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Simple Summary: Loliolus spp., such as Loliolus beka (Sasaki, 1929) and Loliolus uyii (Wakiya and Ishikawa, 1921), represent a dominant fishing bycatch in the East China Sea. However, their seasonal–spatial distribution characteristics are unclear. Here, the generalized linear mixed-effects model sdmTMB was used to evaluate ways of handling merged distribution data for L. beka and L. uyii to predict the variation in their spatial distributions under different climate change scenarios. Model predictions were validated using cross-validation, while model performance was assessed using T-tests. We speculated that the range and density of both species will vary over time, with some areas in the mid-East China Sea becoming potential habitats. In addition, we assumed that individuals of both species in the northern survey area might migrate to the northern Yellow Sea and Bohai Sea to spawn, whereas those in the central and southern Yellow Sea might migrate to coastal areas. During autumn, newborn larvae in the northern survey area would migrate to the southern Yellow Sea, whereas those in the central and southern areas would gradually migrate to offshore areas, resulting in a distribution ranging from coastal sea areas to the central survey area. Thus, this study provides novel insights into modeling habitat distributions for data-limited species and theoretical support for adapting fisheries resource management to climate change. Global climate change profoundly impacts the East China Sea ecosystem and poses a major challenge to fishery management in this region. In addition, closely related species with low catches are often not distinguished in fishery production and relevant data are commonly merged in statistics and fishing logbooks, making it challenging to accurately predict their habitat distribution range. Here, merged fisheries-independent data of the closely related squid Loliolus beka (Sasaki, 1929) and Loliolus uyii (Wakiya and Ishikawa, 1921) were used to explore the construction and prediction performance of species distribution models. Data in 2018 to 2019 from the southern Yellow and East China Seas were used to identify the seasonal–spatial distribution characteristics of both species, revealing a boundary line at 29.00° N for L. uyii during the autumn, with the highest average individual weight occurring during the summer, with both larvae and juveniles occurring during the autumn. Thus, the life history of L. uyii can be divided into winter–spring nursery and summer–autumn spawning periods. L. beka showed a preference for inshore areas (15–60 m) during the summer and offshore areas (32.00–78.00 m) during the winter. High-value areas of both species included inshore areas of the southern Yellow and mid-East China Seas during the autumn, enlarging during the spring to include central areas of the survey region, before significantly decreasing during the summer. Therefore, this study provides both a novel perspective for modeling biological habitat distribution with limited data and a scientific basis for the adjustment of fishery resource management and conservation measures in the context of climate change. [ABSTRACT FROM AUTHOR]

We evaluated the feasibility of classifying ommastrephid and loliginid squid species by statolith shape analysis into fisheries management units or stocks. Statoliths of Illex coindetii (Verany, 1839) and Loligo forbesii (Steenstrup, 1856) were studied from multiple areas of the North East Atlantic and Northern Mediterranean Sea during 2021–2022. I. coindetii and L. forbesii individuals were categorized into multiple stocks across the areas studied. Stocks migrating between fishing areas as well as multiple stocks in the same area, as identified for L. forbesii in this study, need to be considered for sustainable fisheries management. [ABSTRACT FROM AUTHOR]

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Macroecological studies have primarily focused on investigating the relationships between body size and geographic distribution on large scales, including regional, continental, and even global levels. While the majority of these studies have been conducted on terrestrial species, a limited number of studies have been carried out on aquatic species, and even fewer have considered the importance of phylogeny in the observed patterns. Cephalopods provide a good model for examining these macroecological patterns due to their large geographic and bathymetric ranges, wide range of body sizes, as well as diverse fin sizes and shapes. In this study, we assess the relationships between mantle length, fin size, and hatchling size with the geographic and bathymetric distribution of 30 squid species from the worldwide distributed family Loliginidae. To test a macroecological hypothesis, we evaluated the phylogenetic signal and correlated evolution to assess the role of biological traits in squid distribution, using a molecular phylogeny based on two mitochondrial and one nuclear genes. Biological traits (mantle length and fin size) exhibit high phylogenetic signals, while distribution demonstrates low signal. The correlation analyses revealed the existence of a relationship between adult mantle length and fin size with geographic and bathymetric distribution, but not with hatchling size. The geographic distribution of loliginid squids evolved in relation to mantle length, where larger squids with large fins (e.g. Sepioteuthis) have wide distributions, while small-finned species (e.g. Pickfordiateuthis) have narrow distributions. This study paves the way for exploring similar relationships in other squid families or other marine swimming animals. [ABSTRACT FROM AUTHOR]

The study of marine food web models has increased during the last years, but input data of important groups such as cephalopods are missing sometimes which restricts the quality of the model results. Cephalopods feed on a variety of preys, ranging from small crustaceans to large commercially important fish species. In turn, they are taken by larger invertebrates, fish, cephalopods, marine mammals and seabirds, which emphasizes their important role in various marine food webs. Our study presents stomach content analyses of various cephalopod species from the North Sea and describes their general feeding trends. The results further support the inclusion of cephalopods as predators into food web models to increase our knowledge of the North Sea ecosystem and to improve its management. Our data in combination with observed increasing biomasses of North Sea cephalopods suggest that the impact of cephalopods in the North Sea food web has increased and that large-sized cephalopods have become more important as predators for commercially exploited fish species during recent years. [ABSTRACT FROM AUTHOR]

