Economic impacts on key Barents Sea fisheries arising from changes in the strength of the Atlantic thermohaline circulation

A bioeconomic model of key fisheries of the Barents Sea is run with scenarios generated by an earth system model of intermediate complexity to assess how the Barents Sea fisheries of cod (Gadus morhua) and capelin (Mallotus villosus) are affected by changes in the Atlantic thermohaline circulation arising from anthropogenic climate change. Changes in hydrographic conditions have an impact on recruitment success and survival rates which constitute a lasting effect on the stocks. The economic development of the fisheries is assessed for the 21st century, considering both adaptive and profit-maximizing harvesting strategies. Results show that a substantial weakening of the THC leads to impaired cod stock development, causing the associated fishery to become unprofitable in the long run. Simultaneous improvements in capelin stock development help the capelin fishery, but are insufficient to offset the losses incurred by the cod fishery. A comparison of harvest strategies reveals that in times of high variability in stock development, profit maximization leads to more stable economic results of these fisheries than the adaptive fishing strategy.Fisheries, climate change

Economic impacts of changes in fish population dynamics: the role of the fishermen’s harvesting strategies

Using a bioeconomic model of the cod (Gadus morhua) and capelin (Mallotus villosus) fisheries of the Barents Sea, this study assesses the role of the fishermen’s behavior in reducing or intensifying the effects on the stocks caused by altered population dynamics. The analysis focuses on the economic development of the fisheries employing a profit-maximizing harvesting strategy over a given number of fishing periods. The scenarios assessed cover a time period of 100 years with sudden changes of the productivity of both species occurring at the midpoint of each simulation. Stock sizes and landings of fish are determined for each fishing period, and the net present values of profits over periods of interest prior to and following the change in population dynamics are calculated. Results show that if the profit-maximizing harvesting strategy is based on a short optimization period, the fleets with the higher efficiency are generally favored. If the strategy is based on an optimization over two or more fishing periods, fishing activities may be deferred to allow for stock regrowth. In such cases, smaller and less cost-intensive vessels are preferred. A reduction of either the productivity or the carrying capacities of the two species has little impact on the fisheries if the change is fairly small. A substantial reduction of either quantity has a lasting negative economic impact which mainly manifests itself in a severely reduced profitability of mainly the cod fishery.bioeconomic modeling, Barents Sea, cod, capelin, population dynamics, harvesting strategy

Models for an Ecosystem Approach to Fisheries

This document is one outcome from a workshop held in Gizo in October 2010 attended by 82 representatives from government, NGO's private sector, and communities. The target audience for the document is primarily organizations planning to work with coastal communities of Solomon Islands to implement Community-Based Resource Management (CBRM). It is however also envisaged that the document will serve as a reference for communities to better understand what to expect from their partners and also for donors, to be informed about agreed approaches amongst Solomon Islands stakeholders. This document does not attempt to summarize all the outcomes of the workshop; rather it focuses on the Solomon Islands Coral Triangle Initiative (CTI) National Plan of Action (NPoA): Theme 1: Support and implementation of CBRM and specifically, the scaling up of CBRM in Solomon Islands. Most of the principles given in this document are derived from experiences in coastal communities and ecosystems as, until relatively recently, these have received most attention in Solomon Islands resource management. It is recognized however that the majority of these principles will be applicable to both coastal and terrestrial initiatives. This document synthesizes information provided by stakeholders at the October 2010 workshop and covers some basic principles of engagement and implementation that have been learned over more than twenty years of activities by the stakeholder partners in Solomon Islands. The document updates and expands on a summary of guiding principles for CBRM which was originally prepared by the Solomon Islands Locally Managed Marine Area Network (SILMMA) in 2007

Historical Arctic Logbooks Provide Insights into Past Diets and Climatic Responses of Cod

Gadus morhua (Atlantic cod) stocks in the Barents Sea are currently at levels not seen since the 1950s. Causes for the population increase last century, and understanding of whether such large numbers will be maintained in the future, are unclear. To explore this, we digitised and interrogated historical cod catch and diet datasets from the Barents Sea. Seventeen years of catch data and 12 years of prey data spanning 1930–1959 cover unexplored spatial and temporal ranges, and importantly capture the end of a previous warm period, when temperatures were similar to those currently being experienced. This study aimed to evaluate cod catch per unit effort and prey frequency in relation to spatial, temporal and environmental variables. There was substantial spatio-temporal heterogeneity in catches through the time series. The highest catches were generally in the 1930s and 1940s, although at some localities more cod were recorded late in the 1950s. Generalized Additive Models showed that environmental, spatial and temporal variables are all valuable descriptors of cod catches, with the highest occurring from 15–45°E longitude and 73–77°N latitude, at bottom temperatures between 2 and 4°C and at depths between 150 and 250 m. Cod diets were highly variable during the study period, with frequent changes in the relative frequencies of different prey species, particularly Mallotus villosus (capelin). Environmental variables were particularly good at describing the importance of capelin and Clupea harengus (herring) in the diet. These new analyses support existing knowledge about how the ecology of the region is controlled by climatic variability. When viewed in combination with more recent data, these historical relationships will be valuable in forecasting the future of Barents Sea fisheries, and in understanding how environments and ecosystems may respond

