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Publications (99)
There have been several large capelin stock declines (collapses) in the Barents Sea since the 1980s. A recent study by Olsen et al., using a state-space model and parameters from a previously published paper in 2018 covering the years 1980-2015, concluded that the authors can confidently say that they did not find support for the hypothesis that hi...
The 5th International Conference on the Effects of Climate Change on the World’s Ocean (ECCWO5) was held from April 17 to 21, 2023, in Bergen, Norway. Some seven hundred ocean experts from around the world gathered online and under the sunny blue sky at Bryggen, a historic waterfront harbor. The ECCWO conference series was initiated in 2008, aiming...
Climate change continues to exert pressure on ocean ecosystems. The fisheries-related responses, such as altered body growth, recruitment and spatial distribution of the targeted stock(s), have generally been reasonably well investigated. Nevertheless, there are still important knowledge gaps in how biophysical drivers impact stock productivity and...
Methods to reliably identify jump discontinuities in biological time series and to assess the specific contribution of various covariates are rapidly progressing. Here, we took advantage of these statistical improvements as well as those seen in complementary, down‐scaled climate and biogeochemical models to investigate causes of the substantial in...
The reproductive success of marine ectotherms is especially vulnerable in warming oceans due to alterations in adult physiology, as well as embryonic and larval survival prospects. These vital responses may, however, differ considerably across the species' geographical distribution. Here we investigated the life history, focusing on reproductive ec...
Impacts of climate change on ocean productivity sustaining world fisheries are predominantly negative but vary greatly among regions. We assessed how 39 fisheries resources—ranging from data-poor to data-rich stocks—in the North East Atlantic are most likely affected under the intermediate climate emission scenario RCP4.5 towards 2050. This region...
Fisheries independent surveys support science and fisheries assessments but are costly. Evaluating the efficacy of a survey before initiating it could save costs. We used the NORWECOM.E2E model to simulate Northeast Atlantic mackerel and Norwegian spring spawning herring distributions in the Norwegian Sea, and we ran vessel transects in silico to s...
The epi- and mesopelagic ecosystems of four sub-polar ocean basins, the Labrador, Irminger, Iceland and Norwegian seas, were surveyed during two legs from Bergen, Norway, to Nuuk, Greenland, and back to Bergen. The survey was conducted from 1 May to 14 June, and major results were published in five papers (Drinkwater et al., Naustvoll et al., Stran...
We observed herring horizontal and vertical distribution during feeding migration along a 128 km transect across the Arctic front of the Norwegian and Iceland seas, in early June, in relation to its physical, chemical and biological environment, distribution of prey organisms and pelagic and mesopelagic competitors. The Norwegian Spring Spawning he...
The increasing need to account for the many factors that influence fish population dynamics, particularly those external to the population, has led to repeated calls for an ecosystem approach to fisheries management (EAFM). Yet systematically and clearly addressing these factors, and hence implementing EAFM, has suffered from a lack of clear operat...
Results from investigations of the Barents Sea environment and biological resources were presented at a Russian–Norwegian Symposium in Murmansk, Russia on 5–7 June 2018. The thematic focus of the symposium was “Influence of ecosystem changes on harvestable resources at high latitudes”. Contributions to the symposium were organized under five theme...
Navigating the Future is a publication series produced by the European Marine Board providing future perspectives on marine science and technology in Europe. Navigating the Future V (NFV) highlights new knowledge obtained since Navigating the Future IV (2013). It is set within the framework of the 2015 Paris Agreement and builds on the scientific b...
The distribution and population dynamics of zooplankton are affected by the interplay between currents, behavior, and selective growth, mortality, and reproduction. Here, we present an individual based model for a copepod where life-history and behavioral traits are adapted using a genetic algorithm approach. The objectives were to investigate the...
The present study uses bioenergetics modeling to estimate the annual consumption of the main zooplankton groups by some of the most commercially important planktivorous fish stocks in the Northeast Atlantic, namely Norwegian spring-spawning (NSS) herring (Clupea harengus), blue whiting (Micromesistius poutassou) and NEA mackerel (Scomber scombrus)....
