Report on the scientific eel fishery in Norway in 2017

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Sluttrapport forskningsfangst etter ål (2018) - HI prosjekt 81333

Bakgrunn for prosjektet Europeisk ål er en viktig del av kystøkosystemet, spesielt i Sør-Norge. Anguilla anguilla er en katadrom fisk. Det vil si at den gyter i saltvann og vokser opp i ferskvann (gulålstadiet). Imidlertid vokser en god del av ålen som kommer til Norge opp i saltvann langs kysten. Etter gulålstadiet går ålen over i blankålstadiet. Om høsten, mens den fremdeles er seksuelt umoden, starter ålen gytevandringen. Den svømmer da ca. 6000 km for å nå tilbake til Sargassohavet hvor den gyter. I 2007 ble ål inkludert i CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). Den omhandler arter som ikke nødvendigvis er truet av utryddelse, men der handel med arten må kontrolleres for å unngå en utnyttelse som er uforenlig med deres overlevelsesevne (se http://www.cites.org/eng/ plate / how.shtml). Oppføringen ble gjennomført i mars 2009. Etter den ble rødlistet som kritisk truet i Norge, ble alt fiske etter ål forbudt i Norge 1. juli 2009. Dette gjaldt også fritidsfiske. Ålebestanden i Norge har vært overvåket av Havforskningsinstituttet siden 1975. Fangst og innsats ble registrert i dagbøker frem til 2010. En del fiskere fikk dispensasjon til å fiske en gitt mengde ål etter at fiskeforbudet ble innført for at overvåkingen av ål skulle fortsette. På grunn av CITES regulering fikk imidlertid fiskerne problemer omsetningen av ål, da det ble ulovlig å importere ål inn til EU. Forskningsfangsten ble derfor avsluttet i 2010. I 2015 fikk ål en ny vurdering av Artsdatabanken, og ble oppført som VU (sårbar) i den Norske Rødlisten, hvor den hadde stått som CR (kritisk truet) siden 2006. I Fiskeridirektoratets «Handlingsplan 2016» vises det til at det er behov for mer kunnskap om bestandssituasjonen for ål, og at en overvåkningsfangst vil kunne bidra til dette. Det ble da startet et prosjekt med forskningsfangst for å vurdere endringer i lokale bestander. Formålet med prosjektet var å få oversikt over bestanden av Europeisk ål langs norskekysten, og i tillegg øke kunnskapen om biologiske egenskaper som alder ved kjønnsmodning (utvandring til gyteområdet), vekstparametere, parasittbelastning m.m. Denne kunnskapen kan forbedre rådgivningen for denne arten i Norge og bidra til ICES sin vurdering av hele bestanden. Prosjektet bestod av 3 deler: 1) registrering av fangst fra utvalgte fiskere; 2) merkeforsøk; 3) biologisk kunnskapsinnhenting (aldersbestemmelse, vekt, parasittbelastning). Dette er en sluttrapport for 2018 som oppsummerer aktivitetene og resultatene av: overvåkning av ål dette året.publishedVersio

Program rensefisk: atferd og artssamspill i laksemerder. Delrapport FHF-Prosjekt 900978

English: Cleanerfish used in salmon farming are considered the most important non-pharmaceutical tool to reduce salmon lice infestation. Several species of cleanerfish are often used in combination, but there is little knowledge about how the behaviour and interaction between species will affect their efficiency in reducing the number of salmon lice on the fish. In this experiment, we tested combinations of the cleanerfish species ballan wrasse, goldsinny, corkwing and lumpfish. Behaviour of cleanerfish was observed using GoPro video cameras, and the position of cleanerfish was registered using an array of antennae. Each week, lice were counted on salmon from every netpen. Because of a disease outbreak in the salmon, the trial lasted only three weeks. Nonetheless, there was a detectable effect of the cleanerfish on the number of salmon lice compared to controls. Norsk: Rensefisk er lakseoppdretternes viktigste, ikke-medikamentelle verktøy i kampen mot lakselus. Det brukes ofte flere arter rensefisk i kombinasjon, men det er lite kjent om atferd og artssamspill kan påvirke effekten av lusebeiting i merd. I dette forsøket ble kombinasjoner av rensefiskartene berggylt, bergnebb, grønngylt og rognkjeks testet i kombinasjoner. Atferd ble undersøkt ved bruk av kamera og antenner til posisjonsregistrering. Lus ble talt i alle merder ukentlig. Forsøket varte bare i tre uker pga. sykdomsutbrudd på laksen, men vi kunne likevel se tydelig effekt av rensefisken på antall lus sammenlignet med kontrollgrupper

Gene expression and epigenetic responses of the marine Cladoceran, Evadne nordmanni, and the copepod, Acartia clausi, to elevated CO2

Characterizing the capacity of marine organisms to adapt to climate change related drivers (e.g., pCO2 and temperature), and the possible rate of this adaptation, is required to assess their resilience (or lack thereof) to these drivers. Several studies have hypothesized that epigenetic markers such as DNA methylation, histone modifications and noncoding RNAs, act as drivers of adaptation in marine organisms, especially corals. However, this hypothesis has not been tested in zooplankton, a keystone organism in marine food webs. The objective of this study is to test the hypothesis that acute ocean acidification (OA) exposure alters DNA methylation in two zooplanktonic species—copepods (Acartia clausii) and cladocerans (Evadne nordmanii). We exposed these two species to near-future OA conditions (400 and 900 ppm pCO2) for 24 h and assessed transcriptional and DNA methylation patterns using RNA sequencing and Reduced Representation Bisulfite Sequencing (RRBS). OA exposure caused differential expression of genes associated with energy metabolism, cytoskeletal and extracellular matrix functions, hypoxia and one-carbon metabolism. Similarly, OA exposure also caused altered DNA methylation patterns in both species but the effect of these changes on gene expression and physiological effects remains to be determined. The results from this study form the basis for studies investigating the potential role of epigenetic mechanisms in OA induced phenotypic plasticity and/or adaptive responses in zooplanktonic organisms.publishedVersio

