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Rosas Luis Rigoberto - One of the best experts on this subject based on the ideXlab platform.
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Differences in the trophic niche along the gladius of the squids Illex argentinus and Doryteuthis gahi based on their isotopic values
'Elsevier BV', 2017Co-Authors: Rosas Luis Rigoberto, Navarro Joan, Martínez Francisco, Sánchez PilarAbstract:6 pages, 4 figures, 2 tablesThe squids Doryteuthis gahi and Illex argentinus coexist in the Patagonian shelf and other oceanic waters of the South Atlantic Ocean. Both species perform movements to and from shallow waters related to their ontogenetic growth. To examine changes in the trophic habitats in both species and across the ontogeny, we analyzed the stable isotopic values of δC and δN in their gladii. Based on sections of the gladii, we compared the trophic niche in three stages (adult [the newest section], juvenile [middle section], and a near-birth section [near the conus]). δC and δN values differed significantly between the two species and between gladius segments, revealing interspecific and ontogenetic differences in the trophic niche width. In particular, differences between segments of the gladius concurred with the ontogenetic and spawning migrations of these squids, in the Patagonian ShelfJN was supported by the Andalucía Talent Hub Program (European Union)’s Seventh Framework Program, Marie Skłodowska-Curie actions and Andalusian Knowledge Agency, Spain. RRL thanks to CONACyT for the postdoctoral supportPeer Reviewe
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Assessing the feeding ecology of three sympatric squids Illex argentinus, Doryteuthis gahi and Onykia ingens off the Patagonian by combining stomach content and stable isotopic analysis
2016Co-Authors: Rosas Luis Rigoberto, Navarro Joan, Sánchez Pilar, Río, José Luis DelAbstract:Mollusca 2014, The meeting of the Americas, 22-27 june 2014, Mexico City.-- 1 pageThe Ommastrephidae Illex argentinus, the Loliginidae Doryteuthis gahi and the Onychoteuthidae Onikya ingens are squid species coexisting in the south part of the Patagonian Shelf, interacting for similar feeding resources. In the present study, we analyzed the feeding ecology, trophic position and trophic relationships of these three species by combining stomach content and stable isotopic approximations. In particular, stomach content and isotopic analysis were carried out on 20 D. gahi, 20 I. argentinus and 21 O. ingens collected from May 6th and 8th 2013 at depths between 147 and 220 m. The results indicated that the feeding habits of small and larger squids were different in the three species. The two main prey species for small D. gahi individuals were the euphausid Euphausia sp. and the amphipod Eutemisto gaudichaudi, and the main prey for larger D. gahi individuals were a fish and the Munididae Munida subrugosa. The main prey group of small I. argentinus individuals was the amphipod E. gaudichaudi and the myctophid fish, and the main prey for larger size I. argentinus individuals were the paralepididae Arctozenus risso and the Notothenidae Patagonotothen ramsayi, secondly by the squid group. Small O. ingens individuals fed on Micromesistius australis and Notophysis marginata while larger O. ingens individuals fed on Lampanyctus australis and Notoscopelus sp. D. gahi showed higher δ15N values than the other two species and small and larger D. gahi individuals showed similar isotopic values. The δ15N values of I. argentinus and O. ingens were higher for larger individuals. Finally, D. gahi differed in its δ13C values from I. argentinus and O. ingens and the less depleted δ13C values were found in the larger in D. gahi individuals. The results indicate that the three squid species preyed on organisms with similar trophic position, but due to their voracity and their active predation on similar trophic resources, small size individuals segregate their trophic niche from the larger ones. It is important to note that the δ13C values revealed that larger D. gahi individuals had a different distribution in the water column, which probably is a response of the reproductive activity of mature squid near to the surface waterPeer Reviewe
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La modificación del ecosistema marino reflejada en las poblaciones de las especies de calamares Dosidicus gigas, Illex coindetii, Illex argentinus, Todarodes sagittatus, Doryteuthis gahi y Onykia ingens Dinámica y función de los calamares en los ecos
'Edicions de la Universitat de Barcelona', 2014Co-Authors: Rosas Luis RigobertoAbstract:[spa] En esta tesis se revisaron las relaciones que existen entre las poblaciones de dos especies de calamares ommastréfidos Dosidicus gigas y Illex argentinus con las series temporales de la temperatura superficial del mar, clorofila a y las estimaciones de biomasa zooplanctónica, lo que resultó en la comprensión de que la temperatura puede afectar directamente a las poblaciones de organismos productores primarios y a los integrantes del zooplancton, y no así a los organismos juveniles y adultos de ambas especies de calamar. También se observó que en ambas especies la distribución y abundancia de presas potenciales es uno de los principales factores que determinan la localización y en algunos casos migraciones horizontales y verticales en el ecosistema. Para poder entender las relaciones que las especies de calamares guardan en los ecosistemas fue necesario implementar los estudios ecotróficos en los que se determinó la importancia que representan estos calamares en las redes tróficas como depredadores, así como la interacción entre especies semejantes de calamares con las que pueden compartir su hábitat. Para llevar esta investigación se seleccionaron tres áreas de importancia ecológica y comercial, la primera corresponde al océano Atlántico Sur en la plataforma Patagónica y las islas Malvinas/Falkland en las que se identificaron tres especies de calamar I. argentinus, D. gahi y O. ingens, la segunda corresponde al Noroeste del Mar Mediterráneo donde se identificó a I. coindetii y T. sagittatus y la tercera al océano Pacifico en las costas de México y Perú para D. gigas. Los resultados de este trabajo demuestran que la tendencia de las poblaciones de estas especies es afectada directamente por las presas más abundantes y disponibles en el ecosistema, así como el desarrollo de relaciones intrínsecas entre algunas especies presa y su depredador como fue el caso de D. gigas y el pez V. lucetia.