977
1946
p = 0.1l = 15h = 1
AR1 = 0.21 (IP4, m = 9)
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
-3
-2
-1
0
1
2
3Pacific Decadal Oscillation Index, Winter (DJF), 1901-2006
2003
1989
1977
1962
1958
1949
1943
1935
p = 0.3l = 10h = 1
Displacement
Statistically significant shifts in means relativeto within-regime variance
(Rodionov 2004)
Depends on falsepositive parameter p, and time scale l
10
Systematic Changes in Ecosystems
• Rapid shift in species composition and/or abundance
• Rapid shift in dominance (scramble competition, Rice 2001)• Shift in carrying capacity• Shift in productivity• Shift in interaction strengthIs this necessary for species co-existence? Competition,
predation, environmental disturbance (Chesson2000)
11
Mechanisms
See Bakun 2010 J. Mar. Systems 79 361-
373 for review
Concepts of Biology
Carrying capacityLogistic growthLength – weightSpecies-areaDiversity and Latitude
Key factors
CompetitionDensity dependencePrey productionEnvironmental disturbancePredation – thermal tolerances – stability
Match-mis-match Cushing (1971, 1975, 1990)Connectivity – Member vagrant Sinclair (1988)
School trap (Bakun 2001)
Loopholes (Bakun and Broad 2003)
Ocean Triads- Bakun (1996)
Enrichment
ConcentrationRetention
12
20042003200220012000199919981997199619951994199319921991199019891988198719861985198419831982198119801979197819771976197519741973197219711970Year
1995BSPelagic Trawl Duration
1990BS Bottom Trawl Duration
1990AI Bottom Trawl Duration
1993Hook and Line Effort
1982Summer Bottom Temp.
1977FHS (R/S)
1975Rock sole (R/S)
1976ATF (R/S)
1973GT (R/S)
1977Northerns (R/S)
1960POP (R/S)
1964YFS (R/S)
1975RLKI Productivity
1976TBMU Productivity
1975BLKI Productivity
1980Total crab biomass
1982BS Richness
1964Pollock (R/S)
1977Cod (R/S)
1975AK Plaice (R/S)
1982Jellyfish biomass
1982BS Diversity
1982Total CPUE
1977Atka (R/S)
1951AOI
1976COMU Productivity
1970May SST
1978Herring recruits
1901PDO
1900Total salmon catch
1916Surface Winter Air Temp.
1962AI Trophic level of catch
1954Ice Cover Index
1954BS Trophic level of catch
20042003200220012000199919981997199619951994199319921991199019891988198719861985198419831982198119801979197819771976197519741973197219711970Year
1995BSPelagic Trawl Duration
1990BS Bottom Trawl Duration
1990AI Bottom Trawl Duration
1993Hook and Line Effort
1982Summer Bottom Temp.
1977FHS (R/S)
1975Rock sole (R/S)
1976ATF (R/S)
1973GT (R/S)
1977Northerns (R/S)
1960POP (R/S)
1964YFS (R/S)
1975RLKI Productivity
1976TBMU Productivity
1975BLKI Productivity
1980Total crab biomass
1982BS Richness
1964Pollock (R/S)
1977Cod (R/S)
1975AK Plaice (R/S)
1982Jellyfish biomass
1982BS Diversity
1982Total CPUE
1977Atka (R/S)
1951AOI
1976COMU Productivity
1970May SST
1978Herring recruits
1901PDO
1900Total salmon catch
1916Surface Winter Air Temp.
1962AI Trophic level of catch
1954Ice Cover Index
1954BS Trophic level of catch
Bering Sea/Aleutian Islands
1995
2000
1990
1985
1980
1975
1970 Legend
X>2.6
2.6>X>1.6
1.6>X>0.5
0.5>X>-0.5
-0.5>X>-1.6
-1.6>X>-2.7
no data
BS Pelagic Trawl DurationBS Bottom Trawl DurationAI Bottom Trawl Duration
Hook and Line EffortSummer Bottom Temp.
