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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]

Abstract: The jumbo squid Dosidicus gigas supports an important fishery in the central region of the Gulf of California, Mexico. However, in recent years, landings of this species in the port of Guaymas, Sonora has declined significantly. We examined monthly landing records from January 1998 through March 2012 and related this record to monthly sea surface temperature (SST) and chlorophyll a from satellite imagery and coastal upwelling index (CUI) in the fishing area as proxies of inter-annual changes in the epipelagic habitat. Results indicate that jumbo squid catches were high between June 1999 and December 2004 (328,903t) associated with an extended period of prevailing cold SSTs (La Niña 1999) and high chlorophyll a concentrations with intense CUI. From January 2005 through March 2012, a progressive catches decrease; landings were about 31.8% of previous captures (104,829t). Decline is associated with a progressively warmer habitat with less chlorophyll a and considerably lower CUI. Six fishing surveys carried out into the central Gulf of California with jig sampling indicate that jumbo squid tend to be in regions with low SST and high chlorophyll a, confirming its association with cold and productive areas. [Copyright &y& Elsevier]

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: We report on the population dynamics of Dosidicus gigas off Guaymas from the 2002–2003 to 2007–2008 fishing seasons. The study was supported by the catch-at-length data of the commercial fleets. The results showed a large variation in recruitment because during some fishing seasons the recruitment was poor. This condition in the population may also be impacted by migration, a new distribution of jumbo squid in the eastern North Pacific, or the changes in the California current. We identified a pattern in the variability of recruitment. Warmer waters caused by the El Niño conditions in the California current are coincident with low recruitment. Cooler waters identified with negative anomalies in the sea surface temperature caused by La Niña were related to high recruitment. Our time-series showed a reduction in recruits and a fall in the mean biomass. For the jumbo squid fishery off Guaymas, recruitment determines trends of biomass over time. Our results also showed that for all fishing seasons the proportional escapement was between 59% and 89%, which was higher than the target level of 40%. Consequently, the harvest of jumbo squid is less than the optimum level. [ABSTRACT FROM AUTHOR]

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]

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]

This study describes the age and growth of large specimens of the jumbo squid Dosidicus gigas that supported the fishery in the Gulf of California in 1995–1997. Statoliths of 299 females (10.8–87.5 cm mantle length, ML) and 147 males (17–73.9 cm ML) were read.Assuming a daily rhythm of statolith deposition the smallest female (10.8 cm ML) was 84 days old and the largest (87.5 cm ML) 386 days old. The oldest females were 14–15 months old. The smallest male (17 cm ML) was 135 days old and the oldest male (71.5 cm ML) was 372 days old. The logistic model best described growth in jumbo squid. Growth curves were similar to those reported from other studies on this species using statolith reading. However, they suggest a faster growth than that described by size frequency analysis. No differences in growth were noted between seasons, except that females from Sta. Rosalia weighed more than those caught off Guaymas at the same age. Females grew faster than males, but both sexes grew more than 2 mm/day between 140th and 300th day of life: one of the highest absolute growth rates recorded so far for squids.Large size females mature late, at an age of 1 year and 73 cm ML and males matured at 10 months and 60 cm ML. Females of the medium-sized maturing group mature at 7 months and 37 cm ML and males at 7 months and 34 cm. Thus, this latter group was regarded as an early maturing group, living probably less than a year, and the former as a late maturing group, living a year or slightly more. Hatch dates were distributed throughout the whole year, without reflecting any reproductive pattern. Large jumbo squid in the Gulf of California comprised a population of multiple intra-annual cohorts using alternate upwelling seasonal areas during their growth. [Copyright &y& Elsevier]