Outreach

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Published Jan. 5, 2022 9:45 AM

Jellyfish are usually not targeted by scientific surveys that focus on commercial fish stocks. However, they are very often found in the by-catch of egg and larval surveys. In a recent paper in ICES journal of Marine Sciences, we studied such by-catch data from surveys conducted between 1959-1993 in the Barents Sea showing the high value of such historic data.

polar cod under ice
Published Nov. 25, 2021 10:56 AM

In the Arctic part of the Barents Sea, climate change is increasing temperature, melting the sea ice and bringing more predators. All these are a concern for the polar cod (Boreogadus saida) a key species in this food web. In a recent paper published in Marine Ecology Progress Series (Dupont et al. 2021) we explore which of these environmental factors has the most effect on polar cods.

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Published Aug. 26, 2021 9:05 AM

While the importance of early life survival and growth variations for population dynamics is well documented, there is still a relatively limited understanding of how survival and growth is affected by the species’ spatial distribution. In a study published in the ICES Journal of Marine Science, we analysed 24-years of indices of spatial distribution of 1 year old Northeast Arctic cod to study the role of distribution for the change in abundance and mean body size through their second winter of life.

Published Aug. 26, 2020 1:53 PM

“Bio-economic and structural equation modelling for ecosystem-based management and ecosystem accounting: Fisheries management in the Baltic Sea.”

two dell picture symbolysing cold years and warm years withe effect on cod and haddock
Published Aug. 10, 2020 12:16 PM

In the Boreal-Arctic seas, the two most abundant gadoid fish are the Atlantic cod (Gadus morhua) and the haddock (Melanogrammus aeglefinus). Both tend to respond to climate warming by an abundance increase and a change of distribution. Are these changes affecting how they are interacting? Statistical analysis using a state-space threshold model of acoustic and trawl survey data on cod and haddock abundance indicates that the interaction is changing with sea temperature: the cod negatively affecting the haddock when sea temperature is over 4 °C.

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Published Oct. 24, 2019 4:13 PM

Climate warming is changing the timing of among others the reproduction for plankton or fish. Predators depend on an abundant prey supply to feed their young and insure that they survive. When the timing of the prey and the predator are not in synchrony the predator young cannot feed and are dying: there is a mismatch.

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Published Oct. 9, 2019 8:58 AM

Conservation efforts and management decisions on the living environment of our planet often rely on imperfect statistical models. Therefore, managers have to brace for the uncertainty associated with the model and study system i.e., set their acceptable risk level, to make some decisions. However, risk estimates themselves can often be biased. In a recent paper published in Nature communications we demonstrate that one can back-calculate the correct value of risk by combining data fitting with an extensive simulation–estimation procedure.

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Published Sep. 20, 2019 2:09 PM

A new pan-arctic study indicates that Calanus copepods do not necessarily descend deep for diapause in winter; instead, parts of the population remain active. Moreover, the deeper distribution of the larger and more conspicuous Calanus hyperboreus indicates that predation pressure is a key trigger for diapause at depth. In the central Arctic Ocean where visual predation pressure is lower, copepods might be relieved from the incentive to descend and can remain closer to the surface in winter.

Published Sep. 12, 2019 12:29 PM

Since the very first representation of an ecological network (Camerano, 1880), food webs have become an important tool to explore and summarize the trophic interactions between species that coexist in an ecosystem. The architecture of food webs is intimately related to how ecosystems function, and determines the services ecosystems provide.  Changes in the structure of food webs may have drastic consequences for the functioning of ecosystems. Yet, our understanding of how food webs vary over time remains unclear.

 

Accomplishing a complete inventory of species and their interactions requires significant effort, and the diversity and dynamics of nature makes it challenging to follow variability in food webs over time: species come and go, or become more or less abundant.

 

In this study, we asked the question: How are changes in species composition (presence/absence and abundances) influencing food web structure over time?

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Published Sep. 6, 2019 1:00 AM

Extreme events in the marine environment, like marine heatwaves, are likely at least as important as changes in mean values for causing threats to biodiversity, with impacts on ecosystem services and consequences for human systems. The potential of human and natural systems to adapt to such changes remains unclear, but two recent articles in the high-impact journal PNAS look closer at the possibilities.

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Published Aug. 26, 2019 2:58 PM

Population abundance depends on production of young and survival of adults. Assessing the contribution of young production to population growth and identify the main drivers of its variability may help to identify appropriate stock management measures. What happens when several stocks, belonging to different trophic levels and habitats, as well as having different exploitation histories are sharing the same environment?

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Published July 12, 2019 8:06 AM

The Atlantic cod is one of the major predator in the Barents Sea estimated to consume over 5 million tonnes of fish in 2017. In a recent paper (Holt et al. 2019) we explore the diet of this species using a unique dataset encompassing 33 years of cod stomach sampling by Russian and Norwegian scientists. This time-series is the most comprehensive available cod diet dataset to date and is crucial in helping to answer ecologically important questions on what cod eat and why  it matters for predator-prey and food-web dynamics in the Barents Sea ecosystem. 

Published June 14, 2019 3:05 PM

What does it mean when an economist talks about field work? What is experimental economics? How do you do experiments when your sample are humans? If those questions are on your mind then this little text is for you.

Published Apr. 30, 2019 11:26 AM

Climate effects on marine ecosystems are often projected as a bottom-up process. That is, the focus of the projections is often: How do changes in physical conditions and biogeochemical processes at lower trophic levels influence living conditions for fish and other organisms at higher trophic levels? However, this view ignores feedbacks between higher and lower trophic levels.  

Atlantic cod, picture by Heike Schwermer
Published Apr. 4, 2019 5:57 PM

How can two drivers, fishing pressure and climate change, interact in inducing discontinuous dynamics in 20 Atlantic cod stocks? And how can these dynamics affect stocks´ recovery? We are trying to solve this mystery in our new paper1 published in Proceeding of the Royal Society B!

Published Dec. 4, 2018 9:45 AM

Where the fish are spawning is of tremendous importance for the population (see our post) but also for the industry relying on it, especially since harvesting is often concentrated on fish that aggregate for to spawn. Climate change and harvesting are known to strongly affect the fish population with effect on the spawning location. In a recent paper (Langangen et al. Global Change Biology) we explore the question: “who is the culprit of spawning location change: Climate or fishing?”

Published Nov. 26, 2018 1:07 AM

   Late last month, the Intergovernmental Panel on Climate Change issued a Special Report on the Impacts of Global Warming of 1.5 ºC1 above pre-industrial levels (a rather low-emission pathway), triggering a lot of discussions around its origins and impacts on natural and human systems. In this context, it would be interesting to see how the ocean is likely to respond under - what is considered today as - an "optimistic" scenario for greenhouse gas emissions in the future, relative to more severe projections. Particularly for regions vulnerable to climate change (or else "Hot Spots") like the Mediterranean Sea, such a comparison would be more meaningful to be performed for the anomalous sea surface temperatures rather than the mean temperature evolution. And if you wonder why, let’s dive into the next paragraph.