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Leonardo R Castro - One of the best experts on this subject based on the ideXlab platform.
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otolith elemental composition reveals separate spawning areas of anchoveta Engraulis ringens off central chile and northern patagonia
Scientia Marina, 2019Co-Authors: Maria Jose Cuevas, Leonardo R Castro, Konrad Gorski, Aurelien Vivancos, Malcolm R ReidAbstract:The anchoveta (Engraulis ringens) is widely distributed throughout the Humboldt Current (4°30′-44°S). In recent years, its eggs and larvae have also been found inside fjords and channels of northern Patagonia, close to the southern limit of the central-south Chilean fishery zone. Currently, it is unclear whether these southern individuals constitute an independent subpopulation. This study analysed the elemental composition of otoliths from 102 specimens from central Chile and northern Patagonia using laser ablation inductively coupled plasma mass spectrometry. The results indicated that the elemental composition of the otolith cores (Mg, Pb, Zn, Ba) differed significantly between sites, revealing the existence of two discrete spawning zones, one in central Chile and one in northern Patagonia. However, the low significant differences of elemental signatures of otolith edges suggest that either individuals from both areas move between spawning areas and mix at certain periods of the year, or they represent pocket units that form part of a larger stock that moves along the coast.
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uv radiation effects on the embryos of anchoveta Engraulis ringens and common sardine strangomera bentincki off central chile
Marine and Freshwater Research, 2016Co-Authors: Paulina Vasquez, Leonardo R Castro, Alejandra Llanosrivera, C FernandezAbstract:It has been proposed that current levels of ultraviolet B (UVB) radiation could cause lethal or sublethal effects on fish embryos located in the upper layers of the water column. Observed levels of UVB off central Chile (36°S, 73°W) indicate that planktonic fish embryos could be exposed to harmful UVB radiation. From July 2011 to January 2012 embryos from anchoveta (Engraulis ringens) and common sardine (Strangomera bentincki) were used to test experimentally whether the UVB levels in central Chile produce lethal or sublethal effects in epipelagic fish embryos. Simultaneously, whether the embryos might be exposed to harmful UVB levels in the field was investigated. Our experimental results show that UVB may cause a decrease in hatching success, changes in buoyancy and embryonic malformations. These results, along with the observed vertical distribution of embryos and UVB radiation levels in the field during late spring suggest that lethal and sublethal effects may be occurring in the embryos of both species.
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variation in the spawning periods of Engraulis ringens and strangomera bentincki off the coasts of chile a quantitative analysis
Fisheries Research, 2014Co-Authors: Gabriel Claramunt, Leonardo R Castro, Luis A Cubillos, Carola Hernandez, Marcos ArteagaAbstract:Abstract In Chile, anchovy ( Engraulis ringens ) and common sardine ( Strangomera bentincki ) are two commercially important small pelagic fish. In southern Chile (32–41° S), both species coexist and inhabit the coastal zone. In northern Chile (18–25° S), only anchovy is present in the coastal zone. The determine onset, peak, end, and duration of the spawning periods in these small pelagic fish are key factors in population studies and of great interest for fisheries management. The objective of this study is to determine the temporal trends of spawning in these two species. A quantitative method was developed to obtain objective indicators of the spawning periods and the method is a useful tool for comparative studies between populations as well as to study the relationship of spawning periods with other demographic variables affected by fishing or environmental variability. Peak spawning in the three populations was consistent through time but showed changes in the duration of the maximum reproductive period. Anchovy and common sardine of the southern zone show synchrony and a shortening of the duration of spawning periods, probably in response to environmental fluctuations. Anchovy in northern Chile have shown an increase in duration from 1986 that is coincidental with the regime shift reported for the Humboldt Current Ecosystem in the mid-1980s.
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Development of free neuromasts in Engraulis ringens and Strangomera bentincki (Teleostei, Clupeiformes) early larvae
Latin American Journal of Aquatic Research, 2014Co-Authors: Alejandra Llanos-rivera, Guillermo A. Herrera, Eduardo Tarifeño, Leonardo R CastroAbstract:Neuromast morphology and distribution are characterized during early ontogeny of anchoveta (Engraulis ringens) and common sardine (Strangomera bentincki). Although both species share morphological features, they show several differences during their early ontogeny, such as size at hatching and yolk absorption. Larvae were obtained from incubation of planktonic eggs (at 12°C), collected during the spawning season 2001 (August-September) at Coliumo Bay. The neuromasts were observed from hatching to 25 days, and the pattern of neuromast appearance, in newly hatched larva, until yolk absorption, was determined using Janus Green staining and scanning electronic microscope. Results showed a similar pattern of neuromast development in both species. At hatching, two pairs of neuromasts were observed in the cephalic area and 8-9 in the rest of the body, which increased to 19 pairs and to 30-39 pairs at a larval size of 11 mm, respectively. On the average, 12 hair cells per neuromast were counted, with little variation among neuromasts. The polarity of these hair cells was closest to multiple polarity. Neuromast positioning for both species, anchoveta and common sardine larvae, are similar to those of Engraulis mordax and Clupea harengus, respectively. The similar development pattern of these species seems to be related to similar functional constraints and close taxonomic affinity.