Dealing with uncertainty in ecosystem models along three axes; resolution, forcing and projections

With the imminent threat of climate change, there is an urgent need to understand how warmer temperatures will affect marine ecosystems. Models provide the best tools to study the future, but although great efforts have been made to understand the impacts of warming temperatures, there is still large uncertainties related to the model projections. The uncertainties can arise from structural uncertainty of the ecosystem model, uncertainties regarding climate projections, or uncertainties related to how species will respond to future climate changes. In this thesis, we therefore apply ecosystem models of varying complexity, climate models of varying resolution and climate projections under various emission scenarios to understand and quantify uncertainty. By assessing the uncertainty, we highlight consistent results that suggest higher confidence, and areas where differences in the results suggest that more research is needed. The results from this thesis are divided into three research papers. The first paper deals with structural uncertainty regarding model complexity, as we explore the role of Northeast Atlantic cod (Gadus Morhua) in the Barents Sea food web by using a multi-model approach. We apply two ecosystem models of different complexity; the minimalistic Gompertz model and the highly complex Atlantis model, to study how capelin and polar cod respond to changing levels of cod. We highlight consistent results across the models and identify diverging results due to differences in spatial structure and number of foodweb components, and conclude that for fishery management purposes, the two models can complement each other. The second paper deals with uncertainty regarding the resolution of climate projections used to force ecosystem models, where we apply physics (temperature, salinity, volume transport and sea ice) from a regional model (Nemo-NAA10km) and its driving global climate model (NorESM2) to the Nordic and Barents Seas Atlantis ecosystem model (NoBa). We found that few higher trophic level (TL>3) species were affected by using forcing from a global versus a regional model, and there was a general agreement in future biomass trends and distribution patterns. Yet, our results showed how a slight difference in temperature can have dramatic consequences for specific species and demonstrate that species projection uncertainty could arise from poor representation of the physical forcing, as well as due to uncertainty in the ecosystem model parameterization. In the third and final paper, we deal with the uncertainty regarding ecosystem responses to future climate changes. We apply physics from three different climate projections (SPP1-2.6, SSP2-4.5 and SSP5-8.5) to study the impact of rising temperatures in the Nordic and Barents Seas using NoBa. To account for uncertainty in the response of phytoplankton and zooplankton to future climate change, we included variation in phyto- and zooplankton growth levels. We identify potential winners and losers in a warming climate and focus on the underlying mechanisms that drives the changes in the model, including spatial differences, thermal tolerance, and species interactions. Through our work we have demonstrated the value of using ecosystem models of varying complexity, climate models of varying resolution and climate projections under various emission scenarios to quantify uncertainty regarding model projections. By investigating uncertainty along these three axes, we learn more about the models and the mechanisms that drives the changes and provide valuable insight for management and future ecosystem studies.Med klimaendringer som en overhengende trussel, er det et stort og økende behov for å forstå hvordan varmere temperaturer vil påvirke marine økosystemer. Modeller er et av de viktigste verktøyene for å studere hvordan utviklingen vil bli, men selv om stor innsats har blitt lagt ned for å forstå konsekvenser av varmere temperaturer, er det fortsatt stor usikkerhet knyttet til modell-projeksjonene. Usikkerheten kan skyldes strukturell usikkerhet i økosystemmodellene, usikkerhet knyttet til klimaprognoser eller usikkerhet knyttet til hvordan ulike arter vil reagere på fremtidige klimaendringer. I denne oppgaven bruker vi derfor økosystemmodeller med varierende kompleksitet, klimamodeller med varierende oppløsning og ulike klimascenarier for å belyse denne usikkerheten. På den måten kan vi rapportere resultater som samsvarer med høyere pålitelighet, og påpeke forskjeller i resultatene som tilsier at det vil være behov for mer forskning. Resultatene fra denne avhandlingen er delt inn i tre forskningsartikler. Den første artikkelen omhandler strukturell usikkerhet knyttet til modellkompleksitet. Ved å benytte to modeller av ulik kompleksitet (den minimalistiske Gompertz-modellen og den svært komplekse Atlantis-modellen) gransker vi rollen til nordøstatlantisk torsk (Gadus Morhua) i Barentshavet ved å studere hvordan lodde og polartorsk reagerer på endrede nivåer av torsk. Vi synliggjør samsvarende resultater på tvers av modellene og identifiserer divergerende resultater som oppstår på grunn av forskjeller i romlig struktur og antall økosystem-komponenter. Konklusjonene våre er at fiskeriforvaltningen kan dra nytte av å bruke flere modeller, og at de to modellene utfyller hverandre. Den andre artikkelen omhandler usikkerhet rundt oppløsningen av klimamodellene, og i hvilken grad høy oppløsning av fysikken er nødvendig for å studere effekter i økosystemmodeller. Her bruker vi fysikk (temperatur, saltholdighet, volumtransport og havis) fra en regional modell (Nemo-NAA10km) og dens drivende globale klimamodell (NorESM2) i en Atlantis modell (NoBa) for de Nordiske hav og Barentshavet. Resultatene viste at få arter på høyere trofisk nivå (TL>3) ble påvirket av å bruke fysikk fra en global versus en regional modell, og at det var en generell enighet om fremtidige biomassetrender og distribusjonsmønstre. Likevel så vi hvordan selv små temperaturforskjeller kan ha dramatiske konsekvenser for enkelte arter, og hvordan slike forskjeller kan oppstå både med utgangspunkt i usikkerhet rundt fysikken, samt usikkerheter i hvordan modellen representerer artenes temperaturtoleranse. I det tredje og siste artikkelen studerer vi usikkerheten knyttet til påvirkning av fremtidige klimaendringer på økosystemet i de Nordiske hav og i Barentshavet. Ved å anvende av tre ulike klimascenarier (SPP1-2.6, SSP2-4.5 og SSP5-8.5) studerer vi hvordan økende temperaturer vil påvirke artene i NoBa-modellen. For å ta høyde for usikkerhet i fremtidige nivåer av plante- og dyreplankton, inkluderte vi variasjon i disse gruppene. Fokus i studien ligger på de underliggende mekanismene som driver endringene i modellen, og vi identifiserer potensielle vinnere og tapere i et varmere klima. I denne avhandlingen fremhever vi verdien av å bruke økosystemmodeller av varierende kompleksitet, klimamodeller med varierende oppløsning og ulike utslippsscenarier for å håndtere usikkerhet i modellene våre. Ved å undersøke usikkerhet langs disse tre aksene lærer vi mer om modellene og mekanismene som driver endringene, samt gir verdifull innsikt for forvaltning og fremtidige økosystemstudier

