Bunnfiskundersøkelser i Barentshavet vinteren 2006

A combined acoustic and bottom trawl survey to obtain indices of abundance and estimates of length and weight at age has been carried out each winter (4-6 weeks in January- March) since 1981 in the Barents Sea. The target species are cod and haddock, but abundance indices have also been worked out for the redfish species since 1986 and Greenland halibut since 1990. Prior to 1993 a fixed standard area (ABCD in Fig. 2.1) was covered, but in 1993 the survey area was extended to the north and east in order to obtain a more complete coverage of the younger age groups of cod. In winter 1997 only the Norwegian part of the Barents Sea and a small part of the Svalbard area was covered, while in 1998 also a small part of the Russian EEZ was covered. In 1999 and 2000 the Norwegian vessels had full access to the Russian EEZ. In the years 2001-2005 a Russian research vessel covered the areas where the Norwegian vessels did not have access. In 2006 no Russian vessel participated, and an area off the Murman coast could not be covered

Investigations on demersal fish in the Barents Sea winter 2006

A combined acoustic and bottom trawl survey to obtain indices of abundance and estimates of length and weight at age has been carried out each winter (4-6 weeks in January- March) since 1981 in the Barents Sea. The target species are cod and haddock, but abundance indices have also been worked out for the redfish species since 1986 and Greenland halibut since 1990. Prior to 1993 a fixed standard area (ABCD in Fig. 2.1) was covered, but in 1993 the survey area was extended to the north and east in order to obtain a more complete coverage of the younger age groups of cod. In winter 1997 only the Norwegian part of the Barents Sea and a small part of the Svalbard area was covered, while in 1998 also a small part of the Russian EEZ was covered. In 1999 and 2000 the Norwegian vessels had full access to the Russian EEZ. In the years 2001-2005 a Russian research vessel covered the areas where the Norwegian vessels did not have access. In 2006 no Russian vessel participated, and an area off the Murman coast could not be covered

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

Macro- and megafauna on the slopes of the Saya de Malha Bank of the Mascarene Plateau

A first characterization of the distribution and composition of benthic and demersal macro- and megafauna was derived based on video records sampled along five pre-determined transects up the slope on the western, northern and eastern sides of the Saya de Malha Bank on the Mascarene Plateau, starting at a maximum depth of 1000 m. Abundance was highest in the upper parts of eastern slope locations, primarily reflecting a relatively higher abundance of black corals (Antipatharia) than in other locations. A consistent feature of several transects, but most prominent in eastern and northern slopes, was the occurrence of patchy coral and sponge aggregations along the margin where the substrate was mostly hard. In some cases, these aggregations might be considered ‘gardens’ but reefs were not observed. Higher-level taxonomical composition of the fauna is presented. Demersal fish were widespread but not abundant, and within the depth range studied, there was a transition from a marginal shallow fish assemblage to a deepwater assemblage. Fishes were in most cases only assigned to family level, and 49 families were recorded. To thoroughly assess the biodiversity and abundance of fauna of the slopes of Saya de Malha Bank, further studies conducting more detailed video transects and sampling of specimens are warranted

Demersal Fish Assemblages and Spatial Diversity Patterns in the Arctic-Atlantic Transition Zone in the Barents Sea

Direct and indirect effects of global warming are expected to be pronounced and fast in the Arctic, impacting terrestrial, freshwater and marine ecosystems. The Barents Sea is a high latitude shelf Sea and a boundary area between arctic and boreal faunas. These faunas are likely to respond differently to changes in climate. In addition, the Barents Sea is highly impacted by fisheries and other human activities. This strong human presence places great demands on scientific investigation and advisory capacity. In order to identify basic community structures against which future climate related or other human induced changes could be evaluated, we analyzed species composition and diversity of demersal fish in the Barents Sea. We found six main assemblages that were separated along depth and temperature gradients. There are indications that climate driven changes have already taken place, since boreal species were found in large parts of the Barents Sea shelf, including also the northern Arctic area. When modelling diversity as a function of depth and temperature, we found that two of the assemblages in the eastern Barents Sea showed lower diversity than expected from their depth and temperature. This is probably caused by low habitat complexity and the distance to the pool of boreal species in the western Barents Sea. In contrast coastal assemblages in south western Barents Sea and along Novaya Zemlya archipelago in the Eastern Barents Sea can be described as diversity “hotspots”; the South-western area had high density of species, abundance and biomass, and here some species have their northern distribution limit, whereas the Novaya Zemlya area has unique fauna of Arctic, coastal demersal fish. (see Information S1 for abstract in Russian)

Investigations on demersal fish in the Svalbard area autumn 2000 and 2001, with special attention on juvenile Greenlandhalibut

In 1996, Institute of Marine Research in Bergen initiated a program to investigate to what degree Greenland halibut's nursery grounds extended to the north and east of Spitsbergen. Norwegian vessels executed this survey until 1999 with coverage with some stations of the Russian EEZ in 1998 and 1999. At the annual meeting between Russian and Norwegian scientists it was decided to make this survey a joint survey, and the first year with a joint effort of both a Russian and a Norwegian vessel was year 2000. The survey was conducted as a traditional bottom trawl survey with main focus on Greenland halibut, but also analyses were carried out on cod, redfish and long rough dab. The main results in 2000 and 2001 were: signs of improved recruitment of Greenland halibut, the year-classes 1999 and 2000 were the strongest in the time series, mean length and mean weight were in accordance with previous years, low abundance of cod in the survey area with no length groups which substantially dominate the estimates, very low abundance of redfish in the survey area, both S. mentella and S. marinus, long rough dab most abundant in the area with the widest distribution of the surveyed species, the long rough dab estimates strongly dominated by fish smaller than 25 cm

Investigations on demersal fish in the Svalbard area autumn 2003, with special attention on juvenile Greenland halibut

Institute of Marine Research in Bergen started in 1996 a program to investigate to what degree Greenland halibut’s nursery grounds extended to the north and east of Spitsbergen, and Norwegian vessels executed this survey until 1999 with coverage with some stations into the Russian EEZ in 1998 and 1999. The annual meeting between Russian and Norwegian scientists decided to extend this survey to a joint survey, and the first year with joint effort with a Russian and a Norwegian vessel was year 2000. The survey was conducted as a traditional bottom trawl survey with main focus on Greenland halibut, but also analyses were carried out for cod, redfish and long rough dab. The main results in 2003 were: - Ice conditions in 2003 were the worst in the survey history and this caused significant limitation of surveyed area. - Water temperature on the investigated area at surface was less than in 2002, and near bottom slightly lower in the eastern part and higher in the northern area. - Due to heavy ice conditions it had been impossible to conduct observations in the important areas where dense concentrations of young Greenland halibut had been found in previous years. - It leads to a decline in the abundance indices of all Greenland halibut length groups in comparison with estimates obtained in 2002. - Abundance index for cod in 2003 was four times less than in 2002 and interpreted as the second smallest in the time series, only the result from 1998 was lower. The reduction was observed in all length groups with the exception of the young fish within 10-14 cm. - The abundance of redfishes (both S. marinus and S. mentella) was about two times higher than in 2002 in spite of the reduced distribution area. - Long rough dab abundance indices in 2003 were higher than what was found in 2002, but still remained at the low level in comparison with 1999-2001