Суперечності розвитку сучасного регіоналізму: чинники, детермінанти та механізми

A mass-balanced trophic model was developed for the coral reef lagoon of Uvea atoll (New Caledonia) using the Ecopath software. The model accounts for both pelagic and soft-bottom communities to describe the whole trophic structure and biomass flows in the shallowest part of the atoll lagoon. Phytoplankton production approximately equals the benthic primary production. Benthic biomass accounts for more than 80% of the total living biomass in the shallow lagoon. The benthic domain requires input of food from the pelagic system (mainly zooplankton) and from adjacent areas to sustain the biomass of predatory fishes. Predation pressure was found to be a major force structuring the food web, but it is also suggested that water circulation within the lagoon influences the amount of primary resources, such as plankton, benthic microphytes and detritus

How can we minimize the impact of fishing?

How many times do you think you have eaten fish this year? Fish is delicious and it’s really good for you, but we need to make sure that we don’t over-fish our seas and oceans (Fig. 1). That way there are enough fish left to feed us for all the years to come. We propose three simple rules for fisheries management, which would reduce the impact of fishing on the major fish species. The rules would also help to rebalance the ecosystems and reduce the damage that fishing causes when boats scrape their nets over the seabed to catch fish

The environmental impact of the consumption of fishery and aquaculture products in France

In the context of climate change, diet is a key driver of environmental impacts. Previous research has emphasized the environmental benefit of increasing consumption of fishery and aquaculture products (FAPs) in Europe. However, increasing the proportion of FAPs in consumer diets could also lead to a transfer of environmental damage from earth to sea. It is thus important to evaluate the environmental impacts of FAPs on marine ecosystems globally. For that purpose, an original database characterizing the origin of FAPs consumed in France has been constructed, and matched to indicators of environmental impact. Use of the database revealed that the FAPs in the French diets (1.7 Mt live weight) had a corresponding primary production required (PPR) worth 1252 Mt, with an impact per ton of product live weight worth 2622 kg CO2 eq. for climate change, 18 kg PO(4)(3)(-)eq. for eutrophication, and 26,604 MJ for energy use. Some heterogeneity across species was found, implying that the species composition of the FAPS consumed had a strong influence on environmental footprint. Furthermore, production methods also substantially affect global impact. The results show that, among FAPS consumed in France, trawled crustaceans and farmed shrimps or prawns are the greatest contributors to global warming (27,800 and 13,344 kg CO2 eq. per ton live weight, respectively), despite good performances regarding trophic level based ecosystem indicators (a PPR of 3 and 9 Mt respectively). Shellfish register the smallest footprint both globally and at ecosystem level (545 kg CO2 eq., 1 kg PO43- eq., 10,414 MJ, and a PPR of 5 Mt per ton live weight). Our result suggest that, to avoid a transfer of environmental burden from land to sea, policies aimed at promoting consumption of FAPs in European diets should be refined to take account of differential impacts across species, origin and production methods of those FAPs. (C) 2021 Elsevier Ltd. All rights reserved.Peer reviewe

Rendement maximal durable, concept et enjeux.

Rendement maximal durable, concept et enjeux. Fiche technique.Cette fiche technique de deux pages a pour objectif de définir le concept du "Rendement maximal durable" en pêche et d'expliqer les enjeux liés à sa mise en place

Progress towards ending overfishing in the Northeast Atlantic

The reformed Common Fisheries Policy of the EU, in force since 2014, stipulates that overfishing by the fleets of its member states has to end latest in the year 2020. This study examines exploitation and status of 119 stocks fished by 20 countries in the Northeast Atlantic. In the year 2018, about 40% of the stocks were still subject to overfishing (F > Fmsy), about 34% of the stocks were outside safe biological limits (B < Bpa) and about 68% of the stocks were too depleted to produce maximum sustainable yields (B < Bmsy). Reduction in the number of overfished stocks has stalled, possible because of an agreement between the European Commission (EC) and the International Council for the Exploration of the Seas (ICES), its advisory body for total allowed catches (TACs), wherein the EC requests ICES to give TAC advice leading to overfishing for many stocks. As a result, it is unlikely that overfishing will end in the Northeast Atlantic in 2020

