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Survey of Iceland scallop beds north of Svalbard - Survey number 2022839
Get PDFIn August 2022, the scallop beds of Moffen and Parryflaket north of Svalbard were surveyed to assess the state and distribution of Iceland scallops (Chlamys islandica). This represented the first investigation in 30 years after the closing of the scallop fishery in the area, following several years of destructive overfishing. The survey was conducted with video transects inside and outside the protected areas, and dredge stations outside the protected areas parallel to video transects. Dredging was used to collect biological samples for size and age composition, and tissue samples for contaminant, nutrient and population genetic analysis. Furthermore, parallel stations allowed to compare observed scallop densities between dredge and video. Still images were extracted from video to annotate scallops, with repeated annotations of all stations by multiple persons. The results show that the stocks on both scallops bed have recovered from previous fishing to densities that are comparable or higher than those observed in the Bear Island area. The scallop abundance at the two scallop beds combined is estimated to be higher than on the three Bear Island scallop beds, whereas the scallops on Moffen and Parryflaket tended to be smaller and therefore the proportion above minimum legal landing size lower. Geostatistical approaches were tested to estimate density and abundance. Compared to previous design-based approaches, spatial modelling captures the spatial variation in density more adequately, allows for including links to habitat and environment, and to estimate uncertainty of estimates. Furthermore, video and dredge data could be integrated into a joint estimate, improving the resolution and historic comparability. We recommend to consider the inclusion the scallop beds north of Svalbard into the trial fishery to spread fishing effort across a larger stock and area. Toktnummer: 2022839Survey of Iceland scallop beds north of Svalbard - Survey number 2022839publishedVersio
Metodeutvikling for seleksjon i snurrevad - Toktrapport fra MS Fangst, oktober 2022
Get PDFProsjektet «Seleksjon i snurrevad» (FHF-901725) har som hovedmålsetting å estimere størrelsesseleksjon for hyse i snurrevadfiske og utforme snurrevadsekk / seleksjonsinnretning som sorterer ut hyse under minstemålet slik at seleksjonen skjer i størst mulig grad på fiskedypet. I prosjektet arbeides det med å finne løsninger for å oppnå skarpere størrelsesseleksjon, med fokus på å kombinere maskeseleksjon i kvadratmaskesekk med en eller flere seleksjonsinnretninger. I slike forsøk er det behov for undervannsobservasjoner. Fisket foregår som regel på 50 – 100 m dyp som er for dypt for tidligere brukte kompakte kameraer, med tanke på lysforhold uten bruk av kunstig lys. Samtidig er det ikke intuitivt å bruke større kameraer eller undervannsfarkoster i snurrevadfiske. Det er derfor behov for «bedre» kameraer og tekniske løsninger for å kunne filme seleksjonsinnretninger i snurrevad fra 1-5 m avstand. På dette toktet ble både svarte og hvite presenningstunneler montert i en kvadratmaskeforlengelse foran sekken. Tunnelene var tenkt for å stimulere fisk til å søke på maskene i et forsøk å få ut større andel småfisk. Torsk stopper foran både svart og hvit tunnel, men søker i liten grad på maskene. Flatfisk stopper foran svart tunnel men går igjennom den hvite uten å stoppe. Det ble testet kamera, «flygere» med hydrodynamisk oppdrift og tidsstilt utløser for å kunne filme fra avstand. Grunnere enn 50 m får en fine opptak med GoPro kamera, Dark vision kamera ble også brukt og egner seg til filming på mer enn 100 m dyp. Flygerene fungerte etter hensikten og kan erstatte undervannsfarkoster i snurrevadfiske når bruken kombineres med tidsstilt utløser. To versjoner av sekkeutløsere ble også testet; fra Stenevik produktutvikling og Uwitec. Stenevik har utviklet en liten mekanisk utløserprototype som har fungert tilfredsstillende, men har noen konstruksjonsmessige svakheter. Prototypen må bygges litt kraftigere, men det antas at den krever kun mindre modifikasjoner for å kunne brukes. Utløseren fra Uwitec tok inn vann og ble ødelagt. Toktnummer: 2022515Metodeutvikling for seleksjon i snurrevad - Toktrapport fra MS Fangst, oktober 2022publishedVersio
A first ecological coherent assessment of eutrophication across the North-East Atlantic waters (2015-2020)
