Dosidicus gigas (Humboldt/Jumbo Squid)

DWhatley

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Chromogenic behaviors of the Humboldt squid (Dosidicus gigas) studied in situ with an animal-borne video package Hannah Rosen, William Gilly,Lauren Bell, Kyler Abernathy,Greg Marshall 2015
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Abstract
Dosidicus gigas (Humboldt or jumbo flying squid) is an economically and ecologically influential species, yet little is known about its natural behaviors because of difficulties in studying this active predator in its oceanic environment. By using an animal-borne video package, National Geographic's Crittercam, we were able to observe natural behaviors in free-swimming D. gigas in the Gulf of California with a focus on color-generating (chromogenic) behaviors. We documented two dynamic displays without artificial lighting at depths of up to 70 m. One dynamic pattern, termed ‘flashing' is characterized by a global oscillation (2–4 Hz) of body color between white and red. Flashing was almost always observed when other squid were visible in the video frame, and this behavior presumably represents intraspecific signaling. Amplitude and frequency of flashing can be modulated, and the phase relationship with another squid can also be rapidly altered. Another dynamic display termed ‘flickering’ was observed whenever flashing was not occurring. This behavior is characterized by irregular wave-like activity in neighboring patches of chromatophores, and the resulting patterns mimic reflections of down-welled light in the water column, suggesting that this behavior may provide a dynamic type of camouflage. Rapid and global pauses in flickering, often before a flashing episode, indicate that flickering is under inhibitory neural control. Although flashing and flickering have not been described in other squid, functional similarities are evident with other species.
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Natural egg mass deposition by the Humboldt squid (Dosidicus gigas) in the Gulf of California and characteristics of hatchlings and paralarvae
danna j. staaf, susana camarillo-coop , steven h.d. haddock , al c. nyack , john payne , cesar a. salinas-zavala , brad a. seibel, lloyd trueblood , chad widmer and william f. gilly 2007 (PDF)

Abstract
The jumbo or Humboldt squid, Dosidicus gigas, is an important fisheries resource and a significant participant in regional ecologies as both predator and prey. It is the largest species in the oceanic squid family Ommastrephidae and has the largest known potential fecundity of any cephalopod, yet little is understood about its reproductive biology. We report the first discovery of a naturally deposited egg mass of Dosidicus gigas, as well as the first spawning of eggs in captivity. The egg mass was found in warm water (25 –278C) at a depth of 16 m and was far larger than the egg masses of any squid species previously reported. Eggs were embedded in a watery, gelatinous matrix and were individually surrounded by a unique envelope external to the chorion. This envelope was present in both wild and captive-spawned egg masses, but it was not present in artificially fertilized eggs. The wild egg mass appeared to be resistant to microbial infection, unlike the incomplete and damaged egg masses spawned in captivity, suggesting that the intact egg mass protects the eggs within. Chorion expansion was also more extensive in the wild egg mass. Hatchling behaviours included proboscis extension, chromatophore activity, and a range of swimming speeds that may allow them to exercise some control over their distribution in the wild.
 

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Description of food sources used by jumbo squid Dosidicus gigas (D’Orbigny, 1835) in Ecuadorian waters during 2014
R. Rosas-Luis, L. Chompoy-Salazar 2015 (subscription)
Abstract
Jumbo squid, Dosidicus gigas, is a species endemic to the eastern Pacific. Its distribution ranges from the Gulf of Alaska to Chile. These squids are important components of the ecosystem, as they are prey to sharks, billfishes, and marine mammals, and active predators of myctophid fishes, other squids and crustaceans. In Ecuador, D. gigas is a potential resource for industrial and artisanal fisheries, but they are often by-catch in artisanal fisheries that use trammel net and gill-netting methods. Due to the importance of D. gigas as prey and predator, we performed this exploratory research to describe the specific composition of their diet and identify their most important prey. A total of 167 squids were sampled in Santa Rosa, Salinas, Ecuador from May to December 2014. Squids ranged between 17.5 and 52 cm ML, and our results showed an average size of 40 cm ML. According to the %IRI the diet was mainly composed of fish and squids. Two myctophids, Lampanyctus sp. and Myctophum sp., were important food resources. Our results showed that there is no difference between food resources, and the sex, size, and maturity of squids. Cannibalism can also occur and ranges from small to large D. gigas, and is influenced by unavailable prey in the surface waters during fishing activity.
 

