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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]

Cephalopods are harvested in increasingly large quantities but understanding how to control and manage their stocks, and tracking the routes of the consumption that exploits them, lag behind what has been developed for exploiting finfish. This review attempts to redress the imbalance by considering the status of the major cephalopod stock species and the traceability of cephalopod seafood along the trade value chain. It begins with a general overview of the most important exploited cephalopods, their stock status and their market. Four major cephalopod resources are identified: the three squid species Todarodes pacificus, Dosidicus gigas and Illex argentinus; and one species of octopus, Octopus vulgaris. The techniques and problems of stock assessment (to assess sustainability) are reviewed briefly and the problems and possible solutions for assessing benthic stock such as those of octopuses are considered. An example of a stock well managed in the long term is presented to illustrate the value of careful monitoring and management: the squid Doryteuthis gahi available in Falkland Islands waters. Issues surrounding identification, mislabelling and illegal, unreported and unregulated (IUU) fishing are then reviewed, followed by a discussion of approaches and techniques of traceability as applied to cephalopods. Finally, some of the mobile apps currently available and in development for tracking seafood are compared. This review concludes with observations on the necessity for the strengthening and international coordination of legislation, and more rigorous standards for seafood labelling and for taxonomic curation of DNA sequences available in public databases for use in seafood identification. [ABSTRACT FROM AUTHOR]

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.

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]

El calamar diamante Thysanoteuthis rhombus Troschel, 1857 es un calamar oceánico circum-global, de tamaño grande y relativamente raro de encontrar; sin embargo, en algunas regiones de Asia tiene interés pesquero. Aquí reportamos el primer registro de juveniles de T. rhombus en el Golfo de Tehuantepec, Pacífico Tropical Nororiental, junto con juveniles de Dosidicus gigas (d’Orbigny, 1835) y datos oceanográficos asociados. Los calamares fueron colectados en la zona oceánica con surgencia y frente termohalino y nivel máximo de clorofila-a (5.5 µg/L), a diferencia de la zona nerítica que fue más salada, con mayor nivel relativo de oxígeno y menor nivel de clorofila-a.

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]

Dosidicus gigas (D. gigas) is a pelagic cephalopod of ecological and economic importance widely distributed in the eastern Pacific Ocean. Generally, small-, medium-, and large-sized groups of the squids have been respectively identified on the basis of the mantle length (ML) of adults. Intraspecific feeding variability maximizes the utilization of available food resources by D. gigas. However, the coexistence mechanism of three groups has not been fully understood yet. In our study, based on the analyses of beak morphology and stable carbon and nitrogen isotopes, the feeding strategies and coexistence patterns of large-, medium-, and small-sized groups of D. gigas were investigated. D. gigas had a wide range of 13C/12C (δ13C) and 15N/14N (δ15N) values in muscle tissue, variable feeding behaviors, and wide food sources. The δ13C or δ15N values showed no significant difference between the small- and medium-sized groups, which shared the same habitats and fed on preys with the similar trophic level. Compared to small- and medium-sized groups, the large-sized group had a smaller range of habitats and consumed more nearshore foods. Both isotopes and feeding apparatus morphology indicated a high degree of niche overlap between the small- and medium-sized groups, whereas the large-sized group differed significantly from other groups. In addition, the niche width of the female was larger than that of the male in all three groups. We inferred that the sex differences in body length and reproductive behavior led to the difference in niche width. The isotopic niche overlap between female and male samples was the most significant in large-sized group and the least significant in the small-sized group, indicating that different feeding strategies were adopted by the three groups. These findings proved that the three groups of D. gigas off Peruvian waters adopted a feeding strategy with inter- and intra-group regulation. This feeding strategy maximizes the use of food and habitat resources and ensures that different size groups can coexist in the same waters. [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]

