Bottom Trawl Fishery Research Articles

Regional dynamic co-management for sustainable fisheries and ecosystem conservation: a pilot analysis in the Catalan Sea

The complexity of coastal fisheries, which often involve many gears with cross-impacts on various species and life stages, requires a management system that is able to integrate these multiple interactions in order to gradually achieve sustainability. In this paper, we argue that regional co-management can appropriately address the complex interactions between fisheries, including those with other potentially conflicting human activities. Our results, notably obtained through a questionnaire to local fishers’ representatives mainly on bottom trawl fisheries in the Catalan Sea region, show, however, that improved mutual understanding through effective communication and long-term collaboration between stakeholders, and in particular between fishers and scientists, is essential to ensure the successful implementation of fisheries co-management. In addition to balancing the voices of the many stakeholders, co-management needs to be further improved by developing multi-species, multi-gear and multi-use approaches to the oceans. This improvement could in turn support the effectiveness of co-decisions, as they would be based on the recognised administrative structure of co-management committees and sound scientific guidance that addresses both ecosystem protection and sustainable fisheries profitability. Dynamic management over time and space, using real-time essential fish habitat from operational oceanography, can help to make the co-management process more robust by improving collaboration between stakeholders and the effectiveness of measures in a changing environment. The decision-making, social and ecological components are described as integral and dependent parts of the co-management system, with priority given to mutual understanding between stakeholders. This integrated co-management framework is flexible enough to take into account regional complexity, but also national legislation and the EU Common Fisheries Policy, which all promote sustainable use of the oceans and protection of the ecosystem.

Unexpected Records of Newborn and Young Sharks in Ligurian and North Tyrrhenian Seas (North-Western Mediterranean Basin)

Between 2007 and 2022, 112 specimens of newborn and young pelagic sharks were recorded in the waters of Tuscany Region, in the South Ligurian–North Tyrrhenian Seas (north-western Mediterranean basin). The sharks belonged to the Carcharhinus plumbeus (n = 14), Prionace glauca (n = 66), Isurus oxyrinchus (n = 16), Mobula mobular (n = 5) Alopias vulpinus (n = 7) and Hexanchus griseus (n = 4) species. Each animal was correctly identified thanks to the photographs or videos collected. All specimens were incidentally captured with set nets in inshore shallow waters, except bluntnose six-gill sharks, which were bycatch of deep-water bottom-trawl fishery. Body mass, sex, total length and biometric measurements were recorded in 34 baby sharks following the Mediterranean Large Elasmobranches Monitoring (MEDLEM) protocol. The presence of very evident and often non-healed umbilical scar confirmed that some of the sample specimens were newborn. Further confirmation came from the comparison between the total length observed and the size at birth known for the sampled species as reported in the literature. Some baby sharks were preserved in the Museums of Natural History of Pisa and Florence University collections. The importance of the coastal area studied as a possible shark nursery is discussed.

Conservation Status Assessment of Demersal Elasmobranchs in the Balearic Islands (Western Mediterranean) over the Last Two Decades

More than half of the Mediterranean sharks and rays are threatened by fishing exploitation. However, population assessments are limited by the scarcity of specific data on fishing catches. In this study, we assessed temporal trends of the indicators developed within the European Marine Strategy Framework Directive over the last two decades in order to assess the conservation status of demersal sharks and batoids in the Balearic Islands, which represent an important fraction of the bycatch of bottom trawling in this area. On the basis of a georeferenced, fishery-independent dataset of 19 species of elasmobranchs, we analyzed 20 year time series (2002–2021) of nine indicators regarding area distribution, population size, population status, and community structure. Between 30% and 50% of the elasmobranch species and functional groups showed increasing trends in distribution area and population size. This was especially true for batoids, whereas the distribution area and population size of most sharks remained stable over the study period. The remaining indicators showed stability or, in some cases, variable trends. Only in one case did we find a negative trend sustained all along the time series (i.e., the proportion of R. radula large individuals in relation to the reference period). Overall, our results suggest that the populations of elasmobranchs from the Balearic Islands show stable or recovery trends, mainly in terms of distribution area and density. However, it remains elusive whether this community can recover to the levels of more than half a century ago, before the development of the bottom trawl fishery, or whether this apparent current steady state should be interpreted as a new equilibrium.

Atlantic cod (Gadus morhua) assessment approaches in the North and Baltic Sea: A comparison of environmental DNA analysis versus bottom trawl sampling

The assessment of fish stocks is often dependent on scientific trawl fisheries surveys, which are both invasive and costly. The analysis of environmental DNA (eDNA) from water samples is regarded as a non-invasive and cost-effective alternative, but meaningful performance evaluations are required for a wider application. The goal of this study was to comparatively analyze a newly developed, more sensitive real-time PCR based eDNA approach with bottom trawl fisheries catches to locally detect and quantify Atlantic cod (Gadus morhua) in the North and Baltic Seas. With a species-specificity of the qPCR assay of 100%, a minimal limit of 15 Cytochrome b eDNA copies was determined for the detection of cod. In addition, a Gaussian processing regression proved a significant correlation (95%) between eDNA (copies per L of water) and cod biomass (CPUE/Ha) found by bottom trawling. The results presented here prove the potential of eDNA analyses for quantitative assessments of commercial fish stocks in the open ocean, although additional comparative analyses are needed to demonstrate its performance under different oceanographic conditions.

Every animal matters! Evaluating the selectivity of a Mediterranean bottom trawl fishery from a species community perspective.

Bