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Inferring time at sea from scale circuli: implications for the interpretation of salmon lice distributions on sea trout
Get PDFInfestations with the ectoparasite salmon louse Lepeophtheirus salmonis are considered one of the main stressors for wild salmonids in farm-intensive areas. In Norway, lice infestations on sea trout Salmo trutta are monitored annually at fixed stations distributed along the coast, providing management authorities with an empirical basis to evaluate the potential parasite transmission between farmed and wild salmonids and to evaluate the effect of different management strategies. However, the representativeness of these data is debated, as information on where and for how long the fish have been at sea before capture is rarely available. In this study, we used scale circulus counts to determine marine residency time for sea trout postsmolts caught in Hardangerfjord, a farm-intensive area in western Norway, and show how this information can be used for a better interpretation of lice infestations reported by surveillance programs. By analyzing scales from individuals of known marine residency time (n = 48), we established a periodicity of circulus deposition over the first summer at sea of approximately 8 d per circulus [95% CI: 7.6-8.4 d]. Next, we applied zero-altered (‘hurdle’) statistical models to show how marine residency time, inferred from scale circuli, significantly affected both the probability and intensity of infestation with salmon lice among wild sea trout postsmolts of unknown migration timing (n = 321). Importantly, incorporating circulus counts as a proxy for time at sea significantly improved model likelihood, highlighting the importance of incorporating supporting data on individual sea trout migration traits into salmon lice surveillance programs to improve our understanding of the observed distributions.publishedVersio
Assessment of genetically modified maize DP910521 for food and feed uses, import and processing under Regulation (EC) No 1829/2003 (GMFF-2021-2473(#174))
Get PDFVitenskapskomiteen for mat og miljø (VKM) har vurdert en søknad om godkjenning av den genmodifiserte maisen DP910521. Maisen er søkt godkjent til import, videreforedling og til bruk som mat og fôr i EU-området. I et løpende oppdrag fra Mattilsynet og Miljødirektoratet, vurderer VKM om genmodifiserte organismer og prosessert mat og fôr fra disse kan utgjøre en risiko for helse og miljø. EUs forordning 1829/2003/EF (Forordningen) omfatter både genmodifiserte organismer (levende), som faller inn under den norske genteknologiloven, og genmodifisert, prosessert mat og fôr (dødt materiale avledet fra GMO) som faller inn under den norske matloven. Forordningen er i dag ikke en del av EØS-avtalen eller norsk rett. Norge vurderer søknadene som en forberedelse til at forordningen eventuelt implementeres. VKM vurderer søknader både i den vitenskapelige høringsperioden, som den europeiske myndighet for næringsmiddeltrygghet (EFSA) gjennomfører, og i perioden fra EFSA har offentliggjort en risikovurdering og til EUs medlemsland stemmer for eller imot godkjenning av den genmodifiserte organismen i kommisjonen. VKMs oppdraget er delt inn i tre trinn. (lenke oppdragsbrev) Mais DP910521 DP910521 er en genmodifisert mais utviklet ved stedsspesifikk integrering (SSI) av transgener i maisens genom/arvestoff. Mais DP910521 uttrykker transgenene cry1B.34, pat og pmi, som koder for henholdsvis proteinene Cry1B.34, phosphinothricin acetyltransferase (PAT) og phosphomannose isomerase (PMI). Cry1B.34 er et insekticid som gir resistens mot enkelte planteskadegjørere i insektordenen Lepidoptera (sommerfugler og møll), PAT er et enzym som gir økt toleranse for glufosinat-ammonium baserte ugressmidler, og PMI er et enzym benyttet som seleksjonsmarkør under utvikling av planten. Den vitenskapelige dokumentasjonen i søknaden for mais DP910521 er dekkende for risikovurdering, og i samsvar med EFSAs retningslinjer for risikovurdering av genmodifiserte planter til bruk i mat eller fôr. De genetiske endringene i mais DP910521 tilsier ingen økt helse- eller miljørisiko i Norge sammenlignet med EU-land. EFSAs risikovurdering er dermed tilstrekkelig også for norske forhold. Ettersom det ikke har blitt identifisert særnorske forhold vedrørende mais DP910521, har VKMs GMO panel ikke utført en fullstendig risikovurdering. Om oppdraget: I trinn 1 skal VKM, i forbindelse med EFSAs vitenskapelige høring av GMO-søknader, vurdere helse- og miljørisiko ved