[eng] This PhD thesis was focused in the relationships between the ommastrephid squids Dosidicus gigas and Illex argentinus with the time series of sea surface temperature, chlorophyll a and zooplankton biomass. The temperature as factor affected the primary productivity and the abundance of zooplankton, and no effects were found in the populations of juveniles and adult of both squids. In this way the distribution and abundance of squid was related to other factors such as the abundance of prey resources. Then the thesis was complemented with trophic ecology studies performed in the South Atlantic Ocean (Squid species: Doryteuthis gahi, Illex argentinus and Onykia ingens), in the Northwest Mediterranean Sea (Squid species: Todarodes sagittatus and Illex coindetii), and the South Pacific Ocean (Squid Dosidicus gigas). The results showed that the biomass and distribution of squid species are close related to the most abundant and available prey resources, and also it can be found trophic dependencies between some specific prey resources as was observed for Dosidicus gigas and the mesopelagic fish Vinciguerria lucetia
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Feeding habits and trophic interactions of Doryteuthis gahi, Illex argentinus and Onykia ingens in the marine ecosystem off the Patagonian Shelf
'Elsevier BV', 2014Co-Authors: Rosas Luis Rigoberto, Sánchez Pilar, Portela, Julio M., Río, José Luis DelAbstract:8 pages, 3 figures, 5 tablesThe stomach contents of three squids: 57 Doryteuthis gahi with mantle length (ML) ranging from 7.0 to 37.0. cm, 75 Illex argentinus (21.0-32.8. cm) and 116 Onykia ingens (19.9-39.3. cm) from commercial catches on the outer Patagonian shelf grounds during autumn (March and April 2012) were examined to describe their diet and compare their trophic spectrum. D. gahi preyed on 12 different items, I. argentinus on 20 and O. ingens on 29. Prey diversity increased with the sizes of the squids. Along growth, D. gahi shifted from crustaceans, mainly euphausiids to fish (Salilota australis) and squid (D. gahi and Histioteuthis sp.). Small to mid-sized I. argentinus and O. ingens consumed mostly two fish, two squid species D. gahi and Histioteuthis atlantica, two crustaceans Munida gregaria and Munida subrugosa and the Chaetognatha Sagitta elegans. All the three species show a high prey overlapping at similar sizes: Squid of smaller size (5-15. cm ML) fed mainly on crustaceans: D. gahi on euphausiids and squat lobsters (Munididae). Mid-sized squid fed mainly on fish, most frequently Gymnoscopelus sp. and S. australis, and larger I. argentinus and O. ingens fed mostly on squids, including cannibalism. The overlapping of the diet of similar sized squid was large suggesting all preys are abundant species in autumn in the water column in the Patagonian Shelf. © 2013 Elsevier B.V.Rigoberto Rosas Luis was supported by CONACyT (Con-sejo Nacional de Ciencia y Tecnología, México)Peer Reviewe
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Trophic impacts and interaction of Moroteuthis ingens, Illex argentinus and Loligo gahi in the ecosystem of the Southwestern Atlantic Ocean
2014Co-Authors: Rosas Luis Rigoberto, Sánchez Pilar, Río, José Luis Del, Portela, Julio M.Abstract:Cephalopod International Advisory Council (CIAC) Symposium 2012: "Interdisciplinary approaches to cephalopod biology", 27 October - 02 November 2012, Florianópolis, Santa Catarina, BrazilThe collision between the Brazil and the Falkland currents over the Patagonian Shelf near 38ºS, creates an area of biological importance in the Southwestern Atlantic Ocean. In this area the fishing activity is developed by fleets from Argentina, Uruguay, Spain, Estonia and far eastern countries such as Japan, Korea, Taiwan, etc. As results of the fishing activity we could know the components of the ecosystem and we observed that Moroteuthis ingens, Illex argentinus and Loligo gahi are the main cephalopod species caught by these fleets in the area between 45-52ºS and 60-63ºW. 118 M. ingens, 94 I. argentinus and 99 L. gahi squids were cached by the commercial fleet in the area. The interval size of these species where between 7-40 cm dorsal longitude mantle DLM, the three species where represented in the 19-33 cm DLM size interval resulting in a same use of the feeding resources. According to the stomach analysis we observed that a major number of M. ingens showed a stomach fullness index of 3 and 4 (60%) while in I. argentinus 15% and L. gahi 5%. Main food items were similar in the three species and for M. ingens the myctophid group and other cephalopods were the main items and the occurrence of this group varied in the other species. These squid species have different adaptations that promote variations in feeding behavior and trophic habits so that their interaction in the same area can be considered as indicator of a high production in the ecosystemPeer Reviewe
Xinjun Chen - One of the best experts on this subject based on the ideXlab platform.
