World governance indicator definitions, and potential relevance for DWF.

World governance indicator definitions, and potential relevance for DWF.</p

S1 File -

(DOCX)</p

The influence of (normalized) environmental (green) and socio-political variables (blue) on DWF effort, as predicted by our random forest models and expressed as accumulated local effects (ALE), for the four fleets.

Displayed are only informative variables (more important than a random variable, c.f. Fig 2) and for variable values within the 5 to 95 percentile intervals. Grey dashed lines indicate the 0 ALE level and bars along the x-axis indicate distribution of data points for this variable. Not all variables are more important than random for all four gears, therefore each panel may show different numbers of variables.</p

Fig 4 -

Aggregated distant water fishing effort (2017) by host countries’ exclusive economic zone (EEZ) as (A) total hours and (B) total hours divided by EEZ area. Numbers in the bars in chart A indicate the global percentage of the total distant water fishing effort received by each EEZ in 2017. Displayed are the 10 highest ranking EEZs, respectively.</p

Variable importance (VI) scores of environmental and socio-political variables for the four fleets investigated, each relative to the respective highest VI.

We defined variables with a higher VI than that of a random variable (red dotted line) as informative.</p

Standardized distant water fishing hours per exclusive economic zone (EEZ).

The panels display the four fishing gears used in this study. EEZs without any distant water fishing effort in the year 2017 are represented in light grey (e.g., Somalia) and those without or shared sovereignty and disputed claims are represented in dark grey (e.g., Antarctica). Note that due to missing governance indicators for state territories, we did consider these in our statistical analysis (see S2 Table in S1 File).</p

DataSheet_1_Irreversibility of regime shifts in the North Sea.zip

Human impacts can induce ecosystems to cross tipping points and hence unexpected and sudden changes in ecosystem services that are difficult or impossible to reverse. The world´s oceans suffer from cumulative anthropogenic pressures like overexploitation and climate change and are especially vulnerable to such regime shifts. Yet an outstanding question is whether regime changes in marine ecosystems are irreversible. Here we first review the evidence for regime shifts in the North Sea ecosystem, one of the heaviest impacted and best studied marine ecosystems in the world. We then used catastrophe theory to show that fishing and warming have caused a previously undetected and potentially irreversible regime shift. Our study emphasizes the combined effects of local and global human impacts in driving significant ecosystem shifts and suggests that adaptation is likely the central avenue forward for maintaining services in the face of global climate change.</p

SEAwise report on the bycatch mortality risk of potentially endangered and threatened species of fish, seabirds, reptiles and mammals

