Is climate change causing the increasing narwhal (Monodon monoceros) catches in Smith Sound, Greenland?     

Martin Reinhardt Nielsen 《Polar research》2009,28(2):238-245

This paper evaluates recent changes in narwhal ( Monodon monoceros ) catches in Siorapaluk, the northernmost community in Greenland, in consideration of the effects of changing climate and uncertainty of stock delineation. The catch statistics show a significant increase in narwhal catches by hunters in Siorapaluk after 2002, which does not appear to be a result of increased effort. Hunters attribute the increase to changed sea-ice conditions providing access by boat to Smith Sound as early as June and July. This indicates that climate change is likely to have a considerable impact on narwhal hunting in northern Greenland. Traditional ecological knowledge and scientific surveys suggest that narwhal in Smith Sound constitute an independent stock. The absence of scientific recommendations for this stock has been seen as an opportunity to increase quotas in West Greenland. Scientific management recommendations are urgently needed to allow the authorities to assign sustainable quotas for this stock. The development of collaborative management agreements and locally based monitoring are recommended to ensure local acceptance of regulations, and to allow rapid responses to climate change.  相似文献   

AB Doradus C: age,spectral type,orbit, and comparison to evolutionary models     

E. L. Nielsen  L. M. Close  J. C. Guirado  B. A. Biller  R. Lenzen  W. Brandner  M. Hartung  C. Lidman 《Astronomische Nachrichten》2005,326(10):1033-1039

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Carbon cycling in a high-arctic marine ecosystem – Young Sound, NE Greenland     

Sren Rysgaard  Torkel Gissel Nielsen 《Progress in Oceanography》2006,71(2-4):426

Young Sound is a deep-sill fjord in NE Greenland (74°N). Sea ice usually begins to form in late September and gains a thickness of 1.5 m topped with 0–40 cm of snow before breaking up in mid-July the following year. Primary production starts in spring when sea ice algae begin to flourish at the ice–water interface. Most biomass accumulation occurs in the lower parts of the sea ice, but sea ice algae are observed throughout the sea ice matrix. However, sea ice algal primary production in the fjord is low and often contributes only a few percent of the annual phytoplankton production. Following the break-up of ice, the immediate increase in light penetration to the water column causes a steep increase in pelagic primary production. Usually, the bloom lasts until August–September when nutrients begin to limit production in surface waters and sea ice starts to form. The grazer community, dominated by copepods, soon takes advantage of the increased phytoplankton production, and on an annual basis their carbon demand (7–11 g C m⁻²) is similar to phytoplankton production (6–10 g C m⁻²). Furthermore, the carbon demand of pelagic bacteria amounts to 7–12 g C m⁻² yr⁻¹. Thus, the carbon demand of the heterotrophic plankton is approximately twice the estimated pelagic primary production, illustrating the importance of advected carbon from the Greenland Sea and from land in fuelling the ecosystem.In the shallow parts of the fjord (<40 m) benthic primary producers dominate primary production. As a minimum estimate, a total of 41 g C m⁻² yr⁻¹ is fixed by primary production, of which phytoplankton contributes 15%, sea ice algae <1%, benthic macrophytes 62% and benthic microphytes 22%. A high and diverse benthic infauna dominated by polychaetes and bivalves exists in these shallow-water sediments (<40 m), which are colonized by benthic primary producers and in direct contact with the pelagic phytoplankton bloom. The annual benthic mineralization is 32 g C m⁻² yr⁻¹ of which megafauna accounts for 17%. In deeper waters benthic mineralization is 40% lower than in shallow waters and megafauna, primarily brittle stars, accounts for 27% of the benthic mineralization. The carbon that escapes degradation is permanently accumulated in the sediment, and for the locality investigated a rate of 7 g C m⁻² yr⁻¹ was determined.A group of walruses (up to 50 adult males) feed in the area in shallow waters (<40 m) during the short, productive, ice-free period, and they have been shown to be able to consume <3% of the standing stock of bivalves (Hiatella arctica, Mya truncata and Serripes Groenlandicus), or half of the annual bivalve somatic production. Feeding at greater depths is negligible in comparison with their feeding in the bivalve-rich shallow waters.  相似文献   

Bayesian estimation of reservoir properties—effects of uncertainty quantification of 4D seismic data     

Kjersti Solberg Eikrem  Geir Nævdal  Morten Jakobsen  Yan Chen 《Computational Geosciences》2016,20(6):1211-1229

This paper shows a history matching workflow with both production and 4D seismic data where the uncertainty of seismic data for history matching comes from Bayesian seismic waveform inversion. We use a synthetic model and perform two seismic surveys, one before start of production and the second after 1 year of production. From the first seismic survey, we estimate the contrast in slowness squared (with uncertainty) and use this estimate to generate an initial estimate of porosity and permeability fields. This ensemble is then updated using the second seismic survey (after inversion to contrasts) and production data with an iterative ensemble smoother. The impact on history matching results from using different uncertainty estimates for the seismic data is investigated. From the Bayesian seismic inversion, we get a covariance matrix for the uncertainty and we compare using the full covariance matrix with using only the diagonal. We also compare with using a simplified uncertainty estimate that does not come from the seismic inversion. The results indicate that it is important not to underestimate the noise in seismic data and that having information about the correlation in the error in seismic data can in some cases improve the results.  相似文献   

Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence     

Swain  D. P.; Nielsen  G. A.; Sinclair  A. F.; Chouinard  G. A. 《ICES Journal of Marine Science》1994,51(4):493-504

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Using AMOEBAs to display multispecies, multifleet fisheries advice     

Collie  Jeremy S.; Gislason  Henrik; Vinther  Morten 《ICES Journal of Marine Science》2003,60(4):709-720

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From single-species advice to mixed-species management: taking the next step     

Vinther  Morten; Reeves  Stuart A.; Patterson  Kenneth R. 《ICES Journal of Marine Science》2004,61(8):1398-1409

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Can changes in the fisheries yield in the Kattegat (1950-1992) be linked to changes in primary production?     

Nielsen  E.; Richardson  K. 《ICES Journal of Marine Science》1996,53(6):988-994

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Food consumption of the NE Atlantic minke whale (Balaenoptera acutorostrata) population estimated with a simulation model     

Markussen  Nina Hedlund; Ryg  Morten; Lydersen  Christian 《ICES Journal of Marine Science》1992,49(3):317-323

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Limits to transparency exploring conceptual and operational aspects of the ICES framework for providing precautionary fisheries management advice     

Hauge  Kjellrun Hiis; Nielsen  Kare Nolde; Korsbrekke  Knut 《ICES Journal of Marine Science》2007,64(4):738-743

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