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Using citizen science to obtain data on large, floating gelatinous spheres from NE Atlantic, attributed to egg mass of ommastrephid squid (Oegopsida, Cephalopoda, Mollusca)
Abstract and Figures
A total of 27 large, gelatinous spherical masses observed in coastal Norwegian waters from Nordland to Aust-Agder Counties in Norway, and off Lysekil in Sweden, Muljica Island in Croatia, Gulf of Naples in Italy, Reqqa Point in Malta, and Saint Mandrier in France, during the months of April to September 2001 to 2017, are reported. Individual spheres measured 0.3 - 2 m in diameter, averaging one metre (n = 24, +/− 0.53 m), with all but four sighted in suspension in the water column between 0.5 and 52 m depth, in water temperatures ranging between 10 - 21°C. About half of all spheres contained a yellow-red streak through their gelatinous core. Tissue samples were not obtained. We attribute these gelatinous spheres to the egg masses of squid (Cephalopoda, Oegopsida), and most likely to the ommastrephid Todarodes sagittatus, given similarities with egg masses of T. pacificus.
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... Considering that sea water convection (mixing) caused by wind waves expands down to tens of metres and swell to hundreds of metres (Moum and Smyth 2001), it is difficult to imagine how ommastrephid squids in the North Sea rely on a stable density layer (thermocline or halocline). The question is how do ommastrephids survive and increase in numbers, as was testified recently by the survey data (Kooij et al. 2016) and by the fact that their numerous egg masses have been observed there more frequently in recent years (Ringvold and Taite 2018). ...
... For the development of its pelagic egg masses, I. coindetii used the larger, outer gyre going all the way along shores of Scotland, England, Belgium, Netherlands, Denmark, Sweden and Norway. In Norway waters these egg masses were recorded in numbers by recreational divers and were interpreted as belonging to Todarodes sagittatus (Ringvold and Taite 2018), which reproduces on the Mid-Atlantic ridge and is now a very rare immature foraging migrant in the North Sea (Laptikhovsky 2013, Oesterwind et al. 2010. assumed that the egg masses in North Sea waters and surroundings belong to I. coindetii, which has now been confirmed by H. Ringvold through genetic identification of egg masses (Sea Snack Norway 2019). ...
The lesser flying squid (Todaropsis eblanae) and the shortfin squid (Illex coindetii) are two abundant ommastrephids of the northeast Atlantic. Spawning ground existence was inferred from the captures of mature, mated females in summer 2016–2019 and their occurrences were compared with respective oceanographic data from international surveys to gain insight into environmental predictors of their presence throughout the North Sea. Spawning T. eblanae were found in relatively cooler and more saline waters (6–8°C, 34.2–35.1 psu) in the northern North Sea linked to the Fair Isle Current
and East Shetland Atlantic Inflow, whilst spawning I. coindetii occurred across the entire North Sea (mostly at 9–10.5°C, 34.1–34.8 psu). We hypothesize that a combination of water salinity and water temperature are key factors in the spatio-temporal distribution of spawning ommastrephid squids as they define water density that is crucial for pelagic egg mass to attain neutral buoyancy.
... Therefore, a strong emphasis should also be put on obtaining ecological observations of wild sepiolids to increase our understanding of their behaviour. A promising opportunity to receive observations of cephalopod behaviour from the wild could be through citizen science (Dickinson et al. 2010), a usually cost-effective and valuable tool which has recently been used to describe some ecological features of the sepiolid R. macrosoma ) as well as other cephalopods (Ringvold and Taite 2018;Drerup and Cooke 2021;Laptikhovsky et al. 2021;Ringvold et al. 2021;Laptikhovsky et al. 2022;Freitas et al. 2022). ...