Uroteuthis duvaucelii (D' Orbigny, 1835) also known as the Indian Ocean Squid is a highly important commercial marine organism along the Java coast, Indonesia. Based on genetic variation this species-complex are polymorphic and cryptic. In the present study, the genetic diversity and stock structure of loliginid squid U. duvaucelii is investigated using a mitochondrial gene cytochrome oxidase subunit I (COI). Samples were collected by hand-jigging onboard of an 8hp small fisher-boat equipped with a few lamps during May to August 2015, May 2016 and August to November 2018. Sample collection started at dusk until midnight. The attractor was a weighed-quill attached to nylon string, manually immersed into the water and pulled quickly and continuously for about 3-5 minutes at each effort. The determination was conducted with BLAST. Phylogenetic analysis showed two separate clusters with 100% bootstrap value, in which cluster II from Palabuhanratu has divergences of 5.9 - 7.0%, compared to cluster I. Genetic variations exist within and among individuals over the locations. Palabuhanratu individuals have the highest polymorphism levels compared to other locations as shown by 40 segregating sites (S). Frequencies of A, C, G, and T in mtDNA of the 20 specimens U. duvaucelii are biased toward A and T, with T being the most favoured and G being the least favoured nucleotide. All specimen showed no amino acid frequency for glutamic acid and all four individuals in cluster II (south coast) also have no amino acid frequencies for aspartic acid and valine as well. [ABSTRACT FROM AUTHOR]

The first well‐preserved soft‐body imprint of a fossil squid was discovered from the Lower Oligocene of the Krasnodar region, Russia. The squid is perfectly preserved, with many details of its body available for study, such as imprints of eyes and head, a pair of statoliths, jaws, and stomach contents. Statoliths of this squid are the first finds of in situ statoliths in fossil non‐belemnoid coleoids, and their shape is characteristic of the genus Loligo (family Loliginidae). Although some Mesozoic coleoids were previously classified as teuthids, these finds remain controversial and the squid described herein is the first unquestionable representative of fossil Teuthida known to date. It should be noted that the squid is preserved not due to phosphatization, which is typical for fossil coleoids, but by pyritization and carbonization. Numerous fish remains in the stomach contents of the squid indicate its piscivorous diet. A small cutlassfish Anenchelum angustum, which was buried together with the squid and whose bones are located near the squid's jaws, sheds light on the circumstances of the death of this animal. Most likely, the squid suffocated in the anoxic bottom waters, where it drowned along with its last prey (distraction sinking). [ABSTRACT FROM AUTHOR]

The biological aspects size, weight, and reproductive indicators of the Panama brief squid were analyzed. A total of 2,354 individuals caught during 7 exploratory fishing cruises and 5 sampling events in bays in the Gulf of California from 2014 to 2017 were studied. The individuals were grouped by system: coastal fronts (fishing cruises for Jumbo squid, Shrimp, Hake, and Small pelagics) and coastal lagoons (Agiabampo, Yavaros, Tóbari, Lobos, and Las Guásimas Bays). In the coastal fronts 1,687 individuals were sampled (44.2% females, 25.7% males, and 30.1% unsexed), and in the coastal lagoons 667 individuals (59.7% females, 36.7% males, and 3.6% unsexed), with females being the most abundant in both ecosystems. Females were most abundant in sizes >60 mm mantle length (ML), while males were most abundant in sizes <60 mm ML. Negative allometric growth was evidenced for both sexes (b = 2.59). Mean size at first maturity (LM50) showed that females matured at larger sizes than males, and the frequency of gonad development stages by system showed that the immature stages were the most frequent in both sexes. The sex ratio was 1.7F:1.0M. According to our results, the Panama brief squid inhabits both systems, the coastal fronts and the lagoons, with mature males using coastal lagoons to pass sperm packets to immature females during mating and females then moving to coastal fronts to mature and spawn. [ABSTRACT FROM AUTHOR]

Identification of squids in the family Loliginidae is a time-consuming exercise because of the highly overlapping distributions of species and their overall similarity (fin shape and size, sucker ring dentition, and color). Identifying squid based on statolith morphology is considered more accurate than identifying species based on beaks or gladius morphology. We report and compare the statolith shape of five commercially Loliginidae squid (Uroteuthis (Photololigo) duvaucelii, U. edulis, U. chinensis, Loliolus beka, L. japonica) to determine how well these structures discriminate species. Based on statolith morphology, variation in the lateral and dorsal domes enables an 84.8% success rate at classifying species. Environmental factors correlate with statolith shape, and for vertically migrating squid, statolith relative size decreases with increased depth of habitation. Statolith morphology can be used to effectively and accurately identify species of Loliginidae squid occurring in Chinese waters, and may prove valuable for identifying and managing squid resources. [ABSTRACT FROM AUTHOR]

Heterogeneous environmental conditions along the Humboldt Current System (HCS) influence the life-history strategy of a variety of species in different ways. There is limited information on latitudinal traits of coastal cephalopods as part of the interacting species in pelagic and benthic environments. The present study used the loliginid squid Doryteuthis gahi as a model organism to: (1) evaluate latitudinal traits on egg laying patterns, (2) characterize a particular spawning ground, (3) quantify the isotopic variation from different tissues, (4) evaluate potential trophic ontogenetic changes, (5) determinate trophic position, and (6) isotopically estimate the relative importance of putative preys in the squid’s assimilated diet. Results evidenced that egg-masses collected between 2014 and 2020 presented similar patterns along northern-central Chile (27–36°S), with females attaching small egg-capsules (10–50 mm length) through the year and over a variety of anthropogenic and natural substrates. At a small scale (Coquimbo; 29°S), early life history traits showed distinct patterns depending on SST, with warmer collection periods (∼18°C) evidencing larger capsules and smaller embryos, although small paralarvae were obtained over the 4-year sampling period. In this site, sampling of older ontogenetic stages supported the constant presence of small-sized squids (19–77 mm ML). Males had larger mean sizes compared to females and undetermined specimens, with a high proportion of mature stages. Observations in captivity were extended for up to 110 d, validating that small females (45–64 mm ML) spawn the small egg-capsules typically observed in the field. Differences in stable isotope composition between beaks and soft tissues of adult squids were lower for δ13C values (1.1 vs. 1.4‰, respectively) and higher for δ15N values (5.3 vs. 4.7‰, respectively). Isotopic composition through ontogeny found similar δ13C and δ15N values, suggesting that carbon sources (pelagic origin) and trophic position did not change significantly, with copepods, euphausiids and nereid polychaetes being the most important preys. This study unveils the permanent occurrence of a small reproductive morphotype of D. gahi in shallow coastal habitats of northern-central Chile (i.e., center of the distribution range), providing the first insights for understanding the species’ potential adaptations to heterogeneous conditions in the HCS and the unexplored distribution gap between the two centers of abundance (Peru and the Falkland/Malvinas islands).

