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Behavioral and neurophysiological effects of buspirone in healthy and depression-like state juvenile salmon
Get PDFA proportion of farmed salmon in seawater show a behaviorally inhibited, growth stunted profile known as a depression-like state (DLS). These DLS fish are characterized by chronically elevated serotonergic signaling and blood plasma cortisol levels and the inability to react further to acute stress, which is suggestive of chronic stress. In this study, we characterize the neuroendocrine profile of growth stunted freshwater parr and confirm that they show a DLS-like neuroendocrine profile with a blunted cortisol response and no serotonergic increase in response to acute stress. Furthermore, we attempted to reverse this DLS-like profile through pharmacological manipulation of the serotonin (5-HT) system with buspirone, an anxiolytic medication that acts as a serotonin receptor agonist (i.e., decreases serotonergic signaling). We found that while buspirone decreases anxiolytic-type behavior in healthy fish, no quantifiable behavioral change was found in DLS-like fish. However, there was a physiological effect of diminished basal serotonergic signaling. This suggests that at the physiological level, buspirone appears to reverse the neuroendocrine DLS profile. With a deeper understanding of what causes DLS profiles and growth stunting in juvenile fish, steps can be taken in terms of husbandry to prevent repeated stressors and the formation of the DLS profile, potentially reducing losses in aquaculture due to chronic stress.publishedVersio
A multi-scenario analysis of climate impacts on plankton and fish stocks in northern seas
Get PDFGlobally, impacts of climate change display an increasingly negative development of marine biomass, but there is large regional variability. In this analysis of future climate change on stock productivity proxies for the North Sea, the Norwegian Sea, and the Barents Sea, we have provided calculations of accumulated directional effects as a function of climate exposure and sensitivity attributes. Based on modelled changes in physical and biogeochemical variables from three scenarios and knowledge of 13 different stocks' habitats and response to climate variations, climate exposures have been weighted, and corresponding directions these have on the stocks have been decided. SSP1-2.6 gives mostly a weak cooling in all regions with almost negligible impacts on all stocks. SSP2-4.5 and SSP5-8.5 both provide warmer conditions in the long term but are significantly different in the last 30 years of the century when the SSP5-8.5 warming is much stronger. The results show that it is the current stocks of cod and Calanus finmarchicusin the North Sea, and polar cod and capelin in the Barents Sea that will be most negatively affected by strong warming. Stocks that can migrate north into the northern seas such as hake in the Norwegian Sea, or stocks that are near the middle of the preferred temperature range such as mackerel and herring in the Norwegian Sea and cod and Calanus finmarchicus in the Barents Sea, are the winners in a warmer climate. The highly different impacts between the three scenarios show that multiple scenario studies of this kind matter.publishedVersio
Bifangst av sjøfugl i kystnært notfiske – utvikling og testing av avbøtende tiltak - Tokt med MS "Vestbris" 6 - 10.1.2024
Get PDFNotfiskeriene tiltrekker store mengder sjøfugler som beiter på fisken som blir samlet sammen i nøtene og er lett tilgjengelig for fuglene. Dette kan føre til uheldige interaksjoner der sjøfugl blir tatt som bifangst. Det er dokumentasjon på at det kan være utfordringer knyttet til bifangst av sjøfugl i Norske notfiskerier. I tillegg til å ha uheldige konsekvenser for enkelt fugl og muligens sjøfugl populasjoner, har bifangst av sjøfugl ingen økonomisk verdi for fiskeren og kan medføre et tap av omdømme for fiskeriet. Det er derfor ønskelig at slik bifangst reduseres til et minimum, og der det forekommer bifangst av sjøfugl bør det tilstrebes å utvikle metodikk for å forebygge bifangsten. På toktet ble det testet ut skremmemetoder basert på lys og lyd. Resultatene tyder på at måker rundt og i sildenøtene kan skremmes bort med lydsignaler f.eks. ved bruk av enkelte håndholdte signalhorn eller båtens signalhorn. Tilvenning kan være et problem og det var ikke mulig å se på dette i våre forsøk. Fordelen i notfiske er at bifangst episodene er sjeldne og det er en relativt kort periode i den sisten fasen av et notkast der fuglene kan sette seg fast i nota og da det kan være behov for avbøtende tiltak. I tillegg til effektive og enkle løsninger for skremming er det viktig at mannskapet på båtene følger med på situasjonen, er bevisste på problemstillingen og har gode rutiner om sjøfugl skulle sette seg fast i nota.Bifangst av sjøfugl i kystnært notfiske – utvikling og testing av avbøtende tiltak - Tokt med MS "Vestbris" 6 - 10.1.2024publishedVersio