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fatty acid composition and the evidence for mixed income capital breeding in female argentinean short fin squid Illex argentinus
Marine Biology, 2019Co-Authors: Dongming Lin, Fei Han, Sipeng Xuan, Xinjun ChenAbstract:Life histories of organisms are frequently shaped by trade-offs between somatic growth and reproduction. Although previous studies have suggested that sources for reproduction are directly from ingested food in the Argentinean short-fin squid Illex argentinus, recent findings indicate that its reproductive growth probably involves somatic energy use. Therefore, we aimed to determine the reproductive allocation strategy of female I. argentinus, using fatty acids as biochemical indicators. These squid accumulate a substantial amount of fatty acids in the ovary after the onset of sexual maturation. The fatty acid composition in the ovaries was found to have a stronger correlation with that in the digestive gland, a fast turnover tissue reflecting recent dietary information, when compared to the slow turnover mantle tissue, an energy reserve organ. These results suggested that energy for reproduction is primarily from income resources. However, fatty acid composition showed that the ovaries closely resembled mantle tissue during early maturation when the gonadosomatic index increased significantly, and spawning period when the squid showed the lowest feeding activity. This evidence indicated that during these two periods, somatic energy reserve was participating in reproductive growth. Cumulatively, female I. argentinus adopts a mixed income–capital breeding strategy, in that reproduction primarily relies on income resources, coupled with the involvement of storage reserves used during the early maturation and spawning period. This study presents the potential implication of fatty acids to provide insights into the breeding strategies among cephalopods, particularly for oceanic species.
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a stock assessment for Illex argentinus in southwest atlantic using an environmentally dependent surplus production model
Acta Oceanologica Sinica, 2018Co-Authors: Xinjun Chen, Yong Chen, Jintao Wang, Kevin W StaplesAbstract:The southern Patagonian stock (SPS) of Argentinian shortfin squid, Illex argentinus, is an economically important squid fishery in the Southwest Atlantic. Environmental conditions in the region play an important role in regulating the population dynamics of the I. argentinus population. This study develops an environmentally dependent surplus production (EDSP) model to evaluate the stock abundance of I. argentines during the period of 2000 to 2010. The environmental factors (favorable spawning habitat areas with sea surface temperature of 16–18°C) were assumed to be closely associated with carrying capacity (K) in the EDSP model. Deviance Information Criterion (DIC) values suggest that the estimated EDSP model with environmental factors fits the data better than a Schaefer surplus model without environmental factors under uniform and normal scenarios. The EDSP model estimated a maximum sustainable yield (MSY) from 351 600 t to 685 100 t and a biomass from 1 322 400 t to 1 803 000 t. The fishing mortality coefficient of I. argentinus from 2000 to 2010 was smaller than the values of F0.1 and F MSY . Furthermore, the time series biomass plot of I. argentinus from 2000 to 2010 shows that the biomass of I. argentinus and this fishery were in a good state and not presently experiencing overfishing. This study suggests that the environmental conditions of the habitat should be considered within squid stock assessment and management.
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ovarian development in argentinean shortfin squid Illex argentinus group synchrony for corroboration of intermittent spawning strategy
Hydrobiologia, 2017Co-Authors: Dongming Lin, Xinjun Chen, Yong Chen, Guoping Zhu, Jizhou YanAbstract:Modern living cephalopod species have evolved a wide phenotypic diversity and flexibility of reproductive strategies, which is closely linked to the pattern of oogenesis and oocytes ovulation of species. Although it has been suggested that Argentinean shortfin squid Illex argentinus lay eggs intermittently, there is still little evidence for the mode of oocyte production and development. In this study, the ovarian development of I. argentinus was investigated by using histological analysis of ovaries, and six distinct histological stages of ovarian development were found among the ovaries. For each histological stage of the ovary, the frequency distribution of both number and occupied areas by each oogenesis stage was unimodal, and that gradually progressed along with ovarian development. The oocyte size distribution in ovaries before reaching vitellogenic stage was unimodal, bimodal in vitellogenic ovaries, and polymodal in ripe and partially spent ovaries. This evidence indicates that I. argentinus undergoes group-synchronous ovarian development, with a single dominant oocyte stock being produced to develop in several batches for a multiple-batch group-synchronous ovulation and confirms the intermittent spawning strategy of this species.
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the energy accumulation of somatic tissue and reproductive organs in post recruit female Illex argentinus and the relationship with sea surface oceanography
Fisheries Research, 2017Co-Authors: Dongming Lin, Xinjun Chen, Yong Chen, Yanran WeiAbstract:The need to optimize limited energy between reproductive and somatic growth is a vital process for marine animals under variable oceanic environments, especially the cephalopod species with their short monocyclic lifecycle and environment-sensitive growth. In this study, the process of energy accumulated in somatic tissues and reproductive organs of post-recruit female Illex argentinus, an important world fishery cephalopod species, was investigated and its relation to sea surface oceanography was explored using generalized additive models (GAMs). During the course of sexual maturation, the somatic tissues and nidamental glands have a constant value of energy density, while the energy density of both ovary and oviducal complex increases significantly with maturity. Somatic tissues attain maximum energy at the physiologically maturing stage, decreasing slightly, but not significantly, thereafter. In contrast, the reproductive organs accumulate energy throughout sexual maturation. Additionally, the post-recruit female I. argentinus accumulates greater energy in somatic tissues and reproductive organs at lower surface temperature, higher chlorophyll-a concentration, a particular sea-surface height, and later month during the post-recruitment period. This evidence indicates that the reproductive effort is a continuum, and the interactions of sea surface oceanography might result in a higher level of energy accumulation in this species, which should assist future research of reproductive effort aimed at the strategy of spawning and subsequent recruitment processes of this species.
