134 research outputs found
Trophic ecology of deepwater fishes associated with the continental slope of the eastern Norwegian Sea
In June 1995 and 1996 demersal fishes on the continental slope of the eastem
Norwegian Sea were sampled to study distribution patterns and community structure.
The diets of the more abundant slope species were characterised and linkages within
the upper slope food-web identified.
Few cases of predator-prey relationships between the typical slope fishes were found.
Most of the smaller fishes fed on epibenthic crustaceans such as amphipods and
mysids, while pelagic crustaceans and fish dominated the diets of larger fishes.
Herring ( Clupea harengus) and blue whiting (Micromesistius poutassou) were
important prey items of Greenland halibut (Reinhardtius hippoglossoides), and were
also eaten by Lycodesfrigidus, Raja hyperborea and roughhead grenadier (Macrourus berglax). At !east for the latter three species this probably reflected scavenging
Numerous Sublinear Sets of Holes in Sediment on the Northern Mid-Atlantic Ridge Point to Knowledge Gaps in Understanding Mid-Ocean Ridge Ecosystems
On 13 July 2004, during an expedition exploring biodiversity along the northern Mid-Atlantic Ridge, an ROV dive recorded videos of numerous sublinear sets of holes in sediment at ca. 2,082 m depth. The location was north of the Azores. Each set appeared track-like. Lengths of individual series ranged from < 1 m to many meters. Each was straight or gently curved. Some series intersected or crossed. Close examination of the holes showed them to be elongate, with the long axis parallel to the axis of the series. The holes were ca. 6 × 1.5 cm, with distance between holes similar to hole length. The holes that appeared to be most recently formed were each surrounded by raised sediment. Holes that appeared older were partly filled with sediment and the raised surrounding sediment was less obvious. Overall, these lebensspuren created small-scale heterogeneity in the local soft-bottom benthic ecosystem. The source of the holes or how they were constructed is unknown, but the raised sediment may indicate excavation by an infaunal organism or digging and removal by e.g., a feeding appendage of a large epifaunal animal. None of our closeups showed any sign of living organisms inhabiting the holes. Whether the holes were connected beneath the sediment surface was not visible. The traces observed are reminiscent of ichnofossils reported from deep marine facies. We hope that future studies of the lebensspuren we report here will resolve the mystery of what created them.publishedVersio
Utbredelse, bestandsstruktur og biologi til smørflyndre Glyptocephalus cynoglossus (L.) i Skagerrak
Rapporten summerer opp eksisterende informasjon om utbredelse, alders- og størrelsessammensetning
og biologi til smørflyndre, Glyptocephalus cynoglossus , i Skagerrak
og Norskerenna, Nye data fra forsøksfiske på Skagerrakkysten i 1991 og forskningstråling
i 1980-årene presenteres og sammenholdes med eldre informasjon.
Det finnes ressursgrunnlag for økt fiske etter smørflyndre i Skagerrak, men beregning
av bestandsstørrelse, produksjon og forventet vedvarende utbytte er vanskkelig på
grunn av metodiske begrensninger
Preliminary Results on Feeding Ecology of Stomiiforme Fishes of the Northern Mid-Atlantic
Few previous studies have focused specifically on the role of the mid-ocean ridges in the ecology of pelagic fishes. This study targets on a dominant nekton component of the mid- Atlantic mesopelagic ichthyofauna - the Stomiiformes - and their food resources including zooplankton and other nekton. Its main goal is to characterize the diets of several species of these midwater fish towards understanding the trophic pathways of the deep-pelagic nekton of the northern MAR. The study material was provided by the G. O. Sars 2004 Expedition under the International project MAR-ECO. On the lab fish were dissected and diet items were identified to the lowest taxonomical level possible. Preliminary results for 8 of the 12 species proposed for this study are presented. Amphipoda and Pteropoda seem to be important in Argyropelecus aculeatus feeding, while in Sternoptix diaphana diet amphipods are clearly the most common prey. Of the identifiable items in the guts of Maurolicus mulleri and Vinciguerria attenuata copepods constitute half of the occurrences but ostracods are also relevant. These four species show more planktivorous affinities when compared with the remaining species. Cyclothone microdon and Sigmops bathyphilum had the fewest identifiable items in the guts. In C. microdon while the stomachs were not completely empty it was very frequent to have a mass of unidentifiable jelly-like material. This may indicate that this species eats gelatinous plankton. Stomias boa reveals a piscivorous behaviour. Malacosteus niger is also a predator but occasionally eats copepods. Future work includes study of the remaining species: Sigmops elongatum, Argyropelecus hemigymnus, Borostomias antarcticus and Chauliodus sloani and more detailed analyses for all the target species, consisting on determination of prey biomass and feeding guilds, calculation of the fish daily ration and predation impact of the midwater fish assemblage on their prey in an attempt to design a food web model of the nekton community associated with the MAR
Return of Norwegian spring spawning herring (Clupea harengus L.) to historical spawning grounds off southwestern Norway
From the mid-1940s to mid-1960s a northward displacement of
the spawning areas of the Norwegian Spring Spawning Herring
was observed. Further retraction of the population from
traditional feeding and spawning grounds occurred as the stock
collapsed in the late 1960s. The spawning grounds off
southwestern Norway were abandoned after 1959. Ever since,
spawning appears to have been restricted to a few coastal
grounds and offshore banks off mid-Norway, primarily off the
Møre district.
