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The Humboldt squid (Dosidicus gigas), is a significant economic species off Peru. The abundance and distribution of the species are highly susceptible to fluctuations in marine environmental conditions. The evolution of mesoscale eddies represents one of the dynamic processes in the ocean, exerting varying degrees of influence on regional biogeochemical processes from generation to dissipation. However, the mechanisms governing the regulation of abundance and spatial distribution of D. gigas off Peru during this evolution remain unclear. Therefore, this study employed normalization techniques and the habitat suitability index (HSI) model, utilizing data from the D. gigas fishery, mesoscale eddies, and marine environmental factors (including sea surface temperature, temperature at 50 m depth, and chlorophyll-a concentration) to analyze the environmental changes and the abundance, spatial distribution, and habitat changes of D. gigas during the evolution of mesoscale eddies. The results indicate that eddies undergo four stages: formation, intensification, maturity, and decay. During eddy evolution, the abundance of D. gigas exhibited an initial increase and a subsequent decrease within cyclonic eddies (CEs), whereas, within anticyclonic eddies (AEs), abundance showed a gradual decline. The outcome of the HSI model revealed that, the habitat suitability and the proportion of suitable habitat areas within eddies were highly consistent with the abundance of D. gigas during all stages of the eddies other than the intensification stage of AEs. The study speculated that both CEs and AEs can create favorable environmental conditions during the maturity stage, thereby leading to an increase in suitable habitat and abundance of D. gigas. These findings emphasize the significant impact of mesoscale eddy evolution on the abundance and habitat distribution of D. gigas. [ABSTRACT FROM AUTHOR]

Dosidicus gigas is a kind of low-fat food with poor gel properties. Fermentation has been proved to be an effective food processing method that could improve the gel properties of meat. Here, we inoculated D. gigas with two strains, Lacticaseibacillus casei and Staphylococcus carnosus, that have been approved for use in meat processing, and studied their impact on the quality of the product. Compared with the uninoculated samples, inoculation with L. casei and mixed inoculation with L. casei and S. carnosus were able to significantly reduce pH during fermentation. The plate counting results showed that L. casei may have adapted well to the environment in the inoculated groups, while the growth of Staphylococcus may have been inhibited in the mixed inoculated group. 16s rRNA sequencing confirmed that inoculation significantly altered the bacterial composition of squid surimi sausages. Both inoculation with L. casei and mixed inoculation with L. casei and S. carnosus were able to inhibit the accumulation of the main biogenic amines, and in the mixed inoculated group, the main biogenic amines were lower. Compared with unfermented squid surimi sausages, mixed inoculation changed the texture, gel properties, color, and appearance of squid surimi sausages. These results showed that mixed inoculation can not only ensure safety, but also improve the quality of squid surimi sausages. [ABSTRACT FROM AUTHOR]

Cephalopods are well-documented for voracious and opportunistic feeding behaviors, but knowledge about individual niche partitioning in energy acquisition is still scarce. Here, we applied the stable isotope analysis to evaluate the individual diet specialization of female jumbo squid (Dosidicus gigas), which is an important pelagic commercial cephalopod and also acts as a vector of energy and nutrient transfer in the marine ecosystem. We detected the δ15N and δ13C values of each squid's paired tissues; the digestive gland and mantle tissue were sampled from three regions (the Equatorial waters, waters off north and south Peruvian Exclusive Economic Zone) in the southeast Pacific. We found that the squid spanned more than one trophic level variation in the ranges of δ15N and δ13C values and consistently increased isotopic niche as they grew in each sampling region. Conversely, the variations between the paired tissues for each individual typically averaged from 0.82‰ to 1.92‰ for the δ15N values, and for the δ13C values, averaged from 1.18‰ to 1.65‰; the isotopic individuality index was close to 0. The inter-individual difference metrics (isotopic evenness and isotopic uniqueness) showed a variability of 1.1–1.7 factor when using the gonadosomatic index as a weight factor, and negligible change when weighed by mantle length, compared to the metrics without a weight factor added. The results indicate that the female jumbo squid is a diet generalist that is composed of individual specialization and that the individual diet specialization may be linked to energy acquisition for reproduction. [ABSTRACT FROM AUTHOR]

Two nektonic squid species, Illex argentinus in the Southwest Atlantic and Dosidicus gigas in the Eastern Pacific, are amongst the largest commercial cephalopod resources; presently comprising from one third to almost one half of the global cephalopod catch. These squids are straddling stocks exploited during their ontogenetic migrations both within exclusive economic zones of coastal States and in adjacent high seas. At present, fisheries of these squids lack an agreement to undertake comprehensive international stock assessments and management, resulting in minimal data exchanges among coastal States and those fishing in the high seas. In the high seas, there is little to no regulation and control of fishing activities, with very limited information on catch and effort. However, the high seas have been very important for commercial exploitation of both species, with annual averages of 45% of the total I. argentinus catch and 30–40% of the total D. gigas catch over the last decade. With uncontrolled harvest in the high seas, and without any unified international regulation, these straddling squid resources are highly vulnerable to overfishing; especially during years of poor recruitment and low abundance. Recent dramatic increases of fishing pressure pose a significant threat to the sustainability of these globally important squid resources. A proposal to reduce the risk of squid stocks depletion would be the establishment of a multi-national advisory forum to explicitly monitor stocks, coordinate assessment of population dynamics, and provide management recommendations for cephalopod fisheries around the world. [ABSTRACT FROM AUTHOR]

Jumbo squid (Dosidicus gigas) is a commercially valuable mollusk in Mexico; 80% of its body is edible. Despite the high protein content (∼18%) and low cholesterol content of this species, its high proteolytic activity (microbial and endogenous enzymes) induces protein degradation and consequent reduction in functional properties from a structural viewpoint. Gelation capacity (texture profile of the gels obtained), solubility, water holding capacity, foaming capacity, emulsification capacity, and emulsion stability were evaluated in protein concentrates obtained by foam‐aided pH‐shift processing: (A) myofibrillar protein extraction with distilled water and no pH‐shifting; (B) alkaline solubilization and isoelectric precipitation; (C) acidic solubilization and isoelectric precipitation; and (D) process A and isoelectric precipitation. Process B showed superior gelation capacity, D had high emulsion stability across a wide range of pH values (4.0–8.0) and C lower plate counts of aerobic mesophilic. Therefore, all three alternative extraction processes showed techno‐functional advantages. Practical Application: Jumbo squid is an abundant protein source in México, most of which is exported. Functional and physicochemical properties of muscle protein were improved by pH‐shift processing. The recovered protein showed modifications of technological properties, using one of the methods described can lead to produce a protein extract with the most desirable attributes, such as foaming, emulsifying, or gelling capacities. The functional and physicochemical properties of protein from squid can be enhanced by selecting a certain pH‐shift processing, depending on the desirable use. There is a broad perspective on the use of these protein extracts as ingredients or additives. [ABSTRACT FROM AUTHOR]