Social learning can be fundamental to cohesive group living, and schooling fishes have proven ideal test subjects for recent work in this field. For many species, both demographic factors, and inter- (and intra-) generational information exchange are considered vital ingredients in how movement decisions are reached. Yet key information is often mi...
There are indications of top down control of zooplankton by pelagic planktivorous fish in the Norwegian Sea (NS). The present study uses bioenergetics modeling to estimate the annual consumption of the main zooplankton groups by the most abundant small pelagic fish feeding in the NS: the Norwegian spring-spawning (NSS) herring (Clupea harengus), bl...
High abundance of Northeast Atlantic mackerel (Scomber scombrus L.), combined with limited food resources, may now force mackerel to enter new and productive regions in the northern Norwegian
Sea. However, it is not known how mackerel exploit the spatially varying feeding resources, and their vertical distribution
and swimming behaviour are also la...
Johan Hjort’s so-called second recruitment hypothesis addressed the fate of offspring that drift out of areas suitable for their survival. This hypothesis has forged the concept of a population as a closed life cycle, making countercurrent adult spawning migration a necessary mechanism in balancing larval drift. The Norwegian spring-spawning (NSS)...
The North Atlantic is a productive marine region which has supported
important commercial fisheries for centuries. Many of these fisheries have
exploited the pelagic species, including herring, blue whiting and tuna.
Here we present data on the distribution of herring and blue whiting based
on the international ecosystem survey in the Nordic Seas (...
Fish stock productivity, and thereby sensitivity to harvesting, depends on physical (e.g. ocean climate) and biological (e.g. prey availability, competition and preda-tion) processes in the ecosystem. The combined impacts of such ecosystem pro-cesses and fisheries have lead to stock collapses across the world. While traditional fisheries management...
Ytterst få av verdens fiskebestander forvaltes etter prinsippene i såkalt økosystembasert fiskeriforvaltning. Det mest vanlige er énbestandsforvaltning, som behandler hver bestand for seg. Men fiskebestandene er ikke frikoblet økosystemet; de påvirker og påvirkes av andre arter og mange ulike prosesser: Hvor mye byttedyr som er tilgjengelig, konkur...
The north Atlantic is a productive marine region which has supported important com-
mercial fisheries for centuries. Many of these fisheries have exploited the pelagic
species, including herring, blue whiting and tuna. Here we present data on the dis-
tribution of herring and blue whiting based on surveys in the Norwegian Sea, the Bay
of Biscay and...
Marine ecosystem acoustics (MEA): quantifying processes in the sea at the spatio-temporal scales on which they occur. – ICES Journal of Marine Science, doi: 10.1093/icesjms/fsu116. Sustainable management of fisheries resources requires quantitative knowledge and understanding of species distribution, abundance, and prod-uctivity-determining process...
It has long been recognized that there are strong interactions and feedbacks between climate, upper ocean biogeochemistry and marine food webs, and also that food web structure and phytoplankton community distribution are important determinants of variability in carbon production and export from the euphotic zone. Numerical models provide a vital t...
This paper reviews the current knowledge on the ecology of widely distributed pelagic fish stocks in the North Atlantic basin with emphasis on their role in the food web and the factors determining their relationship with the environment. We consider herring (Clupea harengus), mackerel (Scomber scombrus), capelin (Mallotus villosus), blue whiting (...
Patterns in the co-occurrence of small pelagic fish species within single shoals were investigated using data from 6 814 throws of commercial purse-seiners in South Africa. Assuming that the throw composition reflected the true composition of the assemblage, it was shown that: (1) mixed pelagic assemblages were as prevalent as pure shoals; (2) asse...
The copepod Calanus finmarchicus is the dominant species of the meso-zooplankton in the Norwegian Sea, and constitutes an important link between the phytoplankton and the higher trophic levels in the Norwegian Sea food chain. An individualbased model for C. finmarchicus, based on super-individuals and evolving traits for behaviour, stages, etc., is...
