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The Scenario C project aims at a dynamic minimal realistic model for capelin, herring, cod, harp seals and minke whales in the Barents Sea and for herring in the Norwegian Sea. This report is an attempt to estimate a consumption function for cod from estimated monthly abundances of capelin, herring...
| Main Authors: | , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.417.7644 http://publications.nr.no/3908/Zhu_-_Scenario-C_The_cod_predation_model.pdf |
| Summary: | The Scenario C project aims at a dynamic minimal realistic model for capelin, herring, cod, harp seals and minke whales in the Barents Sea and for herring in the Norwegian Sea. This report is an attempt to estimate a consumption function for cod from estimated monthly abundances of capelin, herring and younger cod in regions of the Barents Sea, and the observed stomach contents of cods. The data are obtained from Institute of Marine Research. A discrete choice model for the diet choice and consumption function of cod in the Barents Sea is implemented using the data of cod and three main prey species (herring, capelin, cod) from 1992-2000. It uses the notion of choice probability to describe the foraging behavior. In particular, it estimates how prey selection varies with respect to environmental changes. By using diet choice model, prey consumption can be easily computed and predicted from environmental variables. In conclusion, the empirical results are quite consistent with the hypothesis that prey selection probability is highly related to the biomass amount of the specific prey. Particularly when the biomass is at low levels, even a small increase will lead to a large probability change, with the more available biomass, the smaller the growth. At high levels, the probability is nearly linear in biomasses. As a whole, the probability change is modeled to have a logistic pattern. In addition, it shows that cod prefers capelin, rather than young cod and herring. Emneord/Keywords: Scenario, cod, predation, multinomial logit modell |
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