den genmodifiserte organismen og dens avledete produkter. VKM skal gjennomgå den vitenskapelige dokumentasjonen som søker har sendt inn og evt. gi innspill til EFSA. VKM skal også vurdere: i) om det er særnorske forhold som vil kunne gi andre risikoer i Norge enn de som er omtalt i søknaden, ii) om norsk kosthold kan gi en økt helserisiko for befolkningen i Norge ved en eventuell godkjenning, sammenliknet med befolkningen i resten av Europa, og iii) risiko knyttet til sameksistens med konvensjonell og/eller økologisk produksjon for genmodifiserte planter som søkes godkjent for dyrking. Aktuelle virkemidler for å sikre sameksistens skal også vurderes. I trinn 2 skal VKM vurdere om innspill fra Norge er tilfredsstillende besvart av EFSA. I tillegg skal VKM vurdere om noen av EFSAs kommentarer til andre lands innspill gir grunnlag for videre oppfølging. Dersom EFSAs svar til norske innspill ikke er tilfredsstillende, eller andre lands innspill gir grunnlag for videre oppfølging, skal VKM i trinn 3 utføre en risikovurdering av de aktuelle forholdene, inkludert eventuelle særnorske forhold.Assessment of genetically modified maize DP910521 for food and feed uses, import and processing under Regulation (EC) No 1829/2003 (GMFF-2021-2473(#174))publishedVersio
Long-distance migrations, population mixing, and growth rate of lumpfish (Cyclopterus lumpus) revealed from tag-recaptures
Get PDFWe reveal that lumpfish (Cyclopterus lumpus) frequently migrate over long distances between their summer feeding area in the open ocean and their spring spawning sites in coastal areas, through applying tag-recapture methodology. A total of 2750 C. lumpus were tagged in the Irminger Sea around Iceland and in the Norwegian Sea over 6 years, of which 17 C. lumpus were recaptured. Interestingly, four individuals were recaptured more than 1000 km distant from where they were tagged. C. lumpus tagged in the Irminger Sea and north of Iceland were recaptured around Iceland, whereas none of the fish tagged in other areas of the Norwegian Sea were recaptured in Iceland. This difference in recapture rate from different areas suggests that a higher proportion of C. lumpus from the Irminger Sea and north of Iceland spawns around Iceland in comparison with C. lumpus in other areas. Two fish tagged east of Iceland were recaptured on the coast of Denmark, with one fish having a displacement distance of 1612 km. The recapture of these two fish in Denmark demonstrates that part of the C. lumpus population spawning in Denmark utilizes the Norwegian Sea as a major feeding area and that the Norwegian Sea is a common feeding area for several distinct populations of C. lumpus. The growth rate of tagged fish varied from 1.2 to 11.1 cm year−1, indicating that males that are >20 cm and females that are >25 cm during the summer are capable of sufficient growth to achieve a suitable size for spawning (≥25 and ≥35 cm for males and females, respectively) the following spring.publishedVersio
Occurrence of ‘soft flesh’ condition induced by Kudoa thyrsites parasite in the Iberian European sardine stock
Get PDFEuropean sardine Sardina pilchardus is a commercially valuable coastal pelagic fish species. Spain is one of the largest sardine suppliers in Europe and the Iberian stock is of particular significance. Kudoa parasites are known to infect sardines causing the so-called ‘soft flesh’ condition; however, data on the occurrence of ‘soft flesh’ in this sardine stock are limited. This study investigates the occurrence of Kudoa-induced ‘soft flesh’ in the Iberian sardine stock caught in 2023 off the northern Spanish Atlantic coast (Division 8.c). Five hundred specimens were examined for ‘soft flesh’ by manual texture testing and visual inspection 48 h post-catch using standardized procedures. ‘Soft flesh’ was detected in 5.4% (27/500) of the sardines. Microscopic examination of muscle samples revealed the presence of Kudoa thyrsites–like myxospores in all ‘soft flesh’–affected fish, which based on SSU rDNA gene sequence analysis was identified as K. thyrsites. The unsightly appearance of infected fillets represents a substantial food quality issue for the Iberian sardine stock that could reduce marketability and consumer confidence in both local and international markets. This is particularly relevant since larger Iberian sardines, which are highly appreciated by consumers, appear to be the most affected.publishedVersio
Conservation benefits of marine reserves depend on knowledge integration of genotypic and phenotypic diversity