There is growing interest in models of marine ecosystems that deal with the effects of climate change through the higher trophic levels. Such end-to-end models combine physicochemical oceanographic descriptors and organisms ranging from microbes to higher-trophic-level (HTL) organisms, including humans, in a single modeling framework. The demand fo...
Assessment of open-ocean ecosystems relies on understanding ecosystem dynamics, and development of end-to-end ecosystem models represents an approach that addresses these challenges. These models incorporate the population structure and dynamics of marine organisms at all trophic levels. Satellite remote sensing of ocean colour and direct at-sea me...
This paper reviews the current knowledge on the ecology of widely distributed pelagic fish stocks in the North Atlantic basin with emphasis on their role in the food web and the factors determining their relationship with the environment. We consider herring (Clupea harengus), mackerel (Scomber scombrus), capelin (Mallotus villosus), blue whiting (...
The Norwegian Sea is one of the core areas of the copepod Calanus finmarchicus. We use 33 drift trajectories of RAFOS floats over 6 months to describe and discuss overwinter transportation of C. finmarchicus in the Norwegian Sea. The mean drift speed of the floats was 5.7 cms−1, which resulted in a mean trajectory length of 881 km. The correspondin...
Energy flow and trophic regulation are often well understood in closed freshwater ecosystems. Such regulation is harder to understand in large marine ecosystems, as they extend over vast areas and are influenced by adjacent marine areas. Fully coupled biophysical models have increased in popularity during recent years, but these models are still in...
The Norwegian Sea harbours several large pelagic fish stocks, which use the area for feeding during the summer. The period 1995–2006 had some of the highest biomass of pelagic fish feeding in the Norwegian Sea on record. Here we address the horizontal distribution and overlap between herring, blue whiting and mackerel in this period during the summ...
The copepod Calanus finmarchicus is the dominant species of the meso-zooplankton in the Norwegian Sea, and constitutes an important link between the phytoplankton and the higher trophic levels in the Norwegian Sea food chain. An individual-based model for C. finmarchicus, based on super-individuals and evolving traits for behaviour, stages, etc., i...
The most abundant pelagic fish species in the Norwegian Sea, Norwegian spring-spawning herring, Northeast Atlantic mackerel and Northeast Atlantic blue whiting have inter-annual variation in their summer feeding migrations. Knowledge about the spatial distribution and overlap is essential for understanding the species’ interactions and their impact...
This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the cont...
The Norwegian Sea harbours some of the largest pelagic fish stocks in the world including the Norwegian spring-spawning (NSS) herring and blue whiting, and it has been hypothesized that there are foraging interactions between these stocks. Here we address the vertical distribution and interactions of these stocks based on 12 years of survey data. T...
A new concept for modelling habitat choice, called an adapted random walk, is presented. The concept is based on the evolution of threshold values for departures and destinations using a genetic algorithm. A habitat is departed if the fitness value associated with it is below the evolved threshold value. Movement is determined probabilistically usi...
Background:
Individual-based biophysical larval models, initialized and parameterized by observations, enable numerical investigations of various factors regulating survival of young fish until they recruit into the adult population. Exponentially decreasing numbers in Northeast Arctic cod and Norwegian Spring Spawning herring early changes emphas...
Fish learning skills in the human worldFisheriesAquacultureStock enhancement and sea-ranchingEscapees from aquacultureCapture-based aquacultureConclusions and perspectivesAcknowledgementsReferences
The Terms of Reference for WGECO in 2011 were more diverse, and also more focused on responses to other groups within ICES than has been the case in some previous years. There was also a considerable overlap in scope between the ToR. As in previous years, there was considerable focus on the science needed to support the objectives of the Marine Str...
We investigate the trade-offs associated with vertical migration and swimming speed of Atlantic cod (Gadus morhua) using an adaptive individual-based model. Simulations with varying distribution and occurrence of prey, with and without swimbladder constraints, and visual predation were performed. Most simulations resulted in cod migrations between...