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vertical distribution and gas bladder inflation deflation in postlarval anchoveta Engraulis ringens during upwelling events
Journal of the Marine Biological Association of the United Kingdom, 2013Co-Authors: Mauricio F Landaeta, Leonardo R CastroAbstract:Vertical distribution of fish larvae can be modified by a series of physical processes occurring in the water column at different time and spatial scales and also by biological processes occurring during larval development. To assess the factors affecting the vertical distribution of larval anchoveta Engraulis ringens during austral spring, meteorological and oceanographic features were measured and stratified ichthyoplankton sampling was carried out in central Chile during active upwelling events. In November 2001, during the upwelling season, southerly winds dominate, and intrusion of low dissolved oxygen occurred in nearshore waters; preflexion larvae of E. ringens were collected in the mixed layer of the water column (the Ekman layer) irrespective of day and night hours. Larvae larger than 10 mm showed an inflated gas bladder during night collections, and non-inflated gas bladder during day hours. Larvae with inflated gas bladders were located significantly at shallower depths during night than at day hours, indicating a direct relationship between gas bladder inflation, diel vertical migration of larval E. ringens and decrease of wind-induced turbulence at night. We discuss the potential implications of larval E. ringens vertical distribution and its variability on the horizontal transport off coastal waters during the upwelling season off central Chile as a biophysical coupling to enhance coastal retention.
Mauricio F Landaeta - One of the best experts on this subject based on the ideXlab platform.
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short term variations in the early life history traits of common sardine strangomera bentincki and anchoveta Engraulis ringens off central chile
Fisheries Research, 2020Co-Authors: Victor Molinavaldivia, Mauricio F Landaeta, Manuel I Castillo, Darly Alarcon, Guido PlazaAbstract:Abstract A comparison of the early life history traits of two small pelagic fish species occurring in nearshore waters of central Chile was carried out based on the analysis of sagittal otolith microstructure. Plankton samples were collected in a shallow embayment at weekly scale, during six nights of austral spring 2015. Mixed schools of larval common sardine Strangomera benticki and anchoveta Engraulis ringens were studied, where the former was two to three-times more abundant than the latter. Anchoveta larvae grew faster (0.738 mm day−1) than larval sardine (0.639 mm day−1) but hatched at smaller size (2.62 vs. 4.85 mm, respectively); larval mortality rates was higher for sardines than anchovetas (ZSb = -0.164 day−1; ZEr = -0.136 day−1). Back-calculated hatch dates indicate that both species were temporally coupled, excepting during early November 2015, when a large hatch event of anchoveta occurred. Both species showed similar growth trajectories during early ontogeny; however, the residuals of the micro-increment width in sagittal otoliths were negatively correlated between species. A regional warming event (SST > 15 °C) of coastal waters during late October 2015, negatively affected the recent growth rates of larval anchoveta, but not for sardines. Therefore, during spring, larvae of small epipelagic species display different responses to the same environmental forcing in the nearshore.
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intra seasonal variability of sea surface temperature influences phenological decoupling in anchovy Engraulis ringens
Journal of Sea Research, 2019Co-Authors: Carola Hernandezsantoro, Javier E Contrerasreyes, Mauricio F LandaetaAbstract:Abstract Changes in phenology are an ecological response to climate changes, in addition to other factors that may stress or dampen phenological responses. For this study, we investigated how climate variability can affect the phenology of the reproductive process of the anchovy Engraulis ringens. We used 29 years of sea surface temperature (SST) data and biological information from northern Chile stock, particularly, gonadosomatic index (GI), body condition (K), and mean weight (MTW) between 1988 and 2017. The Breaks for Additive Season and Trend (BFAST) method was applied to SST to estimate seasonal breaks and to correlate them with the seasonality of the GI. Seasonality and trend were extracted from the series to evaluate them as co-variables in GAM and GLM models in the explanation of the GI variability. The GAM model explained 56% of the variance, because it rescues the nonlinear relationships of the variables. The seasonality of the temperature explained 40%, followed by the body condition of the fish (10%). BFAST results indicate a seasonal change in SST, recording three periods: prior to 1993, 1994–1998 and after 2009. This seasonal change in the SST determines a delay in the start and the maximum in the GI. The K presented a negative relationship such as the MTW, associated with energy expenditure during the reproductive period. Faced with projections of climate change, the effects of the decoupling between larvae and the abundance during spring are not known; therefore, knowing the mechanisms that control phenology can improve our capacity to monitor and manage marine resources under climate change.
