Egg distribution, bottom topography and small-scale cod population structure in a coastal marine system

Coastal marine species with pelagic egg and larval stages, such as the Atlantic cod Gadus morhua, can be structured into genetically distinct local populations on a surprisingly small geographic scale considering their dispersal potential. Mechanisms responsible for such small-scale genetic structure may involve homing of adults to their natal spawning grounds, but also local retention of pelagic eggs and larvae. For example, spawning within sheltered fjord habitats is expected to favour local retention of early life stages. Here, we studied the distribution of cod eggs along inshore-offshore transects in 20 Norwegian fjords. The general pattern exhibited across all fjords was a higher concentration of cod eggs inside the fjords than further offshore. In particular, fjords with shallow sills (model threshold 37 m) show an abrupt reduction in egg density over the sill. This study provides empirical support for an offspring retention hypothesis, which may help to explain the maintenance of local population structure in pelagic marine systems

Lobster and cod benefit from small-scale northern marine protected areas: inference from an empirical before - after control-impact study

Marine protected areas (MPAs) are increasingly implemented as tools to conserve and manage fisheries and target species. Because there are opportunity costs to conservation, there is a need for science-based assessment of MPAs. Here, we present one of the northernmost documentations of MPA effects to date, demonstrated by a replicated before-after control-impact (BACI) approach. In 2006, MPAs were implemented along the Norwegian Skagerrak coast offering complete protection to shellfish and partial protection to fish. By 2010, European lobster (Homarus gammarus) catch-per-unit-effort (CPUE) had increased by 245 per cent in MPAs, whereas CPUE in control areas had increased by 87 per cent. Mean size of lobsters increased by 13 per cent in MPAs, whereas increase in control areas was negligible. Furthermore, MPA-responses and population development in control areas varied significantly among regions. This illustrates the importance of a replicated BACI design for reaching robust conclusions and management decisions. Partial protection of Atlantic cod (Gadus morhua) was followed by an increase in population density and body size compared with control areas. By 2010, MPA cod were on average 5 cm longer than in any of the control areas. MPAs can be useful management tools in rebuilding and conserving portions of depleted lobster populations in northern temperate waters, and even for a mobile temperate fish species such as the Atlantic cod

Aktiv forvaltning av marine ressurser – lokalt tilpasset forvaltning

Årsrapport 201

Replicated marine protected areas (MPAs) support movement of larger, but not more, European lobsters to neighbouring fished areas

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Restoration of Abundance and Dynamics of Coastal Fish and Lobster Within Northern Marine Protected Areas Across Two Decades

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Status of the cod along the coast in southern Norway

English: In a report from 2008 an assessment of coastal cod in southern Norway, from the Swedish border to Stad, was presented, together with suggestions to management initiatives. This report shortly summarize the 2008-report, but new knowledge attained the last 10 years is the main part. The cod along the coast in southern Norway are made up of possibly there different components: 1) stationary, local stocks in the fjords, 2) cod from the North Sea along the outer coast, and 3) possibly a more “ migrating cod” along the outer coast. The latter type of coastal cod, if existing, has genetic similarities with the North Sea cod. Much new knowledge indicate that the cod along the coast in southern Norway are exposed to increasing pressure from multiple factors, not at least from recreational fisheries. Local stocks of cod in fjords are the smallest and accordingly most vulnerable stocks of cod. Future regulations should aim at a best possible conservation of the local stocks of cod in the fjords, but also reduce mortality of cod living along the outer parts of the coast. This report also suggest some, possible management initiatives. Norsk:2008 kom en rapport som vurderte status for kysttorsk på strekningen Svenskegrensa-Stad, og som også inkluderte forslag til forvaltningstiltak. Denne rapporten starter med en kort oppsummering av oversikten fra 2008, men bringer i hovedsak ny kunnskap som er kommet til de siste 10 årene. Historisk er det en klar nedgang i fangstene av årets yngel (0-gruppe torsk) i strandnotserien fra Havforskningsinstituttet. De siste ca. 20 årene har nedgangen vært størst. Torskeforekomstene langs kysten ser ut til å være sammensatt av tre komponenter: 1) lokale, stasjonære stammer av fjordtorsk, som særlig forekommer i de indre kystområdene/fjordene, 2) nordsjøtorsk og 3) muligens også en mer vandrende komponent av kysttorsk med genetisk likhetstrekk med nordsjøtorsken, som særlig forekommer i de ytre kystområdene. Det er nå dokumentert at torsken langs kysten både på Vestlandet og Sørlandet er utsatt for økende press fra flere påvirkningsfaktorer, ikke minst et betydelig fritidsfiske. Lokale stammer av fjordtorsk er de klart minste og mest sårbare bestandene langs kysten. Fremtidige reguleringer bør gi best mulig vern for lokale stammer av fjordtorsk, men også redusere fiskedødeligheten for «nordsjøtype» torsk langs den ytre delen av kysten. En rekke forslag til tiltak er oppsummert i rapporten

Biomassemodell for stortare - Ressursmodell for fremtidens forvaltning

En romlig biomassemodell for stortare er utviklet i et pilotområde med gode data for bunn-, dyp- og miljøforhold og med høy oppløsning. Modellen predikerer en total stortarebiomasse på 457 000 tonn innenfor området. Korrelasjonen mellom modellen og uavhengige data var på hele 0,85 og stemte dermed svært godt overens med virkeligheten. Pilotmodellen er første skritt i utviklingen av en ressursmodell for hele Norge som kan gi forvaltning og næring en oversikt over stortareressursene og legge til rette for bærekraftig høsting av denne rike ressursen.publishedVersio

Lobster reserves as a management tool in coastal waters: Two decades of experience in Norway

9 pages, 4 figures.-- Under a Creative Commons licenseThe positive effects of reduced fishing pressure in marine protected areas (MPAs) are now well documented globally. Yet, evidence of MPA benefits from long-term replicated before-after control-impact (BACI) studies and their usefulness in protecting target species are still rare, especially in northern temperate areas. Scientific rigor in the monitoring of MPAs is considered important for obtaining trust and compliance and can increase interest and enthusiasm for the benefits of marine conservation. Off the coast of southern Norway, a MPA implementation process started up in 2002. Based on comprehensive consultations with local fishers and managers, four experimental lobster reserves were appointed in 2004. Two years later (2006), the reserves came into effect as the Norwegian Directorate of Fisheries implemented regulations as a by-law of the Saltwater Fisheries Act that effectively banned all fixed gear. Long-term monitoring of the MPAs and adjacent control areas has enabled a rigorous scientific evaluation of the effects of these MPAs on lobster populations, including effects on density, growth, demography, behavior, and phenotypic diversity. As protection effects started to manifest, the lobster reserves attracted high public attention and were soon considered a credible supplement to traditional fisheries management. In the period from 2002 to 2021, more than 50 lobster reserves have been implemented in Norway. Here, we review the experiences since the lobster reserves were designated, implemented, and embraced by local communities in Norway, and over two decades have become an important tool for fishery management. Thoughts on the future of MPAs along the coast of Norway are discussedLong term monitoring of the MPAs in Skagerrak and preparation of this manuscript was funded by the Institute of Marine Research Coastal Ecosystems Research Program. Preparation of the manuscript was also supported by University of Agder (UiA) through a priority research center grant to the UiA Centre for Coastal Research (CCR)Peer reviewe