Multifarious anchovy and sardine regimes in the Humboldt … · sardine, with sediment cores spanning a range of the preferred water masses - Anchovy are more adapted to productive,

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)

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1

2

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4Anchovy

Sardine

Multi-decadal fluctuations in anchovy and sardine landings in the Peruvian Upwelling Ecosystem

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8

12

Landings (million of tonnes)

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1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

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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)



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.



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



Age (AD)1875 1900 1925 1950 1975 2000

Pisco (14 °S)stacked record

Million of tonnes

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1875 1900 1925 1950 1975 20000

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1875 1900 1925 1950 1975 20000

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Mejillones (23°S)F98-1A

Callao (12 °S)B04-13

1875 1900 1925 1950 1975 2000

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Export production

Anchovy

Sardine

B CA

1875 1900 1925 1950 1975 2000

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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


Million of tonnes

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1875 1900 1925 1950 1975 20000

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1875 1900 1925 1950 1975 20000

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1875 1900 1925 1950 1975 2000

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Export production

Anchovy

Sardine

B CA

1875 1900 1925 1950 1975 2000

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B04-6B05-14


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


Million of tonnes

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1875 1900 1925 1950 1975 20000

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1875 1900 1925 1950 1975 20000

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1875 1900 1925 1950 1975 2000

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Export production

Anchovy

Sardine

B CA

1875 1900 1925 1950 1975 2000

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B04-6B05-14


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

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1 C Tripole Interdecadal Pacific Oscillation

A Pacific zonal wind stress

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1860 1880 1900 1920 1940 1960 1980 2000

N.m

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1E SST - Offshore region

F SST - Coastal region

SST

Wind stress

Year1860 1880 1900 1920 1940 1960 1980 2000

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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.


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1860 1880 1900 1920 1940 1960 1980 2000

N.m

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SST

Wind stress

Year1860 1880 1900 1920 1940 1960 1980 2000

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No relationship of anchovy and sardine with either the PDO or the TPI


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1860 1880 1900 1920 1940 1960 1980 2000

N.m

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SST

Wind stress

Year1860 1880 1900 1920 1940 1960 1980 2000

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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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SDRLandings

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SDR Landings

Export production

Fish abundance

Years1860 1880 1900 1920 1940 1960 1980 2000

Millions

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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

Documents

Multifarious anchovy and sardine regimes in the Humboldt … · sardine, with sediment cores spanning a range of the preferred water masses - Anchovy are more adapted to productive,