FHS (R/S)Rock sole (R/S)
ATF (R/S)GT (R/S)
Northerns (R/S)POP (R/S)YFS (R/S)
RLKI ProductivityTBMU ProductivityBLKI Productivity
Total crab biomassBS RichnessPollock (R/S)
Cod (R/S)AK Plaice (R/S)
Jellyfish biomassBS Diversity
Total CPUEAtka (R/S)
AOI COMU Productivity
May SSTHerring recruits
PDOTotal salmon catch
Surf. Winter Air Temp.AI Trophic levelIce Cover Index
BS Trophic level
Bolt 2006 REFM web site.
13
Gulf of AlaskaGulf of Alaska
Climate IndicesClimate Indices
andand
ShrimpShrimp--Trawl Trawl CatchesCatches
(Biomass)(Biomass)
(Anderson and Piatt, 1999)(Anderson and Piatt, 1999)
14
POLLOCK
-0.20
-0.100.00
0.100.20
0.30
COD
-0.20
0.00
0.20
0.40
0.60
GT
-0.20
0.00
0.20
0.40
ATF
-0.20
-0.10
0.00
0.10
0.20
ROCK SOLE
-0.40
-0.20
0.00
0.20 NORTHERNS
-0.10
0.00
0.10
0.20
YFS
-0.20
0.00
0.20
0.40
1960
1966
1972
1978
1984
1990
1996
2002
FH SOLE
-0.40
-0.20
0.00
0.20
0.4019
60
1966
1972
1978
1984
1990
1996
2002
POP
-0.40
-0.20
0.00
0.20
0.40
1960
1966
1972
1978
1984
1990
1996
2002
AI ATKA
-0.10
0.00
0.10
0.20
0.30
1960
1966
1972
1978
1984
1990
1996
2002
1976/77 shift 1988/89 shift Other shift
AK PLAICE
-0.50
0.00
0.50
1.00
1960
1966
1972
1978
1984
1990
1996
2002
Bering Sea
R/S Anomalies
15
Female spawning biomass (million t)
0.0 0.2 0.4 0.6 0.8 1.0
Spa
wne
r pr
oduc
tivity
-3
-2
-1
0
1
2
3
4
1960s: Low stock, average spawner productivity
1970s: Increasing stock, high spawner productivity1980s: Decreasing stock, low spawner productivity1990s: Average stock, low spawner productivity
Regression (all years)
GOA Walleye Pollock Dorn SAFE Document AFSC REFM website
16
WC
wid
ow r
ockf
ish
BC
pin
k
EB
S h
errin
g
EB
S a
rrow
. flo
unde
r
GO
A p
ollo
ck
WC
mac
kere
l
BC
soc
keye
CA
chi
nook
WC
yel
low
tail
rock
fish
EB
S y
ello
wfin
sol
e
WC
can
ary
BC
chu
m
WC
anc
hovy
WC
hak
e
EB
S p
ollo
ck
WA
soc
keye
AI
PO
P
EB
S P
acifi
c co
d
Sitk
a he
rrin
g
GO
A P
acifi
c co
d
AI
atka
mac
kere
l
PW
S h
errin
g
WC
dov
er s
ole
WC
PO
P
WC
chi
lipep
per
GO
A P
OP
C.
AK
chu
m
WC
boc
acci
o
-0.6
-0.4
-0.2
0
0.2
0.4
C.
AK
. P
ink
BC
chi
nook
WA
chi
nook
S.
AK
soc
keye
W.
AK
chu
mG
OA
hal
ibut
S.
AK
chu
mC
. A
K c
oho
EB
S G
reen
land
tur
bot
GO
A s
able
fish
C.
AK
chi
nook
GO
A a
rrow
toot
h flo
unde
rW
A c
oho
W.
AK
chi
nook
W.
AK
coh
oE
BS
Ala
ska
plai
ceS
. A
K c
oho
C.
AK
soc
keye
S.