Mass stranding events of different taxonomic groups are periodic in certain coastal regions worldwide, but the underlying causes for these occurrences are not yet fully understood. In the Eastern Pacific Ocean (EPO), the most frequent and documented mass strandings correspond to the jumbo squid Dosidicus gigas, but the different hypotheses proposed to explain this phenomenon fail to predict it. Here, we assembled a database with historical stranding occurrences from the nineteenth century to 2022, highlighting the dramatic increase in strandings since the year 2000 along the EPO. The most common regions for jumbo squid strandings in the northern hemisphere are USA and Mexico, whereas in the southern hemisphere these events have mostly occurred in Chile. In both hemispheres the strandings are frequent in summer months. Although we assessed different hypothetical causes (e.g., post-spawning mortality, high temperatures, toxins from harmful algal blooms, human disturbance), we did not find enough evidence to support any of them. Besides, the need to experimentally test the plausible cause(s), we also discuss an alternative ecophysiological hypothesis associated with upwelling shadows and the species' diel migratory behavior, highlighting the importance of stranding events as key components of global nutrient cycles. [ABSTRACT FROM AUTHOR]

Neon flying squid Ommastrephes bartramii and jumbo flying squid Dosidicus gigas are two important commercial ommastrephid species in the Pacific Ocean. As short-lived marine species, squids are highly susceptible to changes in climate and marine environments. According to samples collected from the northwest and southeast Pacific Ocean in different years, we explored the growth characteristics of these two squids in terms of their mantle length (ML) distribution and the relationship between mantle length and body weight (LWR), also considering the relative condition factors (Kn), and explored the effects of the El Niño and Southern Oscillation (ENSO) on their growth. The results showed that the ML for O. bartramii and D. gigas had significant differences among different years and different sexes (p < 0.01), and the size of females was larger than that of males. LWR showed that both squids demonstrated a positive allometric growth pattern (b > 3), and parameters a and b were influenced by year and sex. Furthermore, there were significant differences in Kn in both squids for different years and different sexes (p < 0.01), and their interannual fluctuations were quite significant. In conclusion, the alterations in the marine environment caused by climate change had a significant impact on the growth of O. bartramii and D. gigas in this study. ENSO events had opposite effects on the growth of both squid species. [ABSTRACT FROM AUTHOR]

Jumbo squid Dosidicus gigas play a critical role in the marine ecosystems and are an important commercial species in the East Pacific. Generally, three size groups have been distinguished on the basis of the mantle length (ML) of an adult. Here, fatty acid (FA) analyses of muscle tissues were used to explore the feeding strategies of D. gigas off the Peruvian exclusive economic zone in terms of different size groups and sexes. There was no significant difference in fatty acid composition between the small- and medium-sized groups, whereas the large-sized group differed significantly from other groups. The higher content of C20:4n6 and (C18:2n6 + C18:3n3) indicates that the large-sized group may feed more frequently in nearshore and deep waters. Furthermore, the niches of the three size groups were consistent with the results of fatty acid composition, with the large-sized group occupying the widest trophic niche, followed by the medium-sized group and then the small-sized group. In addition, there was evidence of trophic niche overlap between the small and medium groups. In terms of sexual variability of the small and medium groups, the fatty acid composition significantly differed between females and males. In terms of sexual variation of the large group, the fatty acid composition between females and males was similar, indicating that similar feeding strategies may be adopted by them. This study revealed the variability of the feeding strategies of three size groups of D. gigas off the Peruvian exclusive economic zone. [ABSTRACT FROM AUTHOR]

Dosidicus gigas is an ecologically and economically important squid species extensively distributed in the eastern Pacific Ocean. Its habitat is extremely sensitive to climatic and environmental variability.The relationship between habitat pattern of D. gigas and El Niño–Southern Oscillation (ENSO, divided into the El Niño, ENSO‐neutral, and La Niña events) was assessed from 1950 to 2015, using a habitat suitability index (HSI) modelling approach including two crucial environmental variables: sea surface temperature (SST) and sea surface height anomaly (SSHA).On the basis of cross‐correlation analysis, it showed that both SST anomaly and SSHA were significantly positively related to the ENSO index. Moreover, a significantly negative association was found between the HSI values and the ENSO index.Due to the El Niño events, SST off Peru became higher and sea level rose, resulting in contracted areas of suitable SST and SSHA; consequently, suitable habitats for D. gigas dramatically decreased. In contrast, during the ENSO‐neutral and La Niña years, the extent of suitable SST and SSHA increased due to the colder water and lower sea level, and suitable habitat for D. gigas expanded.Moreover, the latitudinal gravity centre of HSI was significantly positively associated with the ENSO index. Relative to the ENSO‐neutral and La Niña years, a southward movement of the monthly preferred SST isotherm for D. gigas during the El Niño years could explain the occurrence of more suitable habitats in southern waters off Peru.These findings suggested that the ENSO event plays an important role in regulating environmental conditions off Peru and further affected the spatio‐temporal distribution of D. gigas habitat. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The process of thermal gelation involves protein denaturation, leading to the exposure of functional groups to form new interactions; these conformational changes favour protein-water- protein interactions and help to stabilise the gel. It is known that in muscle proteins, myofibrillar proteins such as myosin are responsible for the main functional properties; however, in invertebrate species, actin and paramyosin exert an influence on the rheological properties of the gels. Therefore, in the present work, the gelling property of the actomyosin-paramyosin complex was studied. There were significant differences (p < 0.05) in hardness and water-retention capacity, which was higher for actomyosin-paramyosin isolate (API) than for mantle proteins (MP). This may have been due to its structure being more porous than that of MP, which is agglomerated. The API system favoured protein-protein and water-protein interactions; these formed stronger cross-links, which in turn favoured gelling. Moreover, the presence of sarcoplasmic proteins may be more of a physical-chemical impediment rather than hydrolysis caused by endogenous proteases. [ABSTRACT FROM AUTHOR]

