Biología y ecología del calamar Dosidicus gigas (Cephalopoda) en aguas chilenas: una revisión

Indexación: Web of Science; Scielo.ABSTRACT. The jumbo squid Dosidicus gigas is the most abundant cephalopod species in the southeastern Pacific Ocean, which supports the biggest cephalopod fishery in the world. Due to its growing economic importance, the population growth and distributional expansion of this squid is being increasingly studied. Nevertheless, some basic features of the biology of D. gigas are still unknown or have been poorly investigated. In this review we summarize the known information regarding the biology and ecology of this species in the southeastern Pacific Ocean; we focus on the Chilean region in order to propose hypotheses and research lines for a better understanding the life history of this organism. Available data on the size structure, reproduction and genetics of D. gigas allows us to propose hypotheses related to the squid's life history traits. Based on the current literature and publications of colleagues, we propose two hypotheses regarding the effect of spatial variation on the life history of D. gigas. Hypothesis 1: Squids mature at large sizes and spawn in oceanic waters with warm temperatures where paralarvae and juveniles develop. Immature squids migrate near shore to feed, grow and mature, and then return to the offshore sites to spawn. Hypothesis 2: Alternatively, juvenile D. gigas in the oceanic zone do not migrate to coastal waters and mature at small sizes compared to individuals living near the coast that mature at larger size and migrate to oceanic waters to spawn. We provide background information about the feeding behavior and parasitism of this species, suggesting that D. gigas is an important trophic link in the southeastern Pacific marine ecosystem. However, more studies on the feeding habits, reproduction and parasite load are needed not only to test hypotheses proposed in this study, but also to advance the overall knowledge of this species.RESUMEN. Dosidicus gigas, es el calamar más abundante en el Pacífico suroriental, manteniendo la mayor pesquería mundial de cefalópodos. Su creciente importancia económica, ha motivado el aumento de estudios asociados al crecimiento de sus poblaciones y su expansión geográfica. Sin embargo, algunas características biológicas básicas de esta especie son desconocidas o escasamente estudiadas. En esta revisión, se resume la información sobre la biología y ecología de esta especie para el Pacífico suroriental y se proponen hipótesis y líneas de investigación para el mejor entendimiento de su historia de vida. Los datos sobre estructura de tamaños, reproducción y aspectos genéticos de la especie, permiten avanzar en las hipótesis relacionadas con la historia de vida de estos rasgos. Hipótesis 1: Los calamares maduran a gran tamaño y desovan en aguas oceánicas con temperaturas cálidas, donde paralarvas y juveniles se desarrollan. Los calamares inmaduros migran hacia la costa para alimentarse, crecer y madurar, y luego vuelven a los sitios en alta mar para desovar. Hipótesis 2: Alternativamente, los juveniles de D. gigas en la zona oceánica no migran a las aguas costeras y maduran pequeños en comparación a los individuos que viven cerca de la costa que maduran a un tamaño más grande y migran a las aguas oceánicas para desovar. Se proponen dos hipótesis acerca de la variación espacial de la historia de vida. Además, se proporciona el marco relativo a la alimentación y parasitismo del calamar, que coloca a D. gigas como un importante nexo trófico en los ecosistemas marinos del Pacífico suroriental. No obstante, se necesitan más estudios relacionados con alimentación, reproducción y carga parasitaria del calamar para poner a prueba las hipótesis propuestas en este trabajo.http://ref.scielo.org/hpft7

The Cephalopod Dosidicus gigas of the Humboldt Current System Under the Impact of Fishery and Environmental Variability

Marine organisms are influenced by environmental variability and fishery and cephalopods are especially plastic in their response to exogenous factors. Underlying mechanisms of interactions are often unclear and complex. The ommastrephid jumbo squid (Dosidicus gigas) is an important component in the ecosystems of the Eastern Pacific Ocean and like other cephalopods rapidly changes abundances of its populations and their size structure. Results of the present work show that the morphological and life history traits of D. gigas respond highly variable to changing environmental conditions. Fishery impacts indirectly and rather positive through the reduction of competitors and predators. A synchronous change in the state of expression of traits occurred after the strong La Nina/El Nino-sequence 1996 to 1998. The elevated energetic requirements of the new states compared to those before the shift lead to the conclusion that the changes in traits follow an energy optimization strategy that allows jumbo squid to adjust to changing availability of prey and emphasize either in survival of the population or the increase of individual fitness

Der Tintenfisch Dosidicus gigas des Humboldstromsystems unter dem Einfluss von Fischerei und Umweltvariabilität

Marine organisms are influenced by environmental variability and fishery and cephalopods are especially plastic in their response to exogenous factors. Underlying mechanisms of interactions are often unclear and complex. The ommastrephid jumbo squid (Dosidicus gigas) is an important component in the ecosystems of the Eastern Pacific Ocean and like other cephalopods rapidly changes abundances of its populations and their size structure. Results of the present work show that the morphological and life history traits of D. gigas respond highly variable to changing environmental conditions. Fishery impacts indirectly and rather positive through the reduction of competitors and predators. A synchronous change in the state of expression of traits occurred after the strong La Nina/El Nino-sequence 1996 to 1998. The elevated energetic requirements of the new states compared to those before the shift lead to the conclusion that the changes in traits follow an energy optimization strategy that allows jumbo squid to adjust to changing availability of prey and emphasize either in survival of the population or the increase of individual fitness