The life history of capelin (Mallotus villosus) is presently suggested to be sex specific: while males follow a semelparous batch-spawning strategy, females are iteroparous. This hypothesis is based on predictions from a life history simulation model of Barents Sea capelin that shows that iteroparity is more profitable than semelparity for females,...
The CLIOTOP (mid‐trophic automatic acoustic sampling) project and the EurOcean consortium are organizing a workshop in May 2011 in Bergen, Norway. The presentation will summarize the discussions and conclusions from the workshop. The workshop will deal with the technological and modeling issues related to the mass deployment of acoustic sensors in...
Recent studies in the marine environment have suggested that the limited phenotypic plasticity of cold-adapted species such as Atlantic cod Gadus morhua L. will cause distributions to shift toward the poles in response to rising sea temperatures. Some cod stocks are predicted to collapse, but this remains speculative because almost no information i...
Kempf, A., Dingsør, G. E., Huse, G., Vinther, M., Floeter, J., and Temming, A. 2010. The importance of predator–prey overlap: predicting North Sea cod recovery with a multispecies assessment model. – ICES Journal of Marine Science, 67: 1989–1997.
The overlap between predator and prey is known as a sensitive parameter in multispecies assessment mode...
Petitgas, P., Secor, D. H., McQuinn, I., Huse, G., and Lo, N. 2010. Stock collapses and their recovery: mechanisms that establish and maintain life-cycle closure in space and time. – ICES Journal of Marine Science, 67: 1841–1848.
Experience has established that the recovery of many collapsed stocks takes much longer than predicted by traditional fi...
Norwegian spring spawning (NSS) herring migrate to wintering areas in late summer and remain there for about 5 mo in dense aggregations. First-time spawning cohorts typically adopt the wintering area of the spawning stock. However, over the last 50 yr the NSS herring stock has occupied 7 discrete wintering grounds, spanning from the high seas to na...
Climate and human influences on marine ecosystems are largely manifested by changes in predator-prey interactions. It follows that ecosystem-based management of the world's oceans requires a better understanding of food web relationships. An international workshop on predator-prey interactions in marine ecosystems was held at the Oregon State Unive...
Marine ecosystem models often contain modules for two phytoplankton compartments (flagellates and diatoms) and two zooplankton groups (micro- and mesozooplankton). The models rarely include fish, not even as an agent in zooplankton mortality, which is often formulated as a constant rate. This mortality rate is treated as a free parameter, which can...
Climate may affect marine fish populations through many different pathways, operating at a variety of temporal and spatial scales. Climate impacts may work their way bottom up through the food web or affect higher trophic levels more directly. In this review we try to disentangle and summarize some of the current knowledge made available through th...
The copepod Calanus finmarchicus is an important part of the Norwegian Sea ecosystem because of its dominating abundance and importance as prey for fish larvae and adult planktivorous fish. The abundance of C. finmarchicus on the Norwegian shelf is generally low in winter, whereas in spring the shelf is replenished by individuals that overwinter at...
The spawning strategy of cod has evolved through natural selection to give larvae a good start in life. Therefore, larval drift, growth, and survival are key processes to understand spawning strategies. Spawning of Northeast Arctic (NA) cod stretches from late February to early May over 1500 km along the Norwegian coast. Hatching occurs from late M...
Huse, G., Salthaug, A., and Skogen, M. D. 2008. Indications of a negative impact of herring on recruitment of Norway pout. – ICES Journal of Marine Science, 65: 906–911.
The Norway pout (Trisopterus esmarkii) stock in the North Sea has experienced poor recruitment recently. Herring (Clupea harengus) has been suggested to be a major predator on fish...