The pelagic cephalopod species jumbo flying squid Dosidicus gigas is ecologically and economically important in the Humboldt ecosystem off Peru. This squid species is sensitive to oceanic environmental changes, and regional oceanographical variability is one of the important factors driving its redistribution. Off Peruvian waters, mesoscale eddies are ubiquitous and dominate the biogeochemical processes in this region. This study first explored the role of mesoscale eddies in regulating the environments and their effects on the abundance and habitat distribution of D. gigas off Peru by analyzing squid distribution in eddy-centric coordinates and building a habitat suitability index (HSI) model. Results indicated that the abundance and habitat distribution of D. gigas in mesoscale eddies varied across months, with significant differences observed between anticyclonic eddies (AE) and cyclonic eddies (CE). In AE, a higher abundance and proportion of suitable habitat occurred. While in CE, the abundance was relatively low and the suitable habitat was relatively less, concentrating at the periphery of CE. Based on the HSI model results, sea surface temperature (SST) and 50 m water temperature (T50m) in AE were more favorable for D. gigas , which was 0.3–0.5 °C lower than that in CE, yielding high-quality habitats and higher abundance of D. gigas. Our findings emphasized that mesoscale eddies have a significant impact on water temperature conditions and nutrient concentrations off Peruvian waters. • The eddy-induced changes in Dosidicus gigas distribution were first explored. • Mesoscale eddies have impacts on water temperature and nutrient condition. • A higher abundance of D. gigas and enlarged suitable habitat occurred in anticyclonic eddies. [ABSTRACT FROM AUTHOR]

An integrated habitat suitability index (HSI) model was developed in this study for Dosidicus gigas in the eastern equatorial waters of the Pacific Ocean to explore climate-related spatial and temporal variability in the habitat distribution pattern based on three crucial environmental variables: sea surface temperature (SST), sea surface salinity (SSS) and chlorophyll-a concentration (Chl-a). Results revealed that the HSI model could accurately predict potential habitats for D. gigas. The habitat suitability varied significantly by month, with highest suitability in April and lowest in March. Besides, from December to May, the longitudinal gravity center of the fishing grounds (LONG) and the HSI overall shifted eastward and the latitudinal gravity center shifted northward then southward. In comparison to the warm ENSO phases in 2019, the cold ENSO phases in 2018 produced increased suitable habitat from December to May, leading to a significantly higher CPUE. Prospective high-quality habitats in 2018 primarily occurred in the western regions, with the exception of December, which resulted in a more westward distribution of LONG from January to May. High-quality habitats moved northward from December to February and southward from March to May 2018, compared to minor latitudinal movement in 2019. It was inferred that annual variations in squid abundance and distribution were largely affected by the SST-related habitat pattern of D. gigas in the eastern equatorial waters. Our findings suggested that D. gigas habitats clearly varied by month and year and were greatly influenced by climate-induced environmental changes. • A habitat model was first built for Dosidicus gigas in the eastern equatorial waters. • The habitat suitability of Dosidicus gigas showed clear spatio-temporal variations. • ENSO-related habitat pattern largely affected variations in squid abundance and distribution. [ABSTRACT FROM AUTHOR]

Oceanic squids have distinct population dynamics and life histories compared to most fishes, necessitating tailored fishing and management strategies. To conserve and sustain oceanic squid stocks, the Chinese government has implemented seasonal high seas closures from September 1st to November 30th each year since 2020. Our study aims to evaluate closure efficacy for oceanic squid conservation using the central-eastern Pacific closure as a case study and propose targeted improvements. Based on biological data from equatorial waters in two selected periods (before closure: December 2017 to May 2018; and after closure: December 2021 to May 2022), comparative analyses of mantle length distribution and length at maturity (L m) were used to detect the differences before and after closure for the jumbo squid Dosidicus gigas. Based on biological data from 2009 to 2022, a three-dimensional environment-based general additive model (GAM) was applied to predict the intermonthly distribution of spawning grounds. Comparison analyses indicated increased mantle length and L m following closure. The best-fitted GAM explained 38 % of the deviance. Environmental factors significantly influenced gonad development. Model predictions recognized seasonal core spawning grounds at the Costa Rica Dome and Cocos ridge plus year-round secondary spawning grounds off the Pervian-Chilian waters south of 8 ° S. The current closure protects overlapping feeding grounds and migratory routes for the Costa Rica Dome and Peruvian coastal spawning groups, while Peruvian-Chilian waters south of 8 ° S also represent similar grounds for the Peruvian coastal and Chilean groups. Overall, seasonal closures could have a positive conservation effect on oceanic squids. Maintaining the current closure delayed or advanced 1 month alongside another closure off the southern Peruvian EEZ from October to December or November to January could further enhance jumbo squid conservation [ABSTRACT FROM AUTHOR]

BACKGROUND: The secondary structure of a protein determines its functional properties, such as its gelling capacity. The α‐helix and β‐sheet comprise its main structures. Myofibrillar proteins from jumbo squid are composed mainly of the actomyosin‐paramyosin complex; this complex contains a high percentage of α‐helix, because actin, paramyosin, and myosin constitute 30%, 100%, and 55% of the α‐helix, respectively. It is important to elucidate the role of the secondary structures in the gelation of giant squid proteins as they form gel. The role of the secondary structures in the gelation of giant squid proteins is therefore very important. For this reason, the objective of this work was to evaluate the effect of temperature on the structural behavior of actomyosin‐paramyosin isolate (API) from Dosidicus gigas. RESULTS: The unfolding of the API system, which is composed of the actomyosin‐paramyosin complex, was clarified by studying surface hydrophobicity and viscosity. Three characteristic peaks were found, associated with myosin, paramyosin, and actin. Infrared and circular dichroism corroborated the view that API undergoes major structural changes, because it proceeds from mostly an α‐helix structure to 100% β‐sheet. CONCLUSION: The structural rearrangement favors gelation by cross‐linking, generating new protein–protein and water‐protein interactions, which create a more stable structure compared to mantle proteins (MP). Likewise, the presence of sarcoplasmic and stromal proteins in D. gigas muscle prevents the unfolding of myofibrillar proteins, favoring gelation by agglomeration, decreasing the ability to trap water and thus its gelling capacity. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

