Papers by ricardo tafur - jimenez
Instituto del Mar del Perú - IMARPE, Jun 1, 2020
El Crucero de investigación del calamar gigante Dosidicus gigas (d'Orbigny, 1835) se efectuó entr... more El Crucero de investigación del calamar gigante Dosidicus gigas (d'Orbigny, 1835) se efectuó entre el 21 de noviembre y 12 de diciembre 2017 a bordo de los BIC José Olaya Balandra y Humboldt, para estimar índices de abundancia, determinar el estado biológico y poblacional y la interrelación con las condiciones del ambiente marino en sus áreas de concentración. El Olaya cubrió la zona norte desde 4°S hasta 7°S y el Humboldt el sur desde 15°S hasta 18°S y parte de la zona de pesca de aguas adyacentes. En el norte, las Aguas Costeras Frías (ACF) presentaron mayor extensión frente a Talara-Paita, las Aguas Subtropicales Superficiales (ASS) se distribuyeron fuera de las 100 mn y el agua de mezcla (ACF-AES-ASS) a 150 mn frente a Paita. En el sur, las ASS se presentaron asociadas a TSM de 19 °C a 21 °C, y agua de mezcla (ACF-ASS) entre 50 y 100 mn y fuera de 150 mn de la costa. La captura del recurso fue de 1.394,4 kg, correspondiendo 1.387,7 kg a 121 operaciones con líneas de mano con potera y 6,7 kg a 49 lances con red de arrastre de media agua. Los índices de abundancia fueron mayores en la zona norte, con núcleos densos fuera de 120 mn; en el sur fueron menores, reflejando mayor dispersión del recurso. Asimismo, la CPUE en número presentó mayores valores en la zona norte y en peso en la zona sur, debido a la diferencia de tamaños de los ejemplares capturados (pequeños y medianos en el norte, medianos y grandes en el sur). La estructura de tallas varió de 1 a 93 cm de LM. Con línea de mano con potera, las tallas fluctuaron de 18 a 93 cm de LM y con red de arrastre de 1 a 38 cm; en el norte predominaron ejemplares menores a 30 cm y en el sur mayor a 69 cm de LM. La mayor fracción de ejemplares estuvo inmaduro en la zona norte y en estadios maduros y en desove en el sur.
Instituto del Mar del Perú - IMARPE, Jun 1, 2020
99% con pinta, el resto con red de arrastre pelágica destacando la anchoveta (74%). El Humboldt t... more 99% con pinta, el resto con red de arrastre pelágica destacando la anchoveta (74%). El Humboldt trabajó entre bahía Independencia (14°S) e Ilo (18°S) desde 50 hasta 270 mn; se efectuaron 83 estaciones. Se capturó 5.936,57 kg, 99% con pinta. La biomasa total estimada fue 1.898.428 t, 29% correspondió al norte y 71% al sur. Al norte la talla varió entre 22 y 82 cm, media en 59,9 y moda en 64 cm de LM; al sur entre 25 y 102 cm, moda principal en 93 y moda secundaria en 32 cm de LM. Con la red de arrastre se capturaron 3.817 ejemplares de calamar, la talla varió de 1 a 52 cm, moda 3 cm, media 5,1 cm de LM. La sección Paita presentó termoclina conformada por las isotermas de 16-23 °C. Dentro de las 60 mn, la termoclina estuvo profunda con isotermas de 17 a 14 °C relacionado a un ramal de la contracorriente sur peruana chilena (CSPC) y el afloramiento de las isotermas de 18 a 20 °C. La salinidad mostró presencia de aguas ecuatoriales superficiales (AES) sobre 30 m de profundidad y por fuera de 120 mn, con temperatura mayor a 23 °C. Las aguas costeras frías (ACF) y las aguas de mezcla predominaron por debajo de 50 m de profundidad hasta aproximadamente 200 m. En la zona sur, la temperatura superficial del mar varió de 21,7 a 24,9 °C, con anomalías térmicas de-1,3 a +3,9 °C, indicando condiciones normales en zonas oceánicas y cálidas en zonas próximas a la costa. La salinidad superficial del mar (SSM) osciló entre 35,108 y 35,622 ups, propias de las Aguas Subtropicales Superficiales (ASS), no se registraron aguas de mezcla y ACF. Frente a Quilca, las Aguas Templadas de la Subantártica (ATSA) habrían favorecido el desarrollo del afloramiento costero en áreas próximas a la costa.
