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Revision of the Norwegian-Russian Barents Sea Ecosystem Survey (BESS) - The current status and revision of the Norwegian sector of the BESS survey
Full text linkAn effort to streamline the survey activity at the Institute of Marine Research (IMR) was initiated by the IMR leadership in December 2022. The purpose of this exercise is to balance the costs of the total cruise effort with the allocated budget. One of the candidate cruises of this streamlining, is the Norwegian-Russian Barents Sea Ecosystem Survey (BESS), referred to as NOR-RUS ecosystem cruise in autumn in IMR monitoring strategy and data systems.Revision of the Norwegian-Russian Barents Sea Ecosystem Survey (BESS) - The current status and revision of the Norwegian sector of the BESS surveypublishedVersio
Growth of spring- and autumn-spawned larvae of Atlantic herring Clupea harengus: a long-term experiment mimicking seasonal light conditions
Full text linkAtlantic herring Clupea harengus populations differ in their spawning time, and spring- and autumn-spawning populations are genetically distinct. Offspring of these populations encounter seasonal variations in productivity. We conducted a fertilization experiment using spring-spawning Atlantic herring. Offspring were reared for 3 yr with seasonal varying light cycles starting either in spring or autumn, using 2 fixed temperature levels and food provided in excess. Such long-term experiments from hatching to maturation in small pelagic fish are very rare. We hypothesized that longer daylengths early in life would provide an overall growth advantage resulting in larger size after 1 yr (same amount of light) compared to those experiencing prolonged daylight later in life due to higher size-dependent growth rates at smaller sizes. Larvae with initial spring conditions initially grew faster. However, contrary to our expectations, offspring with initial autumn conditions had caught up to similar size after 1 yr. Herring at higher temperatures grew faster, even when correcting for the amount of degree-days. After the first year, individuals hatched in spring showed higher growth at the higher temperature while herring hatched under autumn light conditions consistently had higher growth rates at lower temperatures. The somatic condition of herring followed the daylength, with best conditions during summer and poorest during winter. This was the first long-term experiment conducted on herring with varying light conditions from hatching to maturation. Our novel results indicate that herring display considerable growth plasticity, reflecting the wide range of environmental conditions and life histories sustaining herring populations.publishedVersio
The underwater soundscape of the North Sea
Full text linkAs awareness on the impact of anthropogenic underwater noise on marine life grows, underwater noise measurement programs are needed to determine the current status of marine areas and monitor long-term trends. The Joint Monitoring Programme for Ambient Noise in the North Sea (JOMOPANS) collaborative project was funded by the EU Interreg to collect a unique dataset of underwater noise levels at 19 sites across the North Sea, spanning many different countries and covering the period from 2019 to 2020. The ambient noise from this dataset has been characterised and compared - setting a benchmark for future measurements in the North Sea area. By identifying clusters with similar sound characteristics in three broadband frequency bands (25–160 Hz, 0.2–1.6 kHz, and 2–10 kHz), geographical areas that are similarly affected by sound have been identified. The measured underwater sound levels show a persistent and spatially uniform correlation with wind speed at high frequencies (above 1 kHz) and a correlation with the distance from ships at mid and high frequencies (between 40 Hz and 4 kHz). Correlation with ocean current velocity at low frequencies (up to 200 Hz), which are susceptible to nonacoustic contamination by flow noise, was also evaluated. These correlations were evaluated and simplified linear scaling laws for wind and current speeds were derived. The presented dataset provides a baseline for underwater noise measurements in the North Sea and shows that spatial variability of the dominant sound sources must be considered to predict the impact of noise reduction measures.publishedVersio
Lakselusinfestasjon på vill laksefisk våren 2024 - Fremdriftsrapport til Mattilsynet
Full text linkOvervåkingsprogrammet for lakselus på vill laksefisk (NALO) gjennomføres på oppdrag fra Mattilsynet og Nærings og Fiskeridepartementet, og har som mål å skaffe robuste data på lakselusinfestasjon hos vill laksefisk i alle 13 produksjonsområder for akvakultur. Fjordene hvor infestasjonen av lakselus er undersøkt på trålfanget postsmolt av laks er endret fra 2023. I tillegg til de faste fjordene på Vestlandet blir det i år også gjennomført postsmolttråling i ytre del av Trondheimsfjorden. Det er ikke gjennomført postsmolttråling i Nord-Norge i 2024. De fleste sjøørretstasjonene undersøkes kun én gang og tidspunktet for dette er lagt omtrent midt mellom tidligere runde 1. og runde 2. Med unntak av Førdefjorden er alle sjøørretstasjoner undersøkt tidligere år. Feltundersøkelsen i NALO gjennomføres fra slutten av mai til slutten av juli. I denne framdriftsrapporten presenteres foreløpige lusedata på laks og sjøørret fra Sørlandet til og med Trøndelag.Lakselusinfestasjon på vill laksefisk våren 2024 - Fremdriftsrapport til MattilsynetpublishedVersio
Management strategy evaluation for northern shrimp in the Barents Sea (ICES subareas 1 and 2)
