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Beckensteiner, J., Scheld, A. M., Fernandez, M., & Kaplan, D. M. (2020). Drivers and trends in catch of benthic resources in Chilean TURFs and surrounding open access areas. Ocean Coastal Manage., 183, 104961.
Résumé: Beginning in the 1990's, Chile implemented an extensive Territorial User Rights for Fisheries (TURFs) network that now comprises nearly 1,000 TURFs. This network provides a rare opportunity to examine spatial and temporal trends in TURF use and impacts on surrounding open access areas (OAAs). In this analysis, landings of keyhole limpet (Fissurella spp.), kelp (Lessonia spp.) and red sea urchin (Loxechinus albus) were used to estimate catch-per-unit effort (CPUEs) and catch-per-unit area (CPUAs) indices inside and outside TURFs by fishing cove. For these species, CPUEs and CPUAs in 2015 were significantly higher inside TURFs. However, temporal trends analyzed with a linear mixed effects model indicate that CPUAs inside TURFs have been significantly decreasing since 2000 for keyhole limpet, red sea urchin and for loco (Concholepas concholepas), while in OAAs this measure only decreased for limpet. An elastic net regression was used to better explain catches in OAAs during 2015, including a variety of variables related to the characteristics and activity of proximal TURFs. Results indicate that exogenous factors unrelated to TURF management were the primary drivers of catches in OAAs during 2015 but that factors related to proximal TURFs appear to have a slight negative impact that grows over time. Collectively, these results indicate that while TURFs are associated with higher catch rates than surrounding OAAs, catch rates appear to be decreasing over time and, though limited, the impact of TURFs on surrounding OAAs may be negative. These findings suggest a need for a more nuanced and dynamic approach to spatial management on benthic resources in Chile.
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Planque, B., & Mullon, C. (2020). Modelling chance and necessity in natural systems. ICES J. Mar. Sci., 77(4), 1573–1588.
Résumé: Nearly 30 years ago, emerged the concept of deterministic chaos. With it came sensitivity to initial conditions, nonlinearities, and strange attractors. This constituted a paradigm shift that profoundly altered how numerical modellers approached dynamic systems. It also provided an opportunity to resolve a situation of mutual misunderstanding between scientists and non-scientists about uncertainties and predictability in natural systems. Our proposition is that this issue can be addressed in an original way which involves modelling based on the principles of chance and necessity (CaN). We outline the conceptual and mathematical principles of CaN models and present an application of the model to the Barents Sea food-web. Because CaN models rely on concepts easily grasped by all actors, because they are explicit about knowns and unknowns and because the interpretation of their results is simple without being prescriptive, they can be used in a context of participatory management. We propose that, three decades after the emergence of chaos theories, CaN can be a practical step to reconcile scientists and non-scientists around the modelling of structurally and dynamically complex natural systems, and significantly contribute to ecosystem-based fisheries management.
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