AK
pin
kW
C s
able
fish
OR
chi
nook
OR
coh
oW
A p
ink
W.
AK
pin
kW
A c
hum
EB
S P
OP
EB
S f
lath
ead
sole
CA
coh
o
GO
A t
horn
yhea
dB
C c
oho
S.
AK
chi
nook
W.
AK
soc
keye
EB
S r
ock
sole
0
0.2
0.4
0.6
0.8
1
Auto-correlation in recruitment (Hollowed et al. 2001)
17
Intervention Analysis (Hollowed et al. 2001)
+0.00228EBS Arrowtooth
0.91231GOA Thornyhead
0.48733GOA POP
+0.04924GOA Halibut
+0.00130GOA Arrowtooth
0.83638EBS POP
-0.01626EBS Greenland Turbot
0.79928EBS AK Plaice
DirectionP(Step77)PtsStock
18
Ho: Proportion of strong year classes is not greater
during Nino North Hollowed et al. (2001)
0.06GOA pollockPost 76
0.41EBS pollockPost 76
0.12EBS codPost 76
0.07GOA codPost 76
0.45EBS pollockAll years
0.10EBS codAll years
0.09GOA pollockAll years
0.05GOA codAll years
0.02WC HakeAll years
P valueSpeciesPeriod
19
Unadjusted comparison(-1992)
18
19
20
21
22
25 26 27 28 29 30 31
ln (unadj larval abund)
ln (
recr
uit
s)
Adjusted comparsion(-1992)
18.519
19.520
20.521
21.522
23 24 25 26 27 28 29
ln (adj larval abund)
ln (
recr
uit
s)
Adjusted comparsion(-1992)
18.519
19.520
20.521
21.522
23 24 25 26 27 28 29 30 31
ln (adj larval abund)
ln (
recr
uit
s)
Late larval abundance
Late larval abundance weighted for lengthand survey date using mean growth and mortality
Late larval abundance weighted for lengthand survey date using temperature dependentmortality and mean growth**significant at p<0.05
Sampling considerations
20
Life stage considerations
Prediction:from initial
conditions of environment and
spawning biomass: from larvalabundance
: from juvenile abundance
: from juvenilesand predatoroverlap
Recruitment level
Time
Abu
ndan
ce
Egg JuvenileLarval Recruit
Scheme of Continuous Refinement of Recruitment Forecast
Small scale….. increasing to…. large scale
Predominantly activating processes
: add habitat,densitydependence
Predominantly constraining processes
Hollowed and Bailey 2009
21
Rock sole
0
0.2
0.4
0.6
0.8
1
67 69 71 73 75 77 79 81 83 85 87 89 91 93 95year
Flathead sole
0
0.2
0.4
0.6
0.8
1
67 69 71 73 75 77 79 81 83 85 87 89 91 93 95year
Figure 1.--Estimated relative recruitment of Eastern Bering Sea flatfish species from
Arrowtooth flounder
0
0.2
0.4
0.6
0.8
1
67 69 71 73 75 77 79 81 83 85 87 89 91 93 95year
Rock sole
0
2000
4000
6000
8000
0 200 400 600 800 1000 1200
fit to 1978-88fit to 1989-961978-88 data1989-96 data
Arrowtooth flounder
0
200
400
600
800
0 200 400 600 800 1000
female spawning biomass (1,000s t)
1978-88 recruits1989-96 recruits1978-88 data1989-96 data
Flathead sole
0
400
800
1200
1600
0 100 200 300 400 500
Rec
ruit
men
t (1
,000
s)
1978-88 recruits
1978-88 data
1989-96 data
Index of Advection in the E. Bering Sea and effects on winter-spawning flatfish recruitment
Rel
ativ
e R
ecru
itmen
t
Transport to nursery areas, 1980-89
Transport away from nursery areas, 1990-97
Wilderbuer et al. 2002, Prog. Oceanogr. 55:235-246
22
Coupled Bio-Physical model forecasts Stockhausen AFSC
23
Assess Performance
northern rock sole recruitment
0
1
2
3
4
5
6
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
year class
recr
uit
men
t (b
illi
on
s)
on shelf wind drift
off shelf wind drift
mid shelf pattern
24
Incorporating Ecosystem Indicators into