Directed formation of the structure of the culture of living cells is the most important task of tissue engineering. New materials for 3D scaffolds of living tissue are critical for the mass adoption of regenerative medicine protocols. In this manuscript, we demonstrate the results of the molecular structure study of collagen from Dosidicus gigas and reveal the possibility of obtaining a thin membrane material. The collagen membrane is characterized by high flexibility and plasticity as well as mechanical strength. The technology of obtaining collagen scaffolds, as well as the results of studies of its mechanical properties, surface morphology, protein composition, and the process of cell proliferation on its surface, are shown in the given manuscript. The investigation of living tissue culture grown on the surface of a collagen scaffold by X-ray tomography on a synchrotron source made it possible to remodel the structure of the extracellular matrix. It was found that the scaffolds obtained from squid collagen are characterized by a high degree of fibril ordering and high surface roughness and provide efficient directed growth of the cell culture. The resulting material provides the formation of the extracellular matrix and is characterized by a short time to living tissue sorption. [ABSTRACT FROM AUTHOR]

Despite concerns about the environmental impact of microplastics (MPs), knowledge of MP contamination levels in pelagic squid is lacking. This study investigated the stomach of an ecologically and commercially important but poorly known squid species, the jumbo squid Dosidicus gigas, found in the tropical and Southern temperate Pacific. We examined the characteristics and spatial distribution of MPs in fifty D. gigas (16.0–37.8 cm mantle length) and assessed potential MP pollution risks. MPs were detected in 50.0% of specimens and had an average abundance of 0.88 ± 1.12 items/individual and 0.24 ± 0.36 items/g stomach weight, and were sized 58.42–2,944.85 μm. The MPs were dominated by polyethylene terephthalate (31.82%) in polymer type, fragments (54.55%) and fibers (43.18%) in shape, and blue (59.59%) in color. All specimens could be evaluated as low risk. No statistically significant correlations were found between the MP abundances and D. gigas stomach weight, stomach fullness index, distance from the coast, and mantle length. While regression analyses showed that fuller stomachs contained larger MPs. Spatial variations in shape and polymer composition suggest that low-density fibrous MPs could be easily transported offshore by upwelling and/or ocean currents. These results indicate intraspecific variation in D. gigas MP contaminants and underscore the need to assess the potential site-specific ecotoxicological consequences of increased plastic pollution to pelagic squid.

Abundance and distribution of jumbo flying squid (Dosidicus gigas) are evidently influenced by the changes of marine environment. In this study, the maximum entropy (MaxEnt) model was applied to examine the impacts of marine environmental variables on its potential distribution, and identified habitat hotspots of D. gigas in summer and autumn along the coast of Chile. The MaxEnt model was constructed by using the fisheries data of D. gigas from summer to autumn during 2011–2017 combined with critical environmental factors including mixed layer depth (MLD), sea surface salinity (SSS), sea surface height (SSH) and water temperature at depths of 0 m, 25 m, 50 m, 100 m, 150 m, 200 m, 300 m, 400 m and 500 m. Results showed that the actual fishing efforts of D. gigas in summer and autumn were mostly distributed in the suitable habitat, indicating that the MaxEnt model can well predict the habitat hotspots of D. gigas off Chile. The key environmental factors and their suitable ranges for D. gigas showed significant inter-monthly changes from December to May. The critical environmental factors of D. gigas off Chile were MLD, SSH, water temperature at different depths in summer (Temp_25m in December, Temp_300m in January and Temp_400m in February) and SSH, SSS, Temp_400m in autumn. Our findings suggest that selecting the key environmental factors is vital to study the potential distribution of D. gigas off Chile in each month to explore its habitat hotspots. [ABSTRACT FROM AUTHOR]

As a cephalopod with a short life cycle, the Dosidicus gigas (jumbo flying squid) is extremely sensitive to climate variability and marine environment changes in terms of individual growth and resource changes. Based on 7514 D. gigas samples collected off Peru from 2008 to 2020, the fishery biological characteristics such as size, sexual maturity, and size‐at‐maturity were analyzed to explore the impacts of climate variability on individual growth. The results showed that there were significant differences in the relationship between mantle length and body weight and in the composition of sexual maturity between male and female individuals in different years (P <.05). La Niña events were conducive to the individual growth of D. gigas and slowed down their sexual maturity, producing D. gigas groups in medium and large sizes; El Niño events inhibited the individual growth of D. gigas and accelerated their sexual maturity, producing D. gigas groups in a smaller size. From 2008 to 2020, the mantle length of the small‐size group decreased by 46 mm, while that of the medium‐size group increased by 28 mm. Size‐at‐maturity of female D. gigas decreased by 201.2 mm and that of male D. gigas decreased by 143 mm. The study concluded that the changes in the marine environment caused by climate variability from 2008 to 2020 have had a significant impact on the population structure, growth, and development of the D. gigas off Peru. [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.

