Argentinus Research Articles

Rapid selection effects in a short-lived semelparous squid species exposed to exploitation: inferences from the optimisation of life-history functions

The short life span of cephalopods suggests a potential for high sensitivity to the artificial selective effects of human exploitation. To explore the effects of such selection life-history optimisation was applied using data for a semelparous squid, Illex argentinus with a life span of one year. Survival and fecundity functions were combined to generate a life time reproductive potential function. The maximum reproductive potential identified the optimum age for the squid to mature. In a situation of a constant mortality rate the maximum reproductive potential was achieved at an earlier age of maturation as mortality rate increased. The exact age when the optimum maturation occurs is sensitive to the rate of mortality and the form of the assumed growth curve but covers the age range when maturation is known to occur in this species. A more realistic seasonal fishing mortality function produced a more complex fitness curve with a temporally more restricted optimal age of maturity. The selection effects will be stronger in a seasonal fishery suggesting potentially very rapid evolutionary rates. Developing analyses specifically considering frequency-dependence and environmental-feedbacks will be valuable to clarify the potential of squid to show rapid evolutionary responses to selection. Strong selection for early age of maturation could affect the yield from the fishery but more importantly, could also make the migratory strategy, on which the fishery is based, an unviable option, resulting in collapse of the fishery that exploits the migratory component of the species.

STOMACH CONTENTS OF FALSE KILLER WHALES (PSEUDORCA CRASSIDENS) STRANDED ON THE COASTS OF THE STRAIT OF MAGELLAN, TIERRA DEL FUEGO

AbstractWe examined the stomachs of 25 false killer whales collected from a mass stranding of 181 animals along both coasts of the Strait of Magellan, Chile, in March 1989. The 21 stomachs (nine males and 12 females), with food remains contained 11 prey species (nine cephalopods and two fishes) with a total of 442 individuals. Except for one case, food remains were meager, indicating that the animals had not eaten for some time or through stress had vomited on the beach. Eleven of the 21 animals had mud (often with squid beaks) in the esophagus and first stomach. The prey were identified employing squid beaks, fish otoliths and bones, and their wet weights were estimated using regressions between hard parts and known weights of species. The most important prey were the oceanic and neritic‐oceanic squids, Martialia byadesi and Illex argentinus, followed by the neritic fish, Macruronus magellanicus. Of less importance were the oceanic squid, Todaroes fillipovae, the oceanic and epipelagic octopus, Ocytboe sp., and the oceanic squid, Moroteuthis ingens. The rest of the prey were poorly represented and included four oceanic squids and one neritic fish. The prey species of these animals were subantarctic, with two antarctic species, abundant over the Patagonian shelf and adjacent oceanic waters around Tierra del Fuego.

Parameters affecting the isolation of collagen from squid ( Illex argentinus) skins

The solubility of collagen from squid ( Illex argentinus) skin in salt solutions and the efficiency of removal of skin chromatophores were determined. Homogenization of minced squid skin in 5–15% NaCl solution at 0°C solubilized 35–24% of total amount of crude protein and caused 2–5% loss of collagen but was not effective in removing pigments from the skin. The treatment of whole squid skins in 5–15% NaCl solutions at room temperature led to separation of the chromatophores, but the loss of soluble collagen was 57–16%. Collagen, soluble in dilute acid solutions was isolated from squid skins by 24 h soaking in 10% NaCl solution at room temperature, washing with water and bleaching for 48 h in 1% H 2O 2 in 0.01 M NaOH. The yield of collagen was 53%. It could be increased to 90% by using NaOH solution at pH 11.5 instead of 10% NaCl but the isolate was less soluble in dilute acid and the viscosity of 0.5% dispersion of collagen was four times lower. The rancid off-odour could be prevented by adding 0.5% of a non-ionic detergent to all solution used in the procedure. ©

Microsatellite analysis of genetic diversity in the squid Illex argentinus during a period of intensive fishing

