Coupling between the environment and the pelagic resources exploited off northern Chile: ecosystem indicators and a conceptual model

Abstract

ABSTRACT.The eastern boundary of the Chile-Peru Current System constitutes one of the most biologically productive ecosystems in the world, due largely to coastal upwelling and the horizontal advection of nutrients. In this ecosystem, El Niño events are of great importance in the interannual variability of the environment. A change was observed in the environmental regime at the beginning of the 1970s with the onset of the 1972-1973 El Niño, marking an important decrease in the anchovy fishery (Engraulis ringens). After the mid-1970s, sardine (Sardinops sagax) landings increased noticeably. A second regime shift at the end of the 1980s was seen mostly in the noticeable recovery of anchovy and the decline of sardine. Herein, we present an integrated conceptual model of the different local and large-scale phenomena that affect the marine environment off northern Chile and the distribution and abundance of pelagic resources. The model considers an analysis of environmental and bio-fishery data on different scales and describes how the interdecadal (associated with regime shifts) and interannual (associated with El Niño events) fluctuations in the Equatorial Pacific are manifested in the eastern South Pacific and, therefore, in the northern zone off Chile, affecting the annual cycle, the dynamic of the coastal trapped waves, and coastal upwelling. In this framework, interdecadal fluctuations play an important role in the anchovy-sardine-anchovy replacement sequence. Keywords: pelagic fishery, environmental variability, conceptual model, northern Chile.Acoplamiento entre el ambiente y los recursos pelágicos explotados en el norte de Chile: indicadores ecosistémicos y modelo conceptual RESUMEN. El borde oriental del Sistema de Corrientes de Chile-Perú constituye uno de los ecosistemas de mayor productividad biológica del mundo, debido principalmente a la surgencia costera y advección horizontal de nutrientes. En este ecosistema, los eventos El Niño son de mayor importancia en la variabilidad interanual del ambiente. No obstante, un cambio de régimen ambiental es observado a inicio de los 70's el que hubiera comenzado con El Niño 1972-73 y que marca la gran disminución de la pesquería de anchoveta (Engraulis ringens); en tanto, desde mediado de los 70's los desembarques de sardina (Sardinops sagax) aumentan notablemente. Un segundo cambio de régimen se observa a finales de los 80's, representado principalmente por la notable recuperación de anchovy y disminución de sardina. Se presenta un modelo conceptual integrador de los diferentes fenómenos locales y de gran escala que afectan el ambiente marino del norte de Chile, y la distribución y abundancia de recursos pelágicos. El modelo considera análisis de datos ambientales y biopesqueros a distintas escalas, y describe como las fluctuaciones interdecadales (asociadas a cambios de régi-men) e interanuales (asociadas a los eventos El Niño) del Pacífico Ecuatorial se manifiestan en el Pacífico Sur Oriental y por tanto en la zona norte de Chile, afectando el ciclo anual, la ...

Using indicators and models for an ecosystem approach to fisheries and aquaculture management: the anchovy fishery and Pacific oyster culture in Chile: case studies

“…This study area is influenced by the Humboldt Current System and is part of a highly productive marine ecosystem due to the transport of nutrients by large-scale horizontal advection and persistent coastal upwelling. In this area, the fishery is based successively on anchovy and sardine, and these noticeable changes in the type of fish caught are a result of changes in fishing effort and environmental fluctuations (Yáñez et al, 2001(Yáñez et al, , 2008. Ocean climate changes have been related to alterations in the marine ecosystems on several spatial temporal scales (Chavez et al, 2003;Yáñez et al, 2003;Alheit & Ñiquen, 2004).…”

“…Over the last decade, the research community has developed methodologies such as the geographic information system (GIS), and predictive models to support decision making for the EAF (Cochrane et al, 2007;Yáñez et al, 2008;Meaden, 2009) and EAA (Ferreira et al, 2007;Silva et al, 2011). However, there is a pressing need for such tools and methodologies to be more targeted at industry and management.…”

Coupling Environmental, Social and Economic Models to Understand Land-Use Change Dynamics in the Mekong Delta

“…The two models are synchronized through the exchange of specific data (mobility needs from UrbanSim to MATSim, accessibility indicators in the reverse way). The literature provides other examples, like Yez et al (2008), with an integrated model of a marine environment composed of local ecosystems of pelagic species, which adds an explicit translation between models at different scales, or Steiner et al (2009), which couples a community land model with the regional climate model of the West African monsoon, and of course others. Simple exchanges of data is in general not sufficient in weak coupling approaches because the sub-models, which can be legacy models that cannot be modified, can operate at different scales of space and time and can also have different objectives (Rajeevan and Nanjudiah, 2009).…”

Variabilidad ambiental y recursos pesqueros en el Pacifico suroriental: estado de la investigacion y desafios para el manejo pesquero

“…No obstante, se ha verificado que no existen fases consecutivas en la dominancia de su abundancia, sino más bien como resultado de un proceso estocástico ligado a la variabilidad ambiental (Gutiérrez-Estrada et al, 2009). Dos décadas de estudio fueron sintetizadas en un modelo conceptual de variabilidad de pelágicos-ambiente a diferentes escalas por Yáñez et al (2008). El modelo describe las fluctuaciones interdecadales asociadas a cambios de régimen, e interanuales asociadas a los eventos El Niño del Pacífico suroriental.…”

“…En términos operacionales, los modelos biofísicos acoplados a modelos de nivel trófico inferior pueden ser utilizados en el asesoramiento como indicadores independientes del reclutamiento, implementaciones explícitas de Tabla 1. Revisión de medios por los cuales el clima afecta poblaciones de peces y ejemplos asociados a Ottersen et al (2010 Vargas et al (1996) Concentración de oxígeno Respiración Yáñez et al 2008); Morales et al (1996) Figura 2. Sistema de modelación biofísica constituido por un modelo hidrodinámico y un modelo biológico y generación de índices independientes de la pesquería que podrían servir para generar lineamientos hacia la asesoría.…”