The length–weight relationship and the condition factor are key parameters in stock assessment. Despite the fisheries potential loliginid squids have in Mexico, the group is scarcely known and no formal management has been implemented. A total of 1,105 squids captured on the Pacific and Atlantic coasts of Mexico were measured to estimate length–weight relations and condition factors. Except for Lolliguncula brevis and Lolliguncula argus, all species showed negative allometric growth. The 2 species with isometric growth showed a poor condition, according to Fulton’s condition factor, and the rest of the species were in good health, according to the relative condition factor. The type of growth exhibited by the species identified in this study could be associated with their swimming habits or otherwise be affected by the same variables that determine the type of growth of other squid found in Mexican waters. The parameters evaluated in this research are now available for incorporation in further fishery stock assessment models for loliginid squids.

Loliginid squids provide a unique model system to explore male alternative reproductive tactics (ARTs) and their linkage to size, behavioral decision making, and possibly age. Large individuals fight one another and the winners form temporary consortships with females, while smaller individuals do not engage in male-male agonistic bouts but use various sneaker tactics to obtain matings, each with varying mating and fertilization success. There is substantial behavioral flexibility in most species, as smaller males can facultatively switch to the alternative consort behaviors as the behavioral context changes. These forms of ARTs can involve different: mating posture; site of spermatophore deposition; fertilization success; and sperm traits. Most of the traits of male dimorphism (both anatomical and behavioral) are consistent with traditional sexual selection theory, while others have unique features that may have evolved in response to the fertilization environment faced by each temporary or permanent male morph. [ABSTRACT FROM AUTHOR]

During two sampling trips carried out over the continental platform of Gulf of Tehuantepec, a total of 101 Lolliguncula panamensis Berry, 1911 were caught. Thirty mature specimens (19 females and 11 males) were found to have unusually short arms. Dorsal mantle length, arm's length, and body weight were measured from the fresh specimens. Evidence of regeneration was observed at different points along arms; these may have been the result of partial autonomies. In the injured arms, the surface of the arm's tip was wholly covered with skin. Fracture planes were found in our histological sections; the autotomized arms exhibited constricted muscle fibers in the longitudinal sections indicative of wound closing. The arms of the specimens observed were very similar to the regenerating arms of other squids. This study represents the first to report arms regeneration and hectocotylus in this squid wild-caught. These results suggest that Lolliguncula panamensis exhibit partial autotomy, and the ability to regenerate the arms. Additionally, each of the eight arms can do so, presumably during defensive interaction or mating. [ABSTRACT FROM AUTHOR]

The grass squid Pickfordiateuthis vossi Brakoniecki, 1996 is a dwarf species distributed along the northwest coast of Mexico. In the eastern Pacific, little is known about its distribution and life cycle. Two specimens, which are considered the smallest individuals of the genus collected to date, were caught in zooplankton trawls during 2 oceanographic cruises (January and March 1998) carried out in the central Mexican Pacific. The paralarval and juvenile stages are described and represent a new record in the area, with a range extension of 600 km southwest from the nearest previous record. [ABSTRACT FROM AUTHOR]

Loliginidae includes many economically important species in trophic systems worldwide. Here, we investigated genetic relationships and diversity in this family. Sequence comparisons and phylogenetic analyses revealed considerable variations between mitochondrial 16 S rRNA gene and cytochrome coxidase subunit I gene among nine Loliginid species. We identified three similar non-coding regions in eight Loliginid species, but not in Sepioteuthislessoniana. We detected a single extended termination-associated sequence and three conserved sequence blocks among these eight species. Our results suggest that Loliginidae forms a major lineage, with S. lessoniana located at the most basal position and forming an individual clade as sister to the remaining species. Loligobeka, Loliolusjaponica, Loliolusuyii, Loligochinensis, Loligoedulis, Loligoduvauceli, Loligobleekeri, and Loligoopalescensare clustered into a monophyletic group. We identified repetitive elements and repeat numbers in the control regions. [ABSTRACT FROM AUTHOR]

Indian squid, Uroteuthis (Photololigo) duvaucelii (Loliginidae) constitute an important component of the inshore cephalopod fisheries along the eastern Arabian Sea. Local environmental variation plays an important role in species-environment interactions in neritic squids, which inhabit nearshore/coastal waters. Such ‘active’ and ‘passive’ responses of squids to environmental changes is crucial in understanding their relationships and influence on the biological processes, distribution and abundance of the fast-growing short-lived coastal loliginids. The empirical relationship between squid abundance and the variability in rainfall and sea surface temperature (SST) were explored in a tropical monsoon fishery. Monthly catch rates (catch per fishing hour) of squids in commercial trawl during 1987-2009 were used as the abundance index. Linear regression models with ARIMA errors were fitted with catch per unit hour time series as dependent variable and rainfall and SST as exogenous variables. While rainfall was observed to have a negative effect on squid abundance, the SST recorded a positive impact. ARIMA models provided satisfactory fit to observed data and forecast of 22 months. Given that the squid life-cycle is a function of their environment, this result is relevant in forecasting squid biomass for the management of tropical monsoon fisheries. [ABSTRACT FROM AUTHOR]