IntroductionSpecifying Individuals in IBMsFeatures of Individual—Based ModelsFormulating and Testing IBMSReview of Individual—Based Models in Fisheries BiologyConclusions
AcknowledgementsReferences
The capelin is a small pelagic fish that performs long distance migrations. It is a key species in the Barents Sea ecosystem
and its distribution is highly climate dependent. Here we use an individual based model to investigate consequences of global
warming on capelin distribution and population dynamics. The model relies on input on physics and p...
The EU project BALANCE (Global Change Vulnerabilities in the Barents region: Linking Arctic Natural Resources, Climate Change and Economies) aims to assess vulnerability to climate change in the Barents Sea Region. As a prerequisite the potential impact of climate
change on selected ecosystems of the study area has to be quantified, which is the su...
The Norwegian Ecological Model (NORWECOM) biophysical model system implemented with the ROMS ocean circulation model has been run to simulate conditions over the last 25 years for the North Atlantic. Modeled time series of water volume fluxes, primary production, and drift of cod larvae through their modeled ambient temperature fields have been ana...
Highly resolved general circulation models (GCMs) now generate realistic flow fields,
and have revealed how sensitive larval drift routes are to vertical positioning in the water column.
Sensible representation of behavioural processes then becomes essential to generate reliable patterns
of environmental exposure (growth and survival), larval drift...
While data storage tags typically provide information about depth and temperature, the horizontal position of fish is difficult
to obtain. The objective of this study is therefore to introduce a method for reconstructing horizontal migration patterns
of fish tagged with DSTs. The method works by: establishing a database on bathymetry and environmen...
While data storage tags typically provide information about depth and temperature, the horizontal position of fish is difficult to obtain. The objective of this study is therefore to introduce a method for reconstructing horizontal migration patterns of fish tagged with DSTs. The method works by: establishing a database on bathymetry and environmen...
Simulation models that describe autonomous individual organisms (individual based models, IBM) or agents (agent-based models, ABM) have become a widely used tool, not only in ecology, but also in many other disciplines dealing with complex systems made up of autonomous entities. However, there is no standard protocol for describing such simulation...
Using a regional ocean circulation model and particle tracking, we have studied the probability of the copepod Calanus finmarchicus being retained within the Nordic Seas' population as a function of its initial location, its vertical migration pattern, and the interannual variability in physical forcing. Defining a retention index in terms of the n...
We present a bioenergetic model for buoyancy regulation that incorporates the restrictions and costs of swimbladder regulation with four means of hydrodynamic lift production: hovering, swimming with extended pectoral fins, swimming with adjusted tilt angle, and body lift. Previous models addressing vertical migration in fish with swimbladders have...
According to the adopted-migrant hypothesis, first time spawning herring Clupea harengus learn their migration pattern from schooling with older individuals. Changes in migration pattern of Norwegian spring-spawning herring co-occur with the recruitment of abundant year classes to the spawning stock. It is argued that this is due to the abundant ye...
The objective of this study was to use spatially explicit individual-based models for simulating the movement, foraging, growth, and mortality of cod and capelin in the Barents Sea in order to identify general features in their migration patterns and the consumption of capelin by cod. The individual-based models are initiated from survey data run o...
Search by olfaction is common in many aquatic animals, and this feature is exploited by the fishing industry, which has a
long tradition in the use of longlines, pots, and other kinds of baited gear. Here we discuss a range of possible search strategies
that fish might apply when searching for prey; this in order to improve our understanding of fis...
We apply an artificial neural network (ANN) to predict recruitment and biomass development of Northeast Arctic cod. The ANN is trained using a genetic algorithm with input time series such as spawning stock biomass of cod, herring and capelin biomass, and temperature. Forecasts were made by training the ANN on parts of the time series (training set...
Organisms in nature are both proximate (operating by rules of thumb) and adapted (the rules influenced by natural selection). We introduce new methods that can be used to study in silico versions of organisms behaving according to proximate adapted rules. Our approach goes beyond neural networks and offers an alternative to optimization methods. It...