• Underwater observations of jumbo squid in a trawl for Chilean hake were made using video cameras. • Quantitative analysis of the selection process using a rigid grid to reduce bycatch was made. • Jumbo squid was positively selected by the rigid grid. • Some obstacles was observed during the selection process, with losing efficiency in the escape. • Redesign components to improve efficiency of the selection system are discussed. Observations via underwater filming were obtained to improve understanding of the behavior and selection process of jumbo squid (Dosidicus gigas) in response to a rigid grid in the Chilean hake (Merluccius gayi gayi) trawl fishery in central Chile. The individual fates of jumbo squid were examined to study the efficiency of the selection system. The number of escaped versus captured specimens was quantified. During the selection process, we observed obstacles that impeded the escape process, leading to retention of jumbo squid and limiting the selectivity effectiveness. The analysis showed that 69.8% of jumbo squid escaped the net and 75.5% faced obstacles that generated retention in the sorting process. Longer retention times led to a saturation of the selection system. The target species was successfully selected by the sorting system, in which 87.1% of Chilean hake entered the codend through the grid. We discuss the need to redesign components of the selection system to improve efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Habitat modeling approach is a useful tool to detect potential habitat of pelagic fish species for better fishery exploitation and management. In this study, an integrated habitat modeling approach was applied to examine seasonal habitat patterns of an ecologically and economically important squid species Dosidicus gigas in the Southeast Pacific Ocean off Peruvian waters. Fisheries data of D. gigas and three crucial remotely-sensed environmental variables including sea surface temperature (SST), net primary production (NPP) and sea surface height anomaly (SSHA) during 2006–2015 were used to develop and validate the habitat model. Results revealed that the model output robust predictions of seasonal habitat suitability for D. gigas stock. Potential habitat exhibited strong seasonal variability, characterized by an expansion of suitable habitat during spring-autumn period and an extreme reduction in winter. These seasonal habitat patterns of D. gigas were largely driven by spatial distribution of favorable environmental conditions. Spatial correlation analysis indicated that the habitat quality of D. gigas was negatively correlated with SST in the areas between 8°–15°S and 87°–79°W and with SSHA on the whole fishing ground. However, a negative relationship was found between HSI values and NPP in the east of 84°W, but with a significantly positive correlation in the west of 84°W. In addition, seasonal variations of CPUEs and latitude distribution of fishing efforts were highly coincided with the variability trends in the area of suitable habitats and their latitudinal distributions. Interannual variability was shown in the averaged HSI of D. gigas. Furthermore, comparing to the strong El Niño year in 2015, the La Niña event in 2011 yielded more enlarged favorable regions of each environmental factor in each season, leading to form extremely high-quality habitats. Highlights • A habitat model was built to examine seasonal habitats of jumbo squid off Peru. • Potential habitats of jumbo squid showed significant seasonal spatial patterns. • Environmental conditions strongly affected seasonal habitats of jumbo squid. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Only 50%–60% of total seafood catch is used for human consumption, seafood processing being considered as one of the main sources of by‐products. Among marine species, jumbo squid (JS; Dosidicus gigas) represents the most important squid fishery, showing an increasing economic interest in many countries. As for any other marine species, the regular cleaning, dressing and processing produce high quantities of by‐products (skin, head, fins, viscera, tentacles, unclaimed mantle, etc.) that are rich in many nutrients (proteins, lipids, minerals, vitamins, enzymes, biopolymers, etc.). This review compiles information about extraction and employment of JS by‐products with the aim of enhancing their economic value and reduce environmental drawbacks. A special emphasis is given to the relevance in developing methods susceptible to transform by‐products into useful and profitable products susceptible to be applied in several industries such as food, medicine, agrochemical or pharmaceutical. Future possible trends for widening this profitable use are mentioned. [ABSTRACT FROM AUTHOR]

The population dynamics of jumbo squid Dosidicus gigas from northwest Mexico was evaluated for the period 1974-2012 using Schaefer's model, where model parameters were estimated with the catch maximum sustainable yield method (Catch-MSY) using two prior intrinsic population increase rate (r) range values (1.0 to 2.0 and 1.5 to 2.0). Estimated parameters with both prior r ranges were 1.23 and 1.68 yr-1 for r and 243,836 and 190,468 ton for carrying capacity (k), respectively. Corresponding management quantities were 75,147 and 80,098 ton for the maximum sustainable yield (MSY) and 121,918 and 95,234 ton for the biomass at MSY (BMSY). Estimated jumbo squid biomass dropped below the BMSY after 2003, and near to 0.2 k in 2012. The Schaefer's model showed that declines in estimated biomass were preceded by catches that exceeded the MSY. Strong El Niño-Southern Oscillation events can change the availability of jumbo squid in northwest Mexico through migratory processes and phenotype changes in maturation size, but stock biomass variability is most likely to be caused by fishing. [ABSTRACT FROM AUTHOR]

The present study investigated the flavour characteristics and key volatile components of fermented squid (Dosidicus gigas) as well as their formation mechanism by three different starter cultures of lactic acid bacteria (LAB) and natural squid. The sensory assessment, volatile compounds, as well as the amino acids of the mixed fermented squid were detected using pickled brine as samples of fermented squid. A total 88 types of volatile compounds were found in four samples by 0-72 h of fermentation. After fermentation by LAB, the volatile compounds of squid showed that the fermented squid with different started cultures differed mainly in terms of numbers of alcohols, ketones, and esters. Furthermore, the amounts of volatile compounds among three starter cultures were also obviously different. Gas Chromatography-Mass Spectrometer (GC-MS) analysis indicated that the mixed fermentation process contained relatively higher (+)-limonene (11.71%) (lemon scent) and 3-hydroxy-2-butanone (5.72%) (creamy taste). These compounds were not detected in the control group. The main flavour compounds of nonanal and 2, 4-decadienal were gradually reduced. Meanwhile, 2, 3-butanedione, 2-heptanone, 2-pentylfuran, and nonanoic acid are the key flavour components. The total principal component is 94.01%, which were clarified by electronic nose in combination with principal components analysis. After mixed fermentation by LAB, the total amino acid (TAA) content reached 85.36 g/100 g, which was almost twice the amount of the control, especially in aspartate, glutamate, and threonine. Our results indicated that LAB has obvious effects on deodorization and flavour promotion during the fermentation of squid. This study provided an important basis for the further development and utilization of squid. [ABSTRACT FROM AUTHOR]

The purpose of the research was to determinate proximal composition and functional properties of the giant squid freeze-dried surimi (Dosidicus gigas). Surimi elaborated from giant squid and it lyophilized until obtaining surimi powder to evaluate its characteristics and functional properties. The protein content was 58.7% and carbohydrate 30.5%. Protein solubility in water and salt (3%) were 21.1% and 40.6% respectively, these values being higher than surimi powder of commercial species. The gelling capacity was 2.4% and the emulsifying capacity was 79.9% at a concentration of 1.0%. The color on the Hunter scale was L*: 91.5; a*: 0.5; b*: 7.0. Giant squid powder surimi considered as a functional protein powder due to its percentage protein content, and had good technological characteristics and great potential in the food industry. [ABSTRACT FROM AUTHOR]