Population genomics of the white-beaked dolphin (Lagenorhynchus albirostris): Implications for conservation amid climate-driven range shifts
Get PDFClimate change is rapidly affecting species distributions across the globe, particularly in the North Atlantic. For highly mobile and elusive cetaceans, the genetic data needed to understand population dynamics are often scarce. Cold-water obligate species such as the white-beaked dolphin (Lagenorhynchus albirostris) face pressures from habitat shifts due to rising sea surface temperatures in addition to other direct anthropogenic threats. Unravelling the genetic connectivity between white-beaked dolphins across their range is needed to understand the extent to which climate change and anthropogenic pressures may impact species-wide genetic diversity and identify ways to protect remaining habitat. We address this by performing a population genomic assessment of white-beaked dolphins using samples from much of their contemporary range. We show that the species displays significant population structure across the North Atlantic at multiple scales. Analysis of contemporary migration rates suggests a remarkably high connectivity between populations in the western North Atlantic, Iceland and the Barents Sea, while two regional populations in the North Sea and adjacent UK and Irish waters are highly differentiated from all other clades. Our results have important implications for the conservation of white-beaked dolphins by providing guidance for the delineation of more appropriate management units and highlighting the risk that local extirpation may have on species-wide genetic diversity. In a broader context, this study highlights the importance of understanding genetic structure of all species threatened with climate change-driven range shifts to assess the risk of loss of species-wide genetic diversity.publishedVersio
Efficiency of salmon production in submerged cages with air domes matches standard surface cages when environments are similar
Get PDFSubmerged cage technology may enable placement of salmon farms at more exposed sites whilst avoiding the impacts of damaging weather on farm structures. Field trials have demonstrated that Atlantic salmon grow well in submerged cages for a full production cycle if an air dome is provided to enable salmon to refill their swim bladders at depth, but on occasion submerged fish have slower growth and poorer fish welfare. This could be due to submerged fish experiencing less optimal environmental conditions, the physiological effects of holding fish submerged at depth, restricted access to surface air, or an interaction between these factors. Here, we designed an experiment to remove possible environmental and depth-related effects, which enabled a direct test of the effect of restricted surface access to air due to submergence. Atlantic salmon were cultured for 11 months in either standard surface cages or submerged cages with air domes installed with a ceiling at 1-m depth to stop normal surface access. Environmental conditions were similar in surface and submerged cages. Restricted surface access had minimal effect on fish behaviour, growth, condition, welfare and harvest quality of submerged fish relative to fish held in standard surface cages. Backscattering from echo signals showed that the volume of air in the swim bladders of submerged and surface cage fish was similar, indicating submerged fish captured enough air via the air dome to maintain neutral buoyancy throughout the production period. These findings help progress commercial use of air domes and submergence, as they show the feasibility of maintaining optimal growth rates in Atlantic salmon when submerged for long periods if environmental conditions during submergence are equivalent or better than surface conditions.publishedVersio
Spawning fish maintains trophic synchrony across time and space beyond thermal drivers