Full text linkTo establish a management plan for northern shrimp (Pandalus borealis) in the Barents Sea, the Norwegian-Russian Fisheries Commission requested in 2023 a proposal for a harvest control rule (HCR). Based on discussions with stakeholders, six different HCRs were defined and evaluated against three performance criteria: 1. precautionarity (less than 5% risk of falling below limit reference point for spawning stock biomass, Blim), 2. achieving a high long-term sustainable yield, and 3. stability (minimizing median interannual catch variability). All six HCRs were based on a standard hockey-stick HCR that differed only in the role of Blim (whether fishing ceases at Blim or not) and the definition of target fishing mortality. To reduce interannual fluctuations in catches, a catch constraint was added that capped year-to-year changes of total catch to 20%. The HCRs were evaluated with a full-loop management strategy evaluation based on the current stock assessment, using a surplus production model parametrized with assessment estimates as operating model and the assessment model SPiCT as observation model. The results showed that only the four HCRs without any fishing below Blim were precautionary, while the two HCRs with a slope to the origin did not fulfill the precautionary criteria. The four remaining HCRs traded off long-term yield with stability and risk, with the two HCRs where target fishing mortality was set to 80% or 90% of FMSY resulting in lower risk and higher stability but also lower median yield. The four HCRs also remained precautionary under a scenario of a substantial decrease in productivity due to environmental change. The northern shrimp stock in the Barents Sea has not been heavily fished over longer periods since the onset of its fishery, representing a challenge for the estimation of the productivity and resilience of the stock at lower biomass levels. This increases the uncertainty of the stock assessment and, subsequently, the management strategy evaluation. Relevant uncertainty is therefore linked to the stock's response to an increase from current catch levels to fishing at or near FMSY, suggesting that constraining the year-to-year increase in total catch is of particular importance when phasing in a management plan. The MSE framework and its results were endorsed at the March meeting 2024 between IMR and VNIRO and evaluated through an external review.Management strategy evaluation for northern shrimp in the Barents Sea (ICES subareas 1 and 2)publishedVersio
Ny målemetode for hummar
Full text linkFiskeridirektoratet ber Havforskingsinstituttet om å greie ut om føremoner og ulemper med å nytte ryggskjoldet (carapax) som mål for å fastsetje minstemål og maksimalmål, og å gje tilråding på bakgrunn av dette. Totallengde har vore standard metode i Noreg. Ryggskjoldlengde er eit mer stabilt mål, ein betre indikator på vekst og modning og kan vere betre for dyrevelferda. Ryggskjoldlengde er også det som vanlegvis brukast i andre land i Europa.Ny målemetode for hummarpublishedVersio
Blue mussel (Mytilus edulis) silage, a possible low trophic marine protein source for Atlantic salmon (Salmo salar L.)
Full text linkBlue mussel (Mytilus edulis) could be a promising marine protein source in fish feeds and is of great interest since it can be cultivated along the Norwegian coastline. However, the use of blue mussels in feeds is dependent on developing suitable preservation and processing methods to produce a feed grade raw material. The present studies were conducted to investigate whether blue mussel silage could be used in the feed for Atlantic salmon post-smolt. Two feeding experiments were conducted using the same reference diet with FM inclusion of 25%, giving a mix of ∼59–63% plant-based ingredients vs ∼34–36% marine ingredients to simulate a standard grower feed for salmon post-smolts in SW. In experiment 1, fish were fed diets containing three different inclusion levels of blue mussel silage (BMS 3, 7, and 11%), a diet containing blue mussel meal (BMM) (12%) as well as the reference feed. In this experiment, the fish that were fed a diet containing BMS had a decline in both weight gain and condition factor when compared to the fish given the reference and BMM. The daily feed intake was similar in all groups, but the feed conversion ratio (FCR) increased in the fish fed BMS. The inclusion of BMS and BMM did not affect the digestibility of nutrients, but reduced retention of whole-body lipid and protein retention was observed. Salmon given BMS in the diet also had lower iron (Fe) concentrations in liver and whole body, indicating lower Fe uptake, irrespective of inclusion level. These findings were followed up in a second feeding experiment aiming to investigate whether different processing methods of blue mussel silage could influence the bioavailability of iron, as well as feed utilization and growth. The reference feed was formulated similar to the feed in exp. 1. Additionally, fish were fed diets containing BMM (9%) and the same batch of BMS (9%) used in exp. 1 as well as two diets containing new productions of BMS (9%) using either a lower acid level or only formic acid at the same level. In experiment 2, no differences were seen in weight gain, feed intake, FCR, nutrient retention or body composition between fish given BMS and reference diet. The lower Fe status observed in experiment 1 was not seen in the second study. In both experiments, there were no differences in fish welfare indicators between the group of fish fed with BMS, BMM and the reference group.