We present an individual-based model that uses artificial evolution to predict fit behavior and life-history traits on the basis of environmental data and organism physiology. Our main purpose is to investigate whether artificial evolution is a suitable tool for studying life history and behavior of real biological organisms. The evolutionary adapt...
The state of the art in spatial modelling in physical and biological oceanography is reviewed in light of its relevance for marine resource management, based on discussions during a workshop in marine spatial modelling. The quality of the spatial models strongly depends on the assimilation of data. With the present level of investment in modelling...
Due to a negative correlation between juvenile herring abundance and Barents Sea capelin recruitment, it has been hypothesised that predation by herring (Clupea harengus, L.) causes poor recruitment in the capelin stock (Mallotus villosus, Müller). In order to investigate whether herring are important predators of larval capelin, stomachs of herrin...
An artificial neural network (ANN) approach for predicting stock abundance of the Barents Sea capelin (Mallotus villosus) is presented. The method is based on training an ANN with a genetic algorithm using input data of ecological importance to the capelin stock. Stock abundance for the coming year is estimated using the trained ANN with the curren...
We evaluated the costs and benefits of long-distance horizontal migration by pelagic planktivores, Atlantic herring (Clupea harengus), blue whiting (Micromesistius poutassou), mackerel (Scomber scombrus), and capelin (Mallotus villosus) in the Norwegian and Barents seas using a numerical model and tested model predictions against field observations...
Even though individual-based models (IBMs) have become very popular in ecology during the last decade, there have been few
attempts to implement behavioural aspects in IBMs. This is partly due to lack of appropriate techniques. Behavioural and life
history aspects can be implemented in IBMs through adaptive models based on genetic algorithms and ne...
A conceptual approach to study spatial movements of fish using an individual-based neural network genetic algorithm model is presented. Artificial neural networks, where the weights are adapted using a genetic algorithm, are applied to evolve individual movement behaviour in a spatially heterogeneous and seasonal environment. A 2D physical model (f...
Our ability to model spatial distributions of fish populations is reviewed by describing the available modelling tools. Ultimate models of the individual's motivation for behavioural decisions are derived from evolutionary ecology. Mechanistic models for how fish sense and may respond to their surroundings are presented for vision, olfaction, heari...
The fecundity and oocyte diameter of 70 female capelin (Mallotus villosus) from the Barents Sea were investigated. The average fecundity (±SE) was 11 542 (±261). Oocyte diameter and fecundity increased
with increasing weight and length of the capelin. Interannual variation in capelin fecundity is large, and corresponds to
differences in body weight...
Capelin (Mallotus villosus) and adolescent Norwegian spring spawning herring (Clupea harengus) cooccur in the southern Barents Sea during early summer. The diets of both species were dominated by calanoid copepods, and the overlap in diet was large. Both for herring and capelin the proportion of copepods in the diet decreased with increasing fish s...
Abundance of Barents Sea capelin larvae (6–25 mm) is estimated every summer using samples from a Gulf III sampler. It has been suggested that a MIK net would be more efficient in sampling larvae exceeding 18–20 mm in length. On this basis the length distributions of larval capelin captured by Gulf III, MIK, and MOCNESS in six consecutive hauls were...
Three aspects linked to the management advice process of Northeast arctic cod have been studied; 1. Changes in the geographical distribution, 2. Recruitment predictions and 3. Food availability and growth. Around 1980, intense cooling caused a redistribution of the cod in the Barents Sea towards the south and west. High fish densities and thus catc...
Conveners: Thomas Noji (USA), Pierre Pepin (Canada), and Geir Huse (Norway) The role of pelagic and benthic marine habitats for the sustainability of fisheries has received considerable theoretical attention over the last decade. It is now accepted by most marine habitat and fisheries scientists that habitat plays a critical role in the life histor...
There is accumulating evidence in favour of the hypothesis that herring migrations are influenced by social learning. The "adopted-migrant hypothesis" postulates that recruit spawning herring learn migration patterns by schooling with older individuals. However, this learning can be interrupted if the stock is unstable or if there are lack of overl...
