clarissk

• Endo, Clarissa Akemi Kajiya; Skogen, Morten D.; Stige, Leif Christian; Hjøllo, Solfrid Sætre & Vikebø, Frode Bendiksen (2023). The effects of spatial and temporal variations in spawning on offspring survival in Northeast Arctic cod. ICES Journal of Marine Science. ISSN 1054-3139. 81(3), s. 616–626. doi: 10.1093/icesjms/fsad034. Fulltekst i vitenarkiv Vis sammendrag

  Climate change and harvesting result in temporal and spatial changes and variability in spawning, and thus in offspring ambient drift conditions. As a result, variable survival of offspring and thereby in recruitment are expected. This is especially true for species with long reproduction migration as is the case for some Atlantic cod stocks. We utilize biophysical model simulations to analyze survival from spawning until age 1 resulting from different scenarios of spatial and temporal changes in spawning. We find that survival is 1.5–2 times higher when spawning is shifted southwards as compared to northerly shifts. In general, survival is more sensitive to shifts in spawning location than in spawning time. Early spawning is only favourable if spawning is concurrently shifted farther north. A future spawning scenario with a northward shift in spawning grounds beyond what has been observed historically suggests reduced offspring survival and increased sensitivity to the timing of spawning.

• Endo, Clarissa Akemi Kajiya; Stige, Leif Christian; Skogen, Morten D.; Ciannelli, Lorenzo & Vikebø, Frode Bendiksen (2022). Two decades of match-mismatch in Northeast Arctic cod – Feeding conditions and survival. Frontiers in Marine Science. 9, s. 1–14. doi: 10.3389/fmars.2022.767290. Fulltekst i vitenarkiv Vis sammendrag

  The successful recruitment of Northeast Arctic (NEA) cod is thought to depend on sufficient and suitable prey for the newly hatched larvae, in particular the nauplii stages of the lipid-rich calanoid copepod species Calanus finmarchicus. The role of spatial and temporal variations in prey availability in combination with temperature and other factors in influencing growth and survival of cod larvae is, however, incompletely understood. By combining an individual based model for NEA cod larvae at the Norwegian coast with a high-resolution ocean model and a nutrient-phytoplankton-zooplankton-detritus model providing 18 years of daily environmental conditions and prey availability we assessed larval growth and survival until they settle in their feeding habitat in the Barents Sea in early fall. We find on average a two-week delay from the peak timing of first-feeding cod larvae to the peak in prey availability. In warm years, more larvae experience food limitation than in normal years. The positive effects of high temperature on growth, survival and ultimately recruitment are nonetheless larger than the negative effects of food limitation. Food limitation mainly affects larvae spawned in southern areas or late in the spawning season as these larvae experience the highest temperatures and have the highest energy requirements. Our findings highlight the spatial and temporal differences in mechanisms that regulate growth and survival of early life stages of NEA cod and suggest that spatially resolved data may be essential for understanding match-mismatch dynamics.

• Lima, Luciana S.; Gherardi, Douglas Francisco Marcolino; Pezzi, Luciano P.; Passos, Leilane G.; Endo, Clarissa Akemi Kajiya & Quimbayo, Juan Pablo (2021). Potential changes in the connectivity of marine protected areas driven by extreme ocean warming. Scientific Reports. 11(10339). doi: 10.1038/s41598-021-89192-6. Fulltekst i vitenarkiv Vis sammendrag

  Projected future climate scenarios anticipate a warmer tropical ocean and changes in surface currents that will likely influence the survival of marine organisms and the connectivity of marine protected areas (MPAs) networks. We simulated the regional effects of climate change on the demographic connectivity of parrotfishes in nine MPAs in the South Atlantic through downscaling of the HadGEM2-ES Earth System Model running the RCP 8.5 greenhouse gas trajectory. Results indicate a tropicalization scenario over the tropical southwest Atlantic following an increase of sea surface temperature (SST) between 1.8 and 4.5 °C and changes in mean surface currents between − 0.6 to 0.5 m s−1 relative to present conditions. High mortality rates will reduce demographic connectivity and increase the isolation of oceanic islands. The simulation of organismal response to ocean warming shows that acclimation can significantly improve (p < 0.001) particle survival, promoting connectivity and tropicalization of MPAs, with potential impacts on their functional integrity and long-term resilience.