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sex specific reproductive investment of summer spawners of Illex argentinus in the southwest atlantic
Invertebrate Biology, 2015Co-Authors: Dongming Lin, Xinjun Chen, Yong Chen, Zhou FangAbstract:Energy investment in reproduction and somatic growth was investigated for summer spawners of the Argentinean shortfin squid Illex argentinus in the southwest Atlantic Ocean. Sampled squids were examined for morphometry and intensity of feeding behavior associated with reproductive maturation. Residuals generated from length-weight relationships were analyzed to determine patterns of energy allocation between somatic and reproductive growth. Both females and males showed similar rates of increase for eviscerated body mass and digestive gland mass relative to mantle length, but the rate of increase for total reproductive organ weight relative to mantle length in females was three times that of males. For females, condition of somatic tissues deteriorated until the mature stage, but somatic condition improved after the onset of maturity. In males, there was no correlation between somatic condition and phases of reproductive maturity. Reproductive investment decreased as sexual maturation progressed for both females and males, with the lowest investment occurring at the functionally mature stage. Residual analysis indicated that female reproductive development was at the expense of body muscle growth during the immature and maturing stages, but energy invested in reproduction after onset of maturity was probably met by food intake. However, in males both reproductive maturation and somatic growth proceeded concurrently so that energy allocated to reproduction was related to food intake throughout the process of maturation. For both males and females, there was little evidence of trade-offs between the digestive gland and reproductive growth, as no significant correlation was found between dorsal mantle length-digestive gland weight residuals. The role of the digestive gland as an energy reserve for gonadal growth should be reconsidered. Additionally, feeding intensity by both males and females decreased after the onset of sexual maturity, but feeding never stopped completely, even during spawning.
Yong Chen - One of the best experts on this subject based on the ideXlab platform.
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a stock assessment for Illex argentinus in southwest atlantic using an environmentally dependent surplus production model
Acta Oceanologica Sinica, 2018Co-Authors: Xinjun Chen, Yong Chen, Jintao Wang, Kevin W StaplesAbstract:The southern Patagonian stock (SPS) of Argentinian shortfin squid, Illex argentinus, is an economically important squid fishery in the Southwest Atlantic. Environmental conditions in the region play an important role in regulating the population dynamics of the I. argentinus population. This study develops an environmentally dependent surplus production (EDSP) model to evaluate the stock abundance of I. argentines during the period of 2000 to 2010. The environmental factors (favorable spawning habitat areas with sea surface temperature of 16–18°C) were assumed to be closely associated with carrying capacity (K) in the EDSP model. Deviance Information Criterion (DIC) values suggest that the estimated EDSP model with environmental factors fits the data better than a Schaefer surplus model without environmental factors under uniform and normal scenarios. The EDSP model estimated a maximum sustainable yield (MSY) from 351 600 t to 685 100 t and a biomass from 1 322 400 t to 1 803 000 t. The fishing mortality coefficient of I. argentinus from 2000 to 2010 was smaller than the values of F0.1 and F MSY . Furthermore, the time series biomass plot of I. argentinus from 2000 to 2010 shows that the biomass of I. argentinus and this fishery were in a good state and not presently experiencing overfishing. This study suggests that the environmental conditions of the habitat should be considered within squid stock assessment and management.
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ovarian development in argentinean shortfin squid Illex argentinus group synchrony for corroboration of intermittent spawning strategy
Hydrobiologia, 2017Co-Authors: Dongming Lin, Xinjun Chen, Yong Chen, Guoping Zhu, Jizhou YanAbstract:Modern living cephalopod species have evolved a wide phenotypic diversity and flexibility of reproductive strategies, which is closely linked to the pattern of oogenesis and oocytes ovulation of species. Although it has been suggested that Argentinean shortfin squid Illex argentinus lay eggs intermittently, there is still little evidence for the mode of oocyte production and development. In this study, the ovarian development of I. argentinus was investigated by using histological analysis of ovaries, and six distinct histological stages of ovarian development were found among the ovaries. For each histological stage of the ovary, the frequency distribution of both number and occupied areas by each oogenesis stage was unimodal, and that gradually progressed along with ovarian development. The oocyte size distribution in ovaries before reaching vitellogenic stage was unimodal, bimodal in vitellogenic ovaries, and polymodal in ripe and partially spent ovaries. This evidence indicates that I. argentinus undergoes group-synchronous ovarian development, with a single dominant oocyte stock being produced to develop in several batches for a multiple-batch group-synchronous ovulation and confirms the intermittent spawning strategy of this species.
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the energy accumulation of somatic tissue and reproductive organs in post recruit female Illex argentinus and the relationship with sea surface oceanography
Fisheries Research, 2017Co-Authors: Dongming Lin, Xinjun Chen, Yong Chen, Yanran WeiAbstract:The need to optimize limited energy between reproductive and somatic growth is a vital process for marine animals under variable oceanic environments, especially the cephalopod species with their short monocyclic lifecycle and environment-sensitive growth. In this study, the process of energy accumulated in somatic tissues and reproductive organs of post-recruit female Illex argentinus, an important world fishery cephalopod species, was investigated and its relation to sea surface oceanography was explored using generalized additive models (GAMs). During the course of sexual maturation, the somatic tissues and nidamental glands have a constant value of energy density, while the energy density of both ovary and oviducal complex increases significantly with maturity. Somatic tissues attain maximum energy at the physiologically maturing stage, decreasing slightly, but not significantly, thereafter. In contrast, the reproductive organs accumulate energy throughout sexual maturation. Additionally, the post-recruit female I. argentinus accumulates greater energy in somatic tissues and reproductive organs at lower surface temperature, higher chlorophyll-a concentration, a particular sea-surface height, and later month during the post-recruitment period. This evidence indicates that the reproductive effort is a continuum, and the interactions of sea surface oceanography might result in a higher level of energy accumulation in this species, which should assist future research of reproductive effort aimed at the strategy of spawning and subsequent recruitment processes of this species.