Get PDFConserving intraspecific trait variation is vital for maintaining the viability of species. It ensures a species to adapt to warming and increasingly stochastic environments, and to recover following extreme events. Here we investigate the selective effects of spatial management on intraspecific genetic and phenotypic variation of two sympatric but genetically distinct Atlantic cod ecotypes in a Norwegian fjord. We found that phenotypic differences between sympatric cod genotypes were mainly driven by morphological and metabolic traits. Offshore cod had higher metabolic maintenance costs at cool temperatures but lower aerobic capacity at warm acclimation than coastal ecotypes, indicative of thermal constraint of aerobic physiological processes beyond metabolic maintenance. Offshore cod also had larger and thicker peduncles and better body condition. We found that protection benefits from the no-take zone (NTZ) of the Tvedestrand marine protected area were independent of individual space-use size, but instead resulted from ecotype-specific differences in habitat occupation. Results specifically show that the current delimitations of the NTZ do not cover habitats occupied by the coastal and highly resident cod ecotype which shows greater metabolic thermal tolerance but is considered to already be in a depleted state. Our study exemplifies why protecting intraspecific diversity is directly relevant for management implementations aimed at reducing the impact of further selection pressures such as ongoing environmental change. Careful investigation of intraspecific diversity and integration of such knowledge to fisheries management and design of protected areas may prevent unwanted additional selective pressures and contribute to offer broad protection to genotypes and phenotypes.publishedVersio
Effect of dietary starch, amylase and ash on nutrient digestibility, faecal waste production and faecal characteristics of rainbow trout, (Oncorhynchus mykiss).
Get PDFWaste management is a critical issue in aquaculture. In this study, we examined nutrient digestibility, faecal waste production, faecal removal efficiency and the faecal characteristics of rainbow trout (Oncorhynchus mykiss) in response to the dietary starch level, amylase and ash supplementation and the interaction of dietary starch with amylase and ash. A basal mixture predominantly consisting of plant-based ingredients was formulated. The basal mixture was diluted with 100, 200, 300 and 400 g/kg gelatinised wheat flour, resulting in four diets of varying starch levels, referred to as 10-WF, 20-WF, 30-WF and 40-WF, respectively. Amylase was supplemented at 125 k-novo-α-amylase units (KNU)/kg to the 20-WF and 40-WF diets and referred to them as 20-WFα and 40-WFα. Two high ash diets were prepared by supplementing 20 g diamol/kg to the 10-WF and 30-WF diets and termed as 10-WFA and 30-WFA. Triplicate group of 25 fish (mean weight, 210 g) were restrictively fed one of the eight diets for five weeks. Higher dietary starch level led to increased faecal waste production, lowered faecal removal efficiency and resulted in greater accumulation of non-removed faeces in the system. Moreover, higher dietary starch level also diminished faecal stability, as evident by an increased share of particles <40 μm size in 40-WF upon exposure to mechanical stress. Amylase supplementation in the diet enhanced starch digestibility without influencing faecal waste production, removal efficiency, or the particle size distribution (PSD) of non-stressed faeces. Conversely, dietary ash supplementation increased faecal waste production and altered faecal characteristics by enhancing density and sinking velocity, although without improving its removal efficiency. In summary, this study underscores the potential of dietary manipulations to affect faecal waste production, removal efficiency, and various faecal characteristics, including viscosity, density, sinking velocity, particle size distribution, and stability.publishedVersio
Fish Atlas of the Southern Ocean, based on the AKES 2008 expedition