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growth and mortality of larval anchoveta Engraulis ringens in northern chile during winter and their relationship with coastal hydrographic conditions
Fisheries Oceanography, 2017Co-Authors: Mauricio F Landaeta, Guido Plaza, Camilo Rodriguezvalentino, Jorge E Contreras, Manuel I Castillo, Monica AlvaradoninoAbstract:Larval growth, age, growth effect and instantaneous mortality were estimated in anchoveta, Engraulis ringens, collected biweekly during the austral winter of 2014 in nearshore waters off Bay of Antofagasta (23°41′W–70°30′S), northern Chile. Through measuring standard length (SL) and sagitta microstructure analysis, it was estimated that the growth rate of E. ringens larvae decreased from June (0.85 mm day−1) to August (0.50 mm day−1). However, the water temperature was homogeneous during the sampling dates (14.6, 15.2, 14.4, and 14.6°C), suggesting that the decelerating larval growth was not linked to changes in sea temperature. Additionally, larvae with slow growth have larger otoliths compared with conspecifics with fast growth (growth effect). Larval mortality rates tended to decrease until the middle of July (0.18 per day) but increased to 0.25 per day in early August, which coincided with lower food availability (i.e., chlorophyll-a, 2.7–5.6 mg m−3) and a high occurrence of smaller larvae (1.58–11.5 mm). Partial least squares analysis indicates low covariance between the biological and oceanographic variables (PLS: 11.71%), suggesting that other factors, such as parental effects, may explain the abrupt decrease in the larval growth rates.
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feeding success and selectivity of larval anchoveta Engraulis ringens in a fjord type inlet from northern patagonia southeast pacific
Revista De Biologia Marina Y Oceanografia, 2014Co-Authors: Mauricio F Landaeta, Maria J Ochoamunoz, Claudia A BustosAbstract:Se investigo la dieta y selectividad de larvas de anchoveta Engraulis ringens durante 4 dias consecutivos (primavera) en el canal Hornopiren, un ambiente tipo fiordo del sur de Chile. Este ambiente estuvo caracterizado por una marcada haloclina alrededor de los 10 m de profundidad, separando aguas salobres y saladas. La oferta potencial de presas, microzooplancton, fue recolectada a 4 profundidades (0, 5, 10 y 30 m), mientras que el ictioplancton fue recolectado en 2 estratos, superficial (0-10 m) y profundo (10-45 m). Los nauplii y copepoditos fueron los principales componentes del microzooplancton. El analisis de 487 contenidos estomacales de larvas de anchoveta indico que se ingirieron volumenes similares de presa en ambos estratos y durante ambas mareas. Sin embargo, en la capa superficial, salobre y mas calida, las larvas de E. ringens ingirieron significativamente menos presas pero de mayor tamano, como nauplii y copepoditos como presas principales. En la capa subsuperficial, en aguas mas frias y saladas, las larvas ingirieron mas presas de menor tamano, con mayor selectividad por los nauplii. La incidencia alimentaria de E. ringens se incremento 2 veces durante la marea llenante, cuando la abundancia de los copepoditos tambien se incremento. Por lo tanto, es posible detectar interacciones biofisicas complejas en los fiordos Patagonicos durante el proceso de alimentacion de los estados larvales de esta especie de importancia comercial, en estrecha relacion con la distribucion espacio-temporal de las presas.
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feeding success and selectivity of larval anchoveta Engraulis ringens in a fjord type inlet from northern patagonia southeast pacific exito alimentario y selectividad en larvas de anchoveta Engraulis ringens en un canal tipo fiordo de patagonia norte
2014Co-Authors: Mauricio F Landaeta, Maria J Ochoamunoz, Claudia A BustosAbstract:The diet and selectivity of larval anchoveta Engraulis ringens was studied during 4 consecutive days (austral spring) in Hornopiren inlet, a fjord-like environment of southern Chile. This environment was charac terised by sharp halocline around 10 m depth, separating brackish and saltier waters. The potential prey field, microzooplankton, was collected at 4 depths (0, 5, 10 and 30 m), while the ichthyoplankton was collected at 2 strata, surface (0-10 m depth) and deep (10-45 m depth). Nauplii and copepodites were the major components of microzooplankton. The analysis of 487 gut contents of larval anchoveta indicates that similar volume of prey was ingested in both layers and during both tides. However, in the upper, brackish and warmer water, larval E. ringens ingested significantly less prey but of larger size, selecting nauplii and copepodites as the main prey items. In the deep, saltier and colder water, larvae ingested more prey of smaller size, showing only selectivity for nauplii. The feeding incidence of E. ringens increased twice during the flood, when the abundance of copepodites in the field also increased. Therefore, complex biophysical intera ctions occur in Patagonian fjords during the feeding process of larval stages of this commercially important species in tight relationship with the spatio-temporal distribution of prey.
Luis A Cubillos - One of the best experts on this subject based on the ideXlab platform.