Instituto del Mar del Perú - IMARPE, 2016
El Instituto del Mar del Perú, tiene como objetivo la evaluación de los recursos marinos, destaca... more El Instituto del Mar del Perú, tiene como objetivo la evaluación de los recursos marinos, destacando entre los moluscos cefalópodos el calamar gigante Dosicidus gigas (d'Orbigny, 1835), calamar común Doryteuthis (Amerigo) gahi (d'Orbigny, 1835) y pulpo Octopus mimus (Gould, 1852). De estas tres especies, D. gigas es de amplia distribución latitudinal y longitudinal, mientras que D. gahi y O. mimus habitan dentro de la plataforma continental. D. gigas es la de mayor importancia económica debido a sus desembarques, que representan el recurso más extraído por la pesquería artesanal. En este documento se describen los procedimientos metodológicos en los muestreos biológico y biométrico de cefalópodos. Palabras clave: Cefalópodos, muestreo biológico-biométrico
Boletin Instituto del Mar del Perú, Dec 10, 2018
El calamar gigante (Dosidicus gigas) se encuentra en gran abundancia a lo largo de toda la costa ... more El calamar gigante (Dosidicus gigas) se encuentra en gran abundancia a lo largo de toda la costa peruana desde 10 hasta más de 500 millas náuticas de la costa. Realiza migraciones verticales de 0 a 1200 m de profundidad, con migraciones ontogénicas regulares hacia la costa y mar adentro y migraciones latitudinales menos regulares de varios cientos de millas náuticas. Es un predador muy agresivo con un amplio espectro alimentario, y en los últimos 14 años entre sus presas han predominado cefalópodos (42,33% en peso) y peces mesopelágicos Vinciguerria lucetia (13,05%) y Myctophidae (12,38%). Diferencias observadas en sus tamaños de madurez sexual, crecimiento y áreas de distribución sugieren que hay al menos tres grupos fenotípicos o subunidades poblacionales frente al Perú. La distribución de frecuencia de tallas en las capturas de flotas artesanales e industriales en aguas peruanas ha sido muy variable, con un cambio significativo a tallas mucho más grandes que se inicia el año 2000 y se hace más evidente a partir del año 2001. Desde entonces, los calamares capturados en aguas peruanas han sido por lo general bastante más grandes que los capturados en la alta mar adyacente. La pesquería peruana de calamar se desarrolló rápidamente a principios de la década de los años 1990, con aumentos en las capturas por una flota potera industrial extranjera operando bajo licencia peruana y una pesquería artesanal local en rápida expansión, que sustituyó gradualmente a la pesquería industrial. Las capturas totales de calamar gigante de Perú alcanzaron un máximo de 556 mil toneladas en 2014, todas capturadas por flotas artesanales locales. El stock, o stocks, de calamar gigante en aguas peruanas se consideran sub-explotado o moderadamente explotado, y las evaluaciones se basan en estimaciones de biomasa de cruceros acústicos combinados con modelos de producción excedente. Se discute la idoneidad de estos y otros métodos de evaluación de stocks, dando particular atención a la estructura de la población, la presencia de tres grupos fenotípicos o posibles subunidades poblacionales, así como otras características observadas en el calamar gigante frente a Perú y sus implicancias para la evaluación y ordenación de su pesquería.
Dosidicus gigas is the largest and heavy ommastrephid in the East Pacific, where his role as pred... more Dosidicus gigas is the largest and heavy ommastrephid in the East Pacific, where his role as predator and prey is important in trophic food webs. It is also considered a multiple spawning, that continues feeding and growing even during their reproductive period. However, it is unknown the relationship between energy storage in the digestive gland and gonadal maturation stage (GMS). The variation of digestive gland index (DGI) by GMS in females and males of D. gigas in Peruvian waters is analyzed. DGI from 1937 squids sampled during 1998, 2006-2009 was analyzed in this work. The mantle size ranged from 111 to 1019 mm. The DGI values by GMS and sex were: Immature: 0.38 to 13.33% of total weight (TW), mean 3.67% (+/- 1.47) for females; 1.00-13.33% TW, mean 3.27% (+/- 1.43%) for males. In maturation: 0.69-9.51% TW, mean 3.46% (+/- 1.40) for females, 0.67-8.60% TW, mean 3.52% (+/- 1.44%) for males. Mature: 1.78-8.44% TW, mean 3.86% (+/- 1.35) for females, 0.91-8.64% TW, mean 3.03% (+/- 1...
GigaScience, 2020
Background The giant squid (Architeuthis dux; Steenstrup, 1857) is an enigmatic giant mollusc wit... more Background The giant squid (Architeuthis dux; Steenstrup, 1857) is an enigmatic giant mollusc with a circumglobal distribution in the deep ocean, except in the high Arctic and Antarctic waters. The elusiveness of the species makes it difficult to study. Thus, having a genome assembled for this deep-sea–dwelling species will allow several pending evolutionary questions to be unlocked. Findings We present a draft genome assembly that includes 200 Gb of Illumina reads, 4 Gb of Moleculo synthetic long reads, and 108 Gb of Chicago libraries, with a final size matching the estimated genome size of 2.7 Gb, and a scaffold N50 of 4.8 Mb. We also present an alternative assembly including 27 Gb raw reads generated using the Pacific Biosciences platform. In addition, we sequenced the proteome of the same individual and RNA from 3 different tissue types from 3 other species of squid (Onychoteuthis banksii, Dosidicus gigas, and Sthenoteuthis oualaniensis) to assist genome annotation. We annotated...