• Vikebø, Frode Bendiksen; Broch, Ole Jacob; Endo, Clarissa Akemi Kajiya; Frøysa, Håvard G; Carroll, JoLynn & Juselius, Jonas [Vis alle 7 forfattere av denne artikkelen] (2021). Northeast Arctic Cod and Prey Match-Mismatch in a High-Latitude Spring-Bloom System. Frontiers in Marine Science. 8, s. 1–13. doi: 10.3389/fmars.2021.767191. Fulltekst i vitenarkiv Vis sammendrag

  By combining an ocean model, a nutrient-phytoplankton-zooplankton-detritus-model and an individual-based model for early life stages of Northeast Arctic cod we systematically investigate food limitations and growth performance for individual cod larvae drifting along the Norwegian coast from spawning grounds toward nursery areas in the Barents Sea. We hypothesize that there is food shortage for larvae spawned early and late in the 2-monthlong spawning period, and to a larger degree to the north and south of the main spawning grounds in the Lofoten. Model results for three contrasting years (1995, 2001, and 2002) show that spawning early in the season at spawning grounds in the Lofoten and farther north is favorable for larval growth close to their size- and temperature-dependent potential. Still, both early and late spawned larvae experience slower growth than individuals originating closer to the time of peak spawning late March/early April. The reasons are low temperatures and shortage in suitable prey, respectively, and this occurs more frequent in areas of strong currents about 1–2 months post hatching. In particular, late spawned larvae grow relatively slow despite higher temperatures later in the season because they are outgrown by their preferred prey.

• Endo, Clarissa; Vikebø, Frode Bendiksen; Yaragina, Natalia A.; Hjøllo, Solfrid Sætre & Stige, Leif Christian (2020). Effects of climate and spawning stock structure on the spatial distribution of Northeast Arctic cod larvae. ICES Journal of Marine Science. ISSN 1054-3139. 78, s. 666–679. doi: 10.1093/icesjms/fsaa057. Fulltekst i vitenarkiv Vis sammendrag

  The spatial distribution of fish early life stages can impact recruitment at later stages and affect population size and resilience. Northeast Arctic (NEA) cod spawning occurs along the Norwegian coast. Eggs, larvae, and pelagic juveniles drift near-surface towards the Barents Sea nursery area. In this study, a 35-year long time series of NEA cod larvae data was analysed in combination with factors that potentially may affect the distribution of eggs and larvae. These factors included biological aspects of the spawning stock, and environmental variables, such as water temperature, wind, ocean current, and prey abundance. Our aim was to shed light on how these factors influence larval abundance and distribution and how larval abundance and distribution influenced recruitment at age 3. We found that biomass and mean weight of the spawners were positively associated with larval abundance and that a high liver condition index of the spawners was associated with a north-easterly distribution of the larvae. The environmental variables showed generally weak or no correlations with abundance or distribution of larvae. Lastly, we found significant association between larval abundance and year-class abundance at age 3, while the spatial distribution metrics of the larvae, i.e. distribution extent, mean longitude, and mean latitude, showed no significant association with future year-class abundance.

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• Endo, Clarissa Akemi Kajiya; Vikebø, Frode Bendiksen; Yaragina, Natalia A.; Hjøllo, Solfrid Sætre & Stige, Leif Christian (2021). Cod's journey back home – from birth to nursery. Frontiers for Young Minds. 9. doi: 10.3389/frym.2021.622088. Fulltekst i vitenarkiv
• Endo, Clarissa; Vikebø, Frode Bendiksen; Yaragina, Natalia A.; Hjøllo, Solfrid Sætre & Stige, Leif Christian (2020). Effects of the environment and the spawning stock structure on the distribution of Northeast Arctic cod larvae. Fulltekst i vitenarkiv
• Endo, Clarissa Akemi Kajiya; Yaragina, Natalia A.; Vikebø, Frode Bendiksen; Skogen, Morten D.; Hjøllo, Solfrid Sætre & Stige, Leif Christian (2019). Long-term ichthyoplankton survey reveal effects of climate and spawning stock structure on the spatial distribution of Northeast Arctic cod larvae. Fulltekst i vitenarkiv

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