Danish Institute for Fisheries Research

Charlottenlund, Denmark

Danish Institute for Fisheries Research

Charlottenlund, Denmark
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Moloney C.L.,University of Cape Town | St John M.A.,University of Hamburg | Denman K.L.,University of Victoria | Karl D.M.,University of Hawaii at Manoa | And 3 more authors.
Journal of Marine Systems | Year: 2011

Marine food web dynamics are determined by interactions within and between species and between species and their environment. Global change directly affects abiotic conditions and living organisms, impinging on all trophic levels in food webs. Different groups of marine researchers traditionally study different aspects of these changes. However, over medium to long time scales perturbations affecting food webs need to be considered across the full range from nutrients to top predators. Studies of end-to-end marine food webs not only span organism sizes and trophic levels, but should also help align multidisciplinary research to common goals and perspectives. Topics are described that bridge disciplinary gaps and are needed to develop new understanding of the reciprocal impacts of global change on marine food webs and ocean biogeochemistry. These include (1) the effects of nutrients on biomass and production, (2) the effects of varying element ratios on food web structure and food quality, (3) bulk flows of energy and material in food webs and their efficiencies of transfer, (4) the ecological effects of species richness and the roles of microbial organisms, (5) the role of feeding behaviour in food web dynamics and trophic controls, (6) the spatial dynamics of communities and links between different food webs, (7) the combined effects of body size and behaviour in determining dynamics of food webs, and (8) the extent to which the ability of marine organisms (and communities) to adapt will influence food web dynamics. An overriding issue that influences all topics concerns the time and space scales of ecosystem variability. Threads link different nodes of information among various topics, emphasizing the importance of tackling food web studies with a variety of modelling approaches and through a combination of field and experimental studies with a strong comparative approach. © 2010 Elsevier B.V.


Vindas M.A.,Norwegian University of Life Sciences | Sorensen C.,University of Oslo | Johansen I.B.,University of Oslo | Folkedal O.,Norwegian Institute of Marine Research | And 6 more authors.
PLoS ONE | Year: 2014

Comparative studies are imperative for understanding the evolution of adaptive neurobiological processes such as neural plasticity, cognition, and emotion. Previously we have reported that prolonged omission of expected rewards (OER, or 'frustrative nonreward') causes increased aggression in Atlantic salmon (Salmo salar). Here we report changes in brain monoaminergic activity and relative abundance of brain derived neurotrophic factor (BDNF) and dopamine receptor mRNA transcripts in the same paradigm. Groups of fish were initially conditioned to associate a flashing light with feeding. Subsequently, the expected food reward was delayed for 30 minutes during two out of three meals per day in the OER treatment, while the previously established routine was maintained in control groups. After 8 days there was no effect of OER on baseline brain stem serotonin (5-HT) or dopamine (DA) activity. Subsequent exposure to acute confinement stress led to increased plasma cortisol and elevated turnover of brain stem DA and 5-HT in all animals. The DA response was potentiated and DA receptor 1 (D1) mRNA abundance was reduced in the OER-exposed fish, indicating a sensitization of the DA system. In addition OER suppressed abundance of BDNF in the telencephalon of non-stressed fish. Regardless of OER treatment, a strong positive correlation between BDNF and D1 mRNA abundance was seen in non-stressed fish. This correlation was disrupted by acute stress, and replaced by a negative correlation between BDNF abundance and plasma cortisol concentration. These observations indicate a conserved link between DA, neurotrophin regulation, and corticosteroid-signaling pathways. The results also emphasize how fish models can be important tools in the study of neural plasticity and responsiveness to environmental unpredictability. © 2014 Vindas et al.


Krogdahl A.,Aquaculture Protein Center | Hillestad M.,BioMar AS | Winberg S.,Uppsala University | Skjerve E.,Center for Epidemiology and Biostatistics | Hoglund E.,Danish Institute for Fisheries Research
British Journal of Nutrition | Year: 2013

The brain monoamines serotonin (5-hydroxytryptamine; 5-HT) and dopamine (DA) both play an integrative role in behavioural and neuroendocrine responses to challenges, and comparative models suggest common mechanisms for dietary modulation of transmission by these signal substances in vertebrates. Previous studies in teleosts demonstrate that 7 d of dietary administration with l-tryptophan (Trp), the direct precursor of 5-HT, suppresses the endocrine stress response. The present study investigated how long the suppressive effects of a Trp-enriched feed regimen, at doses corresponding to two, three or four times the Trp levels in commercial feed, last in juvenile Atlantic cod (Gadus morhua) when the fish are reintroduced to a diet with standard amino acid composition. We also wanted to determine whether Trp supplementation induced changes in brain monoaminergic neurochemistry in those forebrain structures innervated by DA-and 5-HTergic neurons, by measuring regional activity of DA and 5-HT in the lateral pallial regions (Dl) of the telencephalon and nucleus lateralis tuberis (NLT) of the hypothalamus. Dietary Trp resulted in a dose-dependent suppression in plasma cortisol among fish exposed to confinement stress on the first day following experimental diet; however, such an effect was not observed at 2 or 6 d after Trp treatment. Feeding the fish with moderate Trp doses also evoked a general increase in DA and 5-HT-ergic activity, suggesting that these neural circuits within the NLT and Dl may be indirectly involved in regulating the acute stress response. © 2012 The Authors.