The size first maturity, size spawning and spawning season of te octopus Octopus mimus were studi... more The size first maturity, size spawning and spawning season of te octopus Octopus mimus were studied from january 1998 to January 1999. The data used in the analysis correspond to sampling of the artisanal fishery catches in Callao área. The size at firt maturity was 127,7 mm for females and 65,5 mm for males,whose respective weights were 742,5 g and 123,5 g. The mean spawning size was 143 mm for females and 137 mm for male, with weights of 1 002, and 992 g. The spawning seasons were determined by Gonadosomatic Index (GSI), by Maturity Index (MI) and by the monthly proportion of maturity stages. The monthly evolution of the GSI reveals a main period of spawning in November and a secondary in february – March. The analysis of the MI and the proportion of mature individuals show also a third spawning event in July. The results presented here include a year affected by altered oceagraphic conditions due to El Niño 1997-1998 event. That is why a more exhaustive assessment of normal years...
Marine Biology
To determine the habitat and resource use of Dosidicus gigas in the Northern Humboldt Current Sys... more To determine the habitat and resource use of Dosidicus gigas in the Northern Humboldt Current System, we analysed carbon and nitrogen stable isotopes of 234 individuals collected during 2008–2010. Large variations in mantle stable isotope ratios were recorded, with values ranging from -19.1 to -15.1 % (d13C) and from 7.4 to 20.5 % (d15N). Most of the variation was explained by latitude, followed by distance to shelf break for carbon and by squid size for nitrogen. Latitudinal variations with increasing values from north to south were also found in zooplankton samples and were related to changes in isotope baseline values probably due to oxygen minimum zones that occur off Peru. This similar latitudinal trend in both zooplankton and D. gigas samples reveals that D. gigas is a relatively resident species at the scale of its isotopic turnover rate (i.e. a few weeks), even if this is not necessarily the case at the scale of its life. A small but significant size effect on d13C values su...
Progress in Oceanography, 2008
Changes in population structure of the jumbo flying squid Dosidicus gigas in Peruvian waters were... more Changes in population structure of the jumbo flying squid Dosidicus gigas in Peruvian waters were studied based on size-at-maturity from 1989 to 2004. From 1989 to 1999, mature squid belonging to the medium-sized group prevailed, but from 2001 on, mature squids were larger. This change is not related to the changes in sea surface temperature and we hypothesized that it was caused by the population increase of mesopelagic fishes as prey.
Investigaciones marinas, 2002
Scientia Marina, 2011
Acoustic surveys for assessing the biomass and distribution of the jumbo squid (Dosidicus gigas) ... more Acoustic surveys for assessing the biomass and distribution of the jumbo squid (Dosidicus gigas) and the lightfish (Vinciguerria lucetia) were carried out in the Humboldt Current System of Peru in 2007 and 2008. At the same time, 937 jumbo squid were caught and their stomach contents analyzed. The diet of the jumbo squid was dominated by mesopelagic fish. The first component of their fish diet was V. lucetia and the second component was the myctophid fish Diogenichthys laternatus. Acoustic biomass estimates of these species show that V. lucetia is an important component in aggregative structures in the Humboldt Current System of Peru and its distribution and movements are closely related to the migratory movements of the jumbo squid. The trophic relationship observed between D. gigas and V. lucetia promotes an increase in jumbo squid biomass and, has a positive trophic effect on the ocean ecosystem.
PLoS ONE, 2014
The jumbo squid Dosidicus gigas plays an important role in marine food webs both as predator and ... more The jumbo squid Dosidicus gigas plays an important role in marine food webs both as predator and prey. We investigated the ontogenetic and spatiotemporal variability of the diet composition of jumbo squid in the northern Humboldt Current system. For that purpose we applied several statistical methods to an extensive dataset of 3,618 jumbo squid non empty stomachs collected off Peru from 2004 to 2011. A total of 55 prey taxa was identified that we aggregated into eleven groups. Our results evidenced a large variability in prey composition as already observed in other systems. However, our data do not support the hypothesis that jumbo squids select the most abundant or energetic taxon in a prey assemblage, neglecting the other available prey. Indeed, multinomial model predictions showed that stomach fullness increased with the number of prey taxa, while most stomachs with low contents contained one or two prey taxa only. Our results therefore question the common hypothesis that predators seek locally dense aggregations of monospecific prey. In addition D. gigas consumes very few anchovy Engraulis ringens in Peru, whereas a tremendous biomass of anchovy is potentially available. It seems that D. gigas cannot reach the oxygen unsaturated waters very close to the coast, where the bulk of anchovy occurs. Indeed, even if jumbo squid can forage in hypoxic deep waters during the day, surface normoxic waters are then required to recover its maintenance respiration (or energy?). Oxygen concentration could thus limit the co-occurrence of both species and then preclude predator-prey interactions. Finally we propose a conceptual model illustrating the opportunistic foraging behaviour of jumbo squid impacted by ontogenetic migration and potentially constrained by oxygen saturation in surface waters.