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sex specific reproductive investment of summer spawners of Illex argentinus in the southwest atlantic
Invertebrate Biology, 2015Co-Authors: Dongming Lin, Xinjun Chen, Yong Chen, Zhou FangAbstract:Energy investment in reproduction and somatic growth was investigated for summer spawners of the Argentinean shortfin squid Illex argentinus in the southwest Atlantic Ocean. Sampled squids were examined for morphometry and intensity of feeding behavior associated with reproductive maturation. Residuals generated from length-weight relationships were analyzed to determine patterns of energy allocation between somatic and reproductive growth. Both females and males showed similar rates of increase for eviscerated body mass and digestive gland mass relative to mantle length, but the rate of increase for total reproductive organ weight relative to mantle length in females was three times that of males. For females, condition of somatic tissues deteriorated until the mature stage, but somatic condition improved after the onset of maturity. In males, there was no correlation between somatic condition and phases of reproductive maturity. Reproductive investment decreased as sexual maturation progressed for both females and males, with the lowest investment occurring at the functionally mature stage. Residual analysis indicated that female reproductive development was at the expense of body muscle growth during the immature and maturing stages, but energy invested in reproduction after onset of maturity was probably met by food intake. However, in males both reproductive maturation and somatic growth proceeded concurrently so that energy allocated to reproduction was related to food intake throughout the process of maturation. For both males and females, there was little evidence of trade-offs between the digestive gland and reproductive growth, as no significant correlation was found between dorsal mantle length-digestive gland weight residuals. The role of the digestive gland as an energy reserve for gonadal growth should be reconsidered. Additionally, feeding intensity by both males and females decreased after the onset of sexual maturity, but feeding never stopped completely, even during spawning.
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species identification of ommastrephes bartramii dosidicus gigas sthenoteuthis oualaniensis and Illex argentinus ommastrephidae using beak morphological variables
Scientia Marina, 2012Co-Authors: Xinjun Chen, Yong Chen, Bilin Liu, Ma JinAbstract:Four oceanic squid species, Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis and Illex argentinus , not only support important commercial fisheries, but also play a vital role in their marine ecosystems. It is therefore important to identify them in the analyses of their predators’ stomach contents as this can yield critical information on the trophic dynamics of ecosystems. Hard beaks of the four species frequently found in their predators’ stomachs can be used to identify them. In this study, to remove the effect of size differences among individuals, measurements of upper and lower beaks were standardized with an allometric model. A discriminant analysis was carried out to compare morphological differences among the four species and between the sexes for each species. The upper rostral width and upper rostral length showed the greatest interspecific variation in the beak morphological variables of the four Ommastrephidae. The linear discriminant functions of beak morphological variables were developed for the four Ommastraphidae, which resulted in a rate of correct species classification of over 97%. Sexual dimorphism was also found in the beak morphology of O. bartramii and I. argentinus . This study suggests that morphological variables can be used to reliably classify Ommastrephidae at genus level, which can help identify the specie in the stomachs of cephalopod predators. This helps to improve the understanding of the role cephalopods play in their marine ecosystems.
Alexander I. Arkhipkin - One of the best experts on this subject based on the ideXlab platform.
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water density pathways for shelf slope migrations of squid Illex argentinus in the southwest atlantic
Fisheries Research, 2015Co-Authors: Alexander I. Arkhipkin, Michael Gras, Alex BlakeAbstract:Abstract Argentine shortfin squid Illex argentinus (Ommastrephidae) is one of the most abundant cephalopods in the Southwest Atlantic, with total annual catch exceeding 1 mln t in some years. During its annual life cycle, I. argentinus perform long distance migrations, from their subtropical spawning grounds in Uruguay and southern Brazil to temperate feeding grounds on the Patagonian Shelf and back. Oceanography and squid distribution were studied during a research survey carried out in the south-eastern part of the Patagonian Shelf to reveal environmental cues that determine pathways of shelf to continental slope pre-spawning migrations. It was found that the outflows of less dense Patagonian Shelf Waters (PSW) over the slope may act as proxies determining the locations of I. argentinus migrations from the shelf to the slope. During maturation I. argentinus did not significantly change their buoyancy with females becoming slightly more buoyant with depth. Subsequent movement of mature I. argentinus to denser Sub-Antarctic Superficial waters (SASW) located at deeper depths (600–700 m) enable them to approach near-neutral buoyancy and therefore facilitate the distant pre-spawning migrations.
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Illex argentinus, Argentine shortfin squid
2013Co-Authors: Paul G. Rodhouse, Alexander I. Arkhipkin, Vladimir Laptikhovsky, Chingis M. Nigmatullin, Claire M. WaludaAbstract:Illex argentinus, a close relative of the other North Atlantic Illex species, concentrates on the Patagonian shelf edge and spreads over the shelf from Southern Brazil to the Falkland Islands. It supports one of the world’s largest squid fisheries. The fishery mostly exploits the winter spawning, south Patagonian stock, which is more abundant, grows to a larger body size and extends further south than the summer spawners. Spawning takes place in the northern part of the range and the eggs hatch into a typical ommastrephid rhynchoteuthon paralarva. I. argentinus is short-lived and semelparous living approximately one year, at the end of which the squid die after spawning. Growth is rapid and the largest individuals - females from the South Patagonian, winter spawning stock - reach a mean mantle length of 330 mm (maximum of 400 mm ML) when fully grown. Large scale migrations between the spawning grounds and the feeding grounds, and back again, over the one year life cycle are accompanied by diel vertical migrations. Immature and maturing squid occur 3 - 20 m off the bottom during the day but at night they ascend to 5 - 20 m over the shelf and to 20 - 200 m beyond the shelf break. Mature squid of the South Patagonian Stock migrate northward along the continental slope to the spawning grounds in May – July remaining close to the sea bed (500 - 900 m) at night and ascend to 200-300 m above the bottom during the day. The paralarvae are thought to feed using their proboscis, on body mucus enriched with microorganisms and other food particles that stick to it. Juveniles and adults are opportunistic predators feeding on fishes, crustaceans, and cephalopods including smaller conspecifics. The diet generally reflects the plankton and nekton available. Small quid 50% of annual food intake and is also consumed by hoki, red cod, dogfish, and various species of penguin, albatross, some petrels and several seals and dolphins. In the vicinity of the Falkland Islands the southern Patagonian stock has few important predators because squid have grown to a relatively large size before they arrive there. I. argentinus is host to 21 known species of parasite, mostly the larval stages of helminths and trematodes. The fishery is pursued by trawlers but mostly by jiggers which attract the squid with powerful lights that can be seen in visible band satellite imagery. The largest annual catch to date was 1.153 tonnes taken in 1999. There are substantial variations in recruitment and stock size driven by environmental variability.