Sepiolidae (Cephalopoda: Sepiolida) are growing in popularity as model organisms, not least because of their well-studied symbiotic relationship with light producing bacteria. Their easy maintenance and cultivation requirements in captivity have further facilitated their use in a wide range of developmental, anatomical, neurophysiological, behavioural and genetic studies, exhibiting promising opportunities for these cephalopods in research. Considering the rising interest in sepiolids, a detailed overview of their behavioural ecology is necessary to understand their evolution and conservation, as well as to aid establishment of good welfare practice when held in captivity. To date, not all aspects of the sepiolid ecology have been investigated in detail, and our current knowledge of their behavioural ecology is, for the most part, restricted to descriptions from less than 10 of the approximately 80 species, occasionally resulting in a generalisation of specific observations across species, genera, or even subfamilies. This review summarises current knowledge on sepiolid behavioural ecology and life history, including discussions on their habitat, life span, activity patterns, hunting and feeding behaviour, anti-predator behaviour, burying behaviour, and reproductive behaviour. Moreover, future directions as well as areas of interest for upcoming research studies are highlighted.
... Share it!!!/Greece, Cyprus 12 Gledhill et al. (2015) Not specified/New South Wales and Victoria, Australia 13 Gudka et al. (2020) Not specified/Western Indian Ocean 14 Hann et al. (2018) Whale mAPP/Southeast Alaska, USA 15 Harley et al. (2019) CoastSnapManly/New South Wales, Australia 16 Hart and Blenkinsopp (2020) Changing Coasts project; CoastSnap/Wales and England, UK 17 Haywood, Parrish, and Dolliver (2016) COASST (Coastal Observation and Seabird Survey Team)/USA 18 Hieb et al. (2017) Manatee Sighting Network/North-central Gulf of Mexico 19 Hourston, McDonald, and Hewitt, (2015) Aquatic Biosecurity Pest Alert/Western Australia 20 Hunter, Alabri, and van Ingen (2013) CoralWatch/Global 21 Jambeck and Johnsen (2015) Marine Debris Tracker/North America, South America, Europe, Asia 22 Jarvis et al. (2015) SeaSketch 23 Jones et al. (2018) SeagrassSpotter/Global 24 Kelly, Fleming, and Pecl (2019) Redmap Australia (Range Extension Database and Mapping Project)/Australia 25 Komninos (2019) Swymm/Greece 26 Kotovirta et al. (2014) Algae Watch and Lake Wiki/Finland 27 Krželj, Cerrano, and Di Camillo (2020) AmbienteMarino/Croatia, Adriatic Sea 28 LaRue et al. Not specified/Great Barrier Reef, Australia 39 Ringvold and Taite (2018) Not specified/Northeast Atlantic 40 Robinson et al. (2017) Plankton Portal (supported by Zooniverse)/Global 41 Rosenthal et al. (2018) Floating Forests/Global 42 Scyphers et al. (2015) Not specified/Gulf of Mexico 43 Shamir et al. (2014) Whale FM (supported by Zooniverse)/Global 44 Siano et al. (2020) Phenomer/Brittany, France 45 Smith et al. (2018) Bottles on Beaches/New South Wales, Australia 46 Thieler et al. (2016) iPlover/U.S Atlantic Coast 47 Tiralongo et al. (2020) AlienFish/Italy 48 Tunnell et al. (2020) Nurdle Patrol/Gulf of Mexico 49 Ward-Paige, Westell, and Sing (2018) eOceans/Thailand 50 Williams et al. (2017) Not specified/Southern Mozambique 51 Wright et al. (2016) Diveintoscience/UK, global 52 Yeo et al. (2015) International Pellet Watch/Australia, New Zealand 53 Zabbey et al. (2020) Various/Niger Delta, Nigeria coastal management by assessing the complementarity and comparability of CS data with other data (e.g., observations from experienced researchers, earth observations from satellite data), testing different methods of data collection, processing big data, obtaining data at finer spatiotemporal scales, and validating forecasting models. Given the focus of the scoping review, engagement was naturally a central theme. ...
Coastal monitoring and management can be enhanced by citizen science (CS), especially because Information and Communications Technology (ICT) enables remote public engagement in CS. To date, this type of engagement would benefit from a thorough investigation to highlight its supportive role to coastal CS, identify its unique challenges, and propose solutions and research avenues to sustain its development. A systematic scoping review and qualitative analysis of scientific papers (N = 53) described the state of the art in remote public engagement in coastal CS. The analysis revealed unique advantages of remote engagement in coastal CS, including flexibility, social inclusivity, and organised communication management. Challenges, mainly associated with technology, could be solved by simplifying interfaces to streamline communication and participation in CS. The review identified research gaps and confirmed the potentially positive contribution of remote engagement in coastal CS, which could enhance coastal monitoring, management, public participation, and stewardship.