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Spawning marker patterns of Engraulis ringens of northern Chile
Fisheries Research, 2019Co-Authors: Gabriel Claramunt, Luis A Cubillos, Gustavo Herrera, Eduardo DíazAbstract:Abstract The procedures used to estimate the daily spawning fraction of northern Chile anchovy (Engraulis ringens) have been revised based on information from 17 Daily Egg Production Method (DEPM) survey estimates of the anchovy spawning biomass. The most commonly used spawning marker is postovulatory follicles (POFs). POFs are transitory remnants of the ovulated follicles that remain within the ovary after spawning, until they are fully resorbed. As the process of Postovulatory Follicles (POF) degeneration is continuous, the assignment of POF stages to daily cohorts of spawners can be imprecise. Therefore, the main objective of this paper is to review the criteria used to assign females to daily spawning cohorts in anchovy (Engraulis ringens) located off northern Chile. For our first step, we review the peak spawning time using recently fertilized eggs. To study the POF duration, we divided the POF degenerative process into seven stages and then fitted a gamma probability distribution to the hourly POF stage fractions in a daily cycle. This approach is a quantitative, objective way to define the range of time during which the POF stages are present in the samples, as well as the overlap between daily cycles. The hourly distribution of recently fertilized eggs (Stage 1) indicated a strong daily spawning time synchrony that peaked at 4:00 GMT (00:00 local time). We found that the class Day1 cohort (females that spawn on the night before their capture) belongs primarily to POF Stages 1 to 3, with some proportions belonging to POF Stages 4 and 5 according to the capture time. The migratory nucleus (MN) and hydrated (H) phases correspond to the cohort that spawns on the night of capture. The daily spawning fraction estimates the based on the POF or MN and H phases did not show significant differences. Our results indicated an average spawning frequency of four days (S = 0.27 day−1). The prevalence of POFs according to female size follow an asymptotic model of the von Bertalanffy type, indicating an asymptote around 0.27 day−1. The POF presence was higher during cold periods, probably due to a longer period of decay. A general linear model analysis showed that body weight, time of catch and mean temperature significantly influenced the spawning fraction.
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synchronous patterns of fluctuations in two stocks of anchovy Engraulis ringens jenyns 1842 in the humboldt current system
Journal of Applied Ichthyology, 2015Co-Authors: Sandra Cahuin, Luis A Cubillos, Ruben EscribanoAbstract:Summary Most of the studies investigating synchrony in fluctuations of abundance of small pelagic fish have been based on catch data only, which do not describe the dynamics of populations as a relative abundance index. In this paper, catch, biomass, recruitment and recruitment rate, were used to compare synchronous changes for two stocks of anchovy (Engraulis ringens) from 1982 to 2004. One is the North Central Peru stock (NCP) and the other is the shared South Peru-Northern Chile stock (SPNC). Correlation analysis demonstrated a significant association between population time series, particularly during the growing phase of the stocks. Thus, the synchronous fluctuation pattern of the two stocks is due to the recovery phase and probably driven by density-independent effects of simultaneous favorable environmental conditions occurring in the two regions. The conclusions were: (i) both NCP and SPNC anchovy stocks are in an overall positive phase of synchrony, (ii) higher correlations in the synchronous pattern of fluctuations occurred during simultaneous increase of biomass, and (iii) short-term fluctuations were negative when the abundance of the stock was lower and/or impacted by El Nino events.
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variation in the spawning periods of Engraulis ringens and strangomera bentincki off the coasts of chile a quantitative analysis
Fisheries Research, 2014Co-Authors: Gabriel Claramunt, Leonardo R Castro, Luis A Cubillos, Carola Hernandez, Marcos ArteagaAbstract:Abstract In Chile, anchovy ( Engraulis ringens ) and common sardine ( Strangomera bentincki ) are two commercially important small pelagic fish. In southern Chile (32–41° S), both species coexist and inhabit the coastal zone. In northern Chile (18–25° S), only anchovy is present in the coastal zone. The determine onset, peak, end, and duration of the spawning periods in these small pelagic fish are key factors in population studies and of great interest for fisheries management. The objective of this study is to determine the temporal trends of spawning in these two species. A quantitative method was developed to obtain objective indicators of the spawning periods and the method is a useful tool for comparative studies between populations as well as to study the relationship of spawning periods with other demographic variables affected by fishing or environmental variability. Peak spawning in the three populations was consistent through time but showed changes in the duration of the maximum reproductive period. Anchovy and common sardine of the southern zone show synchrony and a shortening of the duration of spawning periods, probably in response to environmental fluctuations. Anchovy in northern Chile have shown an increase in duration from 1986 that is coincidental with the regime shift reported for the Humboldt Current Ecosystem in the mid-1980s.