Eye lens of 196 Loligo vulgaris and 205 Loligo forbesii collected by trawl surveys from 2013 to 2015 in Sardinian waters (Mediterranean Sea) were analysed for age determination. In an alternative to the technique previously used in Sepia officinalis and Enteroctopus megalocyatus, in this study, we proposed the elimination of decalcification and dehydration steps to reduce the time of lens processing. In addition, lenses were included in epoxy resin, which was then subject to lapping, to ensure clear reading and counting of the increments. The number of increments counted in L. vulgaris (59–520) and in L. forbesii (51–543) was strongly related to mantle length and weight of the animals, with no statistical differences between the sexes. Assuming daily growth increments, L. vulgaris was estimated to have a life span of 17 months for males and 14 months for females, while L. forbesii males had an estimated life span of 18 and 16.5 months for females. The exponential model was the best fit for growth data for both species and sexes, showing higher growth for males in comparison with females. These results preliminarily indicate that the eye lens is a valid tool for age determination of the two Loliginidae species, but it would benefit from validation by additional studies. [ABSTRACT FROM AUTHOR]

The family Loliginidae is a diverse and economically valuable group of cephalopods. To investigate the evolution of their mitochondrial genomes, we characterized and compared these genomes among nine species, six newly sequenced. In all nine species, mitochondrial genomes followed the typical invertebrate canonical organization with 13 protein-coding genes, 22 tRNAs, and two rRNAs. However, different from the vertebrates, there were three non-coding control regions for most of the loliginid species. As for the gene arrangement and organization, the mitochondrial genome of Sepioteuthis lessoniana is totally different from the other eight species—there is only one control region, but 25 tRNAs. We analyzed the level of selective pressures imposed on different protein-coding genes, and found that stabilizing selection is strongest on cytb. We then tested the phylogenetic utility of this new mitochondrial genome data using 13 protein-coding genes and the results showed that Loliginidae is divided into two major lineages, with S. lessoniana sister to a clade comprising the remaining species. Loliolus beka, Loliolus japonica, Loliolus uyii, Uroteuthis chinensis, Uroteuthis edulis, Uroteuthis duvauceli, Heterololigo bleekeri, and Doryteuthis opalescens were recovered as a monophyletic group. [ABSTRACT FROM AUTHOR]

The biology and ecology of southwestern Atlantic loliginid squids have been intensively researched in the last few decades, mostly off the Brazilian southern coast. However, information gathered by scientific research cruisers, either past or recent, is limited. Three species of loliginid squids - the warm-tempered Doryteuthis sanpaulensis (Brakoniecki, 1984), plus the tropical D. pleii (Blainville, 1823) and Lolliguncula brevis (Blainville, 1823) - were sampled along 16 degrees of latitude on the southwestern Atlantic (22-38°S). The samples were obtained mostly from oceanographic surveys, but also included squids caught by commercial fisheries, and a few specimens from museum collections. Squid response to abiotic variables, morphological variation and circadian behaviour were surveyed in detail. Doryteuthis sanpaulensis can be divided into at least six distinguishable geographical groups, which do not form a cline. In contrast, D. pleii can be divided into only two morphological groups that are very similar. Doryteuthis spp. were heterogeneously distributed on the shelf, whereas L. brevis was confined nearshore. Our data extended the southernmost distribution range of D. pleii by at least nine degrees of latitude, owing to specimens obtained at ~38°S (Mar del Plata, Argentina). Small, immature D. sanpaulensis were sampled inside the Patos Lagoon estuary (~32°S). The morphologically similar Doryteuthis spp. apparently avoid direct competition by concentrating at different depths, displaying different thermal preferences, and inverse circadian levels of activity. The information reported herein may be regarded as a "snapshot" of the ecology of sympatric squids in a marine environment that has not been deeply affected by climate change. [ABSTRACT FROM AUTHOR]

Loliginid squids constitute marine resources of increasing importance in shelf ecosystems off the coast of South Brazil. However, the existing information and knowledge about the occurrence of early-life stages and causes of distributional patterns are insufficient. Here, we have revisited Brazilian historical plankton samples obtained from 11 oceanographic surveys to identify paralarvae and their abundances over time. The study area and time period cover the region between Cabo de São Tomé (22°S) and Cananéia (25°S) at depths down to 200 m from 1991 to 2005. Of the 246 paralarvae quantified, ~50% were identified to the genus or species level, including Doryteuthis spp. ( D. sanpaulensis and D. plei), Lolliguncula brevis and a single specimen of Pickfordiateuthis pulchella. Paralarval occurrence and abundance peaked in different areas and were associated with distinct oceanographic conditions: D. sanpaulensis occurred in the northern region associated with cold waters and upwelling events, D. plei occurred primarily in the southern region of the study area and in warmer waters, and L. brevis was found in shallow and low salinity waters in the estuarine region off the coast of Santos. Overall, the highest abundance of paralarvae occurred in the nearshore, northernmost areas during summer, and this can be associated with the observed retention mechanisms caused by local circulation, seasonal upwelling, the intrusion of nutrient-rich waters, and spawning peaks. The present study provides new information and evidence for loliginid patterns in the area that may potentially be useful for better understanding the recruitment patterns and fishery assessments of squid populations. [ABSTRACT FROM AUTHOR]