Vindas M.A.,Norwegian University of Life Sciences | Vindas M.A.,University of Oslo | Johansen I.B.,University of Oslo | Vela-Avitua S.,Norwegian University of Life Sciences | And 5 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2014

Animals use aggressive behaviour to gain access to resources, and individuals adjust their behaviour relative to resource value and own resource holding potential (RHP). Normally, smaller individuals have inferior fighting abilities compared with larger conspecifics. Affective and cognitive processes can alter contest dynamics, but the interaction between such effects and that of differing RHPs has not been adjudged. We investigated effects of omission of expected reward (OER) on competing individuals with contrasting RHPs. Small and large rainbow trout (Oncorhynchus mykiss) were conditioned to associate a light with reward. Thereafter, the reward was omitted for half of the fish prior to a contest between individuals possessing a 36-40% difference in RHP. Small control individuals displayed submissive behaviour and virtually no aggression. By contrast, small OER individuals were more aggressive, and twoout of 11 became socially dominant. Increased aggression insmall OER individuals was accompanied by increased serotonin levels in the dorsomedial pallium (proposed amygdala homologue), but no changes in limbic dopamine neurochemistry were observed in OER-exposed individuals. The behavioural and physiological response to OER in fish indicates that frustration is an evolutionarily conserved affective state. Moreover, our results indicate that aggressive motivation to reward unpredictability affects low RHP individuals strongest. © 2014 The Author(s).


Anderwald P.,Durham University | Anderwald P.,University College Cork | Danielsdottir A.K.,Matis Skulagata 4 | Haug T.,Norwegian Institute of Marine Research | And 5 more authors.
Biological Conservation | Year: 2011

The minke whale is the last of the great whale species to be hunted in significant numbers. Effective management must include an understanding of how genetic diversity is divided and distributed among putative local populations, and as for many migratory species, this is complicated for the minke whale by large-scale seasonal movement among geographic regions. The problem is that the geographic identity of breeding populations is not known, and instead these whales are predictably found and hunted where different breeding stocks may mix on seasonal feeding grounds. Here we use microsatellite DNA and mtDNA markers to investigate minke whale population structure across the species' range in the North Atlantic. We found no evidence of geographic structure comparing putative populations in recognized management areas, though some limited structure had been indicated in earlier studies. However, using individual genotypes and likelihood assignment methods, we identified two putative cryptic stocks distributed across the North Atlantic in similar proportions in different regions. Some differences in the proportional representation of these populations may explain some of the apparent differentiation between regions detected previously. The implication would be that minke whales range extensively across the North Atlantic seasonally, but segregate to some extent on at least two breeding grounds. This means that established stock boundaries in the North Atlantic, currently used for management, should be re-considered to ensure the effective conservation of genetic diversity. © 2011.


Ruiz-Gomez M.D.L.,University of Glasgow | Ruiz-Gomez M.D.L.,Norwegian University of Life Sciences | Huntingford F.A.,University of Glasgow | Overli O.,Norwegian University of Life Sciences | And 2 more authors.
Physiology and Behavior | Year: 2011

An extensive literature has documented differences in the way individual animals cope with environmental challenges and stressors. Two broad patterns of individual variability in behavioural and physiological stress responses are described as the proactive and reactive stress coping styles. In addition to variability in the stress response, contrasting coping styles may encompass a general difference in behavioural flexibility as opposed to routine formation in response to more subtle environmental changes and non-threatening novelties. In the present study two different manipulations, relocating food from a previously learned location, and introducing a novel object yielded contrasting responses in rainbow trout selected for high (HR) and low (LR) post stress plasma cortisol levels. No difference was seen in the rate of learning the original food location; however, proactive LR fish were markedly slower than reactive HR fish in altering their food seeking behaviour in response to relocated food. In contrast, LR fish largely ignored a novel object which disrupted feeding in HR fish. Hence, it appears that the two lines appraise environmental cues differently. This observation suggests that differences in responsiveness to environmental change are an integral component of heritable stress coping styles, which in this particular case, had opposite effects on foraging efficiency in different situations. Context dependent fitness effects may thus explain the persistence of stable divergence of this evolutionary widespread trait complex. © 2010 Elsevier Inc.


