María Ángela Barbieri

Climate variability and pelagic fisheries in northern Chile

A time series analysis of long-term climate variability in northern Chile (18 °21-24°00S) shows anomal- ies associated with the El Nino events and the longer warm period observed since 1976, followed by a cooling trend since mid 1980s. The succession of pelagic fisheries, anchovy ( Engraulis ringens) and sardine (Sardinops sagax), occurring in this fishing zone was analyzed taking into account the landings, the CPUE abundance index, the fishing effort, and the environmental variables. The anchovy production model is a negative linear function of fishing effort and turbulence. For sardine, the production model is a negative linear function of fishing effort and a quadratic function of the sea surface temperature. An analysis of the relationship between recruitment, adult biomass and the environment shows that the annual recruitment of anchovy increases with turbulence intensity until wind speed reaches a value of 5.46 ms 1 , decreasing for higher values. For sardine, the recruitment increases with turbulence intensity until 5.63 m s 1 , stabilizing thereafter. It is deduced that the climatic variations associated to the El Nino events affect the abundance of coastal pelagic fishes, without forgetting the most likely effects upon its distribution and the fishing effort. However, it is the long-term variability that mainly affects the fishing activity.  2001 Elsevier Science Ltd. All rights reserved.

An integrated conceptual approach to study the swordfish (Xiphias gladius Linnaeus, 1758) fishery in the eastern South Pacific

espanolSe analizo la informacion disponible sobre el entorno ambiental, biologico, ecologico y pesquero asociado a la explotacion de la unidad de stock de pez espada (Xiphias gladius) del Pacifico suroriental, ademas de una revision bibliografica de modelos que orientan una aproximacion ecosistemica en la administracion de pesquerias. De esta forma, se establecio un modelo conceptual que incorpora procesos definidos en tres planos, con tres escalas espaciales (Oceano Pacifico, Pacifico suroriental y area de la pesqueria) y tres escalas temporales (interanual, estacional e intraestacional). La distribucion geografica, su historia de vida y la actividad migratoria que desarrolla el pez espada, implicaron considerar en el modelo, los estados de huevos y larvas, juveniles y adultos, en las zonas de reproduccion, crianza y alimentacion de adultos. Sin desconocer la investigacion pesquera operativa que se realiza actualmente, el modelo conceptual propone la dimension de trabajo para el desarrollo de un manejo pesquero integrador. EnglishThe available environmental, biological, ecological, and fishery data associated with the exploitation of swordfish (Xiphias gladius) in the eastern South Pacific were analyzed and the literature on models aiming at an ecosystem approach to fisheries management was reviewed. The conceptual model set forth in this work incorporates three planes with processes defined on three spatial (Pacific Ocean, eastern South Pacific, fishing area) and three temporal (interannual, seasonal, intraseasonal) scales. Because of the swordfish�s geographic distribution, life history, and migratory activity, the model must consider several developmental states (eggs and larvae, juveniles, adults) inhabiting different grounds (spawning, breeding, adult feeding). The conceptual model presented herein, without detracting from current operational fisheries research, suggests what must be done to develop integrated fishery management.

El Niño Southern Oscillation and spatial-temporal variability of the nominal performances of swordfish (Xiphias gladius) in the southeastern Pacific