... fish, parasite infection and infestation by crustaceans and protozoans during a first relative short period of their lives 5,51 . Bottom trawlers operate in spawning areas of squids, exposing them to a risk of egg loss, as also for our fisherman at Askøy, Norway, who caught a sphere in his trawl 1,5 . The broadtail shortfin squid, Illex coindetii, is probably the most widespread species found on both sides of the Atlantic and throughout the Mediterranean Sea 12 . ...
In total, 90 gelatinous spheres, averaging one meter in diameter, have been recorded from ~1985 to 2019 from the NE Atlantic Ocean, including the Mediterranean Sea, using citizen science. More than 50% had a dark streak through center. They were recorded from the surface to ~60-70 m depth, mainly neutrally buoyant, in temperatures between 8-24⁰C.
Lack of tissue samples has until now, prohibited confirmation of species. However, in 2019 scuba divers secured four tissue samples from the Norwegian coast. In the present study, DNA analysis using COI confirms species identity as the ommastrephid broadtail shortfin squid Illex coindetii (Vérany, 1839); these are the first confirmed records from the wild. Squid embryos at different stages were found in different egg masses: 1) recently fertilized eggs (stage ~3), 2) organogenesis (stages ~17-19 and ~23), and 3) developed embryo (stage ~30).
Without tissue samples from each and every record for DNA corroboration we cannot be certain that all spherical egg masses are conspecific, or that the remaining 86 observed spheres belong to Illex coindetii. However, due to similar morphology and size of these spheres, relative to the four spheres with DNA analysis, we suspect that many of them were made by I. coindetii.
... Citizen science may be a useful tool to identify spawning sites of ommastrephids, as indicated by reports of probable oegopsid eggs (floating gelatinous spheres) by divers in Northern Europe and the Mediterranean (Ringvold and Taite, 2018). These authors tentatively identified some of the eggs as belonging to Todarodes sagittatus (see section 11.3). ...
With the depletion of many commercial fish stocks and an increasing demand for marine protein for human consumption, cephalopods have become more important as a fishery resource. In EU waters, cephalopod stocks are not routinely assessed and exploitation of these species by large-scale fisheries is largely unregulated. For sustainable exploitation, adequate assessment and scientifically-supported management strategies are needed. However, there is still a lack of data on stock status and inadequate knowledge of the life history and ecology of these species. The present review examined more than 200 scientific articles, on life history and ecology of European cephalopods, published since 2013. It describes recent contributions to knowledge in the context of previously identified research priorities, along with recent advances towards sustainable fishing and aquaculture. It also identifies outstanding knowledge gaps. While some priority areas, such as the development of the species identification guides and evaluation of climate change impacts on cephalopods, have seen significant advances, other challenges remain for the future. These include monitoring of the life history traits and fishery status for the main commercially exploited species in the area, implementation of improved species identification methods during scientific surveys and fisheries monitoring, development of tools to identify stock units, and the study of the environmental and anthropogenic impacts on the stocks of cephalopods inhabiting European waters.
... In Q3, we observed that most females had been mated and carried up to three spermatangia bundles, while no mature or mated females were recorded in Q1. In addition, ommastrephid egg masses were occasionally observed in summer 2017 in Swedish and Norwegian waters including the Skagerrak and Kattegat although tentatively attributed to T. sagittatus (Ringvold and Taite, 2018). Our new observations suggest that those eggs might belong to I. coindetii, at least for the Skagerrak and Kattegat area, as mated I. coindetii were observed in the North Sea in summer and hatching dates suggest that the species most likely reproduces in the North Sea in summer, whereas the nearest known location of reproduction of T. sagittatus is the mid-Atlantic ridge west of Ireland (Laptikhovsky, 2013). ...