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inter annual reproductive trait variation and spawning habitat preferences of Engraulis ringens off northern chile
Revista De Biologia Marina Y Oceanografia, 2012Co-Authors: Gabriel Claramunt, Leonardo R Castro, Luis A Cubillos, Hansjuergen Hirche, Graciela Perez, Mauricio BraunAbstract:A lo largo del Sistema de la Corriente de Humboldt, la anchoveta (Engraulis ringens) se distribuye entre los 4°S y 42°S. Las condiciones ambientales difieren notablemente tanto entre las zonas de desove y las estaciones del ano. Por lo tanto, diferentes tacticas reproductivas se esperan en respuesta al medio ambiente. En este estudio se utilizo la informacion proveniente de cruceros para la aplicacion del Metodo de Produccion Diaria de Huevos (MPDH) para estudiar la variabilidad latitudinal e interanual de los parametros reproductivos de las poblaciones de E. ringens en la zona norte (18° 20' a 26°00'S) y sur (33° 00' a 41° 30'S) de Chile. El objetivo principal es investigar las potenciales preferencias por ciertos rangos de temperatura y concentracion de clorofila-a en el habitat de desove y los cambios en el potencial reproductivo y tamano de los huevos de anchoveta en respuesta a las condiciones del habitat, en especial a la temperatura. Los resultados muestran que la temperatura no es una variable relevante del medio ambiente para determinar la posicion geografica de las zonas de desove de E. ringens. Altas concentraciones de clorofila seria la variable seleccionada para los cambios en la posicion de las areas de desove. Se postula que en lugar de preferir cierto rango de temperatura, anchoveta acomoda los productos del desove de acuerdo a las condiciones predominantes del medio ambiente (ej. tamano del huevo, fecundidad) y esta respuesta seria en la escala de la frecuencia de desove, es decir, semanas.
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climatic regimes and the recruitment rate of anchoveta Engraulis ringens off peru
Estuarine Coastal and Shelf Science, 2009Co-Authors: Sandra Cahuin, Luis A Cubillos, Miguel Niquen, Ruben EscribanoAbstract:Abstract The recruitment rate of Peruvian anchoveta, Engraulis ringens, was studied to test the hypothesis that long-term environmental variation (regime shifts) had a significant impact on density-dependent processes governing the anchovy recruitment during the period 1963–2004. On the basis of previous defined regimes and turning points for the Humboldt Current System, we identified two groups of years for increased recruitment of anchoveta (1963–1971 and 1986–2004), and one unfavorable period (1972–1985). A common intercept and significantly different slopes were found when the recruitment rate was plotted as a function of the spawning stock biomass during those groups of years, suggesting that density-dependent effects on recruitment were affected during different climate regimes. The favorable (unfavorable) regime was characterized by higher (lower) zooplankton volumes, and with a higher frequency of colder (warmer) waters. Dome-shaped relationships between recruitment rate, spawning stock biomass and SST, were detected with a Generalized Additive Model for the favorable regime. Thus, recruitment could be explained by non-linear effects of environmental variables. Ultimately, climatic regimes are affecting the density-dependent effects on recruitment of anchoveta and the mechanisms involved may be associated with changes in the carrying capacity of the spawning habitat of anchoveta off Peru, which in turn are related with the effects of cold and warm regimes.
Gabriel Claramunt - One of the best experts on this subject based on the ideXlab platform.
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Spawning marker patterns of Engraulis ringens of northern Chile
Fisheries Research, 2019Co-Authors: Gabriel Claramunt, Luis A Cubillos, Gustavo Herrera, Eduardo DíazAbstract:Abstract The procedures used to estimate the daily spawning fraction of northern Chile anchovy (Engraulis ringens) have been revised based on information from 17 Daily Egg Production Method (DEPM) survey estimates of the anchovy spawning biomass. The most commonly used spawning marker is postovulatory follicles (POFs). POFs are transitory remnants of the ovulated follicles that remain within the ovary after spawning, until they are fully resorbed. As the process of Postovulatory Follicles (POF) degeneration is continuous, the assignment of POF stages to daily cohorts of spawners can be imprecise. Therefore, the main objective of this paper is to review the criteria used to assign females to daily spawning cohorts in anchovy (Engraulis ringens) located off northern Chile. For our first step, we review the peak spawning time using recently fertilized eggs. To study the POF duration, we divided the POF degenerative process into seven stages and then fitted a gamma probability distribution to the hourly POF stage fractions in a daily cycle. This approach is a quantitative, objective way to define the range of time during which the POF stages are present in the samples, as well as the overlap between daily cycles. The hourly distribution of recently fertilized eggs (Stage 1) indicated a strong daily spawning time synchrony that peaked at 4:00 GMT (00:00 local time). We found that the class Day1 cohort (females that spawn on the night before their capture) belongs primarily to POF Stages 1 to 3, with some proportions belonging to POF Stages 4 and 5 according to the capture time. The migratory nucleus (MN) and hydrated (H) phases correspond to the cohort that spawns on the night of capture. The daily spawning fraction estimates the based on the POF or MN and H phases did not show significant differences. Our results indicated an average spawning frequency of four days (S = 0.27 day−1). The prevalence of POFs according to female size follow an asymptotic model of the von Bertalanffy type, indicating an asymptote around 0.27 day−1. The POF presence was higher during cold periods, probably due to a longer period of decay. A general linear model analysis showed that body weight, time of catch and mean temperature significantly influenced the spawning fraction.
