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Rognkjeks kvoterådgivning fra Havforskningsinstituttet for 2025
Get PDFRåd om fiske - Havforskningsinstituttet anbefaler at samlet fisket kvantum i 2025 ikke overskrider 400 tonn rå rogn. Dette tilsvarer 2 216 tonn rogn-kjeks (rundt vekt med omregningsfaktor = 5.54).Rognkjeks kvoterådgivning fra Havforskningsinstituttet for 2025publishedVersio
Importance of environmental signals for cardiac morphological development in Atlantic salmon
Get PDFThe hearts of salmonids display remarkable plasticity, adapting to various environmental factors that influence cardiac function and demand. For instance, in response to cold temperature, the salmonid heart undergoes growth and remodeling to counterbalance the reduced contractile function associated with dropping temperatures. Alongside heart size, the distinct pyramidal shape of the wild salmonid heart is essential for optimal cardiac performance, yet the environmental drivers behind this optimal cardiac morphology remain to be fully understood. Intriguingly, farmed salmonids often have rounded, asymmetrical ventricles and misaligned bulbi from an early age. These deformities are noteworthy given that farmed salmon are often not exposed to natural cues, such as a gradual temperature increase and changing day lengths, during critical developmental stages. In this study, we investigated whether natural environmental conditions during early life stages are pivotal for proper cardiac morphology. Atlantic salmon were raised under simulated natural conditions (low temperature with a natural photoperiod; SimNat) and compared with those reared under simulated farming conditions (SimFarm). Our findings reveal that the ventricle shape and bulbus alignment in SimNat fish closely resemble those of wild salmon, while functional analyses indicate significant differences between SimNat and SimFarm hearts, suggesting diastolic dysfunction and higher cardiac workload in SimFarm hearts. These findings highlight the profound influence of environmental factors such as water temperature and photoperiod on the structural development of the salmonid heart, underscoring the importance of early environmental conditions for cardiac health.publishedVersio
Climate change impacts on small pelagic fish distribution in Northwest Africa: trends, shifts, and risk for food security
Get PDFClimate change is recognised to lead to spatial shifts in the distribution of small pelagic fish, likely by altering their environmental optima. Fish supply along the Northwest African coast is significant at both socio-economic and cultural levels. Evaluating the impacts of climatic change on small pelagic fish is a challenge and of serious concern in the context of shared stock management. Evaluating the impact of climate change on the distribution of small pelagic fish, a trend analysis was conducted using data from 2363 trawl samplings and 170,000 km of acoustics sea surveys. Strong warming is reported across the Southern Canary Current Large Marine Ecosystem (CCLME), extending from Morocco to Senegal. Over 34 years, several trends emerged, with the southern CCLME experiencing increases in both wind speed and upwelling intensity, particularly where the coastal upwelling was already the strongest. Despite upwelling-induced cooling mechanisms, sea surface temperature (SST) increased in most areas, indicating the complex interplay of climatic-related stressors in shaping the marine ecosystem. Concomitant northward shifts in the distribution of small pelagic species were attributed to long-term warming trends in SST and a decrease in marine productivity in the south. The abundance of Sardinella aurita, the most abundant species along the coast, has increased in the subtropics and fallen in the intertropical region. Spatial shifts in biomass were observed for other exploited small pelagic species, similar to those recorded for surface isotherms. An intensification in upwelling intensity within the northern and central regions of the system is documented without a change in marine primary productivity. In contrast, upwelling intensity is stable in the southern region, while there is a decline in primary productivity. These environmental differences affected several small pelagic species across national boundaries. This adds a new threat to these recently overexploited fish stocks, making sustainable management more difficult. Such changes must motivate common regional policy considerations for food security and sovereignty in all West African countries sharing the same stocks.publishedVersio
Coherent long-term body-size responses across all Northwest Atlantic herring populations to warming and environmental change despite contrasting harvest and ecological factors