Global changes drive abundance and distribution of species worldwide. It seems that at least some cephalopod stocks profit from global changes as indicated by increases in biomass and/or expansion of their geographical distribution, as appears to be the case for the commercially important ommastrephid squid Illex coindetii, in the North Sea. Based on the recently increased abundance of this species seen in research trawl hauls, here we present the first evidence of a summer spawning stock of Illex coindetii in the North Sea and derive a description of its life cycle. Neither mated females nor spent males were reported from the area previously. In quarter 1 the majority of Illex coindetii were immature (maturity stage 0) and maturing (maturity stage 1–3) while in quarter 3 almost exclusively mature and spent individuals (maturity stage 4–6) were caught. We observed up to three spermatangia bundles attached to females in quarter 3, indicating that spawning and reproduction takes place in the North Sea and that the species is already established in this area. Estimated egg hatching dates suggest a prolonged hatching period and therefore likely a long spawning season, although cold temperature seems to limit year round reproduction. The intensity of individual migrations from adjacent waters into the North Sea is unknown and therefore the number of individuals staying permanently in the North Sea could not be estimated. It is consequently still unclear whether the North Sea individuals of I. coindetii constitute a new separate stock.
... 27 segnalazioni sono incluse in un articolo scientifico pubblicat in Journal of Marine Biology Research (* Ringvold & Taite, 2018), e 19 sono successive alla pubblicazione del report suddetto. In questo lavoro si comparano le teche ovigere di varie specie di cefalopodi da tutto il mondo. ...
Ommastrephid squids have a pelagic lifestyle, with reproductive behavior that is characterized by the extrusion of fragile, neutrally buoyant egg masses, the release of paralarvae into the surface plankton, and the use of large-scale current patterns for larval transport, leading to the assisted migration of populations. Although the exact process of egg mass formation is unknown, the most accepted hypothesis suggests that, at spawning, eggs are first coated with oviducal gland secretion and released with nidamental gland secretions. Subsequently, the eggs mix with broken spermatophores or spermatangia for fertilization. The fertilized eggs are then extruded into the seawater to form a globular mass. These neutrally buoyant gelatinous egg masses are thought to maintain their location in the water column by floating at the interface between water layers of slightly different densities (above the pycnocline). The embryos develop within a favorable temperature range. Once hatched, the paralarvae leave the egg mass and swim to the surface. This review assimilates and assesses all available literature on the egg masses of ommastrephid squids. The data presented here clearly show how fragmentary our knowledge is about this important reproductive stage. Thus, increased efforts are required to develop observation and sampling techniques in the wild to obtain more direct evidence about reproduction in squids.
Egg masses of ommastrephid squids are rarely found and not well studied. For the Humboldt squid, Dosidicus gigas, only a single egg mass has been scientifically documented in the wild. Little is known about the size, spatial or temporal distribution of egg masses, or the number of eggs they contain. In this study, we report observations of six egg masses laid in the Gulf of California in May 2015. Egg mass diameters were 2–4x smaller in this study compared to the previously observed mass reported in 2008, consistent with the small and large sizes, respectively, of mature female squid captured during each study. Each egg mass contained 17,000–90,000 embryos, one to two orders of magnitude lower than that estimated for the large egg mass previously observed. Egg masses were observed at 9–14 m depth on or near a thermocline. Developmental stages of embryos and paralarvae differed between egg masses. No egg masses were observed in the 13 dives before or the 4 dives after these masses were found, suggesting that female spawning activity is likely spatially or perhaps temporally patchy. Developmental heterochronies in chromatophore development between Dosidicus gigas and other ommastrephid squids are discussed. Amphipods and ciliates infested the majority of masses, which is the first documented case of biota associated with wild ommastrephid egg masses.
