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Vasquez S.,Institute Investigacion Pesquera INPESCA | Vasquez S.,University of Concepción | Correa-Ramirez M.,Pontifical Catholic University of Valparaíso | Parada C.,Institute Investigacion Pesquera INPESCA | And 2 more authors.
ICES Journal of Marine Science | Year: 2013

Vásquez, S., Correa-Ramírez, M., Parada, C., and Sepúlveda, A. 2013. The influence of oceanographic processes on jack mackerel (Trachurus murphyi) larval distribution and population structure in the southeastern Pacific Ocean. - ICES Journal of Marine Science, 70: 1097-1107.The distribution of jack mackerel larvae in the main oceanic spawning area of the southeastern Pacific Ocean was investigated through three consecutive spring bio-oceanographic surveys (2003-2005). In this study, otolith microstructure analysis revealed a spatial age gradient with the smallest/youngest larvae specimens found primarily in the offshore area and the largest/oldest found in the coastal area, implying offshore-inshore larval drift. This suggests a connection between the oceanic spawning area and the historical coastal nursery ground (north of 30°S). In order to understand the oceanographic processes that drive this larval transport, we inferred circulation patterns from two data sources: mesoscale eddy trajectories identified by applying the Okubo-Weiss parameter to satellite geostrophic currents, and 20 years of satellite tracking data of drifters. Our results showed that eddy trajectories lead to net northwestward offshore transport (the opposite direction of larval connectivity). In addition, mean circulation associated with the subtropical anticyclonic gyre and recurrent energetic meandering structures seem to be the major mechanisms driving the spatial dynamics of the early jack mackerel life history, determining a net transport to nursery grounds. These mechanisms could play a key role in recruitment, which supports the continuity of the jack mackerel population. © 2013 International Council for the Exploration of the Sea.


Parada C.,University of Concepción | Parada C.,Institute Investigacion Pesquera INPESCA | Armstrong D.A.,University of Washington | Ernst B.,University of Concepción | And 2 more authors.
Bulletin of Marine Science | Year: 2010

Landings of the snow crab Chionoecetes opilio (J. C. Fabricius, 1788), which supports a lucrative fishery in the eastern Bering Sea (EBS), dropped to historical lows by 2000, and the geographic range of reproductive females contracted to the northwest. Resilience of the mature female range through larval advection may be hampered because hatching now occurs downstream. These changes have been punctuated by four pulses of recruitment, with a remarkably regular period of 6-7 yrs. Major pulses of the fishery, during the 1990s, were sustained by recruitment pulses that originated in regions of the northwest section of the EBS shelf beyond the reach of the fishery. Here we present, for the first time, a conceptual model of snow-crab spatial dynamics that integrates empirical information with new results from modeling of circulation and larval transport. The geographic region of interest, defined by means of biophysical modeling and tracking ontogenetic migrations, consists of the middle and outer domains of the EBS shelf, bounded by the 50-and 200-m isobaths. Connectivity analysis highlights the significance of subsystems in the southeast and northwest sections of the EBS's middle domain. Predicted settlement regions match historical regions of abundance of immature crabs and are consistent with observed fields of suitable near-bottom temperature. Our study, together with others, highlights the significance of climate change for the fate of important highlatitude fisheries. © 2010 Rosenstiel School of Marine and Atmospheric Science of the University of Miami.


Ospina-alvarez A.,CSIC - Institute of Marine Sciences | Palomera I.,CSIC - Institute of Marine Sciences | Parada C.,Institute Investigacion Pesquera INPESCA
Fisheries Research | Year: 2012