El pez espada (Xiphias gladius) es una especie pelagica altamente migratoria, encontrandose en aguas tropicales, subtropicales y templadas. En el Oceano Pacifico presenta una distribucion latitudinal entre 50oN y 50oS, y varios estudios han relacionado su distribucion a variables ambientales, ya que el alimento es abundante a lo largo de zonas frontales donde convergen las corrientes o masas de aguas. En el Pacifico suroriental, el anticiclon subtropical fuerza positivamente las temperaturas del oceano a lo largo de la costa oeste de America del sur, decreciendo hacia el polo desde las latitudes subtropicales debido al fenomeno El Nino Oscilacion del Sur. Ocupando datos ambientales provenientes de sensores remotos, estudiamos los cambios en la posicion espacial de la isoterma de 18oC en relacion a los cambios espacio temporal de los rendimientos de pesca nominales (CPUE) de pez espada de la flota palangrera industrial que opera frente a las costas de Chile. Se obtuvieron correlaciones entre el centro de gravedad latitudinal (CGL) de la CPUE y la posicion latitudinal de la isoterma de 18oC; entre la posicion latitudinal de la isoterma de 18oC y el area que limita con la de isoterma de 17oC y entre el indice El Nino 12 y la posicion latitudinal de la isoterma de 18oC. A nivel estacional, la isoterma de 18oC se desplaza al sur de los 37oS a principios de ano, hasta alcanzar los 25oS en agosto. Este patron ocurre en forma similar con el area delimitada por las isoterma de 17o y 18oC. Dos fases fueron observadas en la CPUE del pez espada, una con valores de 0,65 ± 0,06 kg por anzuelo registrado desde mediados de abril hasta comienzos de junio, y otra con valores de 0,37 ± 0,05 kg por anzuelo desde comienzo de septiembre hasta finales de noviembre.

DETECTION OF MESOSCALE OCEANIC FEATURES USING RADARSAT-1, AVHRR AND SEAWIFS IMAGES AND THE POSSIBLE LINK WITH JACK MACKEREL (TRACHURUS MURPHYI) DISTRIBUTION IN CENTRAL CHILE

In order to verify the ability of RADARSAT-1 images to detect mesoscale oceanic features and the possible link of these oceanographic patterns with jack mackerel (Trachurus murphyi) distribution in the waters off central Chile, a project was developed as part of the Canada Centre for Remote Sensing Globesar-2 program. The combined use of simultaneously acquired RADARSAT-1, AVHRR sea surface temperature (SST), SeaWiFS Chlorophyll a concentration (Chl), TOPEX/ERS altimeter and ERS-2 scatterometer wind data greatly enhanced SAR imaging capabilities for the detection of oceanic features. Results show that detection of coastal wind-driven upwellings, eddies, frontal boundaries and phytoplankton blooms is possible using SAR imagery, given the proper environmental conditions. Results also suggest that jack mackerel distribution coastal resources is mainly associated with frontal boundaries, upwelling waters and high chlorophyll concentrations detected by the remotely sensing images

Time-space variability of sea surface temperature and pelagic resources in northern Chile (1987-92)

Satellite data of sea surface temperatures (SST) and fishing information of northern Chile is analyzed for the 1987-92 period, by means of a geographical information system. It is concluded that both the anchovy and the sardine showed distributions significantly associated with the timespace variation of SST.

Climate Change and Fisheries in Chile

The possible effects of climate change on Chilean marine ecosystems are considered. Relationships between the abundance of exploited species, fishing effort and environmental variables are elucidated, and conceptual models for an ecosystemic management of fisheries are proposed. A projection for anchovy fisheries in northern Chile is carried out, considering four different temporal climatic change scenarios until 2100. Finally, indications on the necessity to evaluate the spatio-temporal fisheries performance, given the climate change scenario, are suggested.

Subtropical del Pacifico Sur. Determination of factors affecting the bycatch of seabirds in Chilean pelagic longline fleet

We analized the relationship between the variability in the rate of seabird bycatch in pelagic longline fishery for swordfish (Xiphias gladius), and several temporary, environmental, spatial and fisheries factors for the fishing period from 2007 to 2009. The results show that the fishing operations of this fleet mainly affect the albatross, group that accounts for 83.7% of the incidental catch of seabirds recorded in the period. This bycatch is due primarily to the presence of the South Pacific Subtropical Front, a system that causes the overlap between the activities of this fleet with the spatial distribution of these seabird species during the resident phase of the nonbreeding period. By the other hand, the variability in bycatch would be strongly linked to visual stimuli (measured by the percentage of chemical lights and percentage of squid) and the existing ambient lighting conditions during the set (measured by the lag time of sunset with respect to time start set and lunar phase).