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the spatio temporal pattern of argentine shortfin squid Illex argentinus abundance in the southwest atlantic
International Conference on Evolvable Systems, 2005Co-Authors: M Sacau, Alexander I. Arkhipkin, J Portela, Graham J Pierce, Jianjun Wang, Paul Brickle, M B Santos, Alain F Zuur, Xose CardosoAbstract:L'encornet rouge argentin (Illex argentinus) est une espece neritique commune de l'Atlantique Sud-Ouest presente dans les eaux du Bresil, de l'Uruguay de l'Argentine et des iles Malouines (Falklands). Illex argentinus est la principale espece de cephalopode exploitee dans cette region ou elle joue un role majeur dans l'ecosysteme. L'espece est pechee par d'importantes flottilles de chalutiers (principalement de pays europeens) et aux turluttes industrielles (de pays asiatiques) pour une production annuelle de 700000 t en moyenne sur les 15 dernieres annees (1988-2003). Cet article presente des modeles predictifs de l'abondance en fonction des facteurs physiques et environnementaux ; modeles qui pourraient a terme etre appliques a la gestion des peches. Les donnees de capture et les parametres biologiques recoltes, grâce a des observateurs embarques, de 1988 a 2003, ont ete analysees en relation avec les facteurs physiques pour preciser les variations spatio-temporelles de repartition et quantifier l'effet de la temperature et de la profondeur sur l'abondance. Le jeu de donnees porte sur 26 168 traits de peche dont 11 103 comportant des captures d'Illex. Les captures par unite d'effort (CPUE en kg h -1 ) sont utilisees comme indice d'abondance et les analyses utilisent des series de cartes, creees avec un systeme d'information geographique (SIG). Les valeurs les plus elevees de CPUE sont enregistrees durant les quatre premiers mois de l'annee (l'ete et l'automne austral) avec un pic depassant 5000 kg h -1 localise entre 42° S et 46° S dans la partie Nord des Malouines. Les modeles additifs generalises (GAM) ont servi a decrire les variations d'abondance en fonction des variables geographiques et environnementales. La presence ou l'absence de la ressource est modelisee separement de l'abondance. Les modeles optimaux retiennent comme variables explicatives la temperature, la latitude, la longitude, le mois, la profondeur et l'annee. Les deux modeles indiquent un effet saisonnier net: la capturabilite est maximale en mars (presence/absence) et l'abondance (CPUE) est la plus elevee durant le premier trimestre. Les modeles additifs generalises montrent egalement que les captures les plus elevees d'animaux a maturite sont associees a des eaux plus tiedes et des secteurs plus profonds.
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inverse patterns in abundance of Illex argentinus and loligo gahi in falkland waters possible interspecific competition between squid
Fisheries Research, 2002Co-Authors: Alexander I. Arkhipkin, David A J MiddletonAbstract:Abstract Fishery statistics for two abundant commercial squid, Illex argentinus (Ommastrephidae) and Loligo gahi (Loliginidae), in Falkland Islands waters (southwest Atlantic) between 1987 and 1999 were analysed. The areas of the highest densities of the two species are usually separated, with I. argentinus most abundant to the north-west of the Islands in February–May and L. gahi to the south-east in February–May and August–October. However, in some years, I. argentinus intrude in great numbers into nursery or feeding areas of L. gahi in April and May. It could, therefore, affect, either directly (via predation) or indirectly (by competition for food), the abundance and recruitment of the second cohort of L. gahi , exploited around the Islands between April and October. Catch per unit effort (CPUE) of I. argentinus in February–March did not correlate with that of L. gahi in February–May. In contrast, the CPUE of I. argentinus in April–May was negatively correlated with that of L. gahi in April–May and August–October of the same year. Possible reasons for these inverse abundance patterns of the two squid species, and their implications for fisheries management are discussed.
