multifarious anchovy and sardine regimes in the humboldt … · sardine, with sediment cores...
TRANSCRIPT
Renato Salvatteci, David Field, Dimitri Gutierrez, Tim Baumgartner, Vicente Ferreira, Luc Ortlieb†, Abdel Sifeddine, Arnaud Bertrand
Multifarious anchovy and sardine regimes in the Humboldt Current System during the last 150 years
“Drivers of dynamics of small pelagic fish resources’ Victoria (March 2017)
Chavez and Messié (2009)
California
Peru- Chile
Canary
Benguela
Eastern Boundary Upwelling Systems (EBUS) -Upwelling of cool waters, driven by trade winds, brings nutrients to the surface, increasing biological productivity. -Area < than 1% of the world’s oceans but accounts for ~20% of global fish catch -The Peruvian upwelling system yields 10% of the global fish catch and offers 125 000 direct jobs -The EBUS are highly sensitive to climate change
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4
8
12
1950 1960 1970 1980 1990 2000 2010
Landings (million of tonnes)
0
1
2
3
4Anchovy
Sardine
Multi-decadal fluctuations in anchovy and sardine landings in the Peruvian Upwelling Ecosystem
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4
8
12
Landings (million of tonnes)
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1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
-2
-1
0
1
2
75
Anchovy
Sardine
PDO
Multi-decadal fluctuations in anchovy and sardine landings in the Peruvian Upwelling Ecosystem
Chavez et al., 2003
OMZ
Fish scales accumulating in marine laminated sediments provide long-term records of population variability
To understand the physical mechanisms underlying small-pelagic fluctuations and middle- to long-term trends in the HCS since 1860 AD, we reconstruct high-resolution records of marine productivity and anchovy and sardine biomass fluctuations from several sediment cores from Pisco and compare them with other previously published records in the HCS (Valdes et al., 2008 and Gutierrez et al., 2009)
Cross-stratigraphies indicate horizontal extensions of laminae, missing sequences and a need for multiple cores for high resolution records
Salvatteci et al. (2014, Marine Geology)
The sampling of the cores was congruent with the spatial range of anchovy and sardine, with sediment cores spanning a range of the preferred water masses
- Anchovy are more adapted to productive, cold coastal waters
Anchovy Sardine
Sardine prefer the oceanic waters and the front between oceanic and coastal waters
Bertrand et al., 2011
To understand the cause of multidecadal variability in fish populations, we compared the reconstructed fish SDR with tropical and regional indices of ocean-
atmosphere variability
The Tropical Pacific zonal wind stress record (computed from 6°N to 6°S and 180° to 150°W) serves as an indicator of the Walker circulation strength, with stronger (lighter) winds toward the west indicating a stronger (weaker) Walker circulation
England et al., (2014)
To understand the cause of multidecadal variability in fish populations, we compared the reconstructed fish SDR with tropical and regional indices of ocean-
atmosphere variability
Ocean–atmosphere climate variability centered over the midlatitude North Pacific basin. Mantua and Hare (2002)
The TPI (Henley et al., 2015), is based on the difference between sea surface temperature anomalies (SSTA) averaged over the central equatorial Pacific and the average SSTA in the Northwest and Southwest Pacific (Henley et al., 2015). The TPI resembles a multidecadal “El Niño-like” pattern of climate variability. During its positive phase, the tropical Pacific is warm and trade winds are weak, whereas during its negative phase the tropical Pacific is cool and the trade winds are strong.
To understand the cause of multidecadal variability in fish populations, we compared the reconstructed fish SDR with tropical and regional indices of ocean-
atmosphere variability
Tropical Pacific Index (TPI)
Finally we show: - Offshore and coastal SST
anomalies from the ICOADS dataset,
- and a difference between the offshore and coastal area that we refer as a cross-shore temperature gradient and is used as a proxy to infer upwelling intensity
To understand the cause of multidecadal variability in fish populations, we compared the reconstructed fish SDR with tropical and regional indices of ocean-
atmosphere variability
Age (AD)1875 1900 1925 1950 1975 2000
Pisco (14 °S)stacked record
Million of tonnes
0
4
8
12
1875 1900 1925 1950 1975 20000
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75
100
1875 1900 1925 1950 1975 20000
25
50
75
100
Mejillones (23°S)F98-1A
Callao (12 °S)B04-13
1875 1900 1925 1950 1975 2000
40
60
80
100
Export production
Anchovy
Sardine
B CA
1875 1900 1925 1950 1975 2000
0
25
50
75
1001875 1900 1925 1950 1975 2000
0
25
50
75
100
B04-6B05-14
Paleoceanographic reconstructions of export production and fish productivity along the Humboldt Current System
The records show two anchovy (~1910-mid 1970s, and from the late 1990s to the date) and two sardine regimes (~1890–1910, and mid 1970s–late 1990s). High sardine scale fluxes in Pisco indicate the period of time of maximal expansion of sardine in the HCS