Get PDFIncreasing ocean temperature will speed up physiological rates of ectotherms. In fish, this is suggested to cause earlier spawning due to faster oocyte growth rates. Over time, this could cause spawning time to become decoupled from the timing of offspring food resources, a phenomenon referred to as trophic asynchrony. We used biological data, including body length, age, and gonad developmental stages collected from >125,000 individual Northeast Arctic cod (Gadus morhua) sampled between 59 and 73° N in 1980–2019. Combined with experimental data on oocyte growth rates, our analyses show that cod spawned progressively earlier by about a week per decade, partly due to ocean warming. It also appears that spawning time varied by more than 40 days, depending on year and spawning location. The significant plasticity in spawning time seems to be fine-tuned to the local phytoplankton spring bloom phenology. This ability to partly overcome thermal drivers and thus modulate spawning time could allow individuals to maximize fitness by closely tracking local environmental conditions important for offspring survival. Our finding highlights a new dimension for trophic match–mismatch and should be an important consideration in models used to predict phenology dynamics in a warmer climate.publishedVersio
Comments to the EFSA public hearing of genetically modified maize DP202216 (application EFSA-GMO-NL-2019-159)
No full textThe Norwegian Committee for Food and Environment (VKM) has performed a preliminary assessment of an application for authorization for the genetically modified maize event DP202216 in the EAA. The scope of the application includes all uses of maize DP202216 and sub-combinations independently of their origin equivalent to the uses of any other maize grain and forage. The assessment was performed in connection with EFSAs (European Food Safety Authorities) public hearing of application EFSA-GMO-NL-2019-159, on request from the Norwegian Food Safety Authority and the Norwegian Environment Agency. The assessment of maize DP202216 is based on information provided by the applicant in the application EFSA-GMO-NL-2019-159, and relevant peer-reviewed scientific literature. Maize DP202216 has the potential to enhanced grain yield, and provides tolerance to glufosinate-ammonium herbicides. Authorisation process for genetically modified organisms Through the EEA Agreement, the EU Directive 2001/18/EC on deliberate release into the environment of genetically modified organisms is implemented in Norwegian law. Norway is therefore affiliated with the GMO authorisation process in the EU. In the EU, both GMOs and derived products are regulated by the Directive and Regulation 1829/2003/EC. The Regulation concerns genetically modified food and feed and is currently not a part of the EEA Agreement. In preparation for a legal implementation of the Regulation in Norwegian law, Norway follows the EU proceedings for GMO applications. When a company seeks approval of a genetically modified organism, the application is submitted to the national competent authority of an EU Member State, which forwards the application to EFSA. EFSA then submits the application for a public hearing across all EEA countries. VKM conducts its own review of the application and sends its comments to EFSA. EFSA then completes their scientific opinion based on information from the applicant, comments from EEA member countries and independent literature. The scientific opinion is then issued to the European Commission. VKM submitted their comments on application EFSA-GMO-NL-2019-159 to EFSA before the deadline January 3, 2020.Comments to the EFSA public hearing of genetically modified maize DP202216 (application EFSA-GMO-NL-2019-159)publishedVersio
Large-scale culturing of the subpolar foraminifera Globigerina bulloides reveals tolerance to a large range of environmental parameters associated to different life-strategies and an extended lifespan
Get PDFThe subtropical to subpolar planktic foraminifera Globigerina bulloides is a calcifying marine protist, and one of the dominant foraminiferal species of the Nordic Seas. Previously, the relative abundance and shell geochemistry of fossil G. bulloides have been studied for palaeoceanographic reconstructions. There is however a lack of biological observations on the species and a poor understanding of its ecological tolerances, especially for high latitude genotypes. Here, we present observations from the first extensive culturing of G. bulloides under subpolar conditions, including the first low temperature (6–13°C) and variable salinity (30–38) experiments. Carbonate chemistry (pH and [CO32−]) was also manipulated. Experimental conditions were chosen to reflect a range of plausible past and future scenarios for the Nordic Seas. We found G. bulloides to be tolerant of environmental conditions well outside their optimal range (<10°C, salinity <33, pH <8). Observed life span was up to three months, which was attributed to a microalgal diet. Two alternative life strategies were employed, whereby individuals either experienced rapid growth and death, or a prolonged lifespan with minimal growth and death via slow decay. We posit this could help explain differences in geochemical signals recorded from different size fractions of fossil specimens used for palaeoceanographic reconstructionsLarge-scale culturing of the subpolar foraminifera Globigerina bulloides reveals tolerance to a large range of environmental parameters associated to different life-strategies and an extended lifespanpublishedVersio
Continuous sound from a marine vibrator causes behavioural responses of free-ranging, spawning Atlantic cod (Gadus morhua)
Get PDFMarine vibrators are a new technology being developed for seismic surveys. These devices can transmit continuous instead of impulsive sound and operate over a narrower frequency band and at lower peak pressure than airguns, which is assumed to reduce their environmental impacts. We exposed spawning Atlantic cod (Gadus morhua) to sound produced by a prototype, but full-scale, marine vibrator, and monitored behavioural responses of tagged cod using acoustic telemetry. Fish were exposed to 10 × 3 h continuous sound treatments over a 4-day period using a randomised-block design. Sound exposure levels were comparable to airgun exposure experiments conducted previously with the same set-up ranging from ∼115 to 145 dB re 1 μPa2s during exposure. Telemetry data were used to assess 1) whether marine vibrator exposure displaced cod from the spawning ground, through estimation of residence and survival probabilities, and 2) fine-scale behavioural responses within the test site, namely swimming depth, activity levels, displacement, and home ranges. Forty-two spawning cod were tagged prior to the exposure, with 22 present during the exposure. All 22 tags were equipped with pressure sensors and ten of these additionally with accelerometers. While no premature departure from the spawning site was observed, cod reacted to the exposure by decreasing their activity levels (by up to 50%, SE = 7%) and increasing their swimming depth (by up to 2.5 m, SE = 1.0 m) within the test site during the exposure period. These behavioural responses varied by sex and time of day. Cod reactions to a marine vibrator may be more pronounced than reactions to airguns, possibly because continuous sound is more disturbing to fish than intermittent sound at the same exposure levels. However, given sample size limitations of the present study, further studies with continuous sound are necessary to fully understand its impact and biological significance.publishedVersio
Chromosomal aberrations and early mortality in a non-mammalian vertebrate: example from pressure-induced triploid Atlantic salmon
Get PDFIn commercial aquaculture, the production of triploid fish is currently the most practical approach to prevent maturation and farm-to-wild introgression following escapes. However, triploids often exhibit poor welfare, and the underlying mechanisms remain unclear. Inheritance issues associated with sub-optimal hydrostatic pressure treatments used to induce triploidy, or the genetic background of parental fish, have been speculated to contribute. We tested this by quantifying the frequency and type of chromosomal aberrations in Atlantic salmon subjected to a gradient of sub-optimal pressure treatments (Experiment 1) and from multiple mothers (Experiment 2). From these experiments, we genotyped a subsample of ~900 eyed eggs and all ~3300 surviving parr across ~20 microsatellites. In contrast to the low frequency of chromosomal aberrations in the diploid (no hydrostatic pressure) and triploid (full 9500 PSI treatment) controls, eyed eggs subjected to sub-optimal pressure treatments (6500–8500 PSI) had a higher incidence of chromosomal aberrations such as aneuploidy and uniparental disomy, corresponding to lower triploidization success and higher egg mortality rates. We also observed maternal effects on triploidization success and incidence of chromosomal aberrations, with certain half-sibling families exhibiting more aberrations than others. Chromosomal aberrations were rare among surviving parr, suggesting a purge of maladapted individuals during early development. This study demonstrates that sub-optimal hydrostatic pressure treatments and maternal effects not only influence the success of triploidization treatments, but may also affect the incidence of chromosomal aberrations and early mortality. The results have important implications for aquaculture breeding programs and their efforts to prevent farm-to-wild introgression.publishedVersio