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Atlantic cod (Gadus morhua) is among the most important commercial fish species on the world market. Its infection by ascaridoid nematodes has long been known, Pseudoterranova even being named cod worm. In the present study, 755 individuals were sampled in the Barents, Baltic and North Seas during 2012-2014.Prevalences for Anisakis in whole fish and in fillets in the different fishing areas varied from 16 to 100% and from 12 to 90% respectively. Abundance was also greatly influenced by the sampling area. Generalized additive model results indicate higher numbers of Anisakis in the North Sea, even after the larger body size was accounted for. Numbers and prevalence of Anisakis were positively related to fish length or weight. The prevalence of parasites in whole fish and in fillets was also influenced by the season, with the spring displaying a peak for the prevalence in whole fish and, at the same time, a drop for the prevalence in fillets. Whereas 46% of cod had Anisakis larvae in their fillets, the majority (39%) had parasites mainly in the ventral part of the fillet and only 12% had parasites in their dorsal part. This observation is of importance for the processing of the fish. Indeed, the trimming of the ventral part of the cod fillet would allow the almost total elimination of ascaridoids except for cod from the Baltic Sea where there was no difference between the dorsal and the ventral part.The presence of other ascaridoid genera was also noticeable in some areas. For Pseudoterranova, the highest prevalence (45%) in whole fish was observed in the Northern North Sea, whereas the other areas had prevalences between 3 and 16%. Contracaecum was present in every commercial size cod sampled in the Baltic Sea with an intensity of up to 96 worms but no Contracaecum was isolated from the Central North Sea. Non-zoonotic Hysterothylacium was absent from the Baltic Sea but with a prevalence of 83% in the Barents and the Northern North Sea.A subsample of worms was iden

Knowledge of species' ecological niches can be used to assess ecological interactions between different taxa. Sixteen species of cetaceans have been recorded in Galician waters and niche partitioning is expected to occur among these species in order to allow them to co-exist. In this study, the niches occupied by five of the most commonly encountered odontocete species off Galicia (NW Iberia) were compared, based on seven ecogeographic variables, using a PCA-based methodology and Classification trees. Significant differences in niche centres and niche widths were found among all the species. During the summer, the harbour porpoise occupied the narrowest and most differentiated niche when compared to the rest of the species. Three species could be compared during the winter, when long-finned pilot whales preferred colder and less variable water temperatures than did common dolphins. Seasonal differences in habitat preferences were found for bottlenose dolphins. A higher degree of specialisation was found during the summer, resulting in stronger differences in habitat use in this season, which may be related to an increment in resource availability during the upwelling period (April-September). The PCA-based methodology used in this study provides an effective multivariate approach to explore niche partitioning between co-existing species. (c) 2013 Elsevier Ltd. All rights reserved.

Over the past two decades, cephalopod molluscs have attracted increased attention from marine biologists and fishery scientists. Several species are important for European fisheries, as targets of small‐scale coastal fisheries and/or as bycatch in multispecies fisheries for demersal fish. The present report draws on a series of reviews prepared in 2005 for the CEPHSTOCK project (see Section 1). The taxonomy of the main resource species is reviewed (Section 2), and brief descriptions of each species are provided, along with information from studies of population genetics, habitat requirements of paralarvae and adults, and health and ecotoxicology (Section 3). The main fisheries are described, including illustration of gears used in specialized small‐scale fisheries and a discussion of the socio‐economic importance of the fisheries. The current status of cephalopod aquaculture is reviewed, highlighting notable advances in commercial culture of octopus and cuttlefish (Section 4). Current fishery data collection and fishery management are described, noting that there is no setting of landings quotas and no routine assessment of stock status. Options for stock assessment are discussed, drawing on one‐off assessments made during specific projects and current practice elsewhere in the world. The “live fast, die young” lifehistory strategies of cephalopods present particular challenges, but parallels can be drawn with short‐lived fish (Section 5). Finally, the report looks to the future, reviewing possible effects of climate change on cephalopods. It discusses the future development of aquaculture and fisheries for cephalopods, including prospects for fishery forecasting and fishery management – especially in relation to the small‐scale directed fisheries. Various knowledge gaps are identified, and ideas for research to fill these gaps are presented.