Since 2000, jumbo squid Dosidicus gigas catches in Baja California have increased steadily with a record catch in 2011 of 14,243,689 kg. However, little is known about stock size, distribution and seasonality, as well as the possible effects of the environment on the fishery. We tested D. gigas catches (CPUE) from 2006 to 2013 with Pacific sardine Sardinops caeruleus fishery catch data, as well as the primary productivity anomaly, sea surface temperature anomaly (SSTa), Multivariate El Niño Index (MEI), North Pacific Gyre Oscillation Index (NPGO), and price/kg using a general linear model. We also estimated D. gigas population size using two depletion models. More than 80 % of D. gigas captures for 2006-2013 occurred within 20 nmi from the coast, regardless of the fleet. We identified Salsipuedes, Soledad Bay and Vizcaino Bay as the most important D. gigas fishing grounds. D. gigas CPUE showed monthly differences, with July and August being significantly different from other months ( p < 0.041; and p < 0.006, respectively). S. caeruleus and D. gigas fishing grounds overlapped geographically more than 75 %; however no correlation between catch volumes was found ( p < 0.562). There was an inverse linear and significant relation between D. gigas monthly catches and the primary productivity anomaly ( p < 0.021) and price/kg ( p < 0.016), where a positive primary productivity anomaly and price/kg values yielded a D. gigas CPUE below 9 × 10 kg. We did not find any direct relation between SSTa, MEI, NPGO and D. gigas catches ( p < 0.785; p < 0.497; and p < 0.108, respectiveley). Lack of independent fisheries data, as well as thermal tolerance and plastic life history of D. gigas, may provide an explanation on the non-apparent effect of biotical and abiotical factors in the relative abundance of D. gigas along Baja California's west coast. [ABSTRACT FROM AUTHOR]

An analysis was performed on the spatial distribution of the industrial Jumbo flying squid fishery within and outside the Peruvian exclusive economic zone (EEZ) in relation to sea surface temperature (SST) and chlorophyll-a (Chl-a). The locations of vessels were derived from the satellite tracking system (SISESAT) of the Instituto del Mar del Perú. Monthly environmental information came from the MODIS sensor of 4 km spatial resolution for the period 2004–2012. Fishing operations data were divided into three periods based on their distance to shore consequential to the fishing regulations from January 2004 to October 2010, November 2010 to December 2011 and 2012. During the first period, two monthly patterns of spatial distribution were identified; from January to July fishing was along the coast from Paita (05°S) to San Juan de Marcona (15° 22′S) and later it was more concentrated in the northern area between Chimbote and Paita from August to December. In the second period, fishing operations formed small concentrations and widely dispersed points of fishing as a result of fishing restrictions within 80 nautical miles introduced in November 2010. In 2012 the fleet was located outside the EEZ. The highest concentrations of the fleet were found between 30 and 90 nautical miles offshore. The highest concentrations of squid were located from Paita-Chimbote (05°–09°S) and Callao–San Juan de Marcona (12° 03′–15° 22′S). Fishing operations were conducted in a wide range of SST between 14.1° and 26.8 °C, with the highest incidence in temperatures between 18.4 to 22 °C and with a tendency to be located more frequently in areas with higher temperatures in recent years. Regarding chlorophyll-a, the fleet fished between chlorophyll-a concentrations of 0–9.5 mg/m3 within the EEZ, and from 0.2 to 0.5 mg/m3 outside the EEZ. Distribution patterns of the fleet in relation to anomalies of sea surface temperature in the area El Niño 1 + 2, with respect to latitude and cyclic monthly SST variability, were also observed. [ABSTRACT FROM AUTHOR]

In the present work the myosin molecule from jumbo squid mantle (Dosidicus gigas) was isolated and characterized with the aim to evaluate the influence of ionic strength on its gelling properties. It was found that the myosin molecule possesses different chemical and structural characteristics than other vertebrates and invertebrates species, such as some cephalopods, which might explain differences in gelation in comparison to those from other organisms. A lower content of total sulfhydryl groups (TSH) possibly caused an improvement in the myosin molecule flexibility when the ionic strength increased (p ˂ 0.05). The aforementioned possibly affected (p ˂ 0.05) the enzyme activity, surface hydrophobicity, viscosity and RSH groups. The results demonstrate that the myosin molecule from jumbo squid is structurally different from the rest of the marine species. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

Squid are the largest jet propellers in nature as adults, but as paralarvae they are some of the smallest, faced with the inherent inefficiency of jet propulsion at a low Reynolds number. In this study we describe the behavior and kinematics of locomotion in 1 mm paralarvae of Dosidicus gigas, the smallest squid yet studied. They swim with hop-and-sink behavior and can engage in fast jets by reducing the size of the mantle aperture during the contraction phase of a jetting cycle. We go on to explore the general effects of a variable mantle and funnel aperture in a theoretical model of jet propulsion scaled from the smallest (1 mm mantle length) to the largest (3 m) squid. Aperture reduction during mantle contraction increases propulsive efficiency at all squid sizes, although 1 mm squid still suffer from low efficiency (20%) because of a limited speed of contraction. Efficiency increases to a peak of 40% for 1 cm squid, then slowly declines. Squid larger than 6 cm must either reduce contraction speed or increase aperture size to maintain stress within maximal muscle tolerance. Ecological pressure to maintain maximum velocity may lead them to increase aperture size, which reduces efficiency. This effect might be ameliorated by nonaxial flow during the refill phase of the cycle. Our model's predictions highlight areas for future empirical work, and emphasize the existence of complex behavioral options for maximizing efficiency at both very small and large sizes. [ABSTRACT FROM AUTHOR]