No full textAKES (“Antarctic Krill and Ecosystem Studies”, 2008-2011) was an IMR project that focused on mapping the abundance and distribution of Antarctic krill (Euphausia superba) in the central to eastern parts of the Atlantic sector of the Southern Ocean. Through the project IMR has contributed with highly relevant science and new knowledge to the management of ecosystem resources within the management area of CCAMLR (“Commission for the Conservation of Marine Living Resources”). The expedition was conducted during two consecutive surveys carried out during the Austral summer of 2008. In these areas, detailed knowledge of the ecosystem is limited and poorly described. This report presents results from taxonomic analyses performed on fish worked up from trawl catches in the upper ~750 m of the water column. Taxonomic identifications are based on morphological characteristics using the most updated identification keys. Following identification, each species or genus is illustrated by an image, while its distribution and numbers caught are presented in associated figures and tables. This work is important for future surveys in the Southern Atlantic when assessing ecosystem change, bycatch related to ongoing and new fisheries, management as well as the functionality and design of future marine protected areas (MPA’s). For further descriptions of relevant survey design, methodology, trawl gear and associated investigations, see descriptions in Iversen et al. (2008) and Krafft et al. (2010).Fish Atlas of the Southern Ocean, based on the AKES 2008 expeditionpublishedVersio
Long-Term Stability of Marine Forests Facing Moderate Gradual Warming in a Remote Biodiversity Hotspot
Get PDFAim Ocean warming and marine heatwaves are rapidly reconfiguring the composition of seaweed forests—the world's largest coastal vegetated biome. Seaweed forest responses to climate change in remote locations, which constitute the majority of the forest biome, remain however poorly quantified. Here, we examine the temporal stability of the seaweed forests across a global seaweed biodiversity hotspot where several species are predicted to undergo severe range contractions in this century. Location Western south coast of Australia. Methods Seaweed forest canopies were censused at 18 shallow (< 10 m) sheltered reefs between 1997 and 2006 and again between 2021 and 2024 (six sites per location). We also surveyed 24 sites to examine whether temporal changes differed over gradients of wave exposure and depth. Results Seaweed forest canopies across all locations showed surprisingly little change in biomass, cover, stand density and species composition over two decades, with strong spatial structuring across depth and exposure gradients persisting over time. The average thermal affinity of forest canopies (i.e., the community temperature index, CTI) did not track warming, suggesting that factors other than temperature (e.g., wave exposure and depth) are more important drivers of forest stand structure and/or that key thermal thresholds have not yet been crossed. Forests in the location with the most pronounced warming exhibited increased thermal bias over time (total bias of 0.8°C–2.2°C), indicating they were dominated by species with cooler affinities than their local temperatures. Main Conclusions The greater thermal bias in forests at the warmer edge of southern Australia suggests these will be more susceptible to future warming-related compositional changes than forests in cooler locations. The relative stability we found contrasts with a current context of rapidly changing seaweed forests nationally and globally, highlighting the need to deepen our ecological understanding of the region so that future changes to its unique biodiversity and ecosystem services can be predicted and mitigated.publishedVersio
Surface and bottom marine heatwave characteristics in the Barents Sea: a model study
Get PDFAnomalously warm oceanic events, often termed marine heatwaves (MHWs), can potentially impact the ecosystem in the affected region and have therefore become a hot topic for research in recent years. Determining the intensity and spatial extent of marine heatwaves, however, depends on the definition and climatological average used. Moreover, the stress applied by the heatwave to the marine ecosystem will depend on which component of the ecosystem is considered. Here, we utilize a model reanalysis (1991–2022) to explore the frequency, intensity, and duration of marine heatwaves in the Barents Sea, as well as regional heterogeneities. We find that major marine heatwaves are rather coherent throughout the region, but surface marine heatwaves occur more frequently while heatwaves on the ocean floor have a longer duration. Moreover, we investigate the sensitivity to the choice of climatological average length when calculating marine heatwave statistics. Our results indicate that severe marine heatwaves may become more frequent in a future Barents Sea due to ongoing climate change.publishedVersio