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intrapopulation structure of winter spawned argentine shortfin squid Illex argentinus cephalopoda ommastrephidae during its feeding period over the patagonian shelf
2000Co-Authors: Alexander I. ArkhipkinAbstract:Stock structure dynamics of the important commercial squid Illex argentinus were studied by using bio- logical data from about 25 thousand squid caught January-April 1991 by Rus- sian trawlers in three fishery regions: 51-52°S; 47-49°S within the exclusive economic zone of Argentina (EEZA); and 45-47°S outside the EEZA. A total of 2664 statoliths were read to prepare age-length keys for each 10-day interval of the period studied. It was found that between January and April, the Patago- nian shelf south of 45°S was a feeding ground of two intraspecific groups of winter-hatched I. argentinus: a shelf group that matured at medium sizes (ShG) and a slope group that matured at large sizes (SlG). After massive immi- gration of I. argentinus from the north in January-February into the two fish- ery regions within 45-49°S, the stock structure remained rather stable until April, composed predominantly of June- and July-hatched squid. Squid grow and mature rapidly, and males mature at younger ages (from one to two months) than do females. During feeding, some redistribution of the stock was observed: maturing and mature SlG squid (mainly females) tended to shift from the shelf (130-150 m depth) in a northeast direc- tion and concentrate over the shelf edge
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the behavior of the argentine shortfin squid Illex argentinus exposed to bottom trawl gear off southern brazil
Latin American Journal of Aquatic Research, 2018Co-Authors: J A A Perez, Bruna Firmino De Oliveira Yasunaka, Mauricio Rocha VisintinAbstract:The behavior of the Argentine shortfin squid ( Illex argentinus ) in reaction to a trawl net is reported from images obtained during one fishing tow operated by a commercial trawler in May 2015 in slope grounds off southern Brazil (depth 370-361 m; 33°37’S, 50°49’W). Video analysis utilized criteria to classify the horizontal and vertical distribution of squid in the field of view of the camera, posture (pitch and yaw), squid color patterns, escape reaction, swimming time and use of the tail fin. The monitored bottom trawl operation intercepted dense and patchily distributed schools of I. argentinus that could be observed for brief periods of time swimming ahead of the mouth of the trawl. Individuals were evenly distributed in the water column but concentrated on the center and right sectors of the trawl mouth. Most squids in the path of a trawl tended to swim by jet-propulsion for 10-20 s, tail-first and with regularly spaced fin flaps. Estimated speed (1.24 m s -1 ) was higher than cruise speed recorded for other ommastrephid squids in nature (0.3 m s -1 ), possibly reflecting an emergency escape reaction. After a period of sustained swimming ahead of the trawl, squid reacted in different ways including: a) slowing down and swimming into the net tunnel, b) shifting directions to escape through the trawl mouth sides, and c) swimming up, trying to escape over the top trawl panel, sometimes turning around pointing the tail towards the trawl mouth.
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age structure and life cycles of the argentine shortfin squid Illex argentinus cephalopoda ommastrephidae in southern brazil
Journal of the Marine Biological Association of the United Kingdom, 2013Co-Authors: R Schwarz, J A A PerezAbstract:Age structure and hatchling dates of the squid Illex argentinus collected by bottom-trawl fishery in southern Brazilian waters were assessed by the analysis of statolith growth increments. Catches occurred between 2001 and 2002, from 23° to 32°S at depths of 100–700 m. Squid from juvenile to post-spawning stages were collected year round, with age estimated from 98 to 320 days and mantle lengths ranging from 112 to 376 mm. Duration of life cycle events based on statolith growth zones revealed that squids can spend about 14% of their lifespan as paralarva (~30 days), 70% as juvenile (~130 days), leaving maturity and spawning condition to the terminal 10–20% (~30–60 days). The results suggest that, unlike estimates available for Patagonian populations, a general 0.5 year lifespan is predicted for I. argentinus off Brazil. The wide range of size-at-ages implied that catches of shortfin squid off southern Brazil probably include squid hatched throughout the year. Mature and spawning squid caught in summer months hatched in winter and spring, while winter catches revealed mature-spawning individuals hatched both in summer/autumn (~6 months of age) and winter/spring periods (~10–11 months of age). It has been argued that such groups may combine both squid resident of Brazilian outer shelf and slope (22°–34°S) with a six months' lifespan and migrating squid originated from the northern Patagonian shelf (~42°S) with 10–11 months' lifespan.
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growth model identification of short finned squid Illex argentinus cephalopoda ommastrephidae off southern brazil using statoliths
Fisheries Research, 2010Co-Authors: R Schwarz, J A A PerezAbstract:Statoliths of 689 Illex argentinus specimens collected by national and foreign trawlers in Brazilian waters were analyzed. Catches occurred between 2001 and 2008, from 23◦ to 32◦ S and at depths of 80-730 m. Exponential, Power, Gompertz and Schnute models were fitted to size-at-age data and the logistic model was used for maturity modeling. Fitting procedures used the maximum log-likelihood and Akaike criteria for identification of best models. Total age estimates ranged between 56 and 320 days for squid between 35 and 376 mm mantle lengths. Gompertz and Schnute models, which suggest the positive acceleration of growth in the early stages of ontogeny followed by a decrease in the second phase, provided the best fit to the size-at-age dispersion in this study. The inflection point in the maturity curve was 137 days for males and 143 days for females. The age range for post-spawning squid was 116-250 (average 187) days for males and 133-280 (average 201) days for females showing a life cycle close to six months. None of the examined individuals reached one year of age. The wide range of sizes-at-age implied that catches of I. argentinus off southern Brazil probably include mixed micro-cohorts and different population units. © 2010 Elsevier B.V. All rights reserved.