Jumbo (or Humboldt) squid, Dosidicus gigas, is a large jet-propelled top oceanic predator off the Eastern Pacific. The present study reports, for the first time, concentrations of V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd and Pb in gills, mantle and digestive gland of this powerful pelagic squid in the Gulf of California. Zinc and Cu were the most abundant elements. All elements, with the exception of As, were largely stored in digestive gland; particularly Cd that reached concentrations between 57 and 509µgg−1. Significant relationships between tissues were found for Co (digestive gland–gills), As (gills–mantle) and Cd (digestive gland–mantle). Proportionality of Cd concentrations between mantle and digestive gland suggested that detoxification capacity by digestive gland was insufficient to avoid the transfer of this element to mantle and other tissues. Nonetheless, Cd concentrations in the mantle were always below the regulatory limit and, therefore lack of constraints for human consumption. On the basis of the fishery landings, one may estimate that up to 1t of Cd can be annually removed by jumbo squid fisheries. [Copyright &y& Elsevier]

Abstract: Jumbo squid (Dosidicus gigas) is a large oceanic squid endemic off the Eastern Tropical Pacific that undertakes diel vertical migrations into mesopelagic oxygen minimum zones. One of the expected physiological effects of such migration is the generation of reactive oxygen species (ROS) at the surface, promoted by the transition between hypoxia and reoxygenation states. The aim of this study was to investigate the energy expenditure rates and the antioxidant stress strategies of juvenile D. gigas under normoxia and hypoxia, namely by quantifying oxygen consumption rates, antioxidant enzyme activities [including superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST)], heat shock protein expression (Hsp70/Hsc70), and lipid peroxidation [malondialdehyde (MDA) levels]. A high significant decrease (68%) in squid’s metabolic rates was observed during hypoxia (p<0.05). This process of metabolic suppression was followed by a significant increase in Hsp70/Hsc70 expression (p<0.05), which may be interpreted as a strategy to prevent post-hypoxic oxidative damage during the squid’s night upwards migration to the surface ocean. On the other hand, in normoxia, the higher SOD and CAT activities seemed to be a strategy to cope with the reoxygenation process, and may constitute an integrated stress response at shallower depths. GST activity and MDA concentrations did not change significantly from normoxia to hypoxia (p>0.05), with the latter indicating no enhancement of lipid peroxidation (i.e. cellular damage) at the warmer and normoxic surface waters. The understanding of such physiological strategies that are linked to oxygen deprivation and reoxygenation phases may provide valuable information about how this species is quickly responding to the impacts of environmental stressors coupled with global climate change. [Copyright &y& Elsevier]

Abstract: From 2002 to 2010, the jumbo squid (Dosidicus gigas) has been regularly encountered in large numbers throughout the California Current System (CCS). This species, usually found in subtropical waters, could affect coastal pelagic ecosystems and fisheries as both predator and prey. Neither the abundance of jumbo squid nor the optimal ocean conditions in which they flourish are well known. To understand better the potential impacts of this species on both commercial fisheries and on food-web structure we collected nearly 900 specimens from waters of the CCS, covering over 20° of latitude, over a range of depths and seasons. We used demographic information (size, sex, and maturity state) and analyzed stomach contents using morphological and molecular methods to best understand the foraging ecology of this species in different habitats of the CCS. Squid were found to consume a broad array of prey. Prey in offshore waters generally reflected the forage base reported in previous studies (mainly mesopelagic fishes and squids), whereas in more coastal waters (shelf, shelf break and slope habitats) squid foraged on a much broader mix that included substantial numbers of coastal pelagic fishes (Pacific herring and northern anchovy, as well as osmerids and salmonids in northern waters) and groundfish (Pacific hake, several species of rockfish and flatfish). We propose a seasonal movement pattern, based on size and maturity distributions along with qualitative patterns of presence or absence, and discuss the relevance of both the movement and distribution of jumbo squid over space and time. We find that jumbo squid are a generalist predator, which feeds primarily on small, pelagic or mesopelagic micronekton but also on larger fishes when they are available. We also conclude that interactions with and potential impacts on ecosystems likely vary over space and time, in response to both seasonal movement patterns and highly variable year-to-year abundance of the squid themselves. [Copyright &y& Elsevier]

Abstract: The co-products produced in the processing industry of Dosidicus gigas muscle, is a good source of polymeric material for film developing. The objective of this work was to compare different ways of protein recovery to find the best conditions of material for edible film developing. The proteins were recovered by water, salt, alkaline and acidic solubilisation. The highest protein solubilisation was obtained at alkaline conditions (≥70%) and DSC confirmed a partial denaturalization in saline and alkaline solution and total at acidic conditions, while SDS-PAGE confirmed a hydrolysis effect at pH 3. According to FTIR, the loss of secondary structure at pH 10 led to a stronger bonding film network and the hydrolysis at pH 3 resulted in more protein-plasticizer and protein–water interactions. Both alkaline and acidic conditions led to transparent and microbiologically stable films, the alkaline-film being more water resistant and with less protein release in water contact. Both alkaline- and acidic-films resulted in the more flexible and more resistant, especially at alkaline conditions. While salt-extract did not improve any mechanical property of the corresponding film compared with water-film, both films presented the lower solubility and the more water resistance but were not microbiologically stable and had poorer mechanical properties. [Copyright &y& Elsevier]

Squid have been studied extensively since 1982 to quantitatively measure their cost of locomotion and compare it with costs for fishes that are their primary competitors in the ocean. Early work focused on oxygen consumption in swim tunnels and led to the use of jet pressure tags to relate captive studies to behaviour in nature. Dosidicus gigas (d'Orbigny, 1835) (jumbo flying squid or Humboldt squid), which has expanded its range more than 10-fold, is used to illustrate how 'live fast, die young' squid can out compete fishes in changing times by both swimming and flying. Recent work has provided quantitative data on the costs of flying and this report provides some comparisons. Costs of flight in nature require new technology, which has fortunately arrived just in time. Accelerometry tags can now provide similar and perhaps better data on travel rate in nature, both in water and in air. These work on both squid and fish, so more and better comparisons are becoming possible. [ABSTRACT FROM AUTHOR]