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 187:171-178 (1999) - doi:10.3354/meps187171 Microsatellite analysis of genetic diversity in the squid Illex argentinus during a period of intensive fishing Greg J. Adcock1,*, Paul W. Shaw1, Paul G. Rodhouse2, Gary R. Carvalho1 1Molecular Ecology and Fisheries Genetics Laboratory, Department of Biological Sciences, University of Hull, Hull HU6 7RX, United Kingdom 2British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Rd, Cambridge CB3 OET, United Kingdom *E-mail: g.j.adcock@biosci.hull.ac.uk ABSTRACT: Levels of genetic diversity and population differentiation were examined in temporally (1990 to 1997) and geographically separated samples of the argentine short-finned squid Illex argentinus using 7 microsatellite loci. Number of alleles (mean number of alleles per locus over all samples = 24.1) and heterozygosity (mean observed heterozygosity per sample = 0.84) were high for all samples, indicating that these loci have a greater potential utility for investigating population genetic structure than allozyme markers used in previous studies. Genetic diversity did not differ significantly between samples taken 5 yr after commencement of the fishery (1990) and those collected during a period of progressively intense fishing pressure (1994 and 1997). Several small but significant differences in between-sample genetic variation (FST) were observed, but these could not confirm the previous suggestion of cryptic species or several well-defined stocks within the fished population. KEY WORDS: Microsatellite · Genetic diversity · Illex argentinus · Squid · Population genetics · Fishing Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 187. Publication date: October 14, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Influence of oceanographic variability on recruitment in the Illex argentinus (Cephalopoda:Ommastrephidae) fishery in the South Atlantic

The fishery for Illex argentinus in the Southwest Atlantic is subject to large inter-annual variability in recruitment strength. In this paper we attempt to build a predictive model using sea surface temperature (SST) to examine links between recruitment to the Falkland Islands fishery and environmental variability during the juvenile and adult life history stages. SST data from the National center for Atmospheric Research (NCAR) were found to be comparable with near-surface data derived from in situ expendable bathy-thermograph (XBT) profiles in the southern Patagonian shelf. Variation in SST during the early life stages appears to be important in determining recruitment of I. argentin us. SST in the hatching grounds of the northern Patagonian shelf during the period of hatching (particularly June and July) was negatively correlated with catches in the fishery in the following season. SST anomaly data from positions in the Pacific and Southwest Atlantic were used to examine teleconnections between these areas. Links were seen at a lag of 2 yr between the Pacific and southern Patagonian shelf, and at about 5 yr between the Pacific and northern Patagonian shelf. This is consistent with SST anomalies associated with El Niilo in the Pacific propagating around the globe via the Antarctic Circumpolar Wave (ACW). Predicting cold events via teleconnections between SST anomalies in the Pacific and Atlantic would appear to have the potential to predict the recruitment strength of I. argentinus in the Southwest Atlantic.

Summer distribution, abundance and population structure of Illex argentinus on the Argentine shelf in relation to environmental features

The distribution, abundance and population structure of Illex argentinus in relation to oceanographic conditions during summer 1996 were analysed following a research cruise to the Argentine shelf (39°–51°30′S). Squid were distributed over the whole area, but the main concentrations were on the intermediate and outer Patagonian shelf (44°30′–47°30′S), where there was a thermal front (12–15°C). Three squid groups were detected through study of the distributional area, size, maturity stage, age and hatching month. North of 41°S, there were immature individuals of 14–21 cm mantle length (ML) that had hatched mostly in June. Small mature, spawning and spent squid (males 14–22 cm ML, females 18–26 cm ML) were found on the inner and intermediate shelf between 40°30′ and 46°30′S. They had hatched from January to April, with a clear peak in March. South of 45°S, males of 17–25 cm ML and females of 17–29 cm ML were found over the intermediate and outer shelf; most males were mature whereas the majority of the females were immature. They had hatched from May to July, with a peak in June. The relationship between statolith increment and size showed that the growth rates of the later-hatched individuals were faster than those of individuals hatched earlier. The squid preyed almost exclusively on zooplankton (87%), mostly the hyperiid amphipod Themisto gaudichaudii (79%).