The spawning behavior of ommastrephid squids has never been observed under natural conditions. Previous laboratory observations of Japanese flying squid (Todarodes pacificus) suggest that pre-spawning females might rest on the continental shelf or slope before they ascend above the pycnocline to spawn, and that the egg masses might settle in the pycnocline. Here, two mesocosm experiments were conducted in a 300 m3 tank that was 6 m deep to investigate this hypothesis. In the first experiment, a thermocline (2.5–3.5 m) was established in the tank by creating a thermally stratified (17–22°C) water column. In the second experiment, the temperature was uniform (22°C) at all depths. Prior to spawning, females did not rest on the tank floor. In the stratified water column, egg masses remained suspended in the thermocline, but in an unstratified water column, they settled on the tank bottom, collapsed and were infested by microbes, resulting in abnormal or nonviable embryos. Eleven females spawned a total of 18 egg masses (17–80 cm in diameter), indicating that females can spawn more than once when under stress. Paralarvae hatched at stage 30/31 and survived for up to 10 days, allowing us to observe the most advanced stage of paralarvae in captivity. Paralarvae survived after consumption of the inner yolk, suggesting they might have fed in the tank.
Orange-back squid females, Sthenoteuthis pteropus, were found to mature at two different sizes: 230-270 mm and 380-450 mm mantle length (ML). The systematic status of these groups remains unknown. The ML of mature females varied from 155 to 558 mm (body weight 150-5900 g, respectively). Protoplasmic oocytes of 0.1 mm predominated in the ovaries during the entire life cycle providing a resource for further yolk accumulation. The number of yolk oocytes present at any one time represented only a small part of the Potential Fecundity (PF). Ripe eggs were 0.73-0.87 mm, and egg weight was 0.19-0.26 mg. The PF was 0.6 million to 15.8 million in mature animals and 1.2 million to 17.9 million in immature and maturing females, respectively. In mature females, the total number of yolk oocytes was 20 000 to 1.9 million, including 10 000 to 1 million ripe eggs. Spawning was intermittent. Large females presumably released at least 30-50% of the total oocyte stock. Results indicate that S. pteropus is a typical representative of the epipelagic oceanic cephalopod reproductive strategy characterised by small eggs, high fecundity, long intermittent spawning, active feeding, and somatic growth during spawning.
Orange-back squid females, Sthenoteuthis pteropus, were found to mature at two different sizes: 230-270 mm and 380-450 mm mantle length (ML). The systematic status of these groups remains unknown. The ML of mature females varied from 155 to 558 mm (body weight 150-5900 g, respectively). Protoplasmic oocytes of 0.1 mm predominated in the ovaries during the entire life cycle providing a resource for further yolk accumulation. The number of yolk oocytes present at any one time represented only a small part of the Potential Fecundity (PF). Ripe eggs were 0.73-0.87 mm, and egg weight was 0.19-0.26 mg. The PF was 0.6 million to 15.8 million in mature animals and 1.2 million to 17.9 million in immature and maturing females, respectively. In mature females, the total number of yolk oocytes was 20 000 to 1.9 million, including 10 000 to 1 million ripe eggs. Spawning was intermittent. Large females presumably released at least 30-50% of the total oocyte stock. Results indicate that S. pteropus is a typical representative of the epipelagic oceanic cephalopod reproductive strategy characterised by small eggs, high fecundity, long intermittent spawning, active feeding, and somatic growth during spawning.
During the 30-th cruise of the r/v “Professor Vodyanitsky” in March - April 1990 in the North-Western part of the Arabian Sea the specimens of squid Sthenoteuthis oualaniensis (Giant Arabian form) were placed in tanks with running sea water. Nine females with mantle length 51.5-56.1 cm spawned at night. Before and after spawning they were fed by flying fish and pieces of squids. The egg mass of S. oualaniensis was typical for the ommastrephids. Some stages of embryonic development are described and figured. The larvae hatched prematurely on the 2.5 or 3 day after spawning (at 21 - 25.5° C). S. oualaniensis spawns in epipelagic sound-scattering layer.