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The Humboldt (jumbo) squid, Dosidicus gigas, is a part-time resident of the permanent oxygen minimum zone (OMZ) in the Eastern Tropical Pacific and, thereby, it encounters oxygen levels below its critical oxygen partial pressure. To better understand the ventilatory mechanisms that accompany the process of metabolic suppression in these top oceanic predators, we exposed juvenile D. gigas to the oxygen levels found in the OMZ (1% O2, 1 kPa, 10°C) and measured metabolic rate, activity cycling patterns, swimming mode, escape jet (burst) frequency, mantle contraction frequency and strength, stroke volume and oxygen extraction efficiency. In normoxia, metabolic rate varied between 14 and 29 μmol O2 g-1 wet mass h-1, depending on the level of activity. The mantle contraction frequency and strength were linearly correlated and increased significantly with activity level. Additionally, an increase in stroke volume and ventilatory volume per minute was observed, followed by a mantle hyperinflation process during high activity periods. Squid metabolic rate dropped more than 75% during exposure to hypoxia. Maximum metabolic rate was not achieved under such conditions and the metabolic scope was significantly decreased. Hypoxia changed the relationship between mantle contraction strength and frequency from linear to polynomial with increasing activity, indicating that, under hypoxic conditions, the jumbo squid primarily increases the strength of mantle contraction and does not regulate its frequency. Under hypoxia, jumbo squid also showed a larger inflation period (reduced contraction frequency) and decreased relaxed mantle diameter (shortened diffusion pathway), which optimize oxygen extraction efficiency (up to 82%/34%, without/with consideration of 60% potential skin respiration). Additionally, they breathe 'deeply', with more powerful contractions and enhanced stroke volume. This deep-breathing behavior allows them to display a stable ventilatory volume per minute, and explains the maintenance of the squid's cycling activity under such O2 conditions. During hypoxia, the respiratory cycles were shorter in length but increased in frequency. This was accompanied by an increase in the number of escape jets during active periods and a faster switch between swimming modes. In late hypoxia (onset ∼170±10 min), all the ventilatory processes were significantly reduced and followed by a lethargic state, a behavior that seems closely associated with the process of metabolic suppression and enables the squid to extend its residence time in the OMZ. [ABSTRACT FROM AUTHOR]

The article presents a study on the temperature dependence of embryonic development in Humboldt squid Dosidicus gigas. The study artificially fertilized and incubated the eggs of Dosidicus gigas, wherein the rate of development increased along with the increasing temperature. The results have identified a thermal window for a successful development through hatching that may prevent natural spawning in the northern California Current system.

Abstract: We analyzed the catch-at-size data for Dosidicus gigas from the fishing seasons 1996–1997 to 2001–2002. We were interested in alternative methods for stock assessment for this species because of the variability in recruitment and harvest rate. The catch-at-size model (CASA) could be fitted to the catch-at-size data for the different fishing seasons. The CASA model was able to mimic the different size-frequency distributions for jumbo squid. Our estimates of recruitment showed high variability. We estimated the highest recruitment in the time-series to be 8×107 recruits during 1996–1997. During the 1997–1998 fishing season, the recruitment fell to a low level during the 1997–1998 El Niño. We estimated the harvest rate-at-size to be between 0.2 and 0.6 for squid between 30 and 58cm mantle length. The results show that the CASA model can be applied to the available fishery data for the jumbo squid. [ABSTRACT FROM AUTHOR]

Abstract: Based on size at maturity and standardized residuals from mantle length (ML)–total weight (TW) and mantle length–gonad weight (GW) relationships, this paper describes the interannual variability of the size at maturity (SM), somatic and reproductive investment of mature males and females of Dosidicus gigas during the spawning peak (October–March) for the period 1994–2006 in the Northern Humboldt Current Ecosystem (Peruvian waters). Significant changes occurred in the SM in females as well in males: before 2001 the average did not exceed 47cm ML, while from 2001 onwards the average MS varied between 62 and 96cm ML. The average SM was generally higher in females. There was a great individual variability of somatic and reproductive investment, being higher in large-sized mature squids. No relationship was found between SM and somatic condition. The presence of small-sized mature squids in good somatic condition under different scenarios of sea surface temperature (normal, warm or cold periods; El Niño and La Niña events) does not indicate a relationship between somatic condition and SST. The relationship between reproductive and somatic investment was variable and independent of the sex. It also varied among different years. This would indicate that females and males may respond differently under the same environmental conditions. Considering the relationship between fecundity and ML, mature females at larger sizes had a lower reproductive condition, but also a higher potential fecundity. Lower fertility potential for some small mature females is offset by greater investment in reproduction, particularly under adverse environmental conditions. The positive correlation between the abundance (CPUE) and SM shows that the biomass was greater in periods dominated by the presence of large-sized mature squid. [ABSTRACT FROM AUTHOR]

Functional properties of protein from mantle and fin of the jumbo squid Dosidicus gigas were explained based on microscopic muscle fiber and protein fractions profiles as observed in SDS-PAGE. Fin has higher content of connective tissue and complex fiber arrangement, and we observed higher hardness of fin gels as expected. Myosin heavy chain (MHC) was found in sarcoplasmic, myofibril and soluble-in-alkali fractions of mantle and only in sarcoplasmic and soluble-in-alkali fractions of fin. An additive effect of salt concentration and pH affected the solubility and foaming properties. Fin and mantle proteins yielded similar results in solubility tests, but significant differences occurred for specific pH and concentrations of salt. Foaming capacity was proportional to solubility; foam stability was also affected by pH and salt concentration. Hardness and fracture strength of fin gels were significantly higher than mantle gels; gels from proteins of both tissues reached the highest level in the folding test. Structural and molecular properties, such as MHC and paramyosin solubility, arrangement of muscle fibers and the content of connective tissue were useful to explain the differences observed in these protein properties. High-strength gels can be formed from squid mantle or fin muscle. Fin displayed similar or better properties than mantle in all tests. [ABSTRACT FROM AUTHOR]

Abstract: Collagen-based biomaterials have been widely used due to its binding capabilities. However the properties and potential use of new collagen sources are still under investigation. Fish by-products are an excellent source of collagen. Thus, acid-soluble collagen (ASC) was extracted, and biochemical and physicochemically characterized from one under-utilized specie, jumbo squid (Dosidicus gigas). In addition, commercial chitosan (95–50%)-ASC (5–50%) blend films were successfully prepared by casting, and characterized by infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The molecular masses of the ASC subunits were about 190kDa, 110kDa, and 97kDa, the content of proline and hydroxyproline was 10.9% and 2.8%, respectively. The FT-IR and nuclear magnetic resonance spectra (1H NMR) confirmed collagen peptidic crosslinks, and one endothermic peak was found at 119°C. The FT-IR spectrum showed that chitosan and ASC remain linked into the films mainly due to hydrogen bonding. The 85:15 (chitosan:ASC) ratio was selected for its thermal and mechanical analyses. The thermograms of this film indicated the presence of two peaks, one at 87–98°C and the other at 142–182°C. The chitosan:ASC blend produced a transparent and brittle film, with high percentage of elongation at break, and low tensile strength in comparison to chitosan films. D. gigas mantle might be useful as a new source of plasticizer agent in the preparation of biofilms in composites with chitosan. [Copyright &y& Elsevier]

The article presents a study which discusses the reproductive biology of jumbo squid Dosidicus gigas in relation to the environmental variability of industrial fisheries in the Peruvian Humboldt Current System (HCS). It mentions that Dosidicus gigas is considered described as a monocyclic ommastrephid squid and a significant component of the ecosystem in the Easter Pacific Ocean. It affirms that the researchers identified several features of the squid's adjustments to reproduction changes which include temporal decoupling of male and female, changing sex ratios and variable size-at-maturity.

