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Vasiliki Markantonatou Sylvaine Giakoumi Nikoletta Koukourouvli Irida Maina Genoveva Gonzalez-Mirelis Maria Sini Kostas Maistrelis Mavra Stithou Eleni Gadolou Dimitra Petza Stefanos Kavadas Vasiliki Vassilopoulou Lene Buhl-Mortensen Stelios Katsanevakis 《水产资源保护:海洋与淡水生态系统》2021,31(8):2278-2292
- The expansion and intensification of marine uses have severe cumulative impacts on marine ecosystems and human well-being, unless they are properly managed with an ecosystem-based management approach.
- A systematic conservation planning approach, using marxan with zones , was applied to generate alternative marine spatial plans for the Aegean Sea. Relevant human uses were included and their cumulative impact on a wide set of key biodiversity features was considered in the analysis. Different cost scenarios were developed to gain insight on the effects of the approaches used to assess socio-economic factors, and their potential impact on spatial plans.
- The spatial plans generated differed greatly depending on the method used to estimate opportunity costs and evaluate human activities in monetary terms.
- The vulnerability weights (the relative vulnerability of ecological features to specific human activities and their impacts) that were estimated based on a cumulative impact assessment, allowed the assessment of each zone in contributing to the achievement of conservation targets, through a transparent planning approach.
- Results indicate that special care should be given to how socio-economic activities, their impact on the ecosystems, and related costs are incorporated into planning.
- The proposed approach demonstrates how EU member states may effectively comply with the new Biodiversity Strategy 2030 targets, while planning for the sustainable use of their marine resources.
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Good knowledge of the spatial distribution of fish is critical to stock assessment and successful fisheries management. Depth
is often the main gradient along which faunal changes occur when analyzing shelf and upper slope assemblages, and thus knowledge
of the bathymetric distribution of fish species is of great importance. The depth distribution of 16 fish species (Chelidonichthys lucernus, Helicolenus dactylopterus, Hoplostethus mediterraneus, Lepidorhombus boscii, Lophius budegassa, Merlangius merlangus, Merluccius merluccius, Micromesistius poutassou, Mullus barbatus, Mullus surmuletus, Pagellus erythrinus, Peristedion cataphractum, Phycis blennoides, Serranus cabrilla, Trigla lyra, and Trisopterus minutus) of the Aegean and the Ionian Seas was evaluated by analyzing experimental bottom trawl data, using generalized additive
modeling (GAM) techniques. A variety of bathymetric distribution patterns was observed. The main bathymetric zone of each
species was defined based on the modeled relative density. Specifically, the lower and upper limits of the main bathymetric
zone of each species were defined as the depths where the estimated relative density of the species becomes less than 1% of
the maximum. This definition is proposed as a better and more informative alternative than reporting the minimum and maximum
depths of encounter. 相似文献
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The common practice among researchers who study fish growth is to a priori adopt the von Bertalanffy growth model (VBGM), which is the most used and ubiquitous equation in the fisheries literature. However, in many cases VBGM is not supported by the data and many species seem to follow different growth trajectories. The information theory approach frees the researcher from the limiting concept that a ‘true’ growth model exists. Multi‐model inference (MMI) based on information theory is proposed as a more robust alternative to study fish growth. The proposed methodology was applied to 133 sets of length‐at‐age data. Four candidate models were fitted to each data set: von Bertalanffy growth model (VBGM), Gompertz model, Logistic and the Power model; the three former assume asymptotic and the latter non‐asymptotic growth. In each case, the ‘best’ model was selected by minimizing the small‐sample, bias‐corrected form of the Akaike information criterion (AICc). To quantify the plausibility of each model, the ‘Akaike weight’wi of each model was calculated. Following a MMI approach, the model averaged asymptotic length for each case was estimated, by model averaging estimations of interpreting Akaike weights as a posterior probability distribution over the set of candidate models. The VBGM was not selected as the best model in 65.4% of the cases. Most often VBGM was either strongly supported by the data (with no other substantially supported model) or had very low or no support by the data. The estimation of asymptotic length was greatly model dependent; as estimated by VBGM was in every case greater than that estimated by the Gompertz model, which in turn was always greater than that estimated by the Logistic model. The percentage underestimation of the standard error of , when ignoring model selection uncertainty, was on average 18% with values as high as 91%. Ignoring model selection uncertainty may have serious implications, e.g. when comparing the growth parameters of different fish populations. Multi‐model inference by model averaging, based on Akaike weights, is recommended as a simple and easy to implement method to model fish growth, for making robust parameter estimations and dealing with model selection uncertainty. 相似文献
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The abundance and composition of marine benthic debris was investigated in shallow coastal areas of Greece (eastern Mediterranean). The mean total density of marine debris in the areas surveyed was 15 items per 1000 m2 and ranged from 0 to 251 items per 1000 m2, with plastics dominating. Much higher marine debris densities were found in this study than those found in most studies surveying the continental shelf or the deep seafloor, indicating that pollution with marine debris is more intense in coastal areas. Greater abundance of marine debris was found in bays than in open areas. Artisanal fishing activities were found to significantly contribute to marine pollution with debris. In the Saronicos Gulf, a densely populated and highly industrialized area, the abundance of marine debris was higher than the rest of the Greek areas surveyed. 相似文献
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