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Investigaciones marinas

versión On-line ISSN 0717-7178

Investig. mar. v.30 n.1 supl.Symp Valparaíso ago. 2002

http://dx.doi.org/10.4067/S0717-71782002030100087 

Climate Change and Variability of
Pelagic Fish Stocks in the Humboldt
Current Ecosystem

Rodolfo Serra1, Luis Cubillos2,
Miguel Ñiquen3, Patricio Barría1,
Jose Luis Blanco4

1Instituto de Fomento Pesquero, Huito 374, Valparaíso,
Chile, Email: rserra@ifop.cl pbarria@ifop.cl
2Instituto de investigación Pesquera, Colon 2780,
Talcahuano, Chile, Email: lcubillos@inpesca.cl
3Instituto del Mar del Perú, Esquina Gamarra y General
Valle, Callao, Peru, Email: mniquen@imarpe.gob.pe
4Old Dominion University, Center for Coastal Physical
Oceanography, Old Dominion University, 768 w 52nd
Street, Norfolk, VA 23529, USA,
E-mail: jlblanco@ccpo.odu.edu

Different papers have been written comparing the long term changes in abundance among the different eastern margins of the ocean, such as the California, Humboldt, Benguela and Canary currents and the Kuroshio Current. The focus has been on the simultaneous and sequential but opposite changes in abundance of sardine and anchovy stocks, and the concept of the regime shift was developed. In this paper we show that the changes in abundance also involve other pelagic fish stocks and that they occur simultaneously in the whole Humboldt current, affecting not only neritic but also neritic-oceanic stocks. The fish stocks considered are: the stocks of anchovy (Engraulis ringens) distributed in north-central Peru, southern Peru and northern Chile and south-central Chile; the stocks of sardine (Sardinops sagax) distributed in north-central Peru and in southern Peru and northern Chile, the stock of jack mackerel (Trachurus symmetricus murphyi) distributed off the Chilean coast and the common sardine (Strangomera bentincki) in south-central Chile.

Another issue that has not been properly resolved and about which different statements have been made relates to the major turning points in the structure and functioning of marine ecosystems, specifically in the Humboldt ecosystem. Some works suggest that it happened in the middle of the 1970's and others at the edge of the 1960's and 1970's.

These problems are formally addressed based on catch data and new information of abundance estimates produced by catch at age type of analysis, together with time series of sea surface temperature, mean sea level, upwelling index and SOI.

Time series of catch data, using a Loess smoothing algorithm, together with abundance and recruitment estimates for the three anchovy stocks show a synchronous pattern for the Humboldt Current. Similar patterns emerged for sardine and jack mackerel but these were opposite in phase to that of anchovy, i.e. they have high abundance when the anchovy and common sardine show low abundance.

These biological indicators show that the major turning points in the Humboldt current occurred at the edge of the 1960's and 1970's, with a change from an anchovy- to a sardine- dominant system. The second major turning point happened in the mid-1980's.

Analysis relating environmental indices with biological indices will also be undertaken.

Apart from the long-term time scale abundance variation, the Humboldt current is well known for the periodic occurrence of El Niño and La Niña phenomena, which cause a short-term change in the system and their consequences in the abundance of the different fish stocks is also addressed.

Decadal and interdecadal climate variability seem to be the main cause for long term fluctuation in pelagic fish stocks. Existing information may be able to detect short-term variability in recruitment, but large amplitude regime shifts may be more important since they can cause the appearance and disappearance of entire fisheries

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