Embryonic development and hatchlings of Illex argentinus derived from artificial fertilization

The embryonic and early post-hatching development of artificially fertilized eggs of Illex argentinus was observed at several temperatures from 8.5 to 23.2°C. During the fertilization procedure, oviducal gland jelly was added to eggs (about 1.0 mm long). Chorion expansion began 20 minutes after fertilization and continued throughout embryonic development. Before hatching, the chorion diameter measured more than 2.5 mm. Developmental stages were described on the basis of morphological features. Most hatchlings from the least disturbed eggs had well-developed ink sacs, fins, extensible probosces and buccal masses. The mantle length of hatchlings was approximately 1.6 mm. Comparisons are made with embryos and hatchlings of other ommastrephid squid, Illex species and Todarodes pacificus.

A contribution to the biology of the ommastrephid squid martialia hyadesi (Rochebrune and Mabille, 1889) from the South-West Atlantic

Updated knowledge on the distribution and biology of the ommastrephid squid Martialia hyadesi in the South-West Atlantic Ocean is presented. Although the species has an Antarctic circumpolar distribution, its most frequent area of appearance is in the South-West Atlantic, where commercial catches have been made. During the 1995 Illex argentinus fishing season, 852 tons of Martialia hyadesi were caught, the largest catches in recent years. The species was captured on the outer shelf and slope, between 38 and 50°S, from March until June. Catches of up to 40 tons per day were obtained in the area between 45 and 48°S (April–June), where surface temperatures ranged between 7 and 9°C. The squid caught were adults (221–375 mm mantle length ML), 70% of the males were mature and 90% of the females were immature. Statolith readings, assuming daily formation of increments, showed that most had hatched during the months October and November. According to stomach content analysis, fish represented 43.9% of the food consumed (90% myctophids), squid 36.6% (70% cannibalism on small juveniles) and zooplankton 19.5%. Juveniles of the same species were caught on the Patagonian slope and in the adjacent oceanic region during spring of 1988 and 1989, most of them in waters of the Malvinas Current (5–7°C). The sizes of those juveniles ranged between 15 and 81 mm ML and the ages (based on statolith increments) between 137 and 150 days, indicating that they had hatched during April.

Textural and Histological Changes of Different Squid Mantle Muscle during Frozen Storage

Mantles from three species of squids, Loligo edulis, Sepia pharaonis, and Illex argentinus, were frozen and stored at −20 °C for 0, 0.5, 1, 2, and 4 months, and their textural properties were investigated. The toughness of all squid mantles increased during frozen storage, and there was a significant difference between prefrozen and postfrozen storage. There was no significant difference in drip amount and SDS gel electrophoresis patterns after 4 months of frozen storage. Histology observation of mantle showed that the muscle fibers were injured and aggregated while the frozen time increased. These changes in tissue structure during frozen storage might cause the toughening of mantle. Keywords: Squid; frozen storage; freezing drip; electrophoresis; histological properties

An examination of the role of the digestive gland of two loliginid squids, with respect to lipid: storage or excretion?

The role of the digestive gland, with respect to non-structural lipid, was examined using proximal analysis, histochemistry and quantitative histological techniques in the tropical loliginid squids Sepioteuthis lessoniana (Lesson) and Photololigo sp. The digestive gland of both species was characterized by large and numerous lipid droplets in the apical portion of the digestive cells and very few in the basal portion. The apical lipid droplets were released into the lumen of the gland and subsequently rapidly removed. Despite the numerous large apical lipid droplets, the lipid concentration in the digestive glands of S. lessoniana and Photololigo sp. was lower than that reported for most squid species. There was no relationship between lipid concentration and stage of digestion, suggesting that lipid is not stored in the gland after a meal. There was also no relationship between lipid concentration and the sex of an individual or stage of reproductive maturity, suggesting that these squids are not storing lipid in the digestive gland for use in fuelling reproductive maturation or providing an energy source for oocytes. I believe this study is the first to combine proximal analysis and quantitative histological techniques to examine the role of the squid digestive gland with respect to non-structural lipids. The results indicate that the digestive gland of these tropical loliginid squids is excreting, not storing, excess dietary lipid.