Age (AD)1875 1900 1925 1950 1975 2000
Pisco (14 °S)stacked record
Million of tonnes
0
4
8
12
1875 1900 1925 1950 1975 20000
1
2
3
40
25
50
75
100
1875 1900 1925 1950 1975 20000
25
50
75
100
Mejillones (23°S)F98-1A
Callao (12 °S)B04-13
1875 1900 1925 1950 1975 2000
40
60
80
100
Export production
Anchovy
Sardine
B CA
1875 1900 1925 1950 1975 2000
0
25
50
75
1001875 1900 1925 1950 1975 2000
0
25
50
75
100
B04-6B05-14
Paleoceanographic reconstructions of export production and fish productivity along the Humboldt Current System
Multiple combinations of anchovy and sardine abundances are apparent in the HCS at decadal to multidecadal time scales, rather than simple alternations: - Periods of both high anchovy and sardine abundances (e.g. Callao and Mejillones) - Period of high anchovy and no sardine (e.g. Pisco, ~1920 to 1960) - High sardine and low anchovy (e.g. Pisco, ~1890-1900)
Age (AD)1875 1900 1925 1950 1975 2000
Pisco (14 °S)stacked record
Million of tonnes
0
4
8
12
1875 1900 1925 1950 1975 20000
1
2
3
40
25
50
75
100
1875 1900 1925 1950 1975 20000
25
50
75
100
Mejillones (23°S)F98-1A
Callao (12 °S)B04-13
1875 1900 1925 1950 1975 2000
40
60
80
100
Export production
Anchovy
Sardine
B CA
1875 1900 1925 1950 1975 2000
0
25
50
75
1001875 1900 1925 1950 1975 2000
0
25
50
75
100
B04-6B05-14
Paleoceanographic reconstructions of export production and fish productivity along the Humboldt Current System
The duration of the anchovy and sardine regimes display irregular lengths of time in contrast to the suggested 50-60 years periodicity of anchovy and sardine fluctuations derived from fishery .
B Pacific decadal oscillation
-1
0
1 C Tripole Interdecadal Pacific Oscillation
A Pacific zonal wind stress
-2
-1
0
1
2
1860 1880 1900 1920 1940 1960 1980 2000
N.m
-2
-2
-1
0
1
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-2
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-1
0
1E SST - Offshore region
F SST - Coastal region
SST
Wind stress
Year1860 1880 1900 1920 1940 1960 1980 2000
-2
-1
0
1
2G Offshore - coastal SST
Multidecadal changes in tropical and regional indices of ocean-atmosphere variability
The two sardine regimes, from ~1890–1910 and mid-1970s–late 1990s) are generally contemporaneous with time periods of weaker zonal Pacific wind stress, however the correlation of sardine SDR with the Tropical wind stress (r=-0.06, n=35, p<0.74) is not significant.
B Pacific decadal oscillation
-1
0
1 C Tripole Interdecadal Pacific Oscillation
A Pacific zonal wind stress
-2
-1
0
1
2
1860 1880 1900 1920 1940 1960 1980 2000
N.m
-2
-2
-1
0
1
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-2
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-1
0
1E SST - Offshore region
F SST - Coastal region
SST
Wind stress
Year1860 1880 1900 1920 1940 1960 1980 2000
-2
-1
0
1
2G Offshore - coastal SST
Multidecadal changes in tropical and regional indices of ocean-atmosphere variability
No relationship of anchovy and sardine with either the PDO or the TPI
B Pacific decadal oscillation
-1
0
1 C Tripole Interdecadal Pacific Oscillation
A Pacific zonal wind stress
-2
-1
0
1
2
1860 1880 1900 1920 1940 1960 1980 2000
N.m
-2
-2
-1
0
1
2
-2
0
2
-1
0
1E SST - Offshore region
F SST - Coastal region
SST
Wind stress
Year1860 1880 1900 1920 1940 1960 1980 2000
-2
-1
0
1
2G Offshore - coastal SST
Multidecadal changes in tropical and regional indices of ocean-atmosphere variability
The proxy for upwelling intensity more consistently coincide with anchovy and sardine fluctuations throughout the records
Mechanisms: Changes in the regional 3-D habitat (e.g. T/S and oxygenation of coastal waters) as a driver of anchovy and sardine fluctuations
Multidecadal scale variability and trends in the HCS during the last 150 years: Bottom-up process: From upwelling to guano birds 1860 1880 1900 1920 1940 1960 1980 2000
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Milli
on o
f ton
nes
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SDRLandings
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75
100 Million of tonnes
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SDR Landings
Export production
Fish abundance
Years1860 1880 1900 1920 1940 1960 1980 2000
Millions
0
10
20
Guanobirds
Anchovy
Sardine
Cross-shore SST gradient
Anchovy
Sardine
UPWELLING
- The modes and timescales of variability observed in our records demonstrate that the range of variations observed in the late 20th century are only part of the multiple responses of the HCS to climatic and oceanographic changes - The different combinations of anchovy and sardine abundances, and especially the non-alternating fluctuations, do not support the paradigm of regular anchovy and sardine alternations - Regional dynamics as important as basin scale dynamics underlying anchovy-sardine fluctuations. These findings refute a linear driving effect of the PDO in fish fluctuations in the HCS. - Changes in the local 3-D habitat, triggered by decadal to multi-decadal changes in upwelling intensity from either basin-scale and/or regional forcing, may be the main driving factor explaining anchovy and sardine fluctuations in the HCS.
Summary and conclusions