The SEAwise project works to deliver a fully operational tool that will allow fishers, managers, and policy makers to easily apply Ecosystem Based Fisheries Management (EBFM) in their fisheries and bycatch of protected, endangered and threatened (PET) species is a major concern in EBFM implementation. This SEAwise report evaluates the effects of fishing on bycatch of PET species by applying a hierarchical framework that moves from qualitative to quantitative methodologies depending on species vulnerability to bycatch and data availability. By these means, this work identifies current areas of highest bycatch risk across the case studies and assesses the sustainability of bycatch levels on PET populations.The first step of this report consisted of the application of the semi-quantitative Productivity-Susceptibility Analysis (PSA) to a wide range of sensitive species across European waters, including cetaceans, bony and cartilaginous fishes and a single seabird species. PSA measures the risk of a species to over-exploitation by a fishery based on two properties; productivity, defined by the life history characteristics determining the intrinsic rate of population increase, and susceptibility, based on the interactions between population and fishing dynamics. This analysis scores species’ productivity and susceptibility attributes from 1 (low risk) to 3 (high risk) for each fishery or gear of interest, allowing a rapid screening of the species most likely affected by bycatch.Cetaceans were assessed in the Bay of Biscay and Irish waters, and in both cases, gillnets were identified as the gears with the highest bycatch risk, especially for common dolphin (Delphinus delphis) and harbour porpoise (Phocoena phocoena). Cartilaginous fishes were assessed in the Mediterranean Sea, including pelagic species such as the blue shark (Prionace glauca) and demersal species such as the longnose spurgod (Squalus blainville), the bull ray (Aetomylaeus bovinus) and the common smooth-hound (Mustelus mustelus). The blue shark, which is Critically Endangered in the Mediterranean, showed a high risk of being bycaught by pelagic longline, while demersal species were all highly threatened by bottom trawlers. A combination of elasmobranchs and teleost fishes was assessed along the North Sea, Bay of Biscay, and Celtic Seas, including common skate complex (Dipturus spp.), blonde ray (Raja brachyura), spurdog (Squalus acanthias), tope (Galeorhinus galeus), spotted ray (Raja montagui), undulate ray (Raja undulata), starry ray (Amblyraja radiata), John dory (Zeus faber), Atlantic wolffish (Anarhichas lupus) and Atlantic halibut (Hippoglossus hippoglossus). Highest bycatch risk was found for the common skate complex, spurdog and tope, showing highest bycatch risk for both beam- and otter trawls, as well as gillnets. The only seabird species analysed was the critically endangered Balearic shearwater (Puffinus mauretanicus), which showed a high risk to longlines in the Bay of Biscay.Where quantitative data were available for populations size and bycatch in e.g, ICES reports, the impact of fisheries bycatch was estimated quantitively by estimating reference points and by comparing them to total bycatch mortalities. This quantitative assessment was completed for two cetaceans and two elasmobranch species that were also included in the previous step. Bycatch impact for the common dolphin in the Northeast Atlantic and for harbour porpoise in Irish waters was found to be unsustainable, as current bycatch mortalities are above the “allowable” capture limits in both cases. For spurdog and undulate ray in the Northeast Atlantic and English Channel, respectively, the fishing pressure on the stock was sustainable, as it is below the harvest rate of Maximum Sustainable Yield (MSY). Reference points for seabirds were also estimated, but no comparison with bycatch mortality could be done due to lack of data. Additionally, quantitative assessments were produced for grey seal in the North Sea and loggerhead turtle in the Mediterranean (despite not being included in the previous step), where current bycatch rates were evaluated to be sustainable.Specific analyses were conducted for the Baltic Sea harbour porpoise with previously unused bycatch data from gillnets. Bycatch was modelled to estimate total bycatch mortality, addressing several objectives at once. On one hand, estimated total bycatch was compared with reference points, which showed that the current bycatch level was unsustainable for the population. Secondly, estimated total bycatch was compared with the results provided by previous simpler extrapolations, demonstrating that the later should not be applied when the fishery is heterogeneous due to the potential to provide biased estimates.Overall, the qualitative approaches are commonly used as a tool to identify species that are minimally affected, so the more intensive analysed are limited to high-risk species. Here, most species analysed showed-medium-high risk and therefore, all of them should have been analysed in further steps. However, many of those species lack the necessary information to conduct a quantitative assessment, and as result, the impact of bycatch at population level could only be evaluated, as seen above, for a few of them. This highlights the need for more exhaustive data collection and further research that could answer to the requirements of the EBFM.More information about the SEAwise project can be found at https://seawiseproject.org/</p

SEAwise Report on key drivers and impacts of changes in spatial distribution of fisheries and fished stocks

   An ecosystem approach to fisheries management requires the consideration of spatially explicit management measures and other impacts on species and the links between the distribution of fished species, their surrounding environment and productivity. Quantification of the spatial aspects of fisheries and ecology of commercially fished stocks may improve the accuracy of the predicted changes in fish productivity, fisheries yield and costs, benefits and selectivity.  To provide a knowledge base for spatially explicit considerations, SEAwise consulted stakeholders throughout Europe and conducted a systematic review of the scientific literature. As a first step, engagement with relevant stakeholder groups in each Case Study identified key issues of relevance to spatial management. The input from this stakeholder consultation was supplemented by a systematic literature review with careful consideration of the objectives, search terms, inclusion/exclusion criteria, the method for data/knowledge extraction and ultimately how these data and knowledge will be used. The purpose of the task was to quantify the key drivers and pressures behind the changes occurring in commercial fish stocks and fisheries distribution that have a spatially explicit content, map the relevant existing scientific knowledge and provide input to the subsequent SEAwise tasks.  The words identified by the stakeholders consulted focused on factors causing changes to the distribution of commercial fish/shellfish (climate change, MPAs, species interactions, pollution, habitats and invasive species) and fisheries (windfarms, MPAs, Marine spatial planning) as well as the other human impacts. The systematic review extracted data from 331 papers. The most frequently studied topic was the distribution of fish and the region with most papers was the North Sea with about the twice the amount of papers in each of the other regions. The most frequently studied species in the literature were cod, hake and plaice and by far the most frequently studied fisheries was demersal trawl fisheries.  Among the issues identified by stakeholders as key, the effects of environmental conditions on the distribution of fish were particularly well represented in the reviewed material. In contrast, factors determining the distribution of fisheries were almost exclusively studied in trawl fishing in the North Sea and papers on the effect of area restrictions on fish and fisheries were largely restricted to Western waters and the North Sea. While knowledge on the effects of habitats on species did exist, this was restricted to the Baltic Sea and North Sea and papers addressing this outside these areas were close to non-existent. This points to important areas for future work in SEAwise. This report describes part of the results of the SEAwise project. More information about the project can be found at https://seawiseproject.org/ </p