Pampoulie C.,Iceland Marine Research Institute | Danielsdottir A.K.,Iceland Marine Research Institute | Storr-Paulsen M.,Danish Institute for Fisheries Research | Hovgard H.,Greenland Institute of Natural Resources | And 2 more authors.
Transactions of the American Fisheries Society | Year: 2011

The spawning stock of Atlantic cod Gadus morhua in West Greenland waters was characterized by a drastic decline in the late 1960s and has since exhibited considerable variation. It has been suggested that the cod stock in West Greenland waters is composed of several stock components that include (1) a number of distinct local inshore populations spawning in separate fjord systems, (2) an offshore spawning component located on the fishing banks, and (3) a periodic Icelandic-East Greenland cod influx that mixes with the offshore and inshore West Greenland stock components. In an attempt to clarify the status of Atlantic cod in Greenland waters, we investigated the genetic structure at different inshore and offshore feeding grounds east and west of Greenland. A total of 1,581 genetic samples were collected within North Atlantic Fisheries Organization areas at inshore and offshore locations as well as within the International Council for the Exploration of the Sea area XIVb. Those samples were genotyped for 18 microsatellite loci and the pantophysin (Pan I) locus. Both types of genetic markers gave congruent results and suggest the presence of two distinct genetic components with limited connectivity in Greenland waters, namely, an inshore component and an offshore component. © American Fisheries Society 2011.


Bastardie F.,Danish Institute for Fisheries Research | Nielsen J.R.,Danish Institute for Fisheries Research | Kraus G.,Danish Institute for Fisheries Research
ICES Journal of Marine Science | Year: 2010

A management strategy evaluation framework was developed for the international Baltic cod fishery to evaluate the performance and robustness of the 2008 multi-annual management plan for the eastern stock. The spatially explicit management evaluation covered two cod recruitment regimes and various fleet adaptation scenarios. The tested management options included total allowable catch control, direct effort control, and closed areas and seasons. The modelled fleet responded to management by misreporting, improving catching power, adapting capacity, and reallocating fishing effort. The model was calibrated with spatially and temporally disaggregated landings and effort data from five countries covering 83 of the total cod catches. The simulations revealed that the management plan is robust and likely to rebuild the stock in the medium term even under low recruitment. Direct effort reduction limited underreporting of catches, but the overall effect was impaired by the increased catching power or spatio-temporal effort reallocation. Closures had a positive effect, protecting part of the population from being caught, but the effect was impaired if there was seasonal effort reallocation. Over the entire 15-year simulation period, all fleets could realize variable but positive profits under all scenarios tested, owing to stock recovery. © 2009 The Author(s).


Bastardie F.,Danish Institute for Fisheries Research | Nielsen J.R.,Danish Institute for Fisheries Research | Andersen B.S.,Danish Institute for Fisheries Research | Eigaard O.R.,Danish Institute for Fisheries Research
Fisheries Research | Year: 2010

Global concerns about CO2 emissions, national CO2 quotas, and rising fuel prices are incentives for the commercial fishing fleet industry to change their fishing practices and reduce fuel consumption, which constitutes a significant part of fishing costs. Vessel-based fuel consumption, energy efficiency (quantity of fish caught per litre of fuel used), and profitability are factors that we simulated in developing a spatially explicit individual-based model (IBM) for fishing vessel movements. The observed spatial and seasonal patterns of fishing effort for each fishing activity are evaluated against three alternative effort allocation scenarios for the assumed fishermen's adaptation to these factors: (A) preferring nearby fishing grounds rather than distant grounds with potentially larger catches and higher values, (B) shifting to other fisheries targeting resources located closer to the harbour, and (C) allocating effort towards optimising the expected area-specific profit per trip. The model is informed by data from each Danish fishing vessel >15m after coupling its high resolution spatial and temporal effort data (VMS) with data from logbook landing declarations, sales slips, vessel engine specifications, and fish and fuel prices. The outcomes of scenarios A and B indicate a trade-off between fuel savings and energy efficiency improvements when effort is displaced closer to the harbour compared to reductions in total landing amounts and profit. Scenario C indicates that historic effort allocation has actually been sub-optimal because increased profits from decreased fuel consumption and larger landings could have been obtained by applying a different spatial effort allocation. Based on recent advances in VMS and logbooks data analyses, this paper contributes to improve the modelling of fishing effort allocation, fuel consumption and catch distribution on a much disaggregated level compared to the fleet-based models we developed so far. © 2010 Elsevier B.V.


PubMed | Danish Institute for Fisheries Research
Type: Journal Article | Journal: Proceedings. Biological sciences | Year: 2014

Animals use aggressive behaviour to gain access to resources, and individuals adjust their behaviour relative to resource value and own resource holding potential (RHP). Normally, smaller individuals have inferior fighting abilities compared with larger conspecifics. Affective and cognitive processes can alter contest dynamics, but the interaction between such effects and that of differing RHPs has not been adjudged. We investigated effects of omission of expected reward (OER) on competing individuals with contrasting RHPs. Small and large rainbow trout (Oncorhynchus mykiss) were conditioned to associate a light with reward. Thereafter, the reward was omitted for half of the fish prior to a contest between individuals possessing a 36-40% difference in RHP. Small control individuals displayed submissive behaviour and virtually no aggression. By contrast, small OER individuals were more aggressive, and two out of 11 became socially dominant. Increased aggression in small OER individuals was accompanied by increased serotonin levels in the dorsomedial pallium (proposed amygdala homologue), but no changes in limbic dopamine neurochemistry were observed in OER-exposed individuals. The behavioural and physiological response to OER in fish indicates that frustration is an evolutionarily conserved affective state. Moreover, our results indicate that aggressive motivation to reward unpredictability affects low RHP individuals strongest.

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