Evaluación y manejo del recurso marino Haliotis spp. (abulón) en la península de Baja California, México mediante un modelo pesquero-climático

Tesis (magister scientiae en gestión integrada de áreas costeras tropicales)--Universidad de Costa Rica. Sistema de Estudios de Posgrado, 2004.UCR::Vicerrectoría de Investigación::Sistema de Estudios de Posgrado::Ciencias Básicas::Maestría Académica en Gestión Integrada de Áreas Costeras Tropicale

Cannibalism in cephalopods

Cannibalism refers to the action of consuming a member of the same species and is common in many taxa. This paper reviews the available literature on cannibalism in cephalopods. All species of the class Cephalopoda are predators and cannibalism is common in most species whose diet has been studied. Cannibalism in cephalopods is density-dependent due to their aggressive predatory and in case of the octopuses territorial nature. It also depends upon local and temporal food availability and of the reproductive season. Cannibalistic behaviour is positively related to the size of both cannibal and victim. It can affect population dynamics of cephalopods in periods of low food availability and/or high population abundance. Cephalopods are generally restricted in their ability to store energy. It is thus assumed that cannibalism is part of a population energy storage strategy enabling cephalopod populations to react to favourable and adverse environmental conditions by increasing and reducing their number. Finally, we propose five orientation points for future research on cannibalism in cephalopods

Reproductive biology of jumbo squid Dosidicus gigas in relation to environmental variability of the northern Humboldt Current System

Dosidicus gigas is a monocyclic ommastrephid squid and is an important component of its ecosystems in the Eastern Pacific Ocean. The species shows variable reproductive characteristics; among these are 3 spatially separated groups of size-at-maturity. Biological data from the industrial fisheries of the Peruvian Humboldt Current System (HCS) from 1991 to 2007 were analyzed. Changes in reproduction patterns allow jumbo squid to cope with productivity changes in their environment. In the HCS, low productivity is related to warm water masses prevailing during warm periods, and high productivity is found for cool water masses during cool periods. Three general features related to reproduction enabling the squid to adjust to changes have been identified: (1) variable size-at-maturity, (2) temporal decoupling of male and female formation of reproductive tissue in order to temporally distribute the required energy and (3) changing sex-ratios. Smaller sizes-at-maturity are found in warm water masses, specimens maturing at larger sizes in cool water masses. Females mature at the end of their life which leads to a j-shaped increase in maturity when plotted against mantle length, while males mature at a medium size which results in an s-shaped form of maturation. The 3 groups of size-at-maturity proposed in earlier studies may not actually exist, and may only be an observational artifact from a continuous change in size-at-maturity between 2 extremes

The biology and ecology of the jumbo squid Dosidicus gigas (Cephalopoda) in Chilean waters: a review

in Chilean waters: a revie

Dosidicus gigas, Humboldt squid

Dosidicus gigas (Humboldt or jumbo squid) (Orbigny, 1835) is the largest ommastrephid squid, reaching up to 1.2m mantle length and 65kg in weight. This pelagic squid is endemic to the eastern Pacific Ocean and is particularly abundant in the highly productive waters of the California and Humboldt Current systems, and the Costa Rica Dome upwelling region. The intra-specific population structure of D. gigas is complex, since this species quickly responds to environmental variability driven by El Niño and LaNiña events in both current systems by rapidly changing its biological characteristics, such as somatic and reproductive investment. Oocyte development is asynchronous and the potential fecundity averages around 18–21 million oocytes; the maximum value estimated (32 million oocytes) is the largest ever recorded for any cephalopod so far. Hatching occurs between 6 to 9 days after fertilization at 18°C, but temperatures below 15°C and above 25°C do not allow complete embryonic development. D. gigas passes through a post-hatching paralarval stage called the rhynchoteuthion and during this stage the two tentacles are fused into a well-developed proboscis. During the paralarval and subsequent juvenile stages Humboldt squid have a monthly growth rate of up to 80 mm in mantle length, and grow up 60 mm per month in the later stages. This is the highest growth rate reported for any cephalopod species, and enables this species to reach the reported maximum mantle lengths in a short lifespan (12 to 24 months). Although the lack of population structure across its large range suggests a high level of gene flow and substantial horizontal migration, specific migratory pathways in the Pacific Ocean have not yet been demonstrated. Long-distance migration is an important element in the life-history of Humboldt squid and may be associated with differential growth rates and size and at full maturity. The recent poleward range expansion of D. gigasis likely associated with warmer periods following El Niño/La Niña events, an ongoing expansion of the oxygen minimum zone (OMZ) in the Eastern Pacific, and changing ecosystem interactions including food availability, competition and predation. Humboldt squid feed primarily on small mesopelagic (midwater) fishes, crustaceans, and cephalopods as well as commercially important coastal fishes and squid in the recently expanded range. Typical daily behavior involves vertical migrations from near-surface waters at nighttime to mesopelagic depths above or within the OMZ during the daytime. Whereas the OMZ restricts the depth distribution of many competing vertebrate predators to the upper surface layers due to limited hypoxia tolerance, D. gigas circumvents similar restrictions via metabolic suppression. In addition to its critical role both as prey and predator in the eastern Pacific, D. gigas is an economically important species and the target of what has recently become the world’s largest invertebrate fishery