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Evaluation of black soldier fly larvae meal as a functional feed ingredient in Atlantic salmon (Salmo salar) under farm-like conditions
Get PDFAtlantic salmon (Salmo salar) were fed diets containing black soldier fly larvae (BSFL) meal at two inclusion levels for 13 months in open sea-cages. BSFL meal replaced plant-based ingredients and dietary insect meal inclusion levels were at 5% and 10%. A commercial salmon diet was fed as a control diet. Fish were reared from ~173 g to ~ 4 kg and were randomly distributed into nine open sea-cages with ~6000 salmon/cage (12×12 m2; 1900 m3). Fish from the sea-cages were sampled at two time points (mid and final samplings) to study the dietary effects of BSFL meal on the general health and welfare. Monthly assessments of sea-lice and gill score were conducted to evaluate the overall well-being of the salmon. The findings from the current study revealed that dietary inclusion of BSFL meal up to 10% did not have any significant effects in general growth, welfare or survival. However, significant positive response was observed in the general skin mucosal, hematological, and gene expression profiles of salmon. Notably, the group of salmon fed with 5% BSFL meal showed a significant decrease in plasma aspartate transaminase and alanine transaminase. Also, a significantly higher expression of interleukin1β in both skin and gill along with upregulation of matrix metallopeptidase9 and mucin18 in gill were observed in salmon fed BSFL at 5%, which aided in increased immune responses. Apart from that, this group had significantly higher mucus secretions, decreased cortisol response and increased number of erythrocytes. Furthermore, the delousing stress had a significant effect on the plasma cortisol, and these responses were independent of the dietary effect. Moreover, these immune responses behaved differently at different fish size and time points, acknowledging the influence of various factors in immune modulation. Overall, the findings from this study showed the effects of dietary BSFL meal to modulate the immune status of salmon. This study aims to fill the existing knowledge gaps regarding the impact of incorporating BSFL meal as a functional feed ingredient into the salmon diet on health and immune status replicating real farm conditions.publishedVersio
Havforskningsinstituttets rådgivning for menneskeskapt støy i havet - Kunnskapsgrunnlag, vurderinger og råd for 2024
Get PDFHavforskningsinstituttet gir råd for alle operasjoner til havs som involverer bruk av lydkilder, samt elektromagnetiske kilder som kan påvirke marine økosystemer. Dette inkluderer vitenskapelige undersøkelser, utbygging og sprenging i sjø, seismiske og elektromagnetiske undersøkelser i forbindelse med petroleumsvirksomhet , og utbygging og drift av vindkraftanlegg til havs. Denne rapporten er en sammenstilling av tilgjengelig kunnskap omkring hvordan de overnevnte typer av undersjøisk støy påvirker livet i havet. Videre evalueres denne kunnskapen i lys av hvilke konsekvenser dokumenterte effekter kan gi på økosystemet. Denne rapporten er inndelt med et kapittel for hver av de overnevnte støykildene (seismikk, elektromagnetiske undersøkelser, undersjøiske sprenginger og vindkraft til havs), som igjen er inndelt i delkapitler med 1) kunnskapsgrunnlag, 2) konsekvensvurdering og 3) råd. Rapporten inneholder konkrete råd fra Havforskningsinstituttet for 2024 for de ulike støykildene. I tillegg inneholder rapporten en oversikt over hvor det finnes sårbare koraller i norske farvann fordi mange av operasjonene til havs som lager støy også innebærer å plassere ulike måleinstrumenter på bunn som kan føre til skade om de plasseres oppå koraller. Råd for seismikk og elektromagnetiske undersøkelser gis i form av rådgivningskart, som viser perioder og områder som bør unngås. Disse kartene inngår også i Oljedirektoratets meldesystem. Råd for undersjøiske sprenginger og vindkraft til havs gis i form av operasjonelle hensyn, samt hvilke sårbare områder og perioder enkelte av disse operasjonene bør unngås.Havforskningsinstituttets rådgivning for menneskeskapt støy i havet - Kunnskapsgrunnlag, vurderinger og råd for 2024publishedVersio
Applications and analytical approaches using imaging sonar for quantifying behavioural interactions among aquatic organisms and their environment