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variation in the spawning periods of Engraulis ringens and strangomera bentincki off the coasts of chile a quantitative analysis
Fisheries Research, 2014Co-Authors: Gabriel Claramunt, Leonardo R Castro, Luis A Cubillos, Carola Hernandez, Marcos ArteagaAbstract:Abstract In Chile, anchovy ( Engraulis ringens ) and common sardine ( Strangomera bentincki ) are two commercially important small pelagic fish. In southern Chile (32–41° S), both species coexist and inhabit the coastal zone. In northern Chile (18–25° S), only anchovy is present in the coastal zone. The determine onset, peak, end, and duration of the spawning periods in these small pelagic fish are key factors in population studies and of great interest for fisheries management. The objective of this study is to determine the temporal trends of spawning in these two species. A quantitative method was developed to obtain objective indicators of the spawning periods and the method is a useful tool for comparative studies between populations as well as to study the relationship of spawning periods with other demographic variables affected by fishing or environmental variability. Peak spawning in the three populations was consistent through time but showed changes in the duration of the maximum reproductive period. Anchovy and common sardine of the southern zone show synchrony and a shortening of the duration of spawning periods, probably in response to environmental fluctuations. Anchovy in northern Chile have shown an increase in duration from 1986 that is coincidental with the regime shift reported for the Humboldt Current Ecosystem in the mid-1980s.
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inter annual reproductive trait variation and spawning habitat preferences of Engraulis ringens off northern chile
Revista De Biologia Marina Y Oceanografia, 2012Co-Authors: Gabriel Claramunt, Leonardo R Castro, Luis A Cubillos, Hansjuergen Hirche, Graciela Perez, Mauricio BraunAbstract:A lo largo del Sistema de la Corriente de Humboldt, la anchoveta (Engraulis ringens) se distribuye entre los 4°S y 42°S. Las condiciones ambientales difieren notablemente tanto entre las zonas de desove y las estaciones del ano. Por lo tanto, diferentes tacticas reproductivas se esperan en respuesta al medio ambiente. En este estudio se utilizo la informacion proveniente de cruceros para la aplicacion del Metodo de Produccion Diaria de Huevos (MPDH) para estudiar la variabilidad latitudinal e interanual de los parametros reproductivos de las poblaciones de E. ringens en la zona norte (18° 20' a 26°00'S) y sur (33° 00' a 41° 30'S) de Chile. El objetivo principal es investigar las potenciales preferencias por ciertos rangos de temperatura y concentracion de clorofila-a en el habitat de desove y los cambios en el potencial reproductivo y tamano de los huevos de anchoveta en respuesta a las condiciones del habitat, en especial a la temperatura. Los resultados muestran que la temperatura no es una variable relevante del medio ambiente para determinar la posicion geografica de las zonas de desove de E. ringens. Altas concentraciones de clorofila seria la variable seleccionada para los cambios en la posicion de las areas de desove. Se postula que en lugar de preferir cierto rango de temperatura, anchoveta acomoda los productos del desove de acuerdo a las condiciones predominantes del medio ambiente (ej. tamano del huevo, fecundidad) y esta respuesta seria en la escala de la frecuencia de desove, es decir, semanas.
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transition period from larva to juvenile in anchoveta Engraulis ringens length or age related
Journal of Fish Biology, 2011Co-Authors: P Moreno, Gabriel Claramunt, Leonardo R CastroAbstract:To determine the beginning and end of the transition period from larvae to juveniles in anchoveta Engraulis ringens, seven morphometric measurements were carried out in 333 laboratory-reared and 324 field-caught larvae. Measurements of body morphometrics were employed to calculate the six body ratios selected to show transition changes described in this study. The analysis was carried out with ‘dummy variables' (variables that take only one of two possible values: 0 or 1) because a single model was used to indicate the point at which the slope changes in piecewise linear regressions. The regression coefficients of the relationship between ratios of morphometric measurements and body length were not significant in any case (P > 0·05) and, accordingly, a discrete length at which the slope changes could not be estimated. The ratio of the measurements according to the age showed two inflections, corresponding to the beginning and end of the transition period. The first inflection occurred between 32 and 64 days (average 46 days); the second inflection occurred between 81 and 149 days (average 107 days). Therefore, the transition period lasted c. 61 days, starting with a high growth rate, continuing with a slower growth phase, and ending with the onset of a new high growth rate period that corresponded to the start of typical juvenile growth. On the basis of these results, it is hypothesized that the transition from larvae to juveniles in E. ringens is determined more by age than body size.
