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A genetic method to infer ploidy and aberrant inheritance in triploid organisms
Get PDFPolyploidy occurs naturally across eukaryotic lineages and has been harnessed in the domestication of many crops and vertebrates. In aquaculture, triploidy can be induced as a biocontainment strategy, as it creates a reproductive barrier preventing farm-to-wild introgression, which is currently a major conservation issue for the industry. However, recent work suggests that triploidisation protocols may, on occasion, produce ‘failed triploids’ displaying diploidy, aneuploidy and aberrant inheritance. The potentially negative consequences for conservation and animal welfare motivate the need for methods to evaluate the success of ploidy-manipulation protocols early in the production process. We developed a semi-automated version of the MAC-PR (microsatellite DNA allele counting – peak ratios) method to resolve the allelic configuration of large numbers of individuals across a panel of microsatellite markers that can be used to infer ploidy, pedigree and inheritance aberrations. We demonstrate an application of the approach using material from a series of Atlantic salmon (Salmo salar) breeding experiments where ploidy was manipulated using a hydrostatic pressure treatment. We validated the approach to infer ploidy against blood smears, finding a > 99% agreement between these methods, and demonstrate its potential utility to infer ploidy as early as the embryonic stage. Furthermore, we present tools to assign diploid and triploid progeny to families and to detect aberrant inheritance, which may be useful for breeding programmes that utilise ploidy manipulation techniques. The approach adds to the ploidy verification toolbox. The increased precision in detecting ploidy and inheritance aberrations will facilitate the ability of triploidisation programmes to prevent farm-to-wild introgression.publishedVersio
Advice on fishing opportunities for Northeast Arctic haddock in 2025 in ICES subareas 1 and 2
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Contrasting Methane Seepage Dynamics in the Hola Trough Offshore Norway: Insights From Two Different Summers
Get PDFThis study investigates the temporal variations in methane concentration and flare activity in the Hola trough (offshore Norway) during May 2018 and June 2022. Between these time periods, methane seep activity exhibits 3.5 times increase, as evidenced by hydroacoustic measurements. As the seep area in the Hola trough is constantly within the hydrate stability zone, the observed increase cannot be attributed to migration of its shallow boundary due to temperature increase. However, a combination of low tide conditions resulting in a lower sediment pore pressure and a bottom water temperature increase resulting in a lower methane solubility is likely to explain the increase in the number of seeps observed in June 2022. The hypothesis of tide influence is supported by data collected from a piezometer deployed and recovered during the cruise showing that the tidal effect was observed 3 m below the seafloor. Despite the numerous methane seeps detected, methane concentration and gas flow rates near the seafloor were low (<19 nM and <70 mL min−1, respectively) compared to other areas with methane seep activity. This is likely due to strong currents rapidly dispersing methane in the water column. Sub-seafloor investigations identified pathways for gas migration in methane seep areas, influenced by topography. This study provides valuable insights into the temporal dynamics of methane concentrations, flare activity, and gas distribution in the Hola trough, contributing to our understanding of offshore methane dynamics in the regionContrasting Methane Seepage Dynamics in the Hola Trough Offshore Norway: Insights From Two Different SummerspublishedVersio
North Sea Ecosystem - Report_2023002006
Get PDFThe North Sea Ecosystem spring cruise (NSEC) has been run since 2010 by the Institute of Marine Research (IMR) as a multi-purpose survey. The cruise is usually performed in mid-April – mid-May to investigate the horizontal and vertical distributions of hydrography, chemistry, phytoplankton and zooplankton as well as fish eggs and fish larvae.North Sea Ecosystem - Report_2023002006publishedVersio
Length matters: Effects of fishing gear and fishing behavior on the catch efficiency of demersal seines
Get PDFRaiding seals pose a big problem to gillnet fishers in areas with high seal abundances. As moving to active gears could be a potential solution for that problem, one gear of particular interest in areas with relatively flat sea bed structure is the so-called “MiniSeine” – a demersal seine that is reduced in size so it can be operated from small vessels. Besides its ability to catch most of the species targeted by gillnet fishers, it offers various advantages compared to other active gears. To reduce the gear in size to fit on a small vessel, the present study assessed how seine rope length (4 coils vs 8 coils), seine rope diameter (18 mm vs. 22 mm) and seine net configurations of different sizes and shapes (three different designs) affect the catch efficiency and the ratio of fish below minimum conservation reference size (MCRS). In general, shorter seine ropes (4 coils) resulted in significantly lower catches than longer ones (8 coils), except for the smallest seine configuration. Larger seine net configurations and longer seine ropes caught generally less fish below MCRS, both up to around 10 %. The seine rope diameter did not affect catches significantly. As potential “adjusting screw” to counteract lower catches due to shorter seine ropes, the effect of different layout patterns of the seine ropes on the catch efficiency was assessed. Laying out the second seine rope perpendicular to the first one can increase the fishing area to more than three times while CPUE showed a tendency to be increased compared to the standard layout pattern. Besides its importance for a successful development of the MiniSeine, these findings are of equal interest for the large-scale demersal seine fishery.publishedVersio
Risikorapport norsk fiskeoppdrett 2024 - Produksjonsdødelighet hos oppdrettsfisk og miljøeffekter av norsk fiskeoppdrett
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Lophelia reefs (Desmophyllum pertusum (Linnaeus, 1758)) in the oxygen minimum zone of the Mauritania/Senegal region – Distribution and health status