Biochemical genetics in the Argentinean squid, <i>Illex argentinus</i>

Previously reported results on natural populations of the Argentinean squid, Illex argentinus, urged further studies using electrophoretically detectable loci. The muscles of 202 adult squids caught in the Argentinean Sea were examined. Electrophoretic and staining methods for the 46 enzymes studied are given in detail. Forty-seven loci were detected (20 polymorphic), 45 of which are considered useable in population genetics screening. The expression of the loci coding for these enzymes is described and interpreted, and the presented results will serve as a basis for a more detailed examination of genetic variation in Argentinean squid populations.

Variations in the biochemical composition of the squid Illex argentinus from the South Atlantic Ocean

General condition, biochemical composition changes and fatty acids in several tissues of I. argentinus at different sexual stages were studied. Ovarian maturation involves a simultaneous increase in ovary mass and in protein and lipid levels. Testes weights were modified less than the ovary with maturation and showed a constant biochemical composition during spermatogenesis. The digestive gland grew through most of the maturation process in both sexes. Water level was high in immature squid and low in mature females and males, and varied inversely to that of lipids. Dorsal mantle maintained a constant biochemical composition, between February (immature) and June (fertilized females and mature males). All tissues contained high concentration of polyunsaturated fatty acids followed by saturated fatty acids and monosaturated fatty acids. This digestive gland of the squid is rich in polyenoic fatty acids, 20:5n-3 and 22:6n-3. This tissue could be a cheap raw material, presently discarded, for production of polyunsaturated fatty acids.

Mesopelagic fish distribution in the southwest Atlantic in relation to water masses

A total of 150 mesopelagic fishes, representing 23 families and 47 species, were collected at 18 fishing stations occupied during four research cruises between 1988 and 1995. The main objectives of these cruises were to collect biological data of short-fin squid, Illex argentinus, and southern blue whiting, Micromesistius australis, in the southwest Atlantic within coordinates 36°–56°S and 44°–62°W. Different types of gear at a maximum depth of 1000 m were used. Myctophidae was the most diverse family, followed by Stomiidae, Sternoptychidae, Notosudidae and Melamphaidae. The myctophid Gymnoscopelus ( G.) nicholsi and the gempylid Paradiplospinus gracilis were the most abundant species. Zoogeographic grouping of the 47 species on the basis of centres of distribution in relation to the hydrological conditions and types of water masses indicated that the sub-Antarctic species were the most numerous (18), followed by tropical–sub-tropical (13), sub-Antarctic–sub-tropical convergence (8 spp.) and widespread species (8). The transport of the fish fauna by means of an anticyclonic frontal eddy of the Brazil Current out of the sub-tropical zone into the sub-Antarctic is discussed.

Food and feeding of the short-finned squid Illex argentinus (Cephalopoda: Ommastrephidae) off southern Brazil

Diet and feeding habits of the short-finned squid Illex argentinus were studied from the analysis of 729 stomachs of juveniles, subadults and adults caught with trawls on the continental shelf and slope off southern Brazil (26 °35′S–34 °31′S) from 1981 to 1992. Food, in different degrees of digestion, was found in 363 stomachs (49.8%). Feeding activity occurred at day and night and seemed to be most intense at dusk and early night. The proportion of stomachs with food increased with size and sexual maturity. Fish occurred in 43.8%, cephalopods in 27.5% and crustaceans in 18.7% of the stomachs with food. Identified prey included the fish Diaphus dumerilii, Maurolicus muelleri and Merluccius hubbsi, the cephalopods I. argentinus, Loligo sanpaulensis, Spirula spirula, Semirossia tenera and Eledone gaucha and the crustaceans Oncaea media and Euphausia sp. The occurrence of fish increased with squid size, but both cephalopods and crustaceans were equally important for all sizes. Cannibalism was observed at all sizes. The overall low proportion of stomachs with food, the high rate of cannibalism and the low frequency of occurrence of crustaceans for the juveniles and subadults in all seasons, but particularly in the summer and autumn, may reflect a limited availability of food in the region. If this is true, the main nursery grounds for the spawners off southern Brazil are likely to be off the Rio de La Plata Front or in the offshore confluence between the Brazil and Malvinas Currents, where primary and secondary production is higher than off southern Brazil.