The Mediterranean subpopulation of common dolphin ( Delphinus delphis) is classified as endangered by the IUCN. Still, information about their diet in the Mediterranean is scarce. Stomach contents of 37 common dolphins stranded in the Alboran Sea and Strait of Gibraltar were analyzed. A total of 13,634 individual prey of 28 different taxa were identified. For fish, Myctophidae was the most important family as indicated by the highest index of relative importance ( IRI = 8,470), followed by the family Sparidae ( IRI = 609). The most important Myctophidae species was Madeira lantern fish ( Ceratoscopelus maderensis) and for Sparids, the bogue ( Boops boops). Cephalopods, instead, were found in low quantities only with 31 prey from the Loliginidae, Ommastrephidae, and Sepiolidae families. Overall, our results indicate that common dolphins are mainly piscivorous (99.77% N, 94.59% O, 99.73% W), feeding mostly on mesopelagic prey. Although common dolphins inhabit mainly coastal waters in the study area, the narrow continental shelf seems to facilitate the availability of Myctophids and other members of the mesopelagic assemblage to dolphins when the assemblage migrates to the surface at night. Our results represent the first attempt at quantifying the diet of this predator in the Alboran Sea and Strait of Gibraltar. [ABSTRACT FROM AUTHOR]

Chitin is the second most abundant polysaccharide in biomass after cellulose and the term chitosan usually refers to a family of polymers obtained after chitin deacetylation. The aim of this work was the preparation and the characterization of chitin and chitosan from the gladius (pen) of the European squid ( Loligo vulgaris ). A high level of deproteinization (more than 80%) was recorded using Alcalase ® with an enzyme/protein ratio of 10 U/mg. The demineralization of the gladius was completely achieved within 8 h at room temperature in HCl. 13 C NMR, FTIR, and XRD diffractograms of prepared chitin and chitosan were taken and then degree of deacetylation of chitosan was calculated using 13 C CP/MAS-NMR Spectroscopic. Further, in vitro antioxidant capacity of chitosan was evaluated on 1,1-diphenyl-2-picrylhydrazyl method (IC 50 = 3.2 mg mL −1 ) and the β-carotene bleaching assay (IC 50 = 3.3 mg mL −1 ). Antimicrobial activity was also investigated and assays indicated that prepared chitosan exhibited marked inhibitory activity against all microbial strains tested. Additionally, chitosan was tested such as clarifying agent for apple juice and showed powerful clarification capability, without affecting nutritional value. Furthermore, the results suggested that prepared chitosan could be used as alternative additive in pharmaceutical preparations and food industry. [ABSTRACT FROM AUTHOR]

This study was carried out to assess the distribution pattern of two loliginid squid species; Uroteuthis (Photololigo) chinensis (Gray 1849) and Uroteuthis (Photololigo) duvaucelii (d'Orbigny 1835) at different depth contours along the lower part of the Gulf of Thailand sampled by bottom trawl during April to July 2015. Hydrological parameters including temperature, salinity, pH, dissolved oxygen, conductivity and transparency were simultaneously measured. The average abundance, weight and density for U. (P.) chinensis were 32.7±37.9 individuals.hr-1, 2.1±1.7 kg.hr-1 and 1,268.8±1,370.3 individuals.nm-2 and for U. (P.) duvaucelii were 13.6±17.3 individuals.hr-1, 0.3±0.3 kg.hr-1 and 554.5±755.0 individuals.nm-2, respectively. It was found that depth affected both weight and density of both species combined (ANOVA, p < 0.05) and U. (P.) chinensis (ANOVA, p < 0.05) but not for U. (P.) duvaucelii. This study addresses the lack of scientific information on the species, serves to provide fundamental scientific data for their proper management and provides a reliable reference for the advancement of science. [ABSTRACT FROM AUTHOR]

The hard tissues of squid can provide important information for species identification. In this study, we used statolith and beak to identify three squid species including Uroteuthis duvaucelii, Loliolus beka, and U. edulis in the South China Sea. Because of the highly overlapping habitat and similar body morphology of the three squid species, we explored four different ways to identify them, by using statolith, upper beak, lower beak and a combination of statolith and beak. An outline geometric morphometric method and stepwise discriminant analysis were used to evaluate the most suitable method for the identification. We found that the combination of statolith and beak had the highest cross validation rate that was 75.0%, 87.5% and 88.7% for U. duvaucelii, L. beka and U. edulis, respectively. Using two beaks had similar results and the lowest cross validation rate was 60.0%, 50.0%, and 73.7% for the upper beak, 46.9%, 58.5% and 75.3% for the lower beak of U. duvaucelii, L. beka and U. edulis, respectively. Analyzing with the statolith had moderate cross validation which was 72.2%, 80.0%, and 87.7% for U. duvaucelii, L. beka and U. edulis, respectively. From the results it is suggested when the entire body of a squid is available, a combination of statolith and beak should be used for the identification. When only one hard tissue is available, species identification can be subjected to large errors. [ABSTRACT FROM AUTHOR]

