Category: Publications-summaries

Smalås, A., Strøm, J. F., Amundsen, P.-A., Dieckmann, U., & Primicerio, R. (2020). Climate warming is predicted to enhance the negative effects of harvesting on high-latitude lake fish. Journal of Applied Ecology, 57 (2), 270–282. https://doi.org/https://doi.org/10.1111/1365-2664.13535

Summary:

Ecosystems at high latitudes are exposed to some of the highest rates of climate warming on earth, and freshwater ecosystems in those regions are already experiencing extended ice‐free seasons and warmer waters. The dominant fish species in these ecosystems are cold‐water salmonids, which play a central ecological role in lake ecosystems, where they are often exposed to size‐selective fisheries, making them potentially vulnerable to both exploitation and environmental perturbations. This study employed a model approach to address the combined effects of climate‐induced water temperature increase and fishing, over the period from 1950 to 2100 on the growth, demography and vulnerability of Arctic charr Salvelinus alpinus (L.). The model predicted that higher water temperatures would increase the growth of Arctic charr, leading to larger body size at age and increased stock biomass: 80% increase in stock biomass in the absence of fishing, and 40% increase in biomass with fishing mortality of 0.3 year⁻¹ in 2100 in comparison to 2000. In addition, climate warming will affect younger individuals more, thus elevating the vulnerability of the population to environmental perturbations. The model‐based analyses highlight the combined effects of climate change and size‐selective fishing, emphasizing the emerging vulnerability of fish populations to multiple stressors. The authors recommended careful climate‐adapted management strategies permitting only a narrow range of fishing mesh sizes for inland fisheries at high latitudes.

Policy relevant message:

High latitudes ecosystems have been exposed to some of the highest rates of climate warming on earth, with extended ice-free seasons already recorded. The dominant fish species in these ecosystems are cold‐water salmonids, which play a central ecological role in lake ecosystems. These species are often exposed to size‐selective fisheries, making them potentially vulnerable to both exploitation and environmental perturbations. Careful climate‐adapted management strategies permitting only a narrow range of fishing mesh sizes for inland fisheries at high latitudes are strongly recommended.

 

Flecha, S., Pérez, F. F., Murata, A., Makaoui, A., & Huertas, I. E. (2019). Decadal acidification in Atlantic and Mediterranean water masses exchanging at the Strait of Gibraltar. Scientific Reports, 9 (1), 15533. https://doi.org/10.1038/s41598-019-52084-x

Summary:

Seawater pH is undergoing a decreasing trend due to the absorption of atmospheric CO₂, a phenomenon known as ocean acidification (OA). Biogeochemical processes occurring naturally in the ocean also change pH and hence, for an accurate assessment of OA, the contribution of the natural component to the total pH variation must be quantified. In this work, authors used 11 years (2005–2015) of biogeochemical measurements collected at the Strait of Gibraltar to estimate decadal trends of pH in two major Mediterranean water masses, the Western Mediterranean Deep Water (WMDW) and the Levantine Intermediate Water (LIW) and assess the magnitude of natural and anthropogenic components on the total pH change. The assessment was also performed in the North Atlantic Central Water (NACW) feeding the Mediterranean Sea. The analysis revealed a significant human impact on all water masses in terms of accumulation of anthropogenic CO₂. However, the decadal pH decline found in the WMDW and the NACW was markedly affected by natural processes, which accounted for by nearly 60% and 40% of the total pH decrease, respectively. The LIW did not exhibit a significant pH temporal trend although data indicated natural and anthropogenic perturbations on its biogeochemical signatures.

Published 14 October 2019: Senina, I.N. P. Lehodey, J. Hampton, and J.Sibert: Quantitative modelling of the spatial dynamics of South Pacific and Atlantic albacore tuna populations, Deep–Sea Research II, 175, 104667, 2020. https://doi.org/10.1016/j.dsr2.2019.104667

Summary

In this study a model approach was employed to estimate and predict the dynamics of highly migratory albacore tuna populations in the South Pacific and Atlantic oceans. This study successfully explored the capacity of previously used model to predict complex spatial dynamics of highly migratory species that are consistent with 30-year-long data and existing knowledge. The quantitative approach presented could be used to assist stock assessment and to improve management advice internationally.