ATLANTIS: socioECOnomics and ECOsystembased fisheries management

The primary objective of the @ECO Project was to examine how different fisheries management plans and climate change scenarios will potentially impact the ecosystem in the Barents Sea. This was achieved using the state-of-the-art system model, Atlantis, which was developed for the Barents and Nordic seas (NoBa Atlantis). Atlantis includes the effects of the physical oceanography and plankton on fish but also their effects on seabirds and marine mammals. It can also include socio-economic components, such as fishing, transportation, oil and gas development, etc. In this project we focused upon the effects of fishing and particularly compared the different impacts of single stock assessments versus the ecosystem approach to management within the Barents Sea. We also examined the combined effects of climate change and different fisheries scenarios. We joined the Indicator for the Seas (www.indiseas.org) international modelling group, and were included in their indicator-testing runs. NoBa was used in a total of 18 simulations for testing the sensitivity and responsiveness of indicators in the Barents Sea. For indicators, we used those included in the management plans of the Barents Sea, and explored the effect of increased harvest of the main commercial species on these indicators. Although being widely discussed, the large fish indicator (not included in the management plans) gave valuable information about population changes in the Barents Sea following a potential increase in harvest pressure. Preparations for these modelling simulations included defining a maximum sustainable yield (MSY) for the commercially harvested stocks. For the Northeast Arctic cod, this corresponded well to the MSY found for the Barents Sea. We noticed that single-species MSY combined gave a different ecosystem response than each of them did by themselves. The first snow crab was detected in the Barents Sea roughly 30 years ago, and is increasing in numbers. NoBa was used to evaluate the effect of this invasive species on the ecosystem in the Barents Sea, and it was shown that the increasing snow crab population was not all negative. Small snow crabs have been found in the stomachs of both cod and haddock, and with this link present, snow crabs become an important link between unused detritus/benthos and both the haddock and cod stocks (http://forskning.no/meninger/kronikk/2015/05/snokrabben-skurk-eller-nyttig-mellommann). Effects of ocean acidification were explored with NoBa. We used settings provided on the Atlantis-wiki website (http://atlantis.cmar.csiro.au/), which resulted in strong effects on several phytoplankton and zooplankton groups. However, observed effects on the zooplankton species in the Barents Sea are controversial and have been reported to be both negative and positive. Therefore, together with the Fram Ocean Acidification flagship, we attended a workshop where possible effects of OA and temperature increase on the mesozooplankton group in NoBa were discussed. During the project, work continued on improvements to the ecosystem component of the Atlantis model, as well as implementation of the fishing component. Anne Jähkel, successfully defended her masters thesis in June 2013 on tuning the predator-prey interactions in the model. The fisheries component of the model was developed and implemented although unfortunately we could not include the Russian fleets as original planned as the Russian data were not forthcoming.

@ECO will examine the implications for socio-economy and ecosystems under different management and climate scenarios using an end-to-end model (Atlantis). At the time being, management of the fish populations in the Barents Sea is mainly based on single species assessment. The Norwegian government has decided that the management should move in direction of an ecosystem-based approach. To close the gap between these two, there is a need for stepwise approach toward looking at the ecosystem as a whole, and there is at the moment a lack of tools that can build a bridge between them. Multispecies models is one tool that can be used for this purpose, and by Atlantis being an end-to-end model, which in short terms means that it covers all trophic levels of the ecosystem, it is well suited. In addition to a biophysical module, Atlantis also includes industry, assessment, management and socioeconomic submodels, and has been used successfully in ecosystem-based approaches to management (Fulton 07). One challenge by ecosystem-based management is the possible trade-offs between preserving the ecosystem and keeping an economically sustainable fishery, something made even more difficult by shared fish populations and possible climate effects. Increasing temperatures and decreasing sea ice cover might introduce indirect effects on the commercially important stocks through changes for instance in the marine mammal populations. This can cause large differences between the two different approaches to management, both wit h regards to the ecosystem and the socioeconomy. The collaboration between countries on shared resources is crucial to both economic gain and the future of the fish stock. Through @ECO we will identify useful information from Atlantis to scientists involv ed in management, and explore the main differences and challenges with the two different approaches to management.