An isolated population of Todarodes sagittatus inhabits the shelf and slope waters of North African coast from 11°45′ to 26°N within the depth range 65-1100 m. This population has a 1-yr life cycle and spawns year-round, with a clear winter peak. Hatched larvae rise to the subsurface layers above the continental slope and grow there up to 12-15 cm ML. Then immature squid (10-25 cm ML) forage from May to August over the continental shelf from 18° to 25° N (depth range 100-300 m). In this period they formed fishery concentrations. In August-October, when maturation begins, squid concentrations disperse, mature squids (males of 20-28 cm ML, females of 25-35 cm ML) descend to 400-800 (1100) m depth. Squid abundance and density of the summer foraging aggregations vary by years as well as by depth ranges. Annual Soviet catches vary from 17 to 3725 mt (1980-1991) the highest value being of 18,000 mt (1974). Squid biomass was estimated to be 10-30 thousand mt in years of low abundance to 80-120 thousand mt in years of high abundance.
A total of 206 specimens of the ommastrephid squid Todarodes sagittatus, obtained from three areas of the central eastern Atlantic (Canary Islands/African coast, Madeira, and the Gettysburg Bank area south of Portugal) were examined. New information on size, mass, length-mass relationships, reproductive biology, and diet of the squid from a hitherto not very well studied area is supplied. Females dominated the samples (78%) and attained larger size and mass than males. Dorsal mantle lengths of T. sagittatus in the Canary Islands/African coast samples and in the Madeira region were similar, 167 - 348 mm for females and 175 - 269 mm for males. From the Gettysburg Bank all specimens were immature, females ranging between 71 and 276 mm and males from 98 to 233 mm. Mature females were found mainly during winter and mature males nearly year-round, indicating that they mature earlier than females and at a smaller size. Prey consisted mainly offish (54.9%), decapods (18.8%) and cephalopods (12.1%). Otoliths and fish bones identified from stomach contents suggest that myctophids were the most common and diverse prey.
The egg mass and embryos of the ommastrephid squid Nototodarus gouldi McCoy, 1888 are reported for the first time, their identity confirmed by mitochondrial 16S rDNA sequence determination. The egg mass is a free‐floating gelatinous sphere of at least 1.5 m diameter and contains an estimated several thousand randomly distributed eggs; similar egg masses recorded from north‐eastern New Zealand waters of 1.0–2.0 m diameter are reported. Observed fluctuations in populations for this and other squid species may be a partial result of trawl damage to the egg masses.
The jumbo or Humboldt squid, Dosidicus gigas, is an important fisheries resource and a significant participant in regional ecologies as both predator and prey. It is the largest species in the oceanic squid family Ommastrephidae and has the largest known potential fecundity of any cephalopod, yet little is understood about its reproductive biology. We report the first discovery of a naturally deposited egg mass of Dosidicus gigas, as well as the first spawning of eggs in captivity. The egg mass was found in warm water (25–27°C) at a depth of 16 m and was far larger than the egg masses of any squid species previously reported. Eggs were embedded in a watery, gelatinous matrix and were individually surrounded by a unique envelope external to the chorion. This envelope was present in both wild and captive-spawned egg masses, but it was not present in artificially fertilized eggs. The wild egg mass appeared to be resistant to microbial infection, unlike the incomplete and damaged egg masses spawned in captivity, suggesting that the intact egg mass protects the eggs within. Chorion expansion was also more extensive in the wild egg mass. Hatchling behaviours included proboscis extension, chromatophore activity, and a range of swimming speeds that may allow them to exercise some control over their distribution in the wild.
Todarodes
sagittatus (N=1131) were opportunistically sampled from commercial and research trawling in Irish and Scottish waters between 1993 and 1998. The results suggest that the species is common in deep waters (>200 m) to the west of Ireland and Scotland, particularly in late summer and autumn. The size of squid caught was related to depth, with larger squid caught deeper, and is indicative of an ontogenetic, bathymetric migration. Females were more common (sex ratio 1·00:0·46), and attained a larger maximum size (520 mm mantle length (ML)) than males (426 mm ML). Mature females (360–520 mm ML) were caught in deep water (>500 m), between March and November, with a large catch of mature females taken off the west coast of Ireland in August 1996. Mature males (300–426 mm) were found from August to November. Potential fecundity was estimated to range from 205,000–523,500 eggs female−1. Putative daily increments in statoliths indicated a life cycle of slightly over a year, with rapid growth of approximately 1·8 mm d−1 during subadult and adult life. Fish were the most important prey of T.
sagittatus and 17 fish prey taxa were identified, of which pelagic species were the most important.