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egg trait variation in anchoveta Engraulis ringens a maternal response to changing environmental conditions in contrasting spawning habitats
Marine Ecology Progress Series, 2009Co-Authors: Leonardo R Castro, Gabriel Claramunt, Alejandra Llanosrivera, M C Krautz, P MorenoAbstract:The Engraulis ringens distribution (4 to 42° S) covers a wide variety of environmental conditions. We assessed the coping mechanisms used by this anchoveta in different spawning habi- tats, reporting differences in egg traits between populations off northern (Iquique, 20° S) and south- ern Chile (Talcahuano, 36° S) and throughout the spawning season. Eggs were smaller off Iquique, declined in size during the reproductive season (both populations), and inter-population differences persisted throughout the spawning season. Batch fecundity (eggs per batch per female) and relative fecundity (eggs per female weight) were lower off Talcahuano during the peak spawning months. Thus, larger eggs spawned in the southern population seem to be produced at the cost of a reduction in fecundity. The eggs also differed biochemically between the 2 populations; total lipids and triacyl- glycerides were much higher off Talcahuano. The biochemical composition (both populations) also changed throughout the spawning season, with higher lipids early in the spawning season (July to August) off Talcahuano. Hatching success decreased during the spawning season, and correlated positively with egg size and lipid contents. Environmental conditions differed markedly between spawning areas and from mid-winter to late spring. Off Talcahuano, the temperature and winter-time water column productivity are lower and turbulence is higher, while eggs are larger, lipid contents higher, and batch fecundity lower. This mechanism seems to facilitate survival of young offspring in the more adverse winter conditions off Talcahuano. These egg characteristics are determined by the adult female reproductive system, representing a maternal influence on the early life-history traits of anchoveta that might enable rapid changes in population densities in some years of improved habitat conditions.
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ontogenetic and spatiotemporal variability in anchoveta Engraulis ringens diet off peru
Journal of Fish Biology, 2014Co-Authors: Pepe Espinoza, Arnaud BertrandAbstract:In this study, historical data available since 1954 were used to get new insight to ontogenetic and spatiotemporal variability in Peruvian anchovy or anchoveta Engraulis ringens diet. Whatever the period, E. ringens foraged mainly on macrozooplankton and the importance of euphausiids in E. ringens diet appears directly related to euphausiids abundance. This bottom-up effect is also observed at smaller scale because the euphausiids fraction increased with E. ringens total length and euphausiids accessibility. Selecting the largest prey, the euphausiids, provides an energetic advantage for E. ringens in its ecosystem where oxygen depletion imposes strong metabolic constraints on pelagic fishes. This study illustrates the plasticity of E. ringens that allows it to cope with its highly variable environment.
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bags of features for fish school cluster characterization in pelagic ecosystems application to the discrimination of juvenile and adult anchovy Engraulis ringens clusters off peru
Canadian Journal of Fisheries and Aquatic Sciences, 2012Co-Authors: Ronan Fablet, Arnaud Bertrand, Salvatore Peraltilla, Cecilia Pena, Ramiro CastilloAbstract:Whereas fisheries acoustics data processing mainly focused on the detection, characterization, and recognition of individual fish schools, here we addressed the characterization and discrimination of fish school clusters. The proposed scheme relied on the application of the Bags-of-Features (BoF) approach to acoustic echograms. This approach is widely ex- ploited for pattern recognition issues and naturally applies here, considering fish schools as the relevant elementary objects. It relies on the extraction and categorization of fish schools in fisheries acoustic data. Echogram descriptors were computed per unit echogram length as the numbers of schools in different school categories. We applied this approach to the discrimi- nation of juvenile and adult anchovy (Engraulis ringens) off Peru. Whereas the discrimination of individual schools is low (below 70%), the proposed BoF scheme achieved between 89% and 92% of correct classification of juvenile and adult echo- grams for different survey data sets and significantly outperformed classical school-based echogram characteristics (about 10% of improvement of the correct classification rate). We further illustrate the potential of the proposed scheme for the es- timation of the spatial distribution of juvenile and adult anchovy populations. Resume : Alors que le traitement de donnees acoustiques sur les ressources halieutiques est principalement axe sur la detec- tion, la caracterisation et la reconnaissance de bancs individuels de poissons, nous nous penchons sur la caracterisation et la discrimination de groupes de bancs de poissons. Le schema propose repose sur l'application de l'approche des sacs de mots visuels (« Bags-of-Features » ou BoF) au traitement d'echogrammes acoustiques. Cette approche est frequemment appliquee aux problemes de reconnaissance de formes et s'applique donc tout naturellement a l'etude de bancs de poissons en tant qu'objets elementaires. Elle repose sur l'extraction et la categorisation de bancs de poissons a partir de donnees acoustiques sur les ressources halieutiques. Des descripteurs d'echogramme ont ete calcules par unite de longueur d'echogramme, cor- respondant aux nombres de bancs, dans differentes categories de bancs. Nous avons applique cette approche a la discrimina- tion d'anchois (Engraulis ringens) juveniles et adultes au large des cotes du Perou. Si la discrimination de bancs individuels est faible (inferieure a 70 %), la classification des echogrammes de juveniles et d'adultes reposant sur l'approche des BoF s'est averee exacte dans de 89 % a 92 % des cas pour differents ensembles de donnees de leves, ce qui correspond a une augmentation significative de l'exactitude par rapport aux approches classiques reposant sur les caracteristiques d'echogram- mes basees sur le banc (augmentation d'environ 10 % du taux de classification exacte). Nous poussons plus loin la demons- tration du potentiel du schema propose pour l'estimation de la distribution spatiale des populations d'anchois juveniles et adultes. (Traduit par la Redaction)