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]

To compare the trophic ecologies of mother–offspring pairs of the jumbo squid (Dosidicus gigas), we examined carbon and nitrogen stable isotopes in the eye lens core and lens cortex from 18 D. gigas specimens collected from the equatorial waters of the eastern-central Pacific. Both δ13C and δ15N values in lens cores were smaller than in lens cortexes. Significant difference in δ13C between lens cores and lens cortexes suggested that maternal squid used different habitats as compared with their offspring. Higher variation of δ15N in offspring than maternal squid indicated that maternal squid have a more general feeding strategy than their offspring. The degree of fitting of the probability density distribution curves of δ13C and δ15N and the isotopic niches of mothers and their offspring indicate that these squid have a flexible feeding strategy and that mothers and daughters are spawning in different locations. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of temperature and time changes in two typical thermal processing procedures, frying and baking, on squid quality. Increasing the frying/baking temperature and prolonging the time significantly impacted color, L* value decreased over time, and a* value increased (P < 0.05). Total nitrogen, non-protein nitrogen, and cadaverine levels increased significantly after thermal process (P < 0.05), whereas histamine levels increased and subsequently reduced, which was attributed to the process of lipid oxidation. The concentration of pyrazine was dramatically increased (fried: 3.01 ∼ 1468.27 µg/kg; baked: 0.00 ∼ 836.14 µg/kg). The hierarchical cluster analysis was applied to analyze the complicated raw data of squid in order to evaluate the quality under different frying/baking conditions. Squid, whether fried or baked, took on a deeper color, contained more protein per unit weight, and tasted more desirable, although the histamine levels rose at certain temperatures as well. This study indicated the appropriate cooking methods and conditions could help to preserve nutrition while keeping histamine levels under control.

The synchronous response of the spatial distribution pattern of Dosidicus gigas and Trachurus murphyi habitat along the Chilean waters to different-intensity El Niño events was examined based on the habitat suitability index (HSI) models inclusive with the key environmental factors of sea surface height anomaly (SSHA), sea surface salinity (SSS), water temperature at 400-m depth (Temp_400 m) for D. gigas, sea surface temperature (SST), mixed layer depth (MLD), Temp_400 m for T. murphyi, and Niño 1 + 2 index. Results showed that all the environmental factors except MLD were significantly correlated with the Niño 1 + 2 index. Compared with weak (WE) and moderate (ME) El Niño events, the suitable range of SSHA and SSS for D. gigas decreased, resulting in a decreased suitable habitat area and increased poor habitat area during the strong (SE) El Niño years. In space, the suitable habitat of D. gigas was mainly distributed in north-central Chile with an east–west strip pattern; it decreased significantly in the northwestern waters off Chile and moved southwestward under SE El Niño events. For T. murphyi, the ME El Niño events yielded a contracted suitable range of water temperature and MLD decreased, consequently leading to a decreased suitable habitat area and increased poor habitat area of T. murphyi compared to WE and SE El Niño events. The suitable habitat of T. murphyi was mainly distributed in the 42°–47°S area and varied non-significantly during the WE and SE El Niño events; however, it clearly decreased in the southwest area of Chile and shifted northeastward under ME El Niño events. Our results indicated that El Niño events with different intensities strongly affected the habitat pattern of D. gigas and T. murphyi off Chile by changing the regional marine environment.

