Why Does Not the Shrimp Stock in the Barents Sea Respond on Predation by Cod? by

• Main Authors: Michaela Aschan, Edda Johannesen, Bjarte Bogstad, Carsten Hvingel
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Barents Sea
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.562.9975; http://archive.nafo.int/open/sc/2006/scr06-071.pdf

The lack of correlation between changes in the shrimp stock and the cod consumption has been the reason why several assessment models including the predator has failed when applied on the Barents Sea shrimp stock. We modify the current Norwegian procedure to calculate cod consumption of shrimp in the Barents Sea, and explore how this affects the cod consumption estimate. The mean consumption is reduced with almost 30 % with the new approach. In some years the reduction in estimated shrimp consumption is around 70%. We point out the reason for over estimation in the old model, then justify why the new consumption estimates are better. The new consumption estimates do not result in a better cod-shrimp response. The cod was introduced as predator in the assessment model of shrimp in the Barents Sea, but the model is more robust when excluding the cod (Hvingel, 2006). This is because the shrimp stock does not respond on still high cod consumption, not even if a time lag is introduced.