New Ocean Life paper compares ecosystem model predictions for fisheries management

Tuesday 17 Nov 15



Ken Haste Andersen
Professor, Head of Section
DTU Aqua
+45 35 88 33 99

Nis S Jacobsen and Ken H Andersen from Centre for Ocean Life together with Tim Essington from University of Washington has published a paper looking at differences and commonalities in predictions from a trait based fish community model and Ecopath w. Ecosim.  


In the ecosystem approach to fisheries management a crucial tool is ecosystem models that can predict the impact  of fishing on marine ecosystems.  In a new paper  in Canadian Journal of Aquatic and Fisheries Science, Nis Sand Jacobsen and coauthors investigate how assumptions in  models used for ecosystem based fisheries management affect predictions of fisheries impact. They do so by looking at direct (fishery on a stock) and indirect (changes to the community when a species is fished)  effects of fishing in the Northern California Current ecosystem with an Ecopath w Ecosim model and a size based model. Ecopath w Ecosim assumes that species can be described in biomass compartments, whereas size based models consider individual and asymptotic size as the main variables describing a species. 

They find that the models do have some common predictions: biomass increases due to predation release caused by fishing were similar, as well as predictions of the maximum sustainable yield of each species. There were also some differences, i.e., explicitly modeling size structure in the models provided differences in the competition in earlier life-stages, causing different biological predictions of fishing forage fish. Secondly, the fishing mortality needed to reach maximum sustainable yield differed substantially. Similarities in model predictions can be used to evaluate the confidence in predictions, and differences can be used to identify areas of future research. 

The findings have consequences for strategic assessment of marine resources, where model predictions can ultimately affect relevant management decisions. 

The paper can be found here
28 MAY 2020