Two egg masses of the ommastrephid squid Todarodes pacificus (Steenstrup, 1880) are described. Immature squid were collected from inshore waters of southern Hokkaido, Japan, and maintained in a raceway tank where they matured, mated, and spawned. Both gelatinous masses were spherical and nearly neutrally buoyant. The larger mass measured 80 cm in diameter and contained approximately 200,000 eggs. The egg-mass surface layer effectively prevented crustaceans, protozoans, and bacteria from infesting the masses. Paralarvae hatched after 4-6 days at 18-19°C and actively swam at once, with many individuals swimming at the surface. Both masses disintegrated soon after hatching. Paralarvae died approximately 6-7 days after hatching, presumably due to starvation.
We describe "universal" DNA primers for polymerase chain reaction (PCR) amplification of a 710-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from 11 invertebrate phyla: Echinodermata, Mollusca, Annelida, Pogonophora, Arthropoda, Nemertinea, Echiura, Sipuncula, Platyhelminthes, Tardigrada, and Coelenterata, as well as the putative phylum Vestimentifera. Preliminary comparisons revealed that these COI primers generate informative sequences for phylogenetic analyses at the species and higher taxonomic levels.
Har du sett en geleaktig ball på omtrent en meter i diameter i sjøen? Hva er det egentlig for noe - eggkapsler fra blekksprut? Er dette et sjeldent syn, eller er det vanlig? Hvor finnes de, på hvilken tid av året kan man se dem, og på hvilket dyp?
Short-finned squid (Illex illecebrosus) eggs and paralarvae are distributed by the Gulf Stream at least from the Florida Straits to oceanic waters south of Newfoundland, with older stages extending inshore and further north, as far as the southern Labrador shelf. Adults feed in the north and migrate south to spawn. Fishery records only go back to 1880, but jigging for cod bait in Newfoundland may have been among the first occupations for Europeans in North America. For a decade starting in 1975, this squid was the target of an offshore trawl fishery that returned nearly a million tons before collapsing, and extensive field and laboratory research during this period made it one of the best characterized ommastrephid species. This chapter includes re-analyses of these data based on new age estimates. Present efforts, focused on monitoring a slow recovery from the longest series of recruitment failures on record, represent a valuable case study of squid recruitment processes.
Squid, cuttlefish and octopuses, which form the marine mollusc group the cephalopods, are of great and increasing interest to marine biologists, physiologists, ecologists, environmental biologists and fisheries scientists. Cephalopods: ecology and fisheries is a thorough review of this most important animal group. The first introductory section of the book provides coverage of cephalopod form and function, origin and evolution, Nautilus, and biodiversity and zoogeography. The following section covers life cycles, growth, physiological ecology, reproductive strategies and early life histories. There follows a section on ecology, which provides details of slope and shelf species, oceanic and deep sea species, population ecology, trophic ecology and cephalopods as prey. The final section of the book deals with fisheries and ecological interactions, with chapters on fishing methods and scientific sampling, fisheries resources, fisheries oceanography and assessment and management methods. This scientifically comprehensive and beautifully illustrated book is essential reading for marine biologists, zoologists, ecologists and fisheries managers. All libraries in universities and research establishments where biological sciences and fisheries are studied and taught should have multiple copies of this landmark publication on their shelves.
In the course of making some experiments on the spawning of the common squid, Ommastrephes sloani pacificus STEENSTRUP, the present author obtained four egg-masses from a number of fully matured specimens and reared them in an indoor aquarium at Kasumi Branch, Japan Sea Regional Research Laboratory, located on the Japan Sea coast of Hyogo Prefecture during the period from June to August, 1962. Out of the four egg-masses which were demersed and adhesive, three masses were found composed of nidamental gelatin, oviductal gelatin and fertilized eggs. Such masses had also been observed in the previous experiments made by the present author (Hamabe, 1961, Zool. Mag., 70, (11)). But unlike these three, there was still another mass of eggs quite new to the author, which was composed of merely nidamental gelatin and fertilized eggs. It remains to be seen why those two different types of egg-mass are produced, now that they are both found to be fertilized with the larvae in potential. If this unreported mass of eggs were found naturally in the sea, it might be inferred that this particular mass of eggs is obliged to float in the mid-lower water of the sea, being caused by gravimetrical balance, when it is partly or wholly separated by chance from the substance to which it has been adhering.