Stock – Recruitment Equations
( )...)21( EEStt eSR ++−∗∗= βα
Brooks and Powers ICES J. Mar. Sci (2008)
Generalized compensation in stock – recruit functions
),0(~; 2)2/()(
11
2,1
Ry
Ia
y NeeeRR Ryyin
i i σσε
∑= −+
=
25
1960 1970 1980 1990 2000
-2-1
01
23
Year
Link torecruitment
Management Strategy Evaluation: Climate Impacts on Productivity
Age-structured operating model
Management Strategy
TACData
ClimateDecision ruleYears for
defining thecurrent regime
Climatedata
26
Cold Regime (Bottom-Up Regulation)
Beginning of Warm Regime (Bottom-Up Regulation)
Warm Regime (Top-Down Regulation)
Beginning of Cold Regime (Both Top-Down and Bottom-Up Regulation)
Oscillating Control Hypothesis
Zooplankton Larval Survival Abundance of Piscivorous Adult Fish Juvenile Recruits
Hunt et al. 2002
27
2
FEAST Higher trophic level model
NPZ-B-DLower trophic
level
ROMSPhysical
Oceanography
Economic/ecological model
Climate scenarios
BSIERP Integrated Integrated Integrated Integrated modeling
Observational Data
Ne
ste
d m
od
els
BE
ST
28
Comparative Assessment
29
PICES Comparative Approach
30
Month
SpeciesPICES Region Mechanism Index 1 2 3 4 5 6 7 8 9 10 11 12
Walleye pollock GOA
Spawning pre-conditoning(subsurface flow into Shelikof Strait)
Wind Advection
57N, 156W
57N, 156W
GOALarval transport to nursery area
Wind Advection
57N, 156W
GOA Hatch date Temperature 40m
57N, 156W
57N, 156W
GOA
Larval encounter with prey (eddy formation) Precipitation
57N, 156W
57N, 156W
GOALarval encounter with prey Wind Mixing
57N, 156W
57N, 156W
GOA
Larval metabolic rate (growth out of predator range)
Temperature 40m
57N, 156W
57N, 156W
GOA
Duration of summer feeding season (time of stratification)
Solar heat + Wind mixing (timing of stratification)
57N, 156W
57N, 156W
57N, 156W
GOA
Age 0 metabolic rate (growth overwintering success)
Temperature 40m
56N, 157W
56N, 157W
56N, 157W
GOA
Summer prey habitat concentration
Mixed Layer Depth
56N, 157W
56N, 157W
56N, 157W
GOA
Summer prey availability (Basin-Shelf exchange)
Wind Advection
57N, 156W
57N, 156W
57N, 156W
31
Common mechanisms 25 North Pacific Stocks
Mechanism Total
Timing of spring bloom / Spring freshet 7
Abundance of prey for first feeding larvae 8
Hatch date / run timing 9
Concentration 3
Temperature - Metabolic rate 16
Timing of stratification (solar heat + wind mixing) 3
Duration of summer feeding period 5
Wind advection to nursery areas 12
Wind - sustained summer production 12
Settlement habitat volume / watermass 10
Maternal condition 5
Predator abundance 4
Predator distribution 4
Competition - hatchery 2
32
A way forward
Short term: —Form strong interdisciplinary research teams—Conduct deterministic retrospective studies to identify
potential linkages.—Conduct field studies to assess mechanisms.—Develop - mathematical representations of key processes
incorporating ecosystem indicators. —Observe and predict and assess skill.
Medium term 2012:—Couple ocean circulation, prey production, fish production
and predation with spatial and temporal feedbacks (BSIERP).
—MSE A’mar (GOA pollock) Punt and Ianelli (BSAI pollock), rock sole (Wilderbuer), P. cod (A’mar and Thompson)
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