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biological patterns of the argentine shortfin squid Illex argentinus in the slope trawl fishery off brazil
Latin American Journal of Aquatic Research, 2009Co-Authors: J A A Perez, R Schwarz, Tiago Nascimento Silva, Rafael Schroeder, Rodrigo Silvestre MartinsAbstract:La explotacion comercial del calamar argentino (Illex argentinus) no existia en aguas brasilenas hasta el ano 2000, cuando buques extranjeros iniciaron sus operaciones en el talud como parte de un programa gubernamental de arrendamiento. Desde entonces la especie forma parte de un conjunto de recursos que han motivado el desarrollo de una pesqueria de arrastre en el talud del sur y sureste de Brasil. Se colectaron muestras biologicas de las capturas comerciales de 25 buques arrastreros nacionales y siete extranjeros entre los paralelos 23°-33°S y en profundidades de 170 a 740 m. Estas muestras representaron dos periodos de la explotacion comercial de I. argentinus en Brasil: 2001-2003, cuando buques nacionales y extranjeros operaron simultaneamente, y 2006-2007 cuando solo buques nacionales permanecieron explotando el calamar argentino en conjunto con otros recursos del talud. Las capturas estuvieron constituidas por calamares inmaduros y en-maduracion a lo largo de todo el ano, asi como al menos dos grupos distintos de individuos maduros y desovantes: un grupo constituido por machos y hembras de pequeno tamano que estan presentes en todas las estaciones del ano en el borde de la plataforma continental y talud superior (< 400 m), y otro grupo, constituido por calamares de gran tamano, presente solamente durante el invierno-primavera australes en areas surenas (26°-29°S ) y profundidad (400-700 m). Este grupo ha sostenido las grandes capturas invernales reportadas desde 2000 y, dado su largo tamano y concentracion, ha justificado el interes de la industria pesquera como un potencial recurso para la pesca en el talud. Caracteristicas reproductivas y patrones de distribucion temporales/ espaciales de los desovantes de invierno corroboran la hipotesis que les relaciona a concentraciones migratorias de stock del norte de la plataforma Patagonica. Si se confirma esta hipotesis, estos datos resaltan la importancia de considerar estrategias de manejo dirigidas a stocks compartidos en el Atlantico SW.
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Biological patterns of the Argentine shortfin squid Illex argentinus in the slope trawl fishery off Brazil Patrones biológicos del calamar argentino Illex argentinus en la pesquería de arrastre en el talud continental de Brasil
Escuela de Ciencias del Mar Facultad de Recursos Naturales Pontificia Universidad Católica de Valparaíso, 2009Co-Authors: J A A Perez, R Schwarz, Tiago Nascimento Silva, Rafael Schroeder, Rodrigo Silvestre MartinsAbstract:Commercial exploitation of the Argentine shortfin squid (Illex argentinus) was virtually non-existent in Brazilian waters until 2000 when foreign trawlers initiated their operations on slope grounds as part of a government-induced chartering program. Since then, the species has been included among the targets of a developing slope trawl fishing off southeastern and southern Brazil. Biological samples were collected from commercial catches of 25 national and seven foreign (chartered) trawlers between 23°-33°S and 170-740 m depth. These samples represent two periods of the commercial exploitation of Illex argentinus in Brazil: 2001-2003, when both chartered and national trawlers operated simultaneously, and 2006-2007, when only national vessels continued to exploit I. argentinus along with other slope stocks. Catches contained immature and ma-turing squid throughout the year, as well as at least two distinct, fully mature, spawning groups: one composed of small-sized males and females present year-round on the shelf-break/ upper slope (< 400 m), and the other consisting of large squid present only in austral winter-spring in southern (26°-29°S ) and deep fishing grounds (400-700 m). The latter group has sustained the large winter catches reported since 2000 and the large sizes and concentrations of the specimens sparked the interest of the fishing industry as a potential target of the slope fishery. The reproductive attributes and temporal/ spatial distribution patterns of winter spawners support the hypothesis that relates this group to migrating concentrations of a north Patagonian shelf stock. If confirmed, the present data would underscore the need to consider multinational shared stock management strategies in the SW Atlantic.La explotación comercial del calamar argentino (Illex argentinus) no existía en aguas brasilenas hasta el año 2000, cuando buques extranjeros iniciaron sus operaciones en el talud como parte de un programa gubernamental de arrendamiento. Desde entonces la especie forma parte de un conjunto de recursos que han motivado el desarrollo de una pesquería de arrastre en el talud del sur y sureste de Brasil. Se colectaron muestras biológicas de las capturas comerciales de 25 buques arrastreros nacionales y siete extranjeros entre los paralelos 23°-33°S y en profundidades de 170 a 740 m. Estas muestras representaron dos periodos de la explotación comercial de I. argentinus en Brasil: 2001-2003, cuando buques nacionales y extranjeros operaron simultáneamente, y 2006-2007 cuando sólo buques nacionales permanecieron explotando el calamar argentino en conjunto con otros recursos del talud. Las capturas estuvieron constituidas por calamares inmaduros y en-maduración a lo largo de todo el año, así como al menos dos grupos distintos de individuos maduros y desovantes: un grupo constituido por machos y hembras de pequeño tamaño que están presentes en todas las estaciones del año en el borde de la plataforma continental y talud superior (< 400 m), y otro grupo, constituido por calamares de gran tamaño, presente solamente durante el invierno-primavera australes en areas surenas (26°-29°S ) y profundidad (400-700 m). Este grupo ha sostenido las grandes capturas invernales reportadas desde 2000 y, dado su largo tamaño y concentración, ha justificado el interés de la industria pesquera como un potencial recurso para la pesca en el talud. Características reproductivas y patrones de distribución temporales/ espaciales de los desovantes de invierno corroboran la hipótesis que les relaciona a concentraciones migratorias de stock del norte de la plataforma Patagónica. Si se confirma esta hipótesis, estos datos resaltan la importancia de considerar estrategias de manejo dirigidas a stocks compartidos en el Atlántico SW