Get PDFBody size is a key component of individual fitness and an important factor in the structure and functioning of populations and ecosystems. Disentangling the effects of environmental change, harvest and intra- and inter-specific trophic effects on body size remains challenging for populations in the wild. Herring in the Northwest Atlantic provide a strong basis for evaluating hypotheses related to these drivers given that they have experienced significant warming and harvest over the past century, while also having been exposed to a wide range of other selective constraints across their range. Using data on mean length-at-age 4 for the sixteen principal populations over a period of 53 cohorts (1962–2014), we fitted a series of empirical models for temporal and between-population variation in the response to changes in sea surface temperature. We find evidence for a unified cross-population response in the form of a parabolic function according to which populations in naturally warmer environments have responded more negatively to increasing temperature compared with those in colder locations. Temporal variation in residuals from this function was highly coherent among populations, further suggesting a common response to a large-scale environmental driver. The synchrony observed in this study system, despite strong differences in harvest and ecological histories among populations and over time, clearly indicates a dominant role of environmental change on size-at-age in wild populations, in contrast to commonly reported effects of fishing. This finding has important implications for the management of fisheries as it indicates that a key trait associated with population productivity may be under considerably less short-term management control than currently assumed. Our study, overall, illustrates the need for a comparative approach within species for inferences concerning the many possible effects on body size of natural and anthropogenic drivers in the wild.publishedVersio
Regional and temporal variation in escape history of Norwegian farmed Atlantic salmon
Get PDFEach year thousands of farmed Atlantic salmon escape from seawater net pens, and introgression has been documented in a range of wild populations. Due to greater experience in the wild, escapees that have been on the run for a longer period, and successfully transitioned to a wild diet (classified: “early escapees”), could potentially have a higher spawning success and contribute more to introgression than those that have been on the run for a shorter period and/or have not transitioned to a wild diet (classified: “recent escapees”). This is the first study to examine how the escape history of farmed Atlantic salmon captured in multiple rivers and coastal fisheries, varies in time and space. During 2011–2021, adult farmed escaped salmon were captured in four rivers and at six coastal sites in Norway. The level of linoleic acid, a terrestrial fatty acid high in commercial salmon feeds but low in the natural diet of wild salmon, was used to classify the farmed salmon as early or recent escapees. We observed temporal declines in the relative proportions of escaped vs. wild salmon in the catches, and the relative proportion of early vs. recent escapees in the most southern river (driven by samples from 2011 to 2015). Overall, 14% of the escaped salmon caught in the period were classified as early escapees. The relative proportion of early escapees was lower in the two southernmost rivers (21.2% and 6.30%), as compared to the coastal fisheries (40.9%) and the northernmost river (77.6%). Both aquaculture–management regulations and production strategies have likely influenced these observations.publishedVersio
Liste over forvaltningsrelevante naturenheter - Oppfølgende informasjon til rapporten "Forvaltningsrelevante naturenheter i sjø"
Get PDFI forbindelse med forvaltningens oppgave om å lage en framtidig samlet offentlig instruks for kartlegging av marin natur, bestilte fiskeridirektoratet i en oversikt over der havforskningsinstituttet ville foreslå som "Forvaltningsrelevante naturenheter i sjø". Denne rapporten ble levert og publisert 29.04.2024. I den rapporten foreslo Havforskningsinstituttet å utvide begrepet naturenheter til også å omfatte funksjonsområder for arter, og områder viktig for struktur og sentrale økosystemprosesser. Totalt ble det foreslått 20 abiotiske fysiske enheter, 3 biotiske fysiske enheter, 6 hovedgrupper av funksjonsområder (for totalt 46 arter) og 9 struktur og prosessområder som kunne danne grunnlag for kartlegging av marin natur. Denne rapporten er en utdyping av rapporten "Forvaltningsrelevante naturenheter i sjø", der alle naturenhetene som er foreslått blir nærmere forklart samt at det presenteres et perspektiv på ulike aspekter som kan være viktig for prioritering av hva som skal kartlegges. Enkelte naturenheter har fått mindre endringer i navn og innhold til det opprinnelige forslaget, men den første rapporten har vært førende for innhold. Det kan være aktuelt å revidere hvilke naturenheter som vil være viktige og om noen naturenheter ikke nødvendigvis har samme betydning for forvaltningen på et senere tidspunkt.Liste over forvaltningsrelevante naturenheter - Oppfølgende informasjon til rapporten "Forvaltningsrelevante naturenheter i sjø"publishedVersio
A conceptual framework to help choose appropriate blue nature-based solutions
Get PDFBiodiversity loss and climate change have severely impacted ecosystems and livelihoods worldwide, compromising access to food and water, increasing disaster risk, and affecting human health globally. Nature-based Solutions (NbS) have gained interest in addressing these global societal challenges. Although much effort has been directed to NbS in urban and terrestrial environments, the implementation of NbS in marine and coastal environments (blue NbS) lags. The lack of a framework to guide decision-makers and practitioners through the initial planning stages appears to be one of the main obstacles to the slow implementation of blue NbS. To address this, we propose an integrated conceptual framework, built from expert knowledge, to inform the selection of the most appropriate blue NbS based on desired intervention objectives and social-ecological context. Our conceptual framework follows a four incremental