Post-Mortem Changes in Adenosine Triphosphate and Related Compounds in Mantle of Squid (Illex argentinus) at Different Stages of Sexual Maturation

Post-mortem catabolism of ATP and catabolitc compounds of ATP breakdown in the mantle of squid at different sexual maturation stages were investigated during ice storage of either isolated mantle or whole squid. Similar profiles of ATP and catabolites, except AMP, related to ATP breakdown were found in the mantle of ice-stored whole squid at both sexual maturation stages. Independent of the sexual maturation stage of specimens, as compared with whole squid mantles, isolated mantles had a lower (p<0.01) content of AMP and IMP and a higher (p<0.01) content of Hx up to 6 days of storage. IMP was detected in all the samples analyzed. Conversely, adenosine (Ado) was not detected. The K values show that the initial quality of the isolated mantle was lower than that of whole squid mantle. K values increased (p<0.01) in both isolated and whole squid mantles after 6 days of ice storage. The increase was higher (p<0.01) in the mantle from iced whole squid, especially when the specimens were at stage 5 of sexual maturation.

Biochemical Properties of Actomyosin from Frozen Stored Mantles of Squid (Illex argentinus) at Different Sexual Maturation Stages

Mantles of squid at different sexual maturation stages were frozen and stored at −30 °C. Similar biochemical properties of actomyosin from unfrozen mantles of both immature and mature squid were found. A decrease in extractability, reduced viscosity, and Mg2+-ATPase activity of actomyosin was observed during frozen storage. The decrease in the biochemical properties of actomyosin was independent of the sexual maturation stage of the specimens. The relative percentages of myosin and actin in actomyosin from unfrozen mantles of immature squid were significantly different from those of actomyosin of mature squid. Myosin significantly decreased (p < 0.0l) in frozen stored samples. Keywords: Myofibrillar proteins; biochemical properties; frozen storage; squid mantle

Morphology and microstructure of the gladius and statolith from the boreal Pacific giant squid Moroteuthis robusta (Oegopsida; Onychoteuthidae)

Morphology and microstructure of the gladius and statolith were studied from 11 specimens of the boreal Pacific giant squid Moroteuthis robusta (mantle length (ML) ranging from 97.5 to 141.5cm) captured on the slope of the north‐west Bering Sea in summer and autumn 1993. The most specific feature of the M. robusta gladius is a large and, in cross‐section, round rostrum which has been found to be homologous to that of extinct Belemnitida. The functional morphology of the different gladius elements is discussed. Distinct growth increments have been revealed in all three gladius layers in M. robusta. Comparison of peculiarities of microstructure of growth increments, their ways of deposition and their numbers in different gladius layers has shown that all three layers in the M. robusta gladius grow synchronously. M. robusta statoliths are tiny (0.07‐0.1% ML) and resemble in shape those of the ommastrephid Illex argentinus. It was impossible to count the total number of growth increments within the statoliths, owing to their complete disappearance in the outer portion of the peripheral zone, and therefore impossible to estimate the age of the M. robusta by using the statolith ageing technique. However, assuming the deposition of growth increments within the gladius as daily, the age of the specimens analysed may vary from 413 to 520 days.