In this study, we found that there were significant positive correlations between the catch per unit effort (CPUE, a squid abundance index) for the neon flying squid (Ommastrephes bartramii) winter–spring cohort and the satellite-derived chlorophyll a concentrations in their spawning grounds located at 140–160°E where 21°C < sea surface temperature < 25°C from February to May. The spawning grounds of the winter–spring cohort are located in a quiet stream region, and a particle tracking experiment, based on the velocity field obtained from an ocean data assimilation system, showed that paralarvae and juveniles aged <90 days remained in their spawning grounds and the chlorophyll a concentration in their habitat had a significant positive correlation with the CPUE. A backward particle tracking experiment also showed that the chlorophyll a concentration in the spawning grounds had a significant positive correlation with the autumn–winter mixed layer depth. Based on these results, we hypothesize that the CPUE interannual variability is caused by variations in the feeding environment of the paralarvae and juveniles, which may be linked to autumn–winter mixed layer depth variations.
In 2005, 2006, 2007 and 2011, distinct Oegopsida squid egg masses were observed by scuba divers on the narrow southern KwaZulu-Natal (KZN) shelf in depths of 35–50 m off the coastal resorts of Park Rynie, Pumula and Port Edward, South Africa. In 2006, larvae in the egg balloons were sampled. DNA barcoding (i.e. cytochrome c oxidase subunit 1 sequencing) linked the larvae to the genus Lycoteuthis, a group commonly found on the continental slope of the Agulhas Bank and the west coast of South Africa. In all cases, the sightings were concomitant with low water temperatures of 14–18 °C, indicative of shelf edge upwelling. Historical ship-collected CTD data show these cooler waters to originate from a depth of 100–180 m on the KZN continental slope. Complementary satellite imagery revealed the cooler water and discoveries of the egg balloons to be coincident with cold core cyclonic eddies embedded in the shoreward boundary of the Agulhas Current. The temperature data suggest that these egg balloons, in the absence of cyclonic eddy activity, would normally be found in the current on a density surface at a depth of 130 m where velocities are typically around 100 cm s–1.
This chapter illustrates the systematics and ecology of oceanic squids. It describes distribution in sea, life history, egg masses, growth, size, form, structural variation, ecological importance, economic importance, and catching methods of different squids, such as architeuthidae, ommastrephidae, onychoteuthidae, gonatidae, thysanoteuthidae, parateuthidae, valbyteuthidae, brachioteuthidae, pholidoteuthidae, bathyteuthidae, enoploteuthidae, octopoteuthidae, lycoteuthidae, histioteuthidae, chiroteuthidae, lepidoteuthidae, grimalditeuthidae, cranchiidae, and spirulidae.
2000. Changes in inferred spawning areas of Todarodes pacificus (Cephalopoda: Ommastrephidae) due to changing environmental conditions. – ICES Journal of Marine Science, 57: 24–30. Annual catches of Todarodes pacificus in Japan have gradually increased since the late 1980s. Paralarval abundances have also been higher since the late 1980s compared to the late 1970s and mid-1980s. Here is proposed a possible scenario for the recent stock increase based on changing environmental conditions. Based on trends in annual variations in stock and in larval abundances, catches are reviewed and potential spawning areas inferred, assuming that egg masses and hatchlings occur over the continental shelf at temperatures between 15 and 23C. Changes are then inferred in the spawning areas during 1984–1995, based on GIS data. Since the late 1980s, the autumn and winter spawning areas in the Tsushima Strait and near the Goto Islands appear to have overlapped, and winter spawning sites seem to have expanded over the continental shelf and slope in the East China Sea.
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