steps structure: Step 1 aims to identify the societal challenge(s) to address; Step 2 highlights ecosystem services and the underlying biodiversity and ecological functions that could contribute to confronting the societal challenge(s); Step 3 identify the specific environmental context the intervention needs to be set within (e.g. the spatial scale the intervention will operate within, the ecosystem's vulnerability to stressors, and its ecological condition); and Step 4 provides a selection of potential blue NbS interventions that would help address the targeted societal challenge(s) considering the context defined through Step 3. Designed to maintain, enhance, recover, rehabilitate, or create ecosystem services by supporting biodiversity, the blue NbS intervention portfolio includes marine protection (i.e., fully, highly, lightly, and minimally protected areas), restorative activities (i.e., active, passive, and partial restoration; rehabilitation of ecological function and ecosystem creation), and other management measures (i.e., implementation and enforcement of regulation). Ultimately, our conceptual framework guides decision-makers toward a versatile portfolio of interventions that cater to the specific needs of each ecosystem rather than imposing a rigid, one-size-fits-all model. In the future, this framework needs to integrate socio-economic considerations more comprehensively and be kept up-to-date by including the latest scientific information.publishedVersio
Most of the escaped farmed salmon entering a river during a 5-year period were infected with one or more viruses
Get PDFDisease interactions between farmed and wild populations have been poorly documented for most aquaculture species, in part due to the complexities to study this. Here, we tested 567 farmed Atlantic salmon escapees, captured in a Norwegian river during 2014–2018, for five viral infections that are prevalent in global salmonid aquaculture. Over 90% of the escapees were infected with one or more viruses. Overall prevalences were: 75.7% for piscine orthoreovirus (PRV-1), 43.6% for salmonid alphavirus (SAV), 31.2% for piscine myocarditis virus (PMCV), 1.2% for infectious pancreatic necrosis virus (IPNV) and 0.4% for salmon anaemia virus (ISAV). A significantly higher prevalence of PMCV infection was observed in immature compared to mature individuals. The prevalence of both SAV and PMCV infections was higher in fish determined by fatty acid profiling to be ‘recent’ as opposed to ‘early’ escapees that had been in the wild for a longer period of time. This is the first study to establish a time-series of viral infection status of escapees entering a river with a native salmon population. Our results demonstrate that farmed escapees represent a continuous source of infectious agents which could potentially be transmitted to wild fish populations.publishedVersio
Bridging the gap: integrating models and observations for better ecosystem understanding
Get PDFOur understanding of complex marine ecosystem dynamics is often hindered by significant uncertainties and issues of representativeness associated with models and observations. Both observations and models provide a limited view of real-world complexities depending on what is specifically measured or simulated. When used together, they provide the ability to gain a broader understanding of important ecological processes. How to properly integrate models and observations while utilizing the advantages of both approaches remains a challenge. In this paper, we draw attention to commonly overlooked limitations of both observations and models, and use examples to illustrate potential strategies to mitigate bias, properly interpret results, and help improve both models and observations. We emphasize that proper validation of all data sources (models and observations) is necessary in all marine ecosystem studies, with a careful assessment of the spatio-temporal scales that the data represent.publishedVersio
Fiskeri og bruk av rensefisk i norsk oppdrett - Kunnskapsstatus
Get PDFBåde leppefisk og rognkjeks benyttes som rensefisk og er en av metodene som benyttes til reduksjon av lus på laksefisk. Bruk av rensefisk som avlusningsmetode i norsk havbruk økte jevnt fram til 2019, da totalt utsett av rensefisk passerte 60 millioner individer til en samlet verdi på over 1,3 mrd NOK. Siden har bruken av antall rensefisk gått ned for hvert år og i 2021 var tallet omtrent 45,6 millioner og i 2022 var antallet sunket til omtrent 33,4 millioner. Foreløpige tall for 2023 tyder på at utsett av rensefisk nå har stabilisert seg rundt 30 millioner. Nedgangen skyldes i all hovedsak lavere bruk av rognkjeks, som nå utgjør omtrent halvparten av antallet. Rensefisk fungere også forebyggende da de største lusene, inkludert hunnlus med egg, blir spist først (Skiftesvik mfl., 2013, Skiftesvik mfl., 2018). Bruk av rensefisk kan også redusere behovet for andre avlusningsmetoder som krever mer håndtering og dermed redusere stress og skader på fisken. Rensefisk som settes ut i norske oppdrettsanlegg er definert som akvakulturdyr, og dermed underlagt det samme regelverket som andre oppdrettsorganismer. Anlegg med rensefisk er dermed flerartskulturer (polykulturer). All rognkjeks som brukes som rensefisk kommer fra oppdrett. Av leppefisk er noe av berggylten fra oppdrett, men storparten av forbruket kommer fra villfanget leppefisk, og de vanligste artene som høstes er grønngylt, bergnebb og berggylt.Fiskeri og bruk av rensefisk i norsk oppdrett - KunnskapsstatuspublishedVersio