The present results show that blue mussel silage can be used in the diet for Atlantic salmon, however, the different processing and preservation methods to produce BMS influence the nutritional properties and consequently growth performance and feed utilization of Atlantic salmon post-smolts.publishedVersio
Zinc nutrition at first feeding imprints a programming effect on growth and hepatic lipid metabolism in juvenile rainbow trout
Full text linkThe objective of this study was to determine whether supplementation with deficient zinc (Zn) or/and excess copper (Cu) in the first-feeding diet of rainbow trout fry influenced the growth and physiological regulation of juvenile fish subjected to similar challenge feeds again. The feeding trial lasted for 24 weeks and had three phases. In phase I, rainbow trout fry was treated with one of four different plant-based feeds containing or exempting Zn or Cu supplementation (coded Zn-Cu-, Zn+Cu-, Zn-Cu+, Zn+Cu+) for 6 weeks. Thereafter, all groups were fed a common commercial feed for the next 12 weeks (phase II). In phase III, all groups were fed with the “challenge diet” for another 6 weeks which was the basal diet (Zn-Cu-) except that the vegetable oils were replaced by fish oil. The results demonstrated that fish fed a Zn+ diet at first feeding increased larval growth (phase-I), but it had no effect on growth at the end of phase II when fed commercial feeds. In phase III, when re-introduced to a Zn- challenge diet, the feed intake and growth of juveniles with Zn+ history significantly increased, with reduced feed efficiency. Fish growth was neither influenced by dietary Cu levels or by the dietary Cu history in any of the growth phases, but dietary Cu excess (Cu+) reduced body lipid and energy content in fry. In phase I, lower whole-body Zn concentration was observed in the fry of Zn- group compared to Zn+, while the contrary was observed in the juvenile fish as affected by dietary Zn history (phase III). In addition, Zn- dietary history showed increased levels of PUFA and higher mRNA expression of fatty acid biosynthesis genes in the liver. To conclude, early-stage dietary Zn+ history improved growth of juvenile rainbow trout, while dietary Zn- history exhibited signs of improved fatty acid biosynthesis capacity in the liver.publishedVersio
New concept for hook and leader for longline
Full text linkProsjektet «Nytt konsept for krok og forsyn til linefiske" ble igangsatt i 2020 og hadde som mål å (1) utvikle en krok som ikke korroderer og som er mer effektiv og har lengre levetid enn dagens krok, og (2) utvikle et forsyn som ikke avgir mikroplast, kan tilpasses ulike driftsformer og ha lengre levetid enn dagens forsyn. Prosjektet fikk en utfordrende start i koronapandemiåret 2020. Leveringsutfordringer fra underleverandører, men også materialespesifikke utfordringer i utviklingsarbeidet hos MF gjorde det nødvendig å avvike fra målsetningene tidlig i prosjektet. Det ble besluttet å fokusere på en hurtigkobling for krokskifte uten å skifte forsyn. Hurtigkoblinger mellom forsyn og krok hadde en positiv effekt på fangstrate av torsk sammenlignet med en blåkveitekrok med lignende, men ikke helt lik utforming. Fangstøkningen kan forklares utfra økt sviveleffekt fra hurtigkobling. Grunnet utfordringene ble fiskeforsøkene dreid mot testing av visuelle og taktile stimuli. Forsøk med lavenergi LED lys montert på linerygg økte fangstene (antall) av torsk og hyse med henholdsvis med ~75% og ~25% (ikke signifikant). Selvlysende hylser tredd over forsyn endret ikke fangsteffektivitet for torsk og hyse, hylsene var imidlertid ikke fulladet. Hylsene førte til lengdeavhengig seleksjon med høyere andel større fisk. Gummierte kroker førte til en 35% nedgang i hysefangstene, men ikke torskefangstene og forklares med ulik beiteadferd hos torsk og hyse. Prosjektet har frembrakt en rekke interessante innledende funn på visualisering, krokutforming og materialvalg med betydning for både fangsteffektivitet og seleksjon. Funnene kan ha betydning for utviklingsløpene på både krok, forsyn og linerygg både nasjonalt og internasjonalt.Nytt konsept for krok og forsyn til linefiskepublishedVersio
Plastsøppel på havbunnen kartlagt av Mareano
Full text linkMiljødirektoratet har bedt Havforskningsinstituttet om å analysere observasjonsdata for søppel på havbunnen for å øke kunnskapen om hvor mye plastavfall utgjør av dette. Mareano kartlegger søppel på havbunnen som del av omfattende kartleggingen av havbunnens biologi og miljø. Denne kartleggingen gjøres på en ikke- destruktiv måte med videoplattformer. Observasjonene er gjort i felt og er her kategorisert etter relevante protokoller gitt av OSPAR og ICES. Dataene dekker perioden siden Mareano startet i 2006 og inkluderer 3421 videotransekter. De fleste lokalitetene (81%) har ingen søppelforekomst, og søppelmengden avtar generelt mot nord og med avstand fra kysten. 1,8 % av alle lokaliteter har høy tetthet (>2000 enheter/km2) av søppel. Plast ble observert på 8,9 % av alle lokalitetene. Plast ble observert på 8,9% av alle lokalitetene. Tettheten av plastavfall øker med dybden ned til rundt 600 m og er høyest i marine daler og gjel. Fiskerirelatert plast utgjør en betydelig del av funnene.Plastsøppel på havbunnen kartlagt av MareanopublishedVersio