The population structure of the jumbo squid (Dosidicus gigas) is complex, containing several cohorts and three groups defined by their size (small, medium, and large) and by differences in maturation, growth, and life span. Several authors have indicated the possibility of such groups representing discrete genetic units even at level subspecies or species in statu nascendi. Genetic divergence was tested in samples from the Gulf of California (Mexico) and Peruvian Sea by estimation of population divergence statistics, an exact test of homogeneity of allele frequencies, analysis of molecular variance, and genealogical trees applied to data obtained with two molecular markers: RAPDs and mtDNA sequences identified by SSCPs. Neither significant values of θ (FST) nor significant heterogeneity in allele frequencies were detected. Lack of evidence does not imply complete lack of differentiation among the groups but supports the fact that a geographically spread population can have different size groups without relevant genetic differentiation, implying that the hypothetical genetically differentiated groups can occur in different ecological niches. [ABSTRACT FROM AUTHOR]

Abstract: The Humboldt squid is an important predator in the pelagic ecosystem of the central Gulf of California and the commercial catch of this species has increased over the past decade, probable due to a decrease of several top predators (sharks, large pelagic fish and the marine mammals) and the optimal feeding conditions in this area. Its high abundance and important position in the pelagic food web was quantified through two trophic models of the pelagic ecosystem of the central Gulf of California. Models represented conditions in 1980 and 2002, to document the decadal changes in ecosystem structure and function. The models were composed of 18 functional groups, including marine mammals, birds, fish, mollusks, crustaceans, and primary producers. Model results show direct negative effects on principal prey groups such as myctophids and pelagic red crab and positive effects on sharks, marine mammals and specifically sperm whales. It thus appears that the jumbo squid has an important role in the ecosystem and plays a central part in the overall energy flow as main food item for most top predators, and due to its predation of organisms on lower tropic levels. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

A regular seasonal pattern of periodicity was detected in monthly catch data for Dosidicus gigas during the most recent period of high abundance of the species off Chile. Monthly catch data covering from 2002 to 2005 were grouped into three large zones, and the trend of the time series was removed by using loess smoother. The residuals between the original and the loess trend curve were computed and analyzed using autocorrelation and cross-correlation at different lags, and a trigonometric model was fitted to detect seasonal oscillation. A coherent pattern in the short-term monthly residuals was observed in the three time series, revealing a similar underlying process in the catch data, with a six-month cycle. We postulate that the seasonal and interannual fluctuations observed in the catch records could be related to the reproductive success of the species through the average occurrence of two reproductive cycles per year, and hence the generation of two cohorts per year. [ABSTRACT FROM AUTHOR]

This study describes the population structure of jumbo squid (Dosidicus gigas) in the area of Santa Rosalía (central Gulf of California) during the years 2003 and 2004, and analyzes the interannual variability in the size structure over a wider time period, 1996–2004 (except 2000–2002). The results revealed clear differences in the size structure and sexual maturity of males and females between 2003 and 2004. The jumbo squid population observed during the 2003 fishing season showed a high proportion of large and sexually mature individuals, whereas most specimens sampled during 2004 were smaller and immature. Expanding our time period, we observed a strong interannual variability in the size structure of jumbo squid within the Gulf of California, which was also reflected in the size at maturity. These changes in the population structure seem to be related to the occurrence and intensity of El Niño events. We recommend taking this variability into account at the beginning of each fishing season when the authorities establish the management strategy for the jumbo squid fishery in the Gulf of California. [ABSTRACT FROM AUTHOR]

Abstract: The jumbo squid (Dosidicus gigas) supports important fisheries, with the maximum landings being recorded in Mexico, Peru and Chile. To evaluate genetic structure and to measure the impact of temporal variation, randomly amplified polymorphic DNA (RAPD) data were generated and analysed from 210 samples from eight eastern Pacific sites and on two sample sets taken from the same location in consecutive years. The temporal variation was shown to have no significant effect on genetic diversity. In addition, a genetic structure was detected which divided the populations into northern and southern locations. There was marginal isolation by distance between populations. Like in other ommastrephids, genetic structure is considered evidence of an adaptive radiation. [Copyright &y& Elsevier]

Abstract: Stomach contents were analysed for 292 medium size (<45cm mantle length) jumbo squid, Dosidicus gigas, caught in the Gulf of California and adjacent waters in 1998–2000. Diet varied by location and was dominated, in different places, by mesopelagic fishes as Benthosema panamense, Triphoturus mexicanus, and Vinciguerria lucetia. This general pattern of feeding on myctophids coincided with that for large size jumbo squid in 1995–1997. Pteropods, micronektonic squid, megalopae, and euphausiids were second in importance and some were consumed in larger amounts than in previous years. It is difficult to discern whether these differences in diet were due to a smaller squid size or to a change in the pelagic environment after the 1997–98 El Niño event. [Copyright &y& Elsevier]

The oocyte structure of jumbo squid (Dosidicus gigas) female gonads was analyzed to validate morphochromatic sexual maturation stages based on a six-phase scale. Samples were obtained fortnightly from the Santa Rosalia area, Baja California Sur, from June 2001 to November 2002. Histological preparations were obtained from each gonad to count the number of oocytes at each level of development. The frequency of oocytes at each level was then used to estimate a maturity index (MI) to assess the correspondence between morphochromatic maturation stages and the oocyte structure in the gonad tissue. The histological analysis showed that morphochromatic stages I, II and III were ruled by oocytes in developmental level 2 or less (i.e., secondary growth has not yet begun), and thus correspond to sexually immature juveniles. Stages IV, V and VI were ruled by oocytes in more advanced developmental levels and correspond to mature or maturing adults. According to the analysis of variance, the morphochromatic maturity scale allowed sexually immature individuals to be readily and reliably distinguished from mature ones. A detailed analysis of MI confidence intervals showed that each morphochromatic maturity stage had a specific oocyte structure, except for stages II and III, which presented morphological differences. [ABSTRACT FROM AUTHOR]