The sclerotised beaks of cephalopods have emerged as useful material to track their habitat and trophic ecology by using stable isotope analysis, because beaks grow continuously throughout their life without replacement. Here, stable isotopes of d13C and d15N in five continuous sections along the crest were measured to investigate the potential ontogenetic habitat shift and foragingecology change of Dosidicus gigas from the oceanic waters off Ecuador. In total, 90 sections from 18 upper beaks were examined with d13C values of -18.99 to -17.49‰ and d15N values of 0.69 to 7.09‰. Kruskal-Wallis test showed that there were significant differences in both isotopes between sections. The result of generalised additive models showed a significant overall decrease in both d13C and d15N values across the beak crest. The corrected standard ellipse area (SEAc) of the beak sections was 0.48 to 0.93‰2, with no high overlap between the two sections, with values ranging from 0.00 to 0.57. High individual variation of d15N values in most beak sections indicated that D. gigas in our study area appears to have a generalist food spectrum in most of its life history, except for the stage just before being captured. [ABSTRACT FROM AUTHOR]

Jumbo squid (Dosidicus gigas) plays an important role in food webs throughout the eastern Pacific; however, its trophic ecology is complex, because it is a highly migratory and opportunistic predator. In this study, δ13C and δ15N values were measured along the lateral wall of lower beak to investigate the ontogenetic and spatiotemporal feeding strategy shifts of jumbo squid, respectively. Both year and area had significant influences on δ13C (p < 0.01), while sex and stage had no significant influence on δ13C (p > 0.05). All explanatory variables (sex, stage, year, and area) had significant influences on δ15N (p < 0.05). The differences of niche among life stages indicated that the habitat and feeding habit were likely changed with the growth of individuals. Compared with normal years, the habitat of squids might change during the El Niño year. However, during the strong El Niño year, habitat location changed and niche size decreased compared to normal years. The trophic niche of D. gigas differed between different areas. Stable isotopes in early life stages were most effective for distinguishing different geographic populations. Females and males were likely to inhabit similar geographic areas throughout ontogeny. Unexpectedly, we found evidence to suggest females may have larger habitats and wider trophic niche than males. This study revealed the ontogenetic and spatiotemporal plasticity of habitat and feeding strategy of D. gigas.

ENSO‐driven concurrent habitat fluctuations of two economically important marine species jumbo squid Dosidicus gigas and jack mackerel Trachurus murphyi in the Southeast Pacific Ocean off Chile during 1950–2017 were examined using a habitat suitability index (HSI) modeling approach. The optimal HSI models sourced from 10 weighing‐based scenarios were developed, selected and validated using the crucial factors water temperature at 400 m depth (Temp_400m), sea surface height anomaly (SSHA) and sea surface salinity (SSS) for D. gigas and sea surface temperature (SST), Temp_400m, and mixed layer depth (MLD) for T. murphyi. Results suggested that the optimal HSI model could accurately predict the habitat hotspots for D. gigas and T. murphyi. The ENSO event (indicated by Niño 3.4 index, NI) was significantly related to environmental conditions off Chile. Cross‐correlation revealed positive relationships between NI and SST, SSHA, SSS, and Temp_400m and negative correlation between NI and MLD. Synchronous opposite habitat fluctuations were shown between D. gigas and T. murphyi under different ENSO events. The NI was significantly negatively related to the HSI of D. gigas and positively correlated with the HSI of T. murphyi. Comparing with the El Niño years, suitable habitats of D. gigas and T. murphyi dramatically enlarged and contracted, respectively, during the La Niña years. Both suitable habitats moved southwestward under this climate conditions. Our finding suggested that ENSO‐driven environmental changes played important roles in the concurrent habitat fluctuations of D. gigas and T. murphyi. Such studies are conducive to the effective utilization and management of multiple related species. [ABSTRACT FROM AUTHOR]