Small pelagic fish populations exhibit reproductive strategies resulting from past natural selection pressure, by which certain traits become more or less common in a population, allowing them to adapt and become better suited to certain habitats. One such adaptation is the buoyancy of eggs, which is observed as density changes during development. This is an important issue in fisheries and modeling science, as it affects the vertical distribution of eggs and, therefore, egg transport. Recently, individual-based models for anchovies in the Mediterranean have focused on developing adequate biological algorithms to simulate realistic spatial variations of eggs and larvae. Some models that include movements of particles according to Stokes' law also assume a constant value of egg density during egg development. However, field observations show differences in the vertical distribution of eggs when egg density during development is considered. We address the problem of egg density and its vertical distribution within a biological context. In Mediterranean waters, the incubation time for anchovy eggs during peak spawning is approximately 48-70. h; during these first hours, egg density has an influence on the horizontal and vertical trajectories of eggs, as well as their routes and hatching zones. In this study, we introduce an algorithm describing the egg density of European anchovy eggs throughout development. Egg density measurements were carried out in a density gradient column (DGC). We fitted a polynomial model that estimated egg density, as a function of time from fertilization and that was dependent on temperature. Simulations to study the vertical transport of eggs in the Mediterranean were carried out using ICHTHYOP/MARS3D. The vertical distribution of pelagic eggs was determined by a set of interacting biological and physical parameters related to eggs (density, diameter) and ambient seawater (density, viscosity, turbulence), respectively. The egg buoyancy model introduced here was validated and will provide insight for the design of anchovy egg surveys, as the vertical position of the eggs in the water column during development can be inferred by the hydrographic structure of seawater. © 2011 Elsevier B.V.


Ospina-Alvarez A.,CSIC - Institute of Marine Sciences | Parada C.,Institute Investigacion Pesquera INPESCA | Palomera I.,CSIC - Institute of Marine Sciences
Ecological Modelling | Year: 2012

Recruitment of European anchovy has been traditionally thought to largely depend on the passive transport and dispersion of eggs and larvae from spawning to nursery areas. Knowledge of the factors influencing the vertical distribution of fish early stages, and consequently influencing the transport, is a crucial issue in fisheries science. The aim of this study is to assess the relevance of diel vertical migration (DVM) as a mechanism involved in the transport of European anchovy larvae toward nursery areas taking into account age/stage-dependent vertical migration (i.e., the maximum migration). We developed a simplified vertical migration sub-model for anchovy larvae included in an Individual-based (IBM) hydrodynamic coupled model. Two types of simulation experiments were conducted: (1) 'Pure' Lagrangian (passive) transport experiments and (2) biological behavior transport experiments with a realistic scheme for egg-buoyancy, larval growth, and DVM scheme. We detected high variability in the trajectory and final position of larvae with 14. mm length between the passive and biological behavior experiments. The particles were less clustered in the passive transport experiment. In the biological experiment the particles were aggregated depending on the mesoscale oceanographic structures, evidencing a transport associated to filaments and meanders. The formation of schools was facilitated by the transport in filaments and larvae transported within filaments generally avoided the nucleus of the eddies and the central part of the North Current. Moreover, our results suggest that there is interconnectivity between all the anchovy sub-populations in the NW Mediterranean and that the Gulf of Lions and the shelf waters surrounding the Ebro River Delta are the most important areas for anchovy reproduction in this region. Additionally, we detected that the pre-recruitment is higher in those years when the larvae retention is favored. We underline that bottlenecks in larval transport modeling are related to the scarcity of knowledge in developmental biology and behavior of anchovy larvae and emergent mechanistic processes. © 2012 Elsevier B.V.


Krautz M.C.,University of Concepción | Vasquez S.,University of Concepción | Vasquez S.,Institute Investigacion Pesquera INPESCA | Castro L.R.,University of Concepción | And 3 more authors.
Marine Biology | Year: 2010

We assessed the ontogenetic changes in protein content and free amino acids (FAA) in eggs and early larvae of Engraulis ringens (anchoveta) off central Chile on different dates during the spawning season. On all sampling dates, a reduction in embryonic yolk-sac volume, proteins and FAA concentrations occurred during development. Protein electrophoresis (SDS-PAGE) of eggs and larvae showed at least 22 protein bands: 11 were consumed early and not detected after hatching. The proportion of essential FAA (EFAA) was higher than the proportion of non-essential FAA (NEFAA) in early eggs and in 7 day-old larvae (82.5-73% EFAA respectively). During egg development, the FAA pool was dominated by leucine, alanine and lysine, three amino acids contributing 35-44% of the total FAA in eggs. During larval development, histidine was the most abundant FAA. In July, total FAA constituted 13-18% of the egg dry weight. A similar proportion (45-51%) occurred in July between protein plus FAA and total lipids. The differences in egg size during the spawning season along with variability in batch composition suggests that the female spawning condition is a major factor determining egg quality and early offspring success. © 2010 Springer-Verlag.