The high mortality of cephalopod early stages is the main bottleneck to grow them from paralarvae to adults in culture conditions, probably because the inadequacy of the diet that results in malnutrition. Since visual analysis of digestive tract contents of paralarvae provides little evidence of diet composition, the use of molecular tools, particularly next generation sequencing (NGS) platforms, offers an alternative to understand prey preferences and nutrient requirements of wild paralarvae. In this work, we aimed to determine the diet of paralarvae of the loliginid squid Alloteuthis media and to enhance the knowledge of the diet of recently hatched Octopus vulgaris paralarvae collected in different areas and seasons in an upwelling area (NW Spain). DNA from the dissected digestive glands of 32 A.media and 64 O. vulgaris paralarvae was amplified with universal primers for the mitochondrial gene COI, and specific primers targeting the mitochondrial gene 16S gene of arthropods and the mitochondrial gene 16S of Chordata. Following high-throughput DNA sequencing with the MiSeq run (Illumina), up to 4,124,464 reads were obtained and 234,090 reads of prey were successfully identified in 96.87 and 81.25% of octopus and squid paralarvae, respectively. Overall, we identified 122 Molecular Taxonomic Units (MOTUs) belonging to several taxa of decapods, copepods, euphausiids, amphipods, echinoderms, molluscs, and hydroids. Redundancy analysis (RDA) showed seasonal and spatial variability in the diet of O. vulgaris and spatial variability in A.media diet. General AdditiveModels (GAM) of themost frequently detected prey families of O. vulgaris revealed seasonal variability of the presence of copepods (family Paracalanidae) and ophiuroids (family Euryalidae), spatial variability in presence of crabs (family Pilumnidae) and preference in small individual octopus paralarvae for cladocerans (family Sididae) and ophiuroids. No statistically significant variation in the occurrences of the most frequently identified families was revealed in A. media. Overall, these results provide new clues about dietary preferences of wild cephalopod paralarvae, thus opening up new scenarios for research on trophic ecology and digestive physiology under controlled conditions. [ABSTRACT FROM AUTHOR]

We describe the morphology of egg masses and hatchlings of the squid, Lolliguncula diomedeae (Hoyle, 1904) based on individuals hatched in the laboratory from two egg masses collected in the Gulf of California near Santa Rosalía, Baja California Sur, Mexico, and identified with molecular techniques. The characteristics of the egg mass are described and compared with other related species. Gross morphology, chromatophore pattern and the arrangement of arm and tentacle suckers of hatchlings are described. Among squids in the family Loliginidae, hatchlings of this species represent the second smallest described to date. The morphology of egg masses and paralarvae of related and sympatric species are compared, providing a tool for identification that may foster the understanding of the population dynamics and life history of this species. [ABSTRACT FROM AUTHOR]

Guanabara Bay is one of the most polluted bays in Brazil, although it supports some fisheries resources, among which are three species of loliginid squids:Lolliguncula brevis,Doryteuthis plei, andDoryteuthis sanpaulensis. This study aimed to assess the temporal and spatial variations of squids in the bay, relating their abundance variation to local environmental factors. We also aimed to characterize the population structure of squids, in order to establish their degree of occupancy in this estuarine system. Ten fortnightly hauls were carried out (two per area) from July 2005 to June 2007. Squids were identified, measured, weighed, sexed and classified according to maturity stage. The spatial distribution of the three species was not uniform; most individuals were found near the mouth of the bay. Abundances were significantly different among seasons due to the presence of SACW (South Atlantic Central Water) during the spring–summer season. Most of the populations of the three species consist of juveniles, and most adultDoryteuthiswere also immature, which reinforces the role of Guanabara Bay as a nursery ground for loliginid squids. Concerning the degree of occupancy of squids in Guanabara Bay,L. brevisis considered an estuarine resident,D. pleiuses the estuarine system as a nursery area for feeding and growth, and juveniles ofD. sanpaulensisenter the bay with the flood tide to feed, generally following the SACW intrusion. This is the first study on squids in this estuarine system, which despite the high degree of environmental impact is shown to be an important area for the loliginid species. [ABSTRACT FROM AUTHOR]

Seven specimens of Lolliguncula (Lolliguncula) argus, were collected in the shrimp fisheries of the Gulf of California and five specimens from the western coast of Baja California Peninsula, deposited in the Santa Barbara Museum of Natural History (USA), are examined and reported. These records expand species geographic distribution range for approximately 950 km and report the maximum size of mantle length 38.8 mm for males and 60.8 mm for females. Morphometric data of the 12 collected specimens are presented, and species funnel organ and statoliths are described.

Morphological and morphometric variability of the small-sized coastal squid Lolliguncula brevis was assessed along the largest part of its latitudinal range in the southern hemisphere, off the Brazilian coast (8º S - 27º S). A general homogeneity in form was found throughout the entire latitudinal range. In terms of body proportions, no latitudinal gradients were evident, but a few local "morphotypes" could be distinguished. The distinctive egg mass morphology, and size and form features, including a hectocotylus 20-40% longer than the opposing ventral arm and the presence of suckers on the buccal membrane, indicated that Lolliguncula from northern and southern hemispheres might comprise two different taxa.A variabilidade morfológica e morfométrica do pequeno loliginídeo costeiro Lolliguncula brevis foi avaliada ao longo da maior parte de sua amplitude latitudinal no hemisfério sul, ao longo da costa brasileira (8º S - 27º S). Uma homogeneidade na forma foi observada em toda sua área de ocorrência. Em termos de proporções corporais, não foram observados gradientes latitudinais evidentes, mas alguns "morfotipos" locais puderam ser distinguidos. O tamanho e as formas características, incluindo a presença de ventosas na membrana bucal, hectocótilo cerca de 20-40% maior do que o braço oposto ventral e a distinta morfologia da massa dos ovos sugerem que Lolliguncula ocorrentes no hemisférios norte e sul devam pertencer a táxons diferentes.