Long term bilateral Russian-Norwegian scientific co-operation as a basis for sustainable management of living marine resources in the Barents Sea : proceedings of the 12th Norwegian-Russian Symposium, Tromsø, 21-22 August 2007

Since 1986 the Institute of Marine Research, (IMR), Norway and the Knipovich Polar Research Institute of Marine Fisheries and Oceanography (PINRO), Russia, have carried out a joint research program on the trophic relationships in the Barents Sea. As part of this program, the two institutions have exchanged quantitative diet data from fish in the Barents Sea, mainly cod. Diet data can give information about important trophic links in the ecosystem and the strenght of those links. Therefore, diet data is important for quantifying interactions between fish stocks, e.g. by calculating how natural mortality due to predation influences their dynamics. In this paper we give an overview of diet data collected by IMR and PINRO during the last 20 years, and present some results and perspectives for future work

Long term bilateral Russian-Norwegian scientific co-operation as a basis for sustainable management of living marine resources in the Barents Sea : proceedings of the 12th Norwegian-Russian Symposium, Tromsø, 21-22 August 2007

Since 1986 the Institute of Marine Research, (IMR), Norway and the Knipovich Polar Research Institute of Marine Fisheries and Oceanography (PINRO), Russia, have carried out a joint research program on the trophic relationships in the Barents Sea. As part of this program, the two institutions have exchanged quantitative diet data from fish in the Barents Sea, mainly cod. Diet data can give information about important trophic links in the ecosystem and the strenght of those links. Therefore, diet data is important for quantifying interactions between fish stocks, e.g. by calculating how natural mortality due to predation influences their dynamics. In this paper we give an overview of diet data collected by IMR and PINRO during the last 20 years, and present some results and perspectives for future work

Impact of ocean warming on sustainable fisheries management informs the Ecosystem Approach to Fisheries

Acknowledgements Serpetti N., Heymans J.J., and Burrows M.T. were funded by the Natural Environment Research Council and Department for Environment, Food and Rural Affairs under the Marine Ecosystems Research Programme (MERP) (grant No. NE/L003279/1). Baudron A. and Fernandes, P.G. were founded by Horizon 2020 European research projects MareFrame (grant No. 613571) and ClimeFish (grant No. 677039). Payne, B.L. was founded by the Natural Environment Research Council and Department for Environment under the ‘Velocity of Climate Change’ (grant No. NE/J024082/1).Peer reviewedPublisher PD

Evaluating the suitability of coupled biophysical models for fishery management

The potential role of coupled biophysical models in enhancing the conservation, management, and recovery of fish stocks is assessed, with emphasis on anchovy, cod, herring, and sprat in European waters. The assessment indicates that coupled biophysical models are currently capable of simulating transport patterns, along with temperature and prey fields within marine ecosystems; they therefore provide insight into the variability of early-life-stage dynamics and connectivity within stocks. Moreover, the influence of environmental variability on potential recruitment success may be discerned from model hindcasts. Based on case studies, biophysical modelling results are shown to be capable of shedding light on whether stock management frameworks need re-evaluation. Hence, key modelling products were identified that will contribute to the development of viable stock recovery plans and management strategies. The study also suggests that approaches combining observation, process knowledge, and numerical modelling could be a promising way forward in understanding and simulating the dynamics of marine fish populations