The NansClim project (2010–2013) represented a regional collaboration to assess the effects of climate on Benguela dynamics. Based on in situ (since the 1960s in Namibia and South Africa and 1985 in Angola) and satellite (since the 1980s) observations, the project focussed on four subsystems, namely the Angola subtropical, northern Benguela upwelling, southern Benguela upwelling and Agulhas Bank. This contribution summarizes the findings for selected key questions, ranging from changes in the physico‐chemical habitats, plankton, pelagic and demersal fish communities, to cross‐cutting evaluation at subsystem and regional scales. The results underline the overriding importance to of considering the combined effects of climate and fishing as drivers of the dynamics of the ecosystem components. Each subsystem currently continues to function largely as a separate entity as described in earlier reviews. However, some changes have been observed across several subsystems, e.g., a coherent shift from one relatively stable period to another occurred in the northern and southern Benguela in the mid‐1990s. Future climate change could weaken the boundaries between the four subystems. The findings underline the need for continued regional research collaboration and regional surveys focussed at ecosystem, rather than resource, assessment. Our conclusions include implications for ecosystem‐based fisheries management, and recommendations for future regional research.

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Impacts of climate change on ocean productivity sustaining world fisheries are predominantly negative but vary greatly among regions. We assessed how 39 fisheries resources-ranging from data-poor to data-rich stocks-in the North East Atlantic are most likely affected under the intermediate climate emission scenario RCP4.5 towards 2050. This region is one of the most productive waters in the world but subjected to pronounced climate change, especially in the northernmost part. In this climate impact assessment, we applied a hybrid solution combining expert opinions (scorings)-supported by an extensive literature review-with mechanistic approaches, considering stocks in three different large marine ecosystems, the North, Norwegian and Barents Seas. This approach enabled calculation of the directional effect as a function of climate exposure and sensitivity attributes (life-history schedules), focusing on local stocks (conspecifics) across latitudes rather than the species in general. The resulting synopsis (50-82°N) contributes substantially to global assessments of major fisheries (FAO, The State of World Fisheries and Aquaculture, 2020), complementing related studies off northeast United States (35-45°N) (Hare et al.,

In the course of the past two decades, Atlantic mackerel, Scomber scombrus, have expanded their summer feeding distribution in the Norwegian Sea substantially, and now potentially overlap with pelagic larvae of Norwegian spring-spawning herring, Clupea harengus, as these drift northwards. Mackerel are known to be opportunistic predators, and the aim of this study was to evaluate mackerel predation in an area of overlap between mackerel and herring larvae, with particular focus on predation on herring larvae. In early June 2013, we followed a predefined transect in the expected core larvae distribution area on the Norwegian coastal shelf between about 66°N and 69°N. The transect was repeated twice, and samples of mackerel for stomach analyses and subsequent herring larvae samples were obtained at pre-defined stations. Mackerel were caught in all but one of the trawl hauls, but were hardly ever observed acoustically, suggesting that they were dispersed close to the surface throughout the study area. Herring larvae were caught in all samples. Calanoid copepods were the dominant prey of the mackerel, but 45% of the mackerel guts contained herring larvae, with a maximum of 225 larvae counted in a single gut. Both the frequency of guts containing herring larvae and the average amount of herring larvae increased in line with increasing abundance of larvae. On the other hand, no spatial correlation between mackerel abundance and herring larvae abundance was found at the station level. The results suggest that mackerel fed opportunistically on herring larvae, and that predation pressure therefore largely depends on the degree of overlap in time and space. Rough areal projections suggest that the mackerel would be capable of consuming the herring larvae present in the investigation area in 6–7 d, and that such predation therefore could have regulatory effects on stocks of Norwegian spring-spawning herring.

Vikebø, F. B., Husebø, Å., Slotte, A., Stenevik, E. K., and Lien, V. S. 2010. Effect of hatching date, vertical distribution, and interannual variation in physical forcing on northward displacement and temperature conditions of Norwegian spring-spawning herring larvae. – ICES Journal of Marine Science, 67: 1948–1956. Early hatching has been shown to be associated with increased survival of Norwegian spring-spawning herring (Clupea harengus) larvae. We investigated whether the process behind this association is related to larval drift and ambient temperature. A three-dimensional hydrodynamic model was used to simulate the effect of hatching date on northward displacement and temperature conditions of larvae from spawning grounds off western Norway for 1989–2008. The simulations revealed that the displacement during a period of 60 d was greatest if the larvae hatched early in the season and if they were located near the surface. The relationship between drift speed and ambient temperature was significantly negative, but less so later in the season, because the coastal current became progressively warmer. Results from the simulated interannual variations in larval drift compared with the observed survival suggest that a rapid northward displacement to the main nursery area in the Barents Sea is more important for larval survival than ambient temperature. The significant effect of northward displacement on survival could be explained by reduced overlap with predators and/or higher prey densities, but the causal processes involved remain to be investigated.