Cephalopods play a significant role in coastal and oceanic ecosystems, both as consumers of invertebrates and small fish and as the prey of some fish, seabirds and marine mammals and other large predators. Approximately 30 species of cephalopod have been recorded in the north-eastern Atlantic and adjacent waters, including 18 teuthid (squid), seven sepiolid (bobtail), three sepiid (cuttlefish) and 10 octopod (octopus) species. A number of these are exploited commercially and support important target and by-catch fisheries in Western Europe. During the past decade, annual landings of cephalopods from the north-eastern Atlantic (International Council for the Exploration of the Sea [ICES] area) have ranged from 40,000 to 55,000 t, including substantial catches of long-fin (loliginid) squid (7000–11,000 t per annum), short-fin (ommastrephid) squid (3000–10,000 t), cuttlefish (including sepiolids; 16,000–24,000 t) and octopods (12,000–18,000 t). The most important exploited species in the north-eastern Atlantic are Eledone cirrhosa, Illex coindetii, Loligo forbesi, Loligo vulgaris, Octopus vulgaris, Todarodes sagittatus, Todaropsis eblanae and Sepia officinalis. Other species including Alloteuthis subulata, Gonatus fabricii and certain sepiolids, appear to be abundant and may be marketable. Cephalopods tend to rapidly concentrate heavy metals and other toxic substances in their tissues and this plays an important role in the bioaccumulation of these pollutants in marine predators as well as having implications for human consumption. High levels of cadmium and mercury are often recorded in cephalopod tissues. Another important environmental issue concerns the potential impact of widespread human activity on cephalopod spawning areas, particularly bottom-fishing operations but also shipping, and oil exploration and production. In contrast to many finfish species that spawn annually over a number of years, most cephalopods live only 1–2 yr and die after spawning. Therefore

To investigate the trophic ecology of two of the dominant families of deep-sea fish (Macrouridae and Moridae) fatty acid and stable isotope analyses were applied to liver and muscle samples of five abundant species from the NE Atlantic. In conjunction with stomach content data these methods made it possible to identify differences in feeding strategies between the five study species as well as variation in feeding in relation to increasing depth and body size. Biomarkers identified strong similarities between Coryphaenoides armatus and Antimora rostrata though differences were found associating C. armatus more with the benthic food web whereas A. rostrata showed stronger links to the pelagic food web. While Lepidion eques was classified as a species linking benthic and benthopelagic food webs, both fatty acid and stable isotope data suggested that Coryphaenoides guentheri fed on an exclusively benthic diet. Coryphaenoides rupestris on the other hand were largely dependent on a copepod-based food web. Ontogenetic changes in feeding were found for both A. rostrata and C. armatus with the indication of a switch from active predation to scavenging occurring with increasing body size. Biomarkers also reflected the seasonal influx from the photic zone though changes were species-specific and probably reflected the variation in prey availability and abundance in response to these inputs. Our findings have thus demonstrated that the combined use of these biomarkers can elucidate trophic specialisations in situations where conventional methods alone previously provided insufficient data.

