DataSheet_1_Impacts on biodiversity from codend and fisher selection in bottom trawl fishing.pdf

Fisheries have important impacts on marine biodiversity. In this work, combined information on the abundance, species richness, diversity indices, species composition, trophic level and vulnerability index were examined for the first-time to detect differences in five units related to trawl fishing: the fish assemblage entering the trawl codend, and the escaping, retained, discarded and landed fractions, derived by the gear and fisher selection practices. The work was based on a case study conducted in the Mediterranean Sea, using three different meshes in the trawl codend (40mm-40D and 50mm-50D diamond meshes, and 40 mm-40S square meshes) and a cover of the codends with small mesh size. In general, trawl fishing produces an escaping fraction that was always lower in abundance, richness, and vulnerability index, similar in diversity indices and trophic level, and different in species composition compared to the fish assemblage entering the codend. In almost all cases, fishers selected as landings a fraction that was the lowest in diversity indices, and the highest in trophic level. In contrast, fishers discarded a fraction that was the highest in diversity and vulnerability index, and the lowest in trophic level. Although the three codends did not differ significantly in the fraction of escapees in terms of diversity indices, trophic level, and vulnerability index, the 40S codend showed a significantly higher percentage in the escaping number of species and individuals, and less differences in the species composition; in addition, lower percentage in abundance of discards and higher of landings in the retained catch (0.6:1) than did the other two codends (0.9:1). It was suggested that an urgent modification of the trawl for the elimination of the discarded highly vulnerable species (e.g. Elasmobranchs) is needed, and that trawl species-selectivity should be improved by allowing escape or avoiding catch of the discarded fraction to minimize biodiversity losses.</p

SEAwise Report on the key social and economic aspects of regional fisheries

Fishing is a human activity with various social and economic implications. In most countries, those implications are key factors to consider when deciding on specific management strategies. In this report, the fisheries management strategies implemented in the different European marine regions are reviewed, and relevant indicators, models and tools that can be used to predict the effectiveness of these strategies, from a social and economic point of view are identified. The objective was to identify the critical social and economic aspects of fisheries,  relevant social and economic indicators, and regionally‐relevant management measures to be considered in the evaluations of different management strategies later in the project.   The scoping consultations and systematic reviews identified a long list of potentially relevant key social and economic aspects and management measures. Among these, the most frequently mentioned items identified in scoping with stakeholders were windfarms, employment/jobs, MPAs, food supply, small-scale fisheries, local communities and pollution. The systematic review identified landings (volume or value), effort (days at sea), fuel costs, number of vessels, profit, aspects of costs, economic performance, sustainability-resilience, compliance and capacity as frequently occurring topics. The fisheries management policies most frequently mentioned were effort control, landing obligation, Individual Transferable Quota (ITQ), MPAs and TAC. Among the papers analyzed, more than 30%, concerned the Mediterranean region, followed by Western Waters, the North Sea and the Baltic Sea, indicating a higher contribution of Mediterranean studies to the conclusions. Aspects identified frequently in both scoping and in systematic reviews included MPAs and small-scale fisheries, which were all identified in both methods as frequently occurring. However, there were also aspects which appeared to be represented differently in the evaluations (e.g. employment and local communities) indicating discrepancies between the available knowledge and that sought by the end users. The report describes results from the SEAwise project. More information can be found at https://seawiseproject.org/</p

Trawl fishery restricted areas in the Mediterranean Sea.

<p>Trawl fishery restricted areas are shown in blue, trawlable areas are shown in white.</p

Map showing the study area with the position of the MEDITS trawl stations (year 2008).

<p>Numbers refer to Mediterranean FAO-GFCM GSAs (Geographical Sub-Areas). 1 Northern Alboran Sea, 5 Balearic Islands, 6 Northern Spain, 7 Gulf of Lions, 8 Corsica Island, 9 Ligurian and North Tyrrhenian Sea, 10 South Tyrrhenian Sea, 11 Sardinia, 15 Malta Island, 16 South of Sicily, 17 Northern Adriatic, 18 Southern Adriatic Sea, 19 Western Ionian Sea, 20 Eastern Ionian Sea, 22 Aegean Sea, 23 Crete Island, 25 Cyprus Island.</p

List of the species and Mediterranean geographical sub-areas (GSAs) where recruit density was modelled for nursery identification.