Get PDFFor many aquatic animals, distributional patterns, trophodynamic relationships, and reproductive activity are driven by complex biotic and abiotic ecosystem interactions that influence behaviour. Linking behavioural information to environmental stimuli and stressors can, therefore, help to anticipate population and ecosystem responses to changing conditions and inform management. However, behavioural information is challenging to obtain because many sampling gears do not provide adequate spatial or temporal resolution, or potentially alter behaviours. Traditionally, most behavioural studies have been laboratory experiments, while behaviour in situ has often been inferred indirectly. Advancements in imaging sonar technology enable the study of in situ behaviours with the potential to address many understudied relationships. In this review we discuss applications of imaging sonar among a meta-analysis of 155 studies of aquatic organisms in their environments. We evaluate the performance of imaging sonar for studying inter- and intra-specific interactions, associations with complex and sensitive habitats and low-visibility environments, and to evaluate traditional fisheries sampling gears. We examine the data processing and analytical methods used to refine taxonomic resolution, manage time use and autocorrelation through sub-sampling, extract behavioural metrics applied to ecological processes, and for automating abundance estimates and image classification with the goal of providing a resource for researchers.Applications and analytical approaches using imaging sonar for quantifying behavioural interactions among aquatic organisms and their environmentpublishedVersio
Poleward spawning of Atlantic mackerel (Scomber scombrus) is facilitated by ocean warming but triggered by energetic constraints
Get PDFThe Northeast Atlantic mackerel is an income breeder with indeterminate fecundity, spawning in multiple batches at optimal temperatures around 11°C in the upper water column during February–July along the continental shelf from 36–62°N. Based on macroscopic staging of gonads (N ∼62000) collected in 2004–2021, we detected an on-going extension of spawning activities into the Norwegian Sea feeding area (62–75°N), reaching stable levels around 2012 onwards. This poleward expansion increased as more fish entered the area, whilst the maximum proportions of spawners concurrently dropped from about 75 to 15% from May to July. Detailed histological examinations in 2018 confirmed the macroscopic results but clarified that 38% of the spawning-capable females in July terminated their spawning by atresia. We suggest that increased access to suitable spawning areas (≥10°C), following ocean warming from 2002 onwards, functions as a proximate cause behind the noticed expansion, whereas the ultimate trigger was the historic drop in body growth and condition about 10 years later. Driven by these energetic constraints, mackerel likely spawn in the direction of high prey concentrations to rebuild body resources and secure the future rather than current reproduction success. The ambient temperature that far north is considered suboptimal for egg and larval survival.publishedVersio
Prospects for the future of pink salmon in three oceans: From the native Pacific to the novel Arctic and Atlantic
Get PDFWhile populations of other migratory salmonids suffer in the Anthropocene, pink salmon (Oncorhynchus gorbusca Salmonidae) are thriving, and their distribution is expanding both within their natural range and in the Atlantic and Arctic following introduction of the species to the White Sea in the 1950s. Pink salmon are now rapidly spreading in Europe and even across the ocean to North America. Large numbers of pink salmon breed in Norwegian rivers and small numbers of individuals have been captured throughout the North Atlantic since 2017. Although little is known about the biology and ecology of the pink salmon in its novel distribution, the impacts of the species' introduction are potentially highly significant for native species and watershed productivity. Contrasts between pink salmon in the native and extended ranges will be key to navigating management strategies for Atlantic nations where the pink salmon is entrenching itself among the fish fauna, posing potential threats to native fish communities. One key conclusion of this paper is that the species' heritable traits are rapidly selected and drive local adaptation and evolution. Within the Atlantic region, this may facilitate further establishment and spread. The invasion of pink salmon in the Atlantic basin is ultimately a massive ecological experiment and one of the first examples of a major faunal change in the North Atlantic Ocean that is already undergoing rapid changes due to other anthropogenic stressors. New research is urgently needed to understand the role and potential future impacts of pink salmon in Atlantic ecosystems. Atlantification, biological invasions, climate adaptation, Pacific Ocean, regime shiftpublishedVersio