A study of the reproductive biology of the loliginid squid, Alloteuthis subulata in the North Sea, Irish Sea and Portuguese waters was carried out. A predominance of small squid (<50 mm ML) during autumn was observed in all three areas. Multi-modal size-frequency distributions were apparent in both sexes. The greatest complexity was observed in Portuguese waters, with males exhibiting possibly four or more modal size classes. Sexually mature squid were found throughout the year, with generally more mature squid in spring-summer and fewer in autumn-winter. In Portuguese waters, maturity in both sexes peaked in spring, whereas maturity in the other areas peaked in summer. Similar sizes-at-maturity were observed, with male squid maturing over a greater size range (40–125 mm ML) than females (30–50 mm ML). An apparent secondary peak in male maturity at 65 mm ML suggests two different size-maturation patterns in Portuguese waters. Estimates of potential fecundity in the Irish Sea ranged from 2200–13 500 eggs per female. Mean egg diameters of 0.45 mm and 1.55 mm were recorded for developing oocytes and mature ova, respectively. Three to four modal size classes of oocytes were apparent in each ovary. There was some indication of latitudinal effects on growth, maturation and reproduction of A. subulata across its geographic range. The greater complexity of size-structure in warmer waters suggests that water temperature may be the main factor involved, possibly through shorter incubation times, faster growth and maturation rates and extended spawning periods.

Cephalopods are highly sensitive to environmental conditions and changes at a range of spatial and temporal scales. Relationships documented between cephalopod stock dynamics and environmental conditions are of two main types: those concerning the geographic distribution of abundance, for which the mechanism is often unknown, and those relating to biological processes such as egg survival, growth, recruitment and migration, where mechanisms are sometimes known and in a very few cases demonstrated by experimental evidence. Cephalopods seem to respond to environmental variation both ‘actively’ (e.g. migrating to areas with more favoured environmental conditions for feeding or spawning) and ‘passively’ (growth and survival vary according to conditions experienced, passive migration with prevailing currents). Environmental effects on early life stages can affect life history characteristics (growth and maturation rates) as well as distribution and abundance. Both large-scale atmospheric and oceanic processes and local environmental variation appear to play important roles in species–environment interactions. While oceanographic conditions are of particular significance for mobile pelagic species such as the ommastrephid squids, the less widely ranging demersal and benthic species may be more dependent on other physical habitat characteristics (e.g. substrate and bathymetry). Coastal species may be impacted by variations in water quality and salinity (related to rainfall and river flow). Gaps in current knowledge and future research priorities are discussed. Key research goals include linking distribution and abundance to environmental effects on biological processes, and using such knowledge to provide environmental indicators and to underpin fishery management.

Abundance of the loliginid squid Loligo forbesi in Western and Northern Scottish (UK) waters (ICES fishery subdivisions IVa and VIa) 1989–1998 was estimated using “depletion” methods. Fishery catch and effort data for UK and French fishing vessels were obtained from official government statistics. Biological data were collected during monthly sampling visits to Kinlochbervie (Scotland, UK) fish market. Effects of using different indices for natural mortality and different model fits were evaluated. The results indicate initial (pre-fishing season) annual population sizes in the order of 106 animals. Significant between-year variation in the seasonal pattern of body weight and recruitment indicates that contemporaneous biological data, collected every month (or more frequently) are needed to underpin annual estimates.

In this study, we consider the influence of mesoscale oceanographic processes around the Falkland Islands (Islas Malvinas) in the South-west Atlantic, during the period in which the commercial squid fishery for Illex argentinus operates. Spatially referenced fishery data and satellite-derived advanced very high resolution radiometry (AVHRR) sea surface temperature (SST) data were examined using geographic information system (GIS) techniques. The distribution and relative abundance of I. argentinus in the Falkland Islands fishery was examined for the period 1989-96. Three consistent areas of high abundance were observed to the north-east (shelf-break region) and north-west (shelf region) of the islands, and close to the northern coast of East Falkland. Areas of high sea surface temperature gradients (thermal gradients) extracted from remotely sensed satellite images were used as an indicator of mesoscale oceanographic activity and compared with the location of the fishery. I. argentinus were found to be associated with areas of thermal gradients, commonly seen at the interface of Falkland Current and Patagonian shelf waters. The techniques used in this analysis allow the overlay and analysis of physical oceanographic and fishery data with potential applications in fisheries management and operational fisheries oceanography.