Morales C.E.,Center for Oceanographic Research in the Eastern South Pacific | Morales C.E.,University of Concepción | Loreto Torreblanca M.,Center for Oceanographic Research in the Eastern South Pacific | Hormazabal S.,UdeC | And 3 more authors.
Progress in Oceanography | Year: 2010

In the Humboldt Current System, the region off central-southern Chile has relatively high eddy kinetic energy, generating an extensive coastal transition zone (∼600 km offshore) in which coastally derived eddies are recurrent features. This energy might promote strong exchanges of water, biogeochemical properties, and plankton between the coastal upwelling band and the adjacent oceanic zone. In this study, the mesoscale structure of epipelagic copepod assemblages and its relationship to environmental variability and the eddy field in the coastal transition zone and oceanic areas off Concepción (34-39°S, 73-84°W) were investigated. Zooplankton samples were collected during cruises of opportunity carried out during the 2006 coastal upwelling season and the oceanographic conditions were derived from satellite data on sea surface height, temperature, and chlorophyll a. The use of cluster analyses and indicator species revealed two main copepod assemblages: (i) species with a mainly coastal distribution, the maximum in total abundance being found nearshore and (ii) species with a mainly oceanic distribution (beyond ∼500 km from the coast), where a secondary maximum was observed. Both types of assemblages, however, included species widely distributed in the coastal transition zone. An ordination analysis identified sea surface temperature and chlorophyll a as the main factors affecting the distribution of most species and the clustering of stations resembled the distribution of these variables. Some of the large calanoid species that are common in shelf waters were more abundant within nearshore eddies rich in chlorophyll a and other cyclonic eddies far offshore; however, the eddy field alone did not explain the copepod mesoscale distribution. Altogether, the wide distribution of shelf/slope copepod species in this region suggests that physical and biological mechanisms might be acting to extend the productive area of the coastal upwelling zone. © 2009 Elsevier Ltd. All rights reserved.


Riquelme-Bugueno R.,University of Concepción | Nunez S.,Institute Investigacion Pesquera INPESCA | Jorquera E.,University of Concepción | Valenzuela L.,Institute Investigacion Pesquera INPESCA | And 2 more authors.
Progress in Oceanography | Year: 2012

This study assesses the spatial and temporal patterns of the euphausiid community from the coastal upwelling zone and oceanic areas of central-southern Chile, surveyed between August 2007 and November 2008. A total of 22 species were found, most of them already described for the region. The numerically dominant species was Euphausia mucronata for the entire study area (>60%), which was found in more oceanic waters (>90°W), thereby expanding its longitudinal distribution range. The species showed distinct spatial distribution patterns, allowing its classification as a coastal, oceanic, southern and northern species. The community descriptors - species richness, total abundance, Pielou and Shannon index - all had patterns associated with the cross-shelf and alongshore axes. Over a temporal scale, species abundance and community descriptors showed strong seasonal patterns. Abundances decreased offshore but diversity increased towards the oceanic area, revealing an inverse relationship between total abundance and the Shannon index. Diversity was positively related to sea surface temperature. Although the most abundant species were concentrated within the coastal zone, euphausiid abundance and diversity in the oceanic region were high. Our findings suggest that the high productivity of the upwelling region may sustain the euphausiid populations in the coastal transition zone and in the offshore region, and that high abundance and diversity across the entire region may be maintained by a highly heterogeneous environment promoted by upwelling, giving rise to an increased number of potential ecological niches. © 2011 Elsevier Ltd.