According to the vicariant hypothesis proposed by Brakoniecki (1986) the closure of the Sea of Tethys and the opening of the Atlantic Ocean would play an important role in the history of squids of the family Loliginidae, which is reflected in its current neritic distribution. Our study evaluated this hypothesis and alternative ideas to understand the historical biogeography of loliginid squids. This work is based on a phylogenetic hypothesis rebuilt with mitochondrial and nuclear sequences that incorporates the estimation of divergence times and ancestral distribution. Our results sustain that the squids of the family Loliginidae would have originated in the Western Pacific during the Late Paleocene about 59 My, following, during their diversification, at least 20 dispersion and 6 vicariant events. The first vicariant event fragments the ancestral distribution, remaining the ancestor of Sepioteuthis in the south and the subfamily Loligininae in the north. Successive events of dispersion, and some of vicariance (unrelated with the movement of tectonic plates and opening of the Atlantic Ocean), modeled it distribution. Our inference suggest a different origin compared to proposed by Brakoniecki (Tethys Sea), consistent with a center of origin that supports the most diversity of the family, with a predominance of dispersion processes over vicariant events, which explain the present distribution pattern. [ABSTRACT FROM AUTHOR]

Although recent years have seen an increase in genetic analyses that identify new species of cephalopods and phylogeographic patterns, the loliginid squid of South America remain one of the least studied groups. The suggestion that Doryteuthis plei may represent distinct lineages within its extensive distribution along the western Atlantic coasts from Cape Hatteras, USA (36°N) to northern Argentina (35°S) is consistent with significant variation in a number of environmental variables along this range including in both temperature and salinity. In the present study D. plei samples were obtained from a large number of localities along the western Atlantic coasts to investigate the distribution of these possible species in a phylogeographic context. Phylogeographic analyses were performed using the mitochondrial Cytochrome Oxidase I gene and nuclear Rhodopsin gene. Divergence times were estimated using Bayesian strict clock dating with calibrations based on fossil records for divergence from the lineage containing Vampyroteuthis infernalis (162 mya), the probable origins of the North American loliginids (45 mya), and the European loliginids (20 mya) and fossil statolith from Doryteuthis opalescens (3 mya). Our results suggest a deep genetic divergence within Doryteuthis plei . The currently described specie consists of two genetically distinct clades (pair-wise genetic divergence of between 7.7 and 9.1%). One clade composed of individuals collected in northwestern Atlantic and Central Caribbean Atlantic waters and the other from southwestern Atlantic waters. The divergence time and sampling locations suggest the speciation process at approximately 16 Mya, which is in full agreement with the middle Miocene orogeny of the Caribbean plate, ending up with the formation of the Lesser Antilles and the adjacent subduction zone, coinciding with a particularly low global sea level, resulting in the practical absence of continental shelves at the area, and therefore an effective geographic barrier for D. plei . Furthermore, this study also provides evidence of previously undocumented sub-population structuring in the Gulf of Mexico. [ABSTRACT FROM AUTHOR]

Observation of the sexual interactions ofSepioteuthis sepioideasquid during the short reproductive stage of their lives showed a scramble competition system, with both male and female polygyny. Mature females were faithful to a specific location in the daytime, whereas males moved from group to group and formed short-term consortships with females. Males defended females from other males, particularly with an agonistic Zebra display. Male–female pairs exchanged Saddle-Stripe displays, after which males might display an on–off Flicker. There was considerable female choice. Only if a female responded to this display with a parallel Rocking action would she pair and would the male deposit spermatophores at the base of her arms, and only 50% of the time did females move the spermatophores internally to where sperm might be released and stored in the oviducal gland for later fertilization of eggs. This long-term set of interactions and solitary deposition of hidden egg strings contrasts with the attraction of both sexes to a common ‘egg mop’ laid by many females which was a site of competition in other loliginid squid. SinceSepioteuthisis a primitive genus within the family Loliginidae, it may represent a generalist reproductive strategy that evolved into a specialized localization one. [ABSTRACT FROM PUBLISHER]

The commercially important chokka squid Loligo reynaudii occurring in South African waters is currently managed on a single-unit stock hypothesis. We tested this assumption through a spatial comparison of the morphology throughout the distributional range of the species. Forty-three morphometric characters were measured from 1079 chokka collected off the south coast of South Africa, the west coast of South Africa, and southern Angola. While no significant differences were found in the hard body parts, results from classification analysis showed that though all four types of morphometric attributes (soft body parts, beaks, statoliths, sucker rings) resulted in some separation, the most consistent separation of samples from the three regions was based on soft body part morphometric characters. On average, though dependent on the model, the overall correct classification rate ranged from 0.68–0.99 for males and 0.7–0.99 for females in all three regions. Previous DNA analysis had revealed some genetic differences between west coast and south coast samples, suggesting the confluence of the cold Benguela and warm Agulhas current may act as the approximate point of a phenotypic and possible genetic breakpoint. Finer scale genetic analysis of samples collected across the Benguela–Agulhas confluence reported no significant genetic structuring in this area suggesting environmental heterogeneity and not restriction of genetic flow/isolation as the primary driver of the observed phenotypic divergence. [ABSTRACT FROM PUBLISHER]

Coastal spawning grounds of the squidDoryteuthis gahiwere identified for the first time at three sites in Central Chile during 2014 and 2015. A total of 15 egg masses were collected from between 10 and 15 m depth and brought to the laboratory for evaluating capsular, embryonic and when possible, paralarval characters. Egg capsules from all spawning areas were similar in size (∼25 mm in length) and number of embryos per capsule (∼15). Egg-laying patterns, in addition to field observations, suggest that relatively smallD. gahimay be using shallow waters in semi-protected environments to reproduce and spawn. Additionally, the differential use of healthy versus defoliated kelpLessonia trabeculatasuggests that egg-laying females selectively choose substrata that limit mechanical damage to the fragile egg capsules and that also allow for adequate water flow, which could be reduced in a mass of kelp fronds. These findings highlight the opportunistic behaviour ofD. gahiwhich use overgrazedL. trabeculata, a condition that is widespread in areas with high herbivory pressure. [ABSTRACT FROM PUBLISHER]

