Gunnar Stefánsson

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We report on a test of three methods that have been used by ICES in making probability statements about fisheries forecasts to management agencies (XSA/WGMTERM, ICA/ICP, and a stochastic projection method that was first applied to North Sea herring). The principle of the test is to calculate many stock assessments and forecasts using historic data, and to(More)
Populations of rock ptarmigan (Lagopus muta) in Iceland fluctuate in multiannual cycles with peak numbers c. every 10 years. We studied the ptarmigan-parasite community and how parasites relate to ptarmigan age, body condition, and population density. We collected 632 ptarmigan in northeast Iceland in early October from 2006 to 2012; 630 (99.7%) were(More)
The spleen and bursa of Fabricius in birds are organs that play an important role in fighting parasite infections. The size of these organs can be used by ecologists as a measure of immune investment, with larger size implying greater investment. The bursa only occurs in juvenile birds during the development of the B cell repertoire, whereas the spleen,(More)
Generalized linear mixed-effects models can be used to combine bottom trawl data from multiple vessels, each with a different fishing power, into a single time series of relative abundance. However, how important might it be to have a consistent set of vessels and vessel characteristics from year to year given we can model differences in fishing power among(More)
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