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revisiting peruvian anchovy Engraulis ringens trophodynamics provides a new vision of the humboldt current system
Progress in Oceanography, 2008Co-Authors: Pepe Espinoza, Arnaud BertrandAbstract:The Peruvian anchovy or anchoveta (Engraulis ringens) forages on plankton and is a main prey for marine mammals, seabirds, fish, and fishers, and is therefore a key element of the food web in the Humboldt Current system (HCS). Here, we present results from the analysis of 21,203 anchoveta stomach contents sampled during 23 acoustic surveys over the period 1996–2003. Prey items were identified to the genus level, and the relative dietary importance of different prey was assessed by determination of their carbon content. Variability in stomach fullness was examined relative to the diel cycle, the distance from the coast, sea surface temperature, and latitude, using generalized additive models (GAMs). Whereas phytoplankton largely dominated anchoveta diets in terms of numerical abundance and comprised >99% of ingested prey items, the carbon content of prey items indicated that zooplankton was by far the most important dietary component, with euphausiids contributing 67.5% of dietary carbon followed by copepods (26.3%). Stomach fullness data showed that anchoveta feed mainly during daytime between 07h00 and 18h00, although night-time feeding also made a substantial contribution to total food consumption. Stomach fullness also varied with latitude, distance from the coast, and temperature, but with substantial variability indicating a high degree of plasticity in anchoveta feeding behaviour. The results suggest an ecological role for anchoveta that challenges current understanding of its position in the foodweb, the functioning of the HCS, and trophic models of the HCS.
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ecological niches and areas of overlap of the squat lobster munida pleuroncodes monodon and anchoveta Engraulis ringens off peru
Progress in Oceanography, 2008Co-Authors: Mariano Gutierrez, Argiro Ramirez, Sophie Bertrand, Octavio Moron, Arnaud BertrandAbstract:Abstract The world’s largest mono-specific fishery, the Peruvian anchovy or anchoveta ( Engraulis ringens ) fishery, has been the subject of many studies since the 1960s. Details of its relationship with other species have mainly focused on alternations with sardine, Sardinops sagax, and little effort has so far been paid to interactions with other species sharing the same ecosystem. This is the case for Pleuroncodes monodon , the crustacean squat lobster or ’munida’, which has become highly abundant along the Peruvian coast since the mid-1990s. Munida is now an important prey for seabirds, mammals and coastal predatory fish. Knowledge of patterns of distribution and ecological niche of munida is scarce however off Peru. Here we describe and compare spatial patterns of distribution of anchoveta and munida and their ecological niches based on data from 26 acoustic surveys performed along the Peruvian coast between 1998 and 2006. The results indicate that munida and anchoveta share ecological niches but that munida is restricted to the coldest part of the productive cold coastal waters whereas anchoveta do not present any temperature preference over a large range (14–23 °C). The recent increase in munida abundance off Peru is concomitant with colder conditions; with their onset munida extended its range from central Chile northwards. Off Peru the very shallow oxycline keeps munida from its usual bottom habitat and has forced it to adopt pelagic behaviour.
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anchovy Engraulis ringens and sardine sardinops sagax spatial dynamics and aggregation patterns in the humboldt current ecosystem peru from 1983 2003
Fisheries Oceanography, 2007Co-Authors: Mariano Gutierrez, Arnaud Bertrand, Gordon Swartzman, Sophie BertrandAbstract:Three indexes of spatial aggregation are developed and used to examine the aggregation pattern of sardine (Sardinops sagax) and anchovy (Engraulis ringens )i n the Peruvian Humboldt Current System, determined from 36 acoustic surveys conducted from 1983 through 2003 by the Peruvian Marine Institute (IMARPE). Each index assesses a different aspect of aggregation: the concentration, the percent occupancy of space and the clustering of high-fish abundance. Both time-series correlation and tree-based clustering-regression method, classification and regression trees (CART), were used to relate each of the indexes to environmental variables (season, temperature anomaly and year). Additionally, a measure of onshore‐offshore distribution, the average distance from the coast, and abundance variables (the average acoustic backscatter per occupied sampling unit, and the acoustically estimated total abundance of sardine and anchovy from IMARPE) were related to environmental factors by using CART. We show that the 1983‐2003 time series can be divided into three different periods: with shifts in 1992 and in 1997‐98. Sardine and anchovy showed large differences in both abundance and aggregation among these periods. Although upwelling ecosystems support dramatic and sudden changes in environmental conditions, fish responses are sometimes smoother than usually suggested and there are transition periods with concomitant high biomasses of anchovy and sardine, but with different spatial aggregation patterns. Observed relationships between environmental proxies and aggregation patterns support the habitat-based hypothesis that environmentally mediated alterations in range lead to population changes.