Get PDFThe occurrence of cold-water coral (CWC) reefs off Northwest Africa that has a broad oxygen minimum zone (OMZ) is poorly studied. A 400 km long almost continuous coral mound chain off Mauritania that was investigated by earlier expeditions revealed mainly dead corals. In 2021, the EAF-Nansen Programme conducted a survey at the border between Mauritania and Senegal with the main objective to map CWCs. Acoustic mapping with multibeam echosounder was used to target mounds at 450–650 m depth and 14 video lines were conducted using a remotely operated vehicle (ROV). The occurrence and health status of CWC reefs along video transects were annotated using the software “CampodLogger”, oceanographic variables were measured using a CTD sonde, and terrain and backscatter analysis were conducted. Here we present the environment and health status of 13 Lophelia reefs established in the study area, six of them were large and healthy reefs with areas having 15–50% cover of live colonies. Oxygen concentrations were measured to be as low as 1 ml L−1 and temperature ranged from 8.8 to 11.6° C. We compare reef health with the environmental variables: temp, salinity, oxygen, and particle load. A GIS based model was developed to predict the occurrence of live reefs in the study area based on the observed average range of a set of terrain descriptors measured where live Lophelia reefs occurred. Our findings of healthy Lophelia reefs are unexpected and further north in the OMZ reefs have been described as dormant. There is an urgent need for visual seafloor mapping to aid the development of spatial management plans in these understudied waters.publishedVersio
A passive fish sampling method is representative for size but selective for parasite load
Get PDFFish capture in industrial aquaculture is both necessary (i.e., for transfer, monitoring and harvesting) and difficult. The most logistically feasible methods rely heavily on crowding, a process that is detrimental to fish welfare and production outcomes. Jump nets, which rely on passive capture via jumping behaviour, present a welfare-friendly alternative. But reliance on behaviour means capture is not guaranteed, and limited knowledge of their capture rate and sampling biases means they are not yet used to their full potential. Here, in sea-cages stocked with Atlantic salmon Salmo salar, we investigated how capture rate varied with net size, position, and time of day, and if salmon caught via jump net were representative of the sea-cage population. A comparison of jumping rates into surface rings (without nets) indicated that larger jump nets will catch more fish. Capture rate was highest in rings positioned in the centre of cages, and during the morning and evening. Jump nets sampled representatively for fish size but caught salmon with marginally lower condition (<2% difference) and with three times higher parasitic salmon louse (Lepeophtheirus salmonis) loads than fish caught using lift nets. Our results indicate that jump nets can be used as a size-representative sampling tool and to target lice infected salmon for treatment.publishedVersio
Rapid climate change increases diversity and homogenizes composition of coastal fish at high latitudes
Get PDFRapid warming at high latitudes triggers poleward shifts of species' distributionsthat impact marine biodiversity. In the open sea, the documented redistributionsof fish lead to a borealization of Arctic fauna. A climate-driven borealization andincreased species diversity at high latitudes are also expected in coastal fish com-munities, but they have not been previously documented on a large, biogeographicscale. Here, we investigate the impact of temperature change over the last 25 yearson fish communities along the coast of Norway. The study area, spanning differentecoclimatic zones between 62° and 71° N, harbors over 200 species of boreal andArctic fish. Several of these fish species are harvested by coastal and indigenouscommunities, influencing settlement geography and livelihood. The long-term dataon coastal water temperatures and fish species were obtained from monitoring sta-tions and scientific surveys. Water temperature measured at three fixed samplingstations distributed along the coast show increased temperatures during the studyperiod. The fish species distribution and abundance data were obtained from theannually standardized scientific bottom trawl survey program. Fish species rich-ness, which was highest in the south, increased with warming first in the south andthen, gradually, further north, eventually affecting biodiversity in the whole studyarea. Fish community composition showed a distinct latitudinal pattern early in thestudy, with Arctic fish species confined to the north and boreal species dominat-ing the south. The poleward shifts eventually eroded this zoogeographic pattern,resulting in more boreal fish species in the north and an increased homogenizationof species composition along the Norwegian coast. The climate-driven reorganiza-tion of fish communities affects coastal ecosystems that are exposed to fisheries,aquaculture, and other rapidly expanding human activities, stressing the urgentneed for a climate adaptation of integrated coastal management.publishedVersio
Are mesopelagic organisms nutritious food? Impact on metabolism, availability of nutrients, and contaminants from dietary intervention in C57BL/6J mice model
Get PDFMesopelagic species are unexplored novel low-trophic sources of essential micronu-trients and may contribute to combat malnutrition. In this study, common mesopelagicspecies from the North Sea including Northern krill (Meganyctiphanes norvegica),glacier lanternfish (Benthosema glaciale), and Muller’s pearlside (Maurolicus muel-leri) were supplemented in mice feed using a Western diet recipe. The metabolicoutcomes were subsequently compared to those of ordinary seafood. Consumptionof mesopelagic species induced a large variation in weight gain, in the followingorder: lanternfish (7.1 g) > krill (14.4 g) > control (19.7 g) > pearlside (22.6 g). Thelanternfish-supplemented diet containing wax esters reduced weight gain and obesityand improved insulin sensitivity. The wax esters from the lanternfish-supplementeddiet were efficiently absorbed, with more than 92% of the fatty alcohols being assim-ilated. The inclusion of lanternfish and pearlside led to improvements in the fatty acid(FA) composition in the mouse liver, evidenced by increased levels of essential long-chain polyunsaturated FAs and an increased n-3/n-6 ratio (0.7 to 1.45 vs. 0.46 in controlgroup). Notably, no adverse effects were found in mice fed pearlside and lanternfish,although an elevated level of fluoride in femur bone was observed in mice fed a dietsupplemented with krill followed by reduced sperm concentration and sperm motility.Collectively, our findings underscore the diverse array of metabolic and physiologi-cal effects induced by the consumption of mesopelagic species. Furthermore, thesespecies can be considered as good sources of n-3 FAs and essential vitamins, suggestingtheir potential value to human nutrition.publishedVersio