Progress towards ending overfishing in the Northeast Atlantic

The reformed Common Fisheries Policy of the EU, in force since 2014, stipulates that overfishing by the fleets of its member states has to end latest in the year 2020. This study examines exploitation and status of 119 stocks fished by 20 countries in the Northeast Atlantic. In the year 2018, about 40% of the stocks were still subject to overfishing (F > Fmsy), about 34% of the stocks were outside safe biological limits (B < Bpa) and about 68% of the stocks were too depleted to produce maximum sustainable yields (B < Bmsy). Reduction in the number of overfished stocks has stalled, possible because of an agreement between the European Commission (EC) and the International Council for the Exploration of the Seas (ICES), its advisory body for total allowed catches (TACs), wherein the EC requests ICES to give TAC advice leading to overfishing for many stocks. As a result, it is unlikely that overfishing will end in the Northeast Atlantic in 2020

Combining ecosystem indicators and life cycle assessment for environmental assessment of demersal trawling in Tunisia

The approach consisted of conducting LCA and calculating ecosystem indicators to provide a complete assessment of trawling’s environmental impacts and the ecosystem characteristics associated with seafood production. The functional unit for the LCA was set to 1 t of landed seafood, and system boundaries included several operational stages related to demersal trawling. Several ecosystem indicators from EwE were calculated. Demersal trawling in the exploited ecosystem of the Gulf of Gabes (southern Tunisia) was used as a case study to illustrate the applicability of the approach. Several management plans were simulated and their influence on environmental performance was assessed. Ecospace, the spatial module of EwE, was used to simulate management scenarios: establishment of marine protected areas, extension of the biological rest period, and decrease in the number of demersal trawlers

Global change in the trophic functioning of marine food webs

The development of fisheries in the oceans, and other human drivers such as climate warming, have led to changes in species abundance, assemblages, trophic interactions, and ultimately in the functioning of marine food webs. Here, using a trophodynamic approach and global databases of catches and life history traits of marine species, we tested the hypothesis that anthropogenic ecological impacts may have led to changes in the global parameters defining the transfers of biomass within the food web. First, we developed two indicators to assess such changes: the Time Cumulated Indicator (TCI) measuring the residence time of biomass within the food web, and the Efficiency Cumulated Indicator (ECI) quantifying the fraction of secondary production reaching the top of the trophic chain. Then, we assessed, at the large marine ecosystem scale, the worldwide change of these two indicators over the 1950-2010 time-periods. Global trends were identified and cluster analyses were used to characterize the variability of trends between ecosystems. Results showed that the most common pattern over the study period is a global decrease in TCI, while the ECI indicator tends to increase. Thus, changes in species assemblages would induce faster and apparently more efficient biomass transfers in marine food webs. Results also suggested that the main driver of change over that period had been the large increase in fishing pressure. The largest changes occurred in ecosystems where 'fishing down the marine food web' are most intensive

Long-term fishing impact on the Senegalese coastal demersal resources: diagnosing from stock assessment models

For the first time in Senegal, assessments based on both stochastic and deterministic production models were used to draw a global diagnosis of the fishing impact on coastal demersal stocks. Based one national fisheries databases and scientific trawl surveys data: (i) trends in landings since 1971 were examined, (ii) abundance indices of 10 stocks were estimated using linear models fitted to surveys data and commercial catch per unit efforts, and (iii) stock assessments were carried out using pseudo-equilibrium Fox and Pella-Tomlinson models and a Biomass dynamic production model fitted in a Bayesian framework to abundance indices. Most stocks have seen their abundance sharply declining over time. All stocks combined, results of stock assessments suggest a 63% reduction compared to virgin state. Three fifth of demersal stocks are overexploited and excess in fishing effort was estimated until 75% for the worst case. We conclude by suggesting that the fishing of such species must be regulated and an ecosystem approach to fisheries management should be implemented in order to monitor the whole ecosystem