Neon flying squid (Ommastrephes bartramii) and jumbo flying squid (Dosidicus gigas) are two commercially essential oceanic squids in the Pacific Ocean. An in-depth understanding of the mechanisms of their annual and interannual abundance fluctuations under environmental and climate variabilities can ensure ration and suitable management. Thus, the annual and interannual abundance fluctuations of the stock of the western winter-spring cohort of O. bartramii and D. gigas off Peru Exclusive Economic Zone (PEEZ) waters and their association with habitat temperature variabilities are explored in this study based on the historical Chinese Squid-jigging fishery data from 2003 to 2020. The habitat temperature variabilities were defined as the effective principal components of the SST at the squids’ two important habitats (spawning and feeding ground) through life histories according to the principal component analysis. The Hodrick—Prescott filter analysis was conducted to quantify the annual and interannual fluctuations of abundance and habitat temperature variabilities. Furthermore, the generalized additive model (GAM) was employed to investigate their associations. The results demonstrated different but not synchronous trends of abundance for O. bartramii and D. gigas. Regarding O. bartramii, the interannual abundance first decreased (2003∼2013) and then increased (after 2014). For D. gigas, the interannual abundance kept decreasing within 2003∼2020. Their annual trends have presented large fluctuations over years. The results of GAM indicated that using habitat temperature variabilities only can trace the abundance trend of O. bartramii and D. gigas at an interannual but not annual scale. Further studies verified that Pacific Decadal Oscillation (PDO) is a crucial factor affecting the interannual abundance trend of these two squids through the habitat temperature variabilities. However, this study indicates that the habitat temperature variabilities not only are related to other large-scale factors, which are not investigated currently at an interannual scale, but also, are combined with other small- or middle-scale factors at an annual scale on their impacts to the abundance fluctuations of these two squids. Therefore, in order to better explain the mechanisms of annual and interannual abundance fluctuations of O. bartramii and D. gigas under environmental and climate variabilities, the importance of combining other potential factors into consideration is highlighted.

In this study, the eddy characteristics on the fishing ground of the Humboldt squid (Dosidicus gigas) in the eastern equatorial Pacific Ocean were detected based on geometrical characteristics with the flow field during April–June 2017. The influence of the eddies on the biophysical environment, D. gigas abundance, and habitat distribution were explored. The habitat was identified by fishery data, sea surface temperature (SST), vertical water temperature, and chlorophyll-a (Chl-a). Results indicated that the eddy lifetime was relatively short, with only three eddies persisting for more than 2 weeks. The number of eddies in each month showed a similar variability trend with the monthly average catch per unit effort (CPUE) of D. gigas. Two eddies were taken with a lifetime of above 2 weeks, which revealed that the environmental conditions around the eddies significantly changed. When the eddy persisted for 8–10 days, SST and vertical temperature gradually decreased, but Chl-a significantly increased. The habitat quality of D. gigas gradually increased, and the gravity center of the fishing ground was consistent with eddy movement. The eddy-induced Ekman pumping led to the transportation of deep waters with rich nutrients into the euphotic layer, promoted the reproduction of bait organisms, and yielded favorable water temperature conditions for D. gigas. These environmental changes aided the formation of high-quality habitats, which increase D. gigas abundance and catch and drive the shift of the gravity centers of fishing grounds with the eddy. Our findings suggested that eddy activities have significant impacts on D. gigas abundance and habitat distribution.

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]

An analysis was performed in this study to investigate synchronous fluctuations in abundance and distribution of Ommastrephes bartramii in the Northwest Pacific Ocean and Dosidicus gigas in the Southeast Pacific Ocean. The impacts of two Niño indices and regional water surface temperature on the two squids during 2006–2015 were evaluated, which possibly can explain the observed synchronicity. Catch per unit effort (CPUE) and the latitudinal gravity centers (LATG) of fishing effort were used to indicate squid abundance and distribution, respectively. The results indicated that both the CPUE and LATG showed highly interannual variations and synchronous fluctuation with significant negative associations between the two squid species from September to November. Strong positive cross-correlations with 2-month lag was found between sea surface temperature (SST) anomaly in the Niño 3.4 and Niño 1+2 regions, which have significant linkage with the SST on the fishing ground of O. bartramii and D. gigas, respectively. Moreover, the proportion of favorable-SST area (PFSST) and the latitudinal location of the optimal SST for O. bartramii and D. gigas were positively correlated with the CPUE and LATG, respectively. Increased O. bartramii PFSST clearly corresponded to decreased D. gigas PFSST in phase as well as the latitudinal location of the optimal SST from September to November over 2006–2015. Our findings suggest that synchronous changes in abundance and distribution of the two squids were due to simultaneous variations in the PFSST and the latitudinal location of the optimal SST front which were affected by the SSTA changes in the Niño 3.4 and Niño 1+2 regions. [ABSTRACT FROM AUTHOR]