Marine Biology, 2012
To determine the habitat and resource use of Dosidicus gigas in the Northern Humboldt Current Sys... more To determine the habitat and resource use of Dosidicus gigas in the Northern Humboldt Current System, we analysed carbon and nitrogen stable isotopes of 234 individuals collected during 2008-2010. Large variations in mantle stable isotope ratios were recorded, with values ranging from-19.1 to-15.1 % (d 13 C) and from 7.4 to 20.5 % (d 15 N). Most of the variation was explained by latitude, followed by distance to shelf break for carbon and by squid size for nitrogen. Latitudinal variations with increasing values from north to south were also found in zooplankton samples and were related to changes in isotope baseline values probably due to oxygen minimum zones that occur off Peru. This similar latitudinal trend in both zooplankton and D. gigas samples reveals that D. gigas is a relatively resident species at the scale of its isotopic turnover rate (i.e. a few weeks), even if this is not necessarily the case at the scale of its life. A small but significant size effect on d 13 C values suggests that jumbo squid perform offshore-onshore ontogenic migration, with juveniles distributed offshore. For nitrogen, the high interindividual variability observed with mantle length indicates that D. gigas can prey on a high variety of resources at any stage of their life cycle. This large-scale study off the coast of Peru provides further evidence that D. gigas have the capability to explore a wide range of habitats and resources at any stage of their life. Communicated by C. Harrod.
Fisheries Research, 2001
We study the phase synchronized clusters in the diffusively coupled maps on the Cayley tree netwo... more We study the phase synchronized clusters in the diffusively coupled maps on the Cayley tree networks for heterogeneous delay values. Cayley tree networks comprise of two parts: the inner nodes and the boundary nodes. We find that heterogeneous delays lead to various cluster states, such as; (a) cluster state consisting of inner nodes and boundary nodes, and (b) cluster state consisting of only boundary nodes. The former state may comprise of nodes from all the generations forming self-organized cluster or nodes from few generations yielding driven clusters depending upon on the parity of heterogeneous delay values. Furthermore, heterogeneity in delays leads to the lag synchronization between the siblings lying on the boundary by destroying the exact synchronization among them. The time lag being equal to the difference in the delay values. The Lyapunov function analysis sheds light on the destruction of the exact synchrony among the last generation nodes. To the end we discuss the relevance of our results with respect to their applications in the family business as well as in understanding the occurrence of genetic diseases.
PLoS ONE, 2014
The jumbo squid Dosidicus gigas plays an important role in marine food webs both as predator and ... more The jumbo squid Dosidicus gigas plays an important role in marine food webs both as predator and prey. We investigated the ontogenetic and spatiotemporal variability of the diet composition of jumbo squid in the northern Humboldt Current system. For that purpose we applied several statistical methods to an extensive dataset of 3,618 jumbo squid non empty stomachs collected off Peru from 2004 to 2011. A total of 55 prey taxa was identified that we aggregated into eleven groups. Our results evidenced a large variability in prey composition as already observed in other systems. However, our data do not support the hypothesis that jumbo squids select the most abundant or energetic taxon in a prey assemblage, neglecting the other available prey. Indeed, multinomial model predictions showed that stomach fullness increased with the number of prey taxa, while most stomachs with low contents contained one or two prey taxa only. Our results therefore question the common hypothesis that predators seek locally dense aggregations of monospecific prey. In addition D. gigas consumes very few anchovy Engraulis ringens in Peru, whereas a tremendous biomass of anchovy is potentially available. It seems that D. gigas cannot reach the oxygen unsaturated waters very close to the coast, where the bulk of anchovy occurs. Indeed, even if jumbo squid can forage in hypoxic deep waters during the day, surface normoxic waters are then required to recover its maintenance respiration (or energy?). Oxygen concentration could thus limit the co-occurrence of both species and then preclude predator-prey interactions. Finally we propose a conceptual model illustrating the opportunistic foraging behaviour of jumbo squid impacted by ontogenetic migration and potentially constrained by oxygen saturation in surface waters.
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Papers by ricardo tafur - jimenez