Interactions between oceanography, ecology and fishery biology of the ommastrephid squid Martialia hyadesi in the South Atlantic

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 152:205-215 (1997) - doi:10.3354/meps152205 Interactions between oceanography, ecology and fishery biology of the ommastrephid squid Martialia hyadesi in the South Atlantic González AF, Trathan PN, Yau C, Rodhouse PG The seven star flying squid Martialia hyadesi is an oceanic slope ommastrephid with a circumpolar distribution associated with the Antarctic Polar Frontal Zone (APFZ) and is a minor, variable catch in the South Atlantic Illex argentinus fishery. There have been occasional unusually large catches of M. hyadesi, the latest being in 1995. Because of the importance of understanding the influence of the physical environment on fisheries for oceanic squid, and interest in developing a new fishery for M. hyadesi in the CCAMLR area, we examined specimens and data from the 1995 season and analysed 10 yr fisheries and remotely sensed oceanographic data sets from the area. The 1995 data show that M. hyadesi remains in the cool APFZ waters of the Falkland Current where it preys on oceanic fish and crustaceans and its distribution rarely extends over the Patagonian Shelf. The squid exploited by the fishery in 1995 were 6 to 12 mo old; females were immature but some males were fully mature. A remotely sensed sea surface temperature (SST) image revealed mesoscale features at the shelf break front between Patagonian Shelf water and APFZ water where the squid were caught. The appearance of M. hyadesi in the fishery over the last decade, including 1995, has been related to SST anomalies. Teleconnections probably exist between these anomalies, El Niño/Southern Oscillation (ENSO) events in the Pacific and sub-decadal oceanographic instability in the Antarctic. Squid are short-lived and populations are likely to be able to respond rapidly to environmental change. However, it is not clear at what stage in the life cycle of M. hyadesi these oceanographic events exert their effect. We propose 2 alternative, but not mutually exclusive, hypotheses. Warm events prior to the appearance of M. hyadesi may favour reproductive success of the parent generation giving rise to a strong recruitment, or alternatively this cool water species may extend its range to the edge of the Patagonian Shelf early in the development of cold oceanographic events. In either case oceanographic effects are probably mediated via the squid's prey. Martialia hyadesi · Oceanography · Ecology · Fishery biology · South Atlantic Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 152. Publication date: June 26, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

AMINO ACID COMPOSITION AND IN VITRO PROTEIN DIGESTIBILITY OF DRIED SQUID REHYDRATED IN WATER AND ALKALI

Crude protein content, amino acid composition and in vitro protein digestibility of fresh, dried and rehydrated Argentina squid (Illex argentinus) were studied. Most of the nonamino acid nitrogenous compounds in the mantle muscle dissolved in water during rehydration. Rehydration improved the nutritive value of protein in dried squid. Rehydration decreased the concentration of proline relative to total amino acids in muscle. Aromatic amino acids were limiting essential amino acids in fresh and dried squid but not in rehydrated squid. Amino acid scores increased with the extent of rehydration, more so in alkali than in water. The alkali rehydration also increased the in vitro protein digestibility of dried squid.

Geographical variation in growth and maturation of the squid illex coindeth (Oegopsida, Ommastrephidae) off the north-west African coast

Statolith microstructure was studied in 162 specimens of Illex coindetii (mantle length ranging from 48 to 300 mm) captured on the shelves of Sierra Leone and Western Sahara between May and November 1987. Growth increments were revealed in all statoliths studied, but they were not well-resolved as in other congeneric species Illex illecebrosus and Illex argentinus. Age and growth rates were estimated assuming that growth increments within statoliths were produced. In both regions, differences in growth rates between sexes (females become larger than males) occurred first in length and then in weight. Geographical differences in sex-specific growth (Western Sahara squid grow faster and attain larger sizes than Sierra Leone squid) was apparent after 150 d in females and 120 d in males. Illex coindetii in Sierra Leone started maturing at smaller sizes but at approximately the same age as the Western Sahara squid. Small sized early maturing groups of I. coindetii with a life span of ~0.5 y occurred in both regions. However, large sized late maturing squid with a life span of ~1 y were encountered only in the Western Sahara. In waters of the west African shelf, I. coindetii spawn throughout the year.