Molecular evidence of parallel evolution in a cyanophage
Get PDFAntagonistic interactions between bacteriophage (phage) and its bacterial host drives the continual selection for resistance and counter-defence. To date, much remains unknown about the genomic evolution that occurs as part of the underlying mechanisms. Such is the case for the marine cyanobacteria Synechococcus and viruses (cyanophages) that infect them. Here, we monitored host and phage abundances, alongside genomic changes to the phage populations, in a 500-day (~55 bacterial generations) infection experiment between Synechococcus sp. WH7803 and the T4-type cyanophage S-PM2d, run parallel in three replicate chemostats (plus one control chemostat). Flow cytometric count of total abundances revealed relatively similar host-phage population dynamics across the chemostats, starting with a cycle of host population collapse and recovery that led to phases of host-phage coexistence. Whole-genome analysis of the S-PM2d populations detected an assemblage of strongly selected and repeatable genomic changes, and therefore parallel evolution in the phage populations, early in the experiment (sampled on day 39). These consisted mostly of non-synonymous single-nucleotide-polymorphisms and a few instances of indel, altogether affecting 18 open-reading-frames, the majority of which were predicted to encode virion structures including those involved in phage adsorption onto host (i.e., baseplate wedge, short tail fibre, adhesin component). Mutations that emerged later (sampled on day 500), on the other hand, were found at a larger range of frequencies, with many lacking repeatability across the chemostats. This is indicative of some degree of between-population divergence in the phage evolutionary trajectory over time. A few of the early and late mutations were detected within putative auxiliary metabolic genes, but these generally occurred in only one or two of the chemostats. Less repeatable mutations may have higher fitness costs, thus drawing our attention onto the role of trade-offs in modulating the trajectory of a host-phage coevolution.publishedVersio
Natural mortality estimations for beaked redfish (Sebastes mentella) – A long-lived ovoviviparous species of the Northeast Arctic
Get PDFBeaked redfish (Sebastes mentella) is one of the few commercially important fish species producing living offspring. Like many other deep-water fishes, it is slow growing, late maturing and long-lived, getting as old as 65 years or even 75 years in some populations. The stock in the Norwegian and Barents Seas is analytically assessed since 2012, assuming a natural mortality (M) of 0.05 yr−1 across all ages, based on Hoenig’s longevity related estimator. Since then, several reviews and new studies have been published, affording a re-evaluation of the natural mortality in the assessment model. We estimated natural mortality of beaked redfish using 48 different estimators in two categories, either estimating M across the population or dependent on age, length or weight. The obtained estimates were highly variable, ranging from 0.01 to 0.32 yr−1 for estimates across the population, and 0.05–0.62 yr−1 for age or size dependent median-M. These wide ranges demonstrate the sensitivity of SSB to the input parameters as well as the pitfalls of using estimators developed for distant taxa. Of the 48 estimates, 20 were considered as potential candidates for updating the stock assessment model, yet not all of these were realistic. The frequency distribution of the estimators showed a peak around a value of 0.07 yr−1, lowering the estimated spawning stock biomass in the last year by about 300 kt but keeping it above the precautionary reference point for the stock. Estimators across the life-history of beaked redfish indicate a potential underestimation of natural mortality for early and overestimation for late age classes. Age and size related estimators are promising for the older ages but tend to extreme estimates for the early ages, which deserves further investigation.acceptedVersio