At present, the abundance of the spawning stock remains
comparatively low; 1.5-2 mill. tonnes as compared with 7-10
mill. tonnes in the 1950s. However, in the spawning seasons
from 1989 onwards, spring spawners have again been observed at
the southwestern grounds. The herring at these southern
grounds in 1990 and 1991 were Norwegian Spring Spawners and
utilized traditional spawning sites. The spawning time was
about a month later than in the 1930s but similar to that in
the 1950s. Results of acoustic surveys showed that of the
total spawning stock, 1.5 - 2 % used the southwestern grounds
i 1990 and 1991
Acoustic manual for the krill synoptic survey in 2019
The previously presented document at the 2018 ASAM WG meeting (ASAM-18-07) described a design and plans for a synoptic krill acoustic survey in CCAMLR area 48 in 2019. The survey involves the collaborative efforts of Norway, Association of Responsible Krill fishing companies (ARK: companies from Norway, Korea, China and Chile), the United Kingdom, Ukraine, Korea and China, all of whom have confirmed a commitment of survey ship time. With these commitments it is feasible to implement all transects occupied during the 2000 survey. This document is a draft survey manual, produced at the recommendation of the 2018 ASAM meeting, and describes acoustic procedures, acoustic reporting - analysis procedures and contingency plans.Acoustic manual for the krill synoptic survey in 2019publishedVersio
Multinational large scale krill synoptic survey in CCAMLR Area 48 in 2019-survey plan and protocol for consideration by SG-ASAM 2018
The objective for the Multinational Large-Scale Krill Synoptic Survey in CCAMLR area 48 3 in 2019 is to provide an updated estimate of the biomass of Antarctic krill (Euphausia 4 superba) used in models to estimate sustainable yield. The planned survey follows, as close 5 as possible, the design of the CCAMLR 2000 survey, that was undertaken in the year 2000. 6 The basis for comparisons will depend on the degree of coverage and methodology and 7 equipment available. The survey will involve the collaborative efforts of Norway, 8 Association of Responsible Krill fishing companies (ARK: companies from Norway, Korea, 9 China and Chile), United Kingdom, Ukraine, Korea and China, and hopefully also other 10 nations that still needs to confirm their participation. 11 The current survey plan organization is presented for consideration by SG-ASAM. Norway 12 has volunteered to co-ordinate the survey with other members dedicating personnel to 13 specific tasks. It is requested that members who has already made commitments on ship time, 14 also allocate contact personnel as proposed. 15 This paper has been developed after a wider consultation extending beyond the authors list. It 16 discusses some specific organizational and technical challenges to be considered by SG17 ASAM. We request advice from ASAM on “minimum requirements” regarding acoustic 18 instrumentation and sampling gear to achieve approximate consistency with the CCAMLR 19 B0 data collection protocol.Multinational large scale krill synoptic survey in CCAMLR Area 48 in 2019-survey plan and protocol for consideration by SG-ASAM 2018publishedVersio
Feeding Ecology of Coryphaenoides rupestris from the Mid-Atlantic Ridge
The Macrourid fish roundnose grenadier, Coryphaenoides rupestris, is one of the most common benthopelagic fishes on the northern mid-Atlantic Ridge. The ecology of the species is comparatively well studied in continental slope waters of the North Atlantic, but not on the mid-Atlantic Ridge, which is a central mid-ocean area of its distribution. In total, 166 specimens from the RV G.O. Sars cruise in July 2004 were examined. The diet mainly comprised cephalopods, pelagic shrimps and fish. Pelagic and benthopelagic copepods were the most numerous prey, but did not contribute much on a weight basis. Cephalopods were by far the most important prey of the small grenadiers, while shrimps and fish became increasingly significant with increasing size. Previous studies from other areas have also found pelagic prey to be important, but in contrast to this study, cephalopods were generally of less importance. The study was an element of more wide-ranging food-web studies of the mid-Atlantic Ridge macro- and megafauna communities within the international MAR-ECO project
Biologiske ressurser i området som er aktuelt som trasé for kraftkabler fra Norge til kontinentet
Rapporten er utarbeidet på oppdrag fra Statkraft Engineering, i anledning planleggingen av linjenett for overføring av elektrisk kraft fra Norge til kontinentet. Utredningen er en del av arbeidet med å vurdere konsekvensene for marine biologiske ressurser ved overføring av elektrisk kraft i monopol likestrømskabel. Rapporten er en sammenstillelse av kunnskap om biologiske ressurser i området som er aktuellt for elektrodeanlegg og kabel. Det er gitt en beskrivelse samt kartmessig framstilling av utbredelse av viktige fiskebestander i området, samt migasjon av fisk gjennom det aktuelle området
Protocols for trawl sampling, recording of biological data, and hydrography for the 2019 international synoptic krill survey in Area 48
Experience gained through participation in international programmes like BIOMASS and the CCAMLR 2000 Survey has demonstrated that standardization of equipment and methods is one of the most crucial steps for any successful work during the field sampling period and later analytical work. The following net sampling and laboratory protocols are based on the protocols developed for the CCAMLR 2000 Survey. The aim is to facilitate a joint understanding of the field and laboratory work in order for participants that carry out the upcoming International Krill Synoptic Survey 2019 to collect comparable and highquality data. This will hopefully enable the establishment of a uniform and valuable database of comparable quality with data obtained through the CCAMLR 2000 Survey and other more recent surveys that have been conducted within the region of CCAMLR Area 48.Protocols for trawl sampling, recording of biological data, and hydrography for the 2019 international synoptic krill survey in Area 48publishedVersio
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