Circulation patterns of coastal upwelling areas may have central consequences for the abundance and cross-shelf transport of the larval stages of many species. Previous studies have provided evidences that larvae distribution results from a combination of subtidal circulation, species-specific behaviour and larval sources. However, most of these works were conducted on organisms characterised by small-sized and abundant early life phases. Here, we studied the influence of the hydrography and circulation of the Ría de Vigo and adjacent shelf (NW Iberian upwelling system) on the paralarval abundance of two contrasting cephalopods, the benthic common octopus ( Octopus vulgaris ) and the pelagic squids (Loliginidae). We sampled repeatedly a cross-shore transect during the years 2003–2005 and used zero inflated models to accommodate the scarcity and patchy distribution of cephalopod paralarvae. The probability of catching early stages of both cephalopods was higher at night. Octopus paralarvae were more abundant in the surface layer at night whereas loliginids preferred the bottom layer regardless of the sampling time. Abundance of both cephalopods increased when shelf currents flowed polewards, water temperature was high and water column stability was low. The probability of observing an excess of zero catches decreased during the year for octopus and at high current speed for loliginids. In addition, the circulation pattern conditioned the body size distribution of both paralarvae; while the average size of the captured octopuses increased (decreased) with poleward currents at daylight (nighttime), squids were smaller with poleward currents regardless of the sampling time. These results contribute to the understanding of the effects that the hydrography and subtidal circulation of a coastal upwelling have on the fate of cephalopod early life stages. [ABSTRACT FROM AUTHOR]

The characteristics and functional properties of gelatin extracted from squid skin ( Loligo vulgaris ), using commercial pepsin at a level of 15 Units/g skin, were investigated. The gelatin extraction yield was 6.82 g/100 g wet basis, showing high protein content and low fat and ash contents. SDS-PAGE of squid skin gelatin showed high band intensity for the major protein components, especially, α- and β-components. The amino acid profile of squid skin gelatin showed a high percentage of imino acids, essential amino acids and hydrophobic amino acids. Fourier transformed infrared spectroscopy (FT-IR) spectra showed helical structure. Squid skin gelatin was able to form a completely thermo-reversible gel. Gelatin possessed interesting functional properties, which were governed by gelatin concentration. [ABSTRACT FROM AUTHOR]

Pelagic squids of continental shelf ecosystems mostly include oceanic and migratory species of the family Ommastrephidae and neritic species of the family Loliginidae. These two families have contrasting life history strategies; ommastrephids spawn in the open ocean and are thought to have a high dispersal potential, while loliginids spawn on the bottom and are likely to have a low dispersal potential. Consequently, these squid species should display different patterns in their population dynamics, which can be inferred through commercial catches. To study the population dynamics of the Ommastrephidae and the Loliginidae families, monthly time series catches of Dosidicus gigas and Doryteuthis gahi were used. These artisanal fishery catches were made in northern Peru from 1999 to 2010. They were standardized to construct autocorrelation functions so that the relationship between catch dynamics and short-term environmental change (thermal anomalies of sea surface temperature were used as a proxy) could be studied. The results revealed that increases in catches of D. gigas and D. gahi are not related to thermal anomalies, but rather a pattern of drastic fluctuations in D. gahi catch sizes are seen. In, both species, temporal relationships indicate that the annual growth rate and changes in abundance can modelled as a function of the catch density observed in previous years. We propose that these population differences result from the contrasting life history strategies and differential habitat use of these two squid species. [ABSTRACT FROM AUTHOR]

Pepsin-solubilised collagen from the skin of splendid squid (SC) was isolated, partially purified by salt precipitation and dialysis prior to characterisation. The yield of SC was 75.3% (dry weight basis). SC with high purity was obtained as shown by the distinct UV absorption peak at 232 nm and high hydroxyproline content. Total sugar content of SC was 4.70% (dry weight basis), which was higher than that of collagen from calf skin (CC) (1.45% dry weight basis) (P<0.05). Based on SDS-PAGE and elution profile, SC might contain the mixed types of collagen (type SQ-I and type SQ-II), in which α- and β-chains were the major components. SC was rich in glycine and had high content of imino acids (189 residues/1000 residues). The degradation induced by chymotrypsin and lysyl endopeptidase was more pronounced in CC, compared with SC. The maximum transition temperature (Tmax) of SC was 34.1°C, which was about 7°C lower than that of CC. Fourier transform infrared spectra revealed that the triple-helical structure of SC was predominant with the copresence of carbohydrate moieties. Therefore, the skin of splendid squid, a byproduct from squid processing, can be an alternative source for collagen production. [ABSTRACT FROM AUTHOR]

The level of genetic diversity and population differentiation of oval squid Shiro-ika Sepioteuthis sp. 2 around mainland Japan were examined using highly polymorphic DNA markers. Ten microsatellite loci showed relatively low genetic diversity (average observed heterozygosity H = 0.68, overall mean number of alleles N = 10.0) as compared with other squid, which may be explained by a recent history of population expansion. Populations from 12 sites along the coastline of Japan were genetically homogeneous, as measured by F values (global F: −0.0006; pairwise F: from −0.0046 to 0.0083), R values (global R: 0.0025; pairwise R: from −0.0076 to 0.03), a neighbor-joining (NJ) tree based on Cavalli-Sforza and Edwards chord distance, Bayesian clustering or analyses of three geographical groups (Sea of Japan, Seto Inland Sea, and Pacific Ocean; F = −0.0005), and should be considered as a single fishery stock. Allele frequencies also showed a high degree of similarity across different years in the samples taken from Hiroshima. Factors influencing this homogeneity include genetic exchange without barriers preventing gene flow, larval dispersal, and active adult migration of Sepioteuthis sp. 2. [ABSTRACT FROM AUTHOR]