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An ethogram of the Humboldt squid Dosidicus gigas Orbigny (1835) as observed from remotely operated vehicles
Lloyd A. Trueblood, Sarah Zylinski1, Bruce H. Robison, and Brad A. Seibel 2015 (subscription)

Abstract
Many cephalopods can rapidly change their external appearance to produce multiple body patterns. Body patterns are composed of various components, which can include colouration, bioluminescence, skin texture, posture, and locomotion. Shallow water benthic cephalopods are renowned for their diverse and complex body pattern repertoires, which have been attributed to the complexity of their habitat. Comparatively little is known about the body pattern repertoires of open ocean cephalopods. Here we create an ethogram of body patterns for the pelagic squid, Dosidicus gigas. We used video recordings of squid made in situ via remotely operated vehicles (ROV) to identify body pattern components and to determine the occurrence and duration of these components. We identified 29 chromatic, 15 postural and 6 locomotory components for D. gigas, a repertoire rivalling nearshore cephalopods for diversity. We discuss the possible functional roles of the recorded body patterns in the behavioural ecology of this open ocean species.
 

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Reproductive strategy in jumbo squid Dosidicus gigas(D’Orbigny, 1835): A new perspective
Alejandro Tomás Hernández-Muñoz,Carmen Rodríguez-Jaramillo, Arminda Mejía-Rebollo, César Augusto Salinas-Zavala 2015 (subscription)

Abstract
The jumbo squid Dosidicus gigas has been considered to be semelparous by several authors. However, to date no studies to support this assumption have been conducted. The present work tests the hypothesis that female jumbo squid do not die after a single reproductive event and provides evidence of the presence of postovulatory follicles (Pof) in females of different sizes. They indicates previous spawning in females in which they are present.

Histological analysis was performed on reproductive structures of 73 female jumbo squid from the northwest of Mexico using hematoxylin-eosin staining. Using image analysis five ovarian stages were identified: (I) previtellogenesis, (II) vitellogenesis, (III) postvitellogenesis, (IV) spawning (in which 3.73% show atresia and the presence of Pof) and (V) Postspawning, in which a higher proportion (4.86%) show atresia and Pof. It is already known that the jumbo squid has asynchronic ovarian development with partial spawning during the reproductive period. However, the consistent presence of postovulatory follicles and the presence of oocytes of different sizes and development support the hypothesis that the jumbo squid is a multiple spawner with more than one reproductive event during its life cycle.
 

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Paralarvae of the complex Sthenoteuthis oualaniensis-Dosidicus gigas (Cephalopoda: Ommastrephidae) in the northern limit of the shallow oxygen minimum zone of the Eastern Tropical Pacific Ocean (April 2012) (subscription)

Abstract
The three-dimensional distribution of the paralarvae of the complex Sthenoteuthis oualaniensis - Dosidicus gigas (Cephalopoda: Ommastrephidae) was analyzed at the northern limit of the shallow oxygen minimum zone in the Eastern Tropical Pacific in April, 2012. The hypoxic water (∼ 44 μmol/kg or 1 mL/L) rises from ∼ 100 m depth in the entrance of the Gulf of California to ∼ 20 m depth off Cabo Corrientes. Most of the paralarvae of this complex, dominated by D. gigas, were concentrated in the Gulf entrance, between the thermocline (∼20 to ∼ 50 m depth) and the sea surface, in the warmest (> 19°C) oxygenated (> 176 μmol/kg) layer. The highest abundance of paralarvae was detected in an anticyclonic eddy (∼120 km diameter and > 500 m deep), which contained lower salinity water (< 35 g/kg), consistent with formation in the California Current. Lower paralarvae abundance was recorded further south off Cabo Corrientes, where hypoxic layers were elevated as water shoaled near shore. Almost no paralarvae were found in the north of the study area beyond the strong salinity front (∼ 34.8 - 35.4 g/kg) that bounded the anticyclone. These results showed an affinity of the paralarvae for lower salinity, oxygenated water, illustrated by the influence of the mesoscale anticyclonic eddy and the salinity front in their distribution. Based on this study, it can be concluded that the expansion of the depth range of hypoxic water observed in the Eastern Tropical Pacific may be increasing environmental stress on the paralarvae by vertically restricting their habitat, and so affecting their survival. This article is protected by copyright. All rights reserved.
 