Kunnskapsinnhenting Leppefisk – biologi og fiskeri 2013-2018: Rapport til Fiskeridirektoratet for 2018 sesongen

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The three-dimensional prey field of the northern krill, Meganyctiphanes norvegica, and the escape responses of their copepod prey

In the north Atlantic, Meganyctiphanes norvegica feeds predominantly on copepods, including Calanus spp. To quantify its perceptual field for prey, and the sensory systems underlying prey detection, the responses of tethered krill to free-swimming Calanus spp. were observed in 3D using silhouette video imaging. An attack–which occurred despite the krill’s being tethered—was characterized by a pronounced movement of the krill’s antennae towards the target, followed by a propulsion and opening of the feeding basket. Frequency distributions of prey detection distances were significantly different in the light vs. the dark, with median values of 26.5 mm and 19.5 mm, respectively. There were no significant differences in the angles at which prey were detected by krill (relative to the predator’s longitudinal body axis) in the light vs. the dark. Prey detections were symmetrically distributed on either side of the predator, in both light and dark. However, significant asymmetry was found in the dorsal–ventral direction with 80% of the prey detections located below the midline of the krill’s body axis and, given the placement and orientation of the compound eyes, presumably outside its visual field of view. This indicates that, at least under these conditions, vision was not the main sensory modality involved in the detection of active prey by M. norvegica. However, under some circumstances, vision may provide supplemental information. Avoidance responses of copepod prey were nearly twice the velocity of their nominal background swimming speed (153 ± 48 and 85 ± 75 mm s−1, respectively), on average taking them 43 ± 16 mm away from the predator. This is far beyond the krill’s perceptual range, suggesting that the escape reaction provides an effective deterrent to predation (although perhaps less so for free-swimming krill). This information can be used to parameterize models that assess the role of krill as predators in marine ecosystems

A biotest system for optimalization of environmental parameters for production of halibut fry

A system for controlled testing of different environmental parameters in seawater was made. Both the biotest system and an experimental setup using larvae of the Atlantic Halibut (Hippoglossus hippoglossus L.) are described

A unifying hypothesis for the spawning migrations of temperate anguillid eels

Anguillid eels grow in freshwater but spawn in the open ocean. The cues that guide eels over long distances to the spawning area are unknown. The Earth's magnetic field can provide directional and positional information and is likely used by catadromous eels during their spawning migration; as magnetosensitivity and compass orientation have been reported in eels. To test whether this is theoretically possible, we compared the migratory routes of five species of temperate eels that undertake long migrations with the geomagnetic field of their distribution/spawning areas. We found that, regardless of the species and although routes are different between life stages, larvae of those species always drift along paths of increasing magnetic inclination and intensity, while adults follow reverse gradients. This is consistent with an imprinting/retracing hypothesis. We propose a general navigation mechanism based on larvae imprinting on a target magnetic intensity (or inclination) at the hatching area and on the intensity (or inclination) gradient during larval drift. Years later, adults retrace the magnetic route by following the gradient of decreasing total intensity (or inclination) values that occurs towards lower latitudes. As they reach the target value, adults switch to compass orientation to stay on the target isoline and reach the spawning area. The proposed mechanism fits for all temperate eels examined. Knowledge about navigational strategies of eels is important to evaluate the effectiveness of management strategies that involve stocking of juveniles displaced from one area to another to rebuild local populations.publishedVersio

Scientific evaluation of potential new species in Norwegian aquaculture

On request from the Norwegian department of Fisheries are the potential for farming of the most promising species of fish, shellfish, crustaceans and algae evaluated scientifically. The report includes species that are beeing commerialised, species close to commercialisation, species that are beeing developed for farming and exotic species not endogenous in Norway. Economic analysis is not included in this report. NORSK SAMMENDRAG: På oppdrag fra Fiskeridepartementet er potensialet for de mest aktuelle arter av fisk, skjell, tifotkreps og alger vurdert vitenskapelig med hensyn på mulighetene for å drive oppdrett. Rapporten inkluderer arter som er under kommersialisering, arter som er nær kommersialisering, arter som er på utviklingsstadiet til oppdrett, og fremmede arter som naturlig ikke hører hjemme i norsk fauna. Økonomiske analyser er ikke inkludert i denne rapporten

Scientific evaluation of potential new species in Norwegian aquaculture

On request from the Norwegian department of Fisheries are the potential for farming of the most promising species of fish, shellfish, crustaceans and algae evaluated scientifically. The report includes species that are beeing commerialised, species close to commercialisation, species that are beeing developed for farming and exotic species not endogenous in Norway. Economic analysis is not included in this report. NORSK SAMMENDRAG: På oppdrag fra Fiskeridepartementet er potensialet for de mest aktuelle arter av fisk, skjell, tifotkreps og alger vurdert vitenskapelig med hensyn på mulighetene for å drive oppdrett. Rapporten inkluderer arter som er under kommersialisering, arter som er nær kommersialisering, arter som er på utviklingsstadiet til oppdrett, og fremmede arter som naturlig ikke hører hjemme i norsk fauna. Økonomiske analyser er ikke inkludert i denne rapporten