<p>The modelling approaches used are indicated: GLMM (generalized linear mixed models); GAMM (generalized additive mixed models); INLA (Bayesian GLMM); Z (zero inflated generalized additive models, ZIGAM); OK (ordinary kriging); IDW (interpolate distance weighting)</p><p>List of the species and Mediterranean geographical sub-areas (GSAs) where recruit density was modelled for nursery identification.</p

Map showing the spatial overlap among the persistent nursery areas of 11 species of demersal fish and shellfish in EU Mediterranean waters.

<p>Colours indicate different classes of spatial overlap index (<i>SO</i>). Spatial overlap was calculated considering three different classes of the temporal persistence index (<i>I</i>_<i>i</i>): A) <i>I</i>_<i>i</i>>0.05; B) <i>I</i>_<i>i</i>>0.2; C) <i>I</i>_<i>i</i>>0.4. Numbers indicate the numbers of species modelled in each GSA. Note that, since the number of species modelled varied among GSAs, the overlap index <i>SO</i> was calculated separately for each GSA to avoid any comparative analysis at a larger geographical scale that can lead to misleading conclusions.</p

Distribution maps of persistence index (Ii) of nursery areas of commercial fish in the North Mediterranean Sea.

<p>A) European hake (<i>Merluccius merluccius</i>), B) red mullet (<i>Mullus barbatus</i>), C) common Pandora (<i>Pagellus erythrinus)</i>, D) common sole (<i>Solea solea</i>), e) blackmouth catshark (<i>Galeus melastomus</i>) and E) thornback ray (<i>Raja clavata</i>). The index <i>Ii</i> ranges between 0 (portion <i>i</i> of the study area never included in an annual nursery) and 1 (portion <i>i</i> of the study area always included in an annual nursery).</p

Surface extent in km2 of total nursery areas identified and of nursery areas with a temporal persistence >40% (N40), for a set of 11 demersal species in Mediterranean European waters.

<p>The conservation effect of ongoing spatial restriction measures for trawling (TFRA) is measured in terms of total and percentage of protected N40.</p><p>Surface extent in km2 of total nursery areas identified and of nursery areas with a temporal persistence >40% (N40), for a set of 11 demersal species in Mediterranean European waters.</p

SEAwise Report on the key species and habitats impacted by fishing

The implementation of ecosystem-based fisheries management requires knowledge on the ecological impact of fishing activities on species and their habitats – those both targeted and not targeted by fisheries. To identify which ecological impacts are key and what is known about them, SEAwise consulted stakeholders through European Advisory Councils and conducted a systematic review of the scientific literature to map the available knowledge and evidence. Specific reference was given to the bycatch of Protected, Endangered and Threatened (PET) species, benthic habitats, food webs and biodiversity, and impact from fisheries-related litter and ghost nets.  At the stakeholder consultations, sharks and/or elasmobranchs, turtles, species interactions, and seals or marine mammals were identified as top ranked in at least three out of the five regions. Other terms identified by at least two Case Study regions were: seabirds, sensitive species, benthic habitats, litter, PET species, invasive species and species interactions.  Relevant data were extracted from 549 retained papers. The majority of studies were conducted in the Mediterranean Sea, whereas only few papers reported on fishing impacts in the Baltic Sea (see figure below). Bony fish (teleosts) and benthos were the most studied ecosystem components in all Case Study regions, whereas marine mammals and cartilaginous fish were often studied in relation to bycatch of PET species.  Out of the 549 papers, most of them were related to fishing impacts on food webs and biodiversity and benthic habitats, followed by bycatch of PET species and other fishing impact studies (not related to any task). Fewest studies were related to the impact of fisheries-related litter and ghost nets. Demersal trawls were by far the most studied gear in studies on commercial fishing impacts. For recreational fisheries, hooks and lines, in particular angling, was the most studied fishing activity.  Among the items identified by the stakeholders, marine mammals, seabirds and reptiles were all covered in at least 25 papers each, indicating that there is a considerable body of knowledge even though not all areas may have information for all species. Litter was the key item that was least frequently reported on in the literature, especially outside the Mediterranean, where scientific papers were rare. As a consequence, areas outside the Mediterranean may lack information for further analysis unless a dedicated effort is made in SEAwise to remedy this. The regional differences in topics identified by stakeholder scoping did not reflect the regional amount of papers available.  This report describes results of the SEAwise project. More information about the project can be found at https://seawiseproject.org/</p