The limitations that hypoxia imparts on mitochondrial oxygen supply are circumvented by the activation of anaerobic metabolism and prosurvival mechanisms in hypoxia-tolerant animals. To deal with the hypoxia that jumbo squid (Dosidicus gigas) experience in the ocean’s depth, they depress their metabolic rate by up to 52% relative to normoxic conditions. This is coupled with molecular reorganization to facilitate their daily descents into the ocean’s oxygen minimum zone, where they face not only low oxygen levels but also higher pressures and colder frigid waters. Our current study explores the tissue-specific hypoxia responses of three central processes: (1) antioxidant enzymes responsible for defending against oxidative stress, (2) early apoptotic machinery that signals the activation of cell death, and (3) mitogen-activated protein kinases (MAPKs) that act as central regulators of numerouscellular processes. LuminexxMAP technology was used to assess protein levels and phosphorylation states under normoxic and hypoxic conditions in brains, branchial hearts, and mantle muscles. Hypoxic brains were found to activate apoptosis via up-regulation of phospho-p38, phospho-p53, activated caspase 8, and activated caspase 9, whereas branchial hearts were the only tissue to show an increase in antioxidant enzyme levels. Hypoxic muscles seemed the least affected by hypoxia. Our results suggest that hypoxic squid do not undergo large dynamic changes in the phosphorylation states of key apoptotic and central MAPK factors, except for brains, suggesting that these mechanisms are involved in squid hypometabolic responses. [ABSTRACT FROM AUTHOR]

Dosidicus gigas (D. gigas) is a commercially important squid species in the Eastern Pacific Ocean. Due to the wide distribution of the species and its variable biological characteristics, there is a lack of reliable information regarding its genetic structure, which restricts the stock assessment and management of the D. gigas fishery resource. Therefore, there is an urgent need to develop sufficient molecular markers for the conservation and management of this species. In this study, 101 novel single nucleotide polymorphism (SNP) markers were developed using genotyping-by-sequencing (GBS). The observed heterozygosity (Ho) and expected heterozygosity (He) ranged from 0.0000 to 1.0000 and 0.0340 to 0.5000, respectively. The polymorphism information content ranged from 0.0333 to 0.3750. Twenty-five loci significantly deviated from the Hardy–Weinberg equilibrium after a Bonferroni correction (p < 0.001). These polymorphic SNPs will be useful for further population genetic analyses for D. gigas. [ABSTRACT FROM AUTHOR]

Commercially important pelagic squid such as jumbo squid Dosidicus gigas play a key role in energy and nutrient transfer in marine ecosystem. Geographic variations in the foraging strategy of D. gigas can provide valuable information on cephalopod trophic diversification and adaption to natural and anthropogenic impacts. Here, we used a novel combination of stable isotope (SI) and fatty acid (FA) analyses of muscle tissues and morphometric measurements of feeding apparatuses to evaluate spatial patterns of habitat and resource use of D. gigas collected from three main fishing grounds in the tropical and southern temperate Pacific Ocean. Results showed that the δ13C and δ15N values were different among geographic stocks within D. gigas, possibly because of site-specific dietary sources and isotopic baseline values. Spatial variabilities in FA profiles/biomarkers, combined with SI results, suggests two foraging patterns: utilization of resources mainly from oceanic food webs or from both neritic and oceanic food webs. This behavior likely promotes the site-specific trophic niche width, increases adaptation to inhabiting oceanographic conditions, and could be driven by differences in feeding apparatuses morphology, body size, and trophic position. These results emphasize the dietary flexibility of D. gigas and their important ecological roles in ecosystems as cross-biome trophic linkages. Trophic diversification of pelagic squid like D. gigas may have important implications for their population dynamics, ecological associations, and subsequent management.

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]

BACKGROUND Protein glycation by Maillard reaction is commonly used to improve the functional and bioactive properties of food proteins. It is also known that this glycation method can be accelerated by heat without the need for chemical reagents that could be harmful to health. In this study, glycoconjugates were obtained from a mixture of connective tissue proteins (CTP) from jumbo squid (Dosidicus gigas) and two different sugars, dextran (DEX; 10 kDa) and glucose (GLU), using protein‐to‐carbohydrate ratios of 1:2 and 1:3, in solution at 50 °C for 6 h. The glycation products were characterized by means of their physicochemical properties and cytotoxic effect. RESULTS: The intensity of the browning measured at A420nm and A294nm in glycoconjugates showed no significant difference (P < 0.05). CTP‐DEX (1:2) and CTP‐DEX (1:3) were those products with the greatest fluorescence related to the intermediate stage in the Maillard reaction, and also with the highest degree of glycation, which was confirmed using o‐phthaldialdehyde assay and Fourier transform infrared analysis. The values of cellular viability for CTP‐GLU (1:3), CTP‐DEX (1:2, 1:3) as well as CTP (0, 6 h) were around 92–103%. CONCLUSIONS: The operational parameters used in the glycation process achieved the formation of glycoconjugates from proteins of D. gigas, showing no cytotoxic effect on the HaCaT cell line. This research proposes an alternative for the modification of proteins and opens the way to future investigations regarding the bioactivity of these macromolecules to have applications for the use of byproducts in food science and technology. © 2020 Society of Chemical Industry [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]

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.

Ommastrephid squids are short-lived ecological opportunists and their recruitment is largely driven by the surrounding environment. While recent studies suggest that recruitment variability in several squid species can be partially explained by environmental variability derived from synoptic oceanographic data, assessment of ommastrephid stocks using environmental variability is rare. In thisstudy, we modified asurplus production model to incorporate environmental variability into the assessment of threeommastrephid squids (Ommastrephes bartramii in the northwest Pacific, Illex argentinus in the southwest Atlantic and Dosidicus gigas in the southwest Pacific). We assumed that the key environmental variables—suitable sea surface temperature on spawning grounds during the spawning seasons and feeding grounds during the feeding seasons—have effects on the carrying capacity and the instantaneous population growth rate, respectively, in the surplus production model. For each squid stock, the assessment model with environmental variability had the highest fitting accuracy and the lowest mean squared error and coefficient of variation, and the management reference points based on the optimal model were more precautionary. This study advances our understanding of the interactions between the environment and ommastrephid squid population dynamics and can therefore improve the management of these commercially valuable stocks with a short life cycle.

We quantified the δ13C and δ15N values in the lower beaks of Humboldt squid, Dosidicus gigas, collected from international waters off Costa Rica, Ecuador, Peru and Chile by Chinese squid jigging vessels during 2009, 2010 and 2013. There was a significant difference in the isotopic values among regions with the lowest value off Ecuador and the highest off Chile, which were interpreted as a function of trophic effects as well as baseline values. However, constant trophic level of D. gigas across its geographic range showed that spatial variation in the baseline of primary production is the main driver responsible for the observed geographic isotope variability. Inter-regional difference and intra-regional convergence of isotope values indicated squid off Costa Rica, Ecuador and Chile belong to different geographically segregated populations, which were previously proved by integrated population identifying method. In contrast, the higher variations in δ13C and δ15N values in a given size group suggest the squid off Peru move and forage in different places. Moreover, potential population exchange could be responsible for the overlap of the isotope values between the squid off Peru and off Chile. On the whole, the spatial difference in isotopic values of Humboldt squid beaks improves our understanding of potential geographic population connectivity and movement. [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]