Yannicelli B.,Católica del Norte University | Yannicelli B.,University of Concepción | Castro L.,University of Concepción | Parada C.,Institute Investigacion Pesquera INPESCA | And 5 more authors.
Progress in Oceanography | Year: 2012

In situ and modeled spatial distribution of squat lobster (Pleuroncodes monodon) larvae over the continental shelf off south central Chile (35-37°S) was analyzed along with currents and hydrography. We aimed to identify the main larval transport/retention characteristics in the study area, which constitutes the southernmost P. monodon fishing grounds embedded in the Humboldt Current System. We hypothesized that the main contribution to population renewal originates in the two persistent adult aggregations close to the nursery ground that occurs over a continental shelf terrace limited by two submarine canyons. Two extensive bio-physical field campaigns were carried out during the main 2001-2002 upwelling season field data indicated that larvae were released from late austral winter to spring from spots to the north and south of the nursery. Zoea I were found mainly below 50. m depth in southward-flowing waters, whereas older zoea dominated in northward flowing layers above 50. m. Larvae were circumscribed between the coast and the shelf break front and pelagic retention areas were identified over the widest shelf area. Megalopa and juveniles during March, were only found over the nursery area. Individual based simulations coupled to the output of a hydrodynamic model (climatological configuration) for the studied area, showed that the release sites close to the nursery made the largest contribution to recruitment. Sites further north could also contribute to recruitment if hatching occurred later in the upwelling season. The contribution of vertical behavior to larval success was also important, as was the former's interaction with the site and time of larval release. Our results support the relevance of coastal circulation (affected by topography) on the persistence of P. monodon populations off southern Chile, and the modulation of temporal variability. These results might apply to other abundant species in the area. © 2011 Elsevier Ltd.


Soto-Mendoza S.,University of Concepción | Parada C.,Institute Investigacion Pesquera INPESCA | Parada C.,University of Concepción | Castro L.,University of Concepción | And 3 more authors.
Progress in Oceanography | Year: 2012

A hydrodynamic model was coupled to an individual-based model (IBM) initialized with conditions observed during 2004 to examine the influence of spatial and temporal spawning parameters on transport and survival of Engraulis ringens in central-southern Chile. Processes modeled were transport, growth, and mortality of the early stages. The results showed that spatial and temporal variations in spawning modulated the survival of anchoveta eggs and yolk-sac larvae. The resultant transport of the early stages had an important south-north direction. In terms of connectivity, the greatest transfer of eggs and larvae to the pre-recruitment zone came from four spawning zones. Retention occurred in all spawning zones and was strongest in the Gulf of Arauco and at Lebu-Corral. Mortality due to temperature and advective losses was more intense at higher latitudes (Lebu-Corral). Observed and simulated distributions of eggs and larvae were compared, and the differences are discussed herein. A conceptual model is proposed, and we discuss the relevance of IBMs as useful tools with which to assess spawning zones for purposes of management. © 2011 Elsevier Ltd.


Parada C.,Institute Investigacion Pesquera INPESCA | Parada C.,University of Concepción | Colas F.,University of California at Los Angeles | Colas F.,University Pierre and Marie Curie | And 2 more authors.
Progress in Oceanography | Year: 2012

An individual-based model (IBM) of anchoveta (Engraulis ringens) larvae was coupled to a climatological hydrodynamic (Regional Oceanic Modeling System, ROMS) model for central-southern Chile to answer the question as to whether or not across- and alongshore transport off central-southern Chile enhances retention in the spawning areas during the winter and summer reproductive periods, using model-based pre-recruitment indices (simulated transport success to nursery areas). The hydrodynamic model validation showed that ROMS captures the mean Seas Surface Temperature and Eddie Kinetic Energy observed in satellite-based data over the entire region. The IBM was used to simulate the transport of eggs and larvae from spawning zones in central Chile (Constitución, Dichato, Gulf of Arauco and Lebu-Corral) to historical nursery areas (HRZ, region between 35°S and 37°S). Model results corroborated HRZ as the most successful pre-recruitment zone (particles originated in the Dichato and Gulf of Arauco spawning areas), as well as identifying Lebu-Corral as a zone of high retention with a high associated pre-recruitment index (particles originated in the Lebu-Corral spawning zone). The highest pre-recruitment values were mainly found in winter. The Constitución and Dichato spawning zones displayed a typical summer upwelling velocity pattern, while the Gulf of Arauco in summertime showed strong offshore and alongshore velocity components. The Lebu-Corral region in winter presented important near-surface cross-shore transport towards the coast (associated with downwelling events), this might be one of the major mechanisms leading to high retention levels and a high pre-recruitment index for Lebu-Corral spawning zone. The limitations of the modeling approach are discussed and put into perspective for future work. © 2011 Elsevier Ltd.

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