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POPULATION DYNAMICS OF JUMBO SQUID DOSIDICUS GIGAS IN PACIFIC ECUADORIAN WATERS
ENRIQUE MORALES-BOJORQUEZ, JOSE LUIS PACHECO-BEDOYA 2016 (PDF Journal of Shellfish Research, Vol. 35, No. 1, 1–14)

ABSTRACT Population dynamic studies of Dosidicus gigas have not been reported in Ecuadorian waters. The number of cohorts in the population and reproductive features such as sex ratio, seasonal changes in maturity stages, and size at first maturity are unknown. This knowledge is crucial in the study area, because it can provide fishery management support to Ecuadorian stakeholders. Biological data from 2013 (March–December) and 2014 (January–December) in Ecuadorian waters were analyzed. Biological sampling per month was carried out during every year in different coastal waters off of Ecuador. The biological findings indicated the presence of three size groups in the Ecuadorian squid stock, which estimated to be individuals less than 50 cm mantle length (ML). The monthly size groups changed between one and three size groups in 2013 and 2014. The ML at first maturity for females of jumbo squid estimated in 2013 was L50% ¼ 32.4 cm ML, and L50% ¼ 35.5 cm ML in 2014. For both fishing seasons, the ML–mantle weight relationship estimated for jumbo squid presented isometric growth, and the sex ratio for D. gigas showed that females were more abundant than males. This study found that the ML structure of jumbo squid, the number of size groups, and ML at first maturity are different from that previously estimated in traditional fishing areas of D. gigas in the eastern Pacific Ocean.
 

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Characterization of the northernmost spawning habitat of Dosidicus gigaswith implications for its northwards range extension
Jorge E. Ramos, Alejandro Ramos-Rodríguez, Gastón Bazzino Ferreri, J. Alejandro Kurczyn, David Rivas, César A. Salinas-Zavala 2017 (subscription Marine Ecology)

ABSTRACT: The jumbo squid Dosidicus gigas is an ecologically and commercially important species whose northernmost geographic limit is the Gulf of California. However, over the last decades this species has extended its geographic distribution polewards, with associated impacts on the ecosystem. The origin of range-shifting individuals is poorly understood; therefore, we aimed to identify and characterize the northernmost spawning habitat of this species. Implications of the location and oceanographic conditions of the spawning habitats, migration capacity and life history characteristics of D. gigas are also discussed to elucidate its migration pattern. The northernmost spawning area was located between the biological activity centres (BACs) around the Gulf of Ulloa at the west coast of southern Baja California Peninsula during winter, summer and autumn 2005. Generalized linear models indicated that the interaction of sea surface salinity and thermocline depth, and the effect of latitude and sea surface temperature explained most of the variability in paralarval presence, whereas chlorophyll a and latitude explained paralarval abundance. Simulations indicated that paralarvae were dispersed towards the southwest or temporarily remained between BACs. The northwards incursion of D. gigas may be favoured by BACs and upwelling events along the coast of the northeastern Pacific. In warm years, D. gigas is likely to spawn off the Baja California Peninsula, it may actively migrate as far north as Alaska (USA) tracking BACs and upwelling conditions in search of feeding grounds, and it may return from different areas along the northeastern Pacific to spawn off the Baja California Peninsula.
 

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