The Humboldt squid Dosidicus gigas has a short life span, and environmental variability plays a significant role in regulating its population dynamics and distribution. An analysis of 1 096 samples of D. gigas collected by the Chinese commercial fishing vessels during 2013, 2014, and 2016 off the Peruvian Exclusive Economic Zone, was conducted to evaluate the impacts of El Niño events on the somatic condition of D. gigas. This study indicates that the slopes of all beak variables in relation to ML for females were greater than those of males during 2013, 2014, and 2016, and slopes of the upper crest length and the lower rostrum length significantly differed between females and males in 2013 (P <0.05). Variation in the slopes for beak variables among years was studied; no significant difference was observed (ANCOVA, P >0.05). The Fulton's condition coefficients (K) of females and males in 2013 and 2014 were significantly greater than those in 2016 (P < 0.01). The K values of females were greater than those of males in 2013, 2014, and 2016, and K values significantly differed between females and males in 2013. In normal years, the chlorophyll a (Chl a) concentration showed an N-shaped variability from January to December. However, in the El Niño period, it tended to weaken the upwelling coupled with warm and low Chl a concentration waters. We suggest that the poor somatic condition of D. gigas during the El Niño year was resulted from the low Chl a concentration in the waters, and the abundance of D. gigas would decrease due to the unfavourable environment and the lack of prey items in the El Niño year. [ABSTRACT FROM AUTHOR]

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]

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]

Abstract The giant squid (Dosidicus gigas) might be used as a raw material for a protein concentrate. However, it has been observed that colloidal systems formed from squid proteins have limited functionality. Therefore, several investigations have been done to improve the functional properties of squid proteins. Recently ultrasound has been considered a technology for improving the functional properties of proteins. For this reason and considering that jumbo squid is an important fishery in northwest Mexico, the purpose of this research was to determine the effect of sonication time on the main functional properties of proteins. Sonication at 20 kHz and 20% amplitude were used during 0, 30, 60, and 90 s for foam and emulsion evaluations, and for 0, 1, and 3 min to evaluate gelling capacity. The emulsifying activity index was the highest at 60 s, while the emulsion stability index was the best at 90 s. Foaming capacity was significantly higher at 60 and 90 s, while the foam stability was 100% for all treatments. Finally, the water holding capacity and the texture profile analysis of gels showed an improvement. [ABSTRACT FROM AUTHOR]

Stable isotopes (δ13C and δ15N) have been widely used to track cephalopod habitat, migration and trophic structure. In this study, we analyzed the δ13C and δ15N values in 245 Dosidicus gigas beaks collected during 2009-2010 and in 2013 off Peruvian Exclusive Economic Zone (EEZ) waters. High individual variation in beak stable isotopes was shown with values ranging from −19.4‰ to −15.8‰ for δ13C and from 5.0‰ to 15.1‰ for δ15N. A generalized additive model (GAM) showed that latitude, mantle length and distance to shelf break significantly described the isotope variation with deviance ranging from 16.6% in δ13C to 36.3% in δ15N. Large variability in beak δ13C values for a given size and sampling station indicated that D. gigas off the Peruvian EEZ waters migrate in different ways when they occupy a large range of habitats for their ontogeny. Low baseline δ15N values suggested that spatial changes in diet trophic level may be the main determinative factor in beak δ15N variation. We conclude that high variability in beak δ15N values for a given set of explanatory variables indicated that D. gigas is an opportunistic predator with highly diverse dietary habitats. This study further develops our knowledge of the life history of D. gigas in such a highly dynamic region. [ABSTRACT FROM AUTHOR]

Gelatines from three different jumbo squid (Dosidicus gigas) by-products (fins, arms, and skin) were compared based on their chemical and biochemical properties (amino acid composition, molecular weight distribution, and in vitro digestibility), antioxidant capacity (ABTS+ and ORAC assays) and effect on oxidative stress biomarkers (serum antioxidant capacity (TAC) and serum malondialdehyde levels (MDA)) in healthy rats. Gelatine from the skin showed the highest polar and imino amino acid contents and a higher proline hydroxylation degree. Gelatine β-component was not detected in either fins or arms. These differences may explain the higher in vitro digestibility and higher antioxidant capacity (before and after digestibility) of the skin gelatine. Fin gelatines decreased TAC-ORAC values. All obtained gelatines decreased the MDA levels. Jumbo squid gelatine, administered during feeding, may help decrease a breakdown product of spontaneous lipid peroxidation in serum.

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.