This study assesses the seabed pressure of towed fishing gears and models the physical impact (area and depth of seabed penetration) from trip-based information of vessel size, gear type, and catch. Traditionally fishing pressures are calculated top-down by making use of large-scale statistics such as logbook data. Here, we take a different approach starting from the gear itself (design and dimensions) to estimate the physical interactions with the seabed at the level of the individual fishing operation. We defined 14 distinct towed gear groups in European waters (eight otter trawl groups, three beam trawl groups, two demersal seine groups, and one dredge group), for which we established gear “footprints”. The footprint of a gear is defined as the relative contribution from individual larger gear components, such as trawl doors, sweeps, and groundgear, to the total area and severity of the gear's impact. An industry-based survey covering 13 countries provided the basis for estimating the relative impact-area contributions from individual gear components, whereas sediment penetration was estimated based on a literature review. For each gear group, a vessel size–gear size relationship was estimated to enable the prediction of gear footprint area and sediment penetration from vessel size. Application of these relationships with average vessel sizes and towing speeds provided hourly swept-area estimates by métier. Scottish seining has the largest overall gear footprint of ∼1.6 km 2 h −1 of which 0.08 km 2 has an impact at the subsurface level (sediment penetration ≥ 2 cm). Beam trawling for flatfish ranks low when comparing overall footprint size/hour but ranks substantially higher when comparing only impact at the subsurface level (0.19 km 2 h −1 ). These results have substantial implications for the definition, estimation, and monitoring of fishing pressure indicators, which are discussed in the context of an ecosystem approach to fisheries management.

A framework to assess the impact of mobile fishing gear on the seabed and benthic ecosystem is presented. The framework that can be used at regional and local scales provides indicators for both trawling pressure and ecological impact. It builds on high-resolution maps of trawling intensity and considers the physical effects of trawl gears on the seabed, on marine taxa, and on the functioning of the benthic ecosystem. Within the framework, a reductionist approach is applied that breaks down a fishing gear into its components, and a number of biological traits are chosen to determine either the vulnerability of the benthos to the impact of that gear component, or to provide a proxy for their ecological role. The approach considers gear elements, such as otter boards, twin trawl clump, and groundrope, and sweeps that herd the fish. The physical impact of these elements on the seabed, comprising scraping of the seabed, sediment mobilization, and penetration, is a function of the mass, size, and speed of the individual component. The impact of the elements on the benthic community is quantified using a biological-trait approach that considers the vulnerability of the benthic community to trawl impact (e.g. sediment position, morphology), the recovery rate (e.g. longevity, maturation age, reproductive characteristics, dispersal), and their ecological role. The framework is explored to compare the indicators for pressure and ecological impact of bottom trawling in three main seabed habitat types in the North Sea. Preliminary results show that the Sublittoral mud (EUNIS A5.3) is affected the most due to the combined effect of intensive fishing and large proportions of long-lived taxa.

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Turkey's marine fisheries catches were estimated for the 1950-2010 time period using a reconstruction approach, which estimated all fisheries removals, including unreported landings, recreational landings and discards. We added these estimates to the 'official' data, as reported in TURKSTAT, which are also available from the United Nations' Food and Agriculture Organization (FAO). The total reconstructed catch for the 1950-2010 time period (inclusive of the reported data) is approximately 30 million t, or 63% more than the 18.4 million t of reported data. This added 11.6 million t to the reported data, consisting of 7.4 million t of unreported landings, nearly 2.6 million t of discards, and 1.45 million t of recreational catches and 1.15 million t of subsistence catches. In 2010, total reported marine landings for Turkey were 445,617 t and the total reconstructed catch was 726,272 t, or 63% more than the reported data. The main unreported taxon by tonnage was European anchovy (Engraulis encrasicolus) due to its sheer high proportion of catch. The major reasons for underreporting include a general distrust fishers have towards the system combined with inefficient fisheries monitoring and surveillance capabilities. Accounting for all fisheries components is crucial in understanding the development of fisheries resources, improving management, and reducing threats to the domestic food security of Turkey.

The Mediterranean Sea is classified as a "data-poor" region in fisheries due to its low number of assessed stocks given its biodiversity and number of exploited species. In this study, the CMSY method was applied to assess the status and exploitation levels of 54 commercial fish and invertebrate stocks belonging to 34 species fished by Turkish fleets in the Eastern Mediterranean (Levantine) and Black Seas, by using catch data and resilience indices. Most of these marine taxa currently lack formal stock assessments. The CMSY method uses a surplus production model (SPM), based on official catch statistics and an abundance index derived from scientific surveys. The SPM estimates maximum sustainable yield (MSY), fishing mortality (F), biomass (B), fishing mortality to achieve sustainable catches (F msy ), and the biomass to support sustainable catches (B msy ). Our results show the estimated biomass values for 94% of the stocks were lower than the required amount to support sustainable fisheries (B msy ). Of the 54 stocks, 85% of them can be deemed as overfished; two stocks were not subject to overfishing (Sardina pilchardus and Trachurus mediterraneus in the Marmara Sea) while only one stock (Sprattus sprattus in the Black Sea) is healthy and capable of producing MSY. Annual values of the stock status indicators, F/F msy and B/B msy , had opposing trends in all regions, suggesting higher stock biomasses could only be achieved if fishing mortality is drastically reduced. Recovery times and levels were then explored under four varying F/F msy scenarios. Under the best-case scenario (i.e., F = 0.5F msy ), over 60% of the stocks could be rebuilt by 2032. By contrast, if normal fishing practices continue as usual, all stocks will soon be depleted [if not already] (F = 0.95F msy ), whose recover may be impossible at later dates. The results of this study are supported by previous regional assessments confirming the overexploitation of Turkish fisheries is driving the near-total collapse of these marine wild fisheries. Hence, the need to urgently rebuild Turkey's marine fisheries ought to be prioritized to ensure their future viability.

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A correction to "Estimating seabed pressure from demersal trawls, seines and dredges based on gear design and dimensions". -

Summary Seasonal landings and survey data from the Turkish shrimp beam trawl fishery were analyzed. A total of 32 valid hauls from twelve boats were analyzed 17 in autumn, 12 in spring and three in winter. The estimated by‐catch to shrimp ratios exhibited a seasonal pattern, with autumn having the highest ratio. In total, the by‐catch consisted of 57 species belonging to six groups of marine fauna, including Osteichthyes (25 species), Chondrichthyes (three species), Crustacea (six species), Mollusca (11 species), Cephalopoda (five species) and Echinodermata (seven species). The Osteichthyes form the most abundant (52.6%) by‐catch group, followed by Crustacea > Chondrichthyes > Echinodermata > Cephalopoda > and Mollusca. Whiting, Merlangius merlangus euxinus and hake, Merluccius merluccius dominated in the commercially utilized part of the by‐catch, while swimming crab, Leocarcinus depurator and gobies, Gobius bucchichi, G. niger dominated the discarded part of catches. The mean catch per unit effort (CPUE) obtained from all hauls was 5.91 ± 0.62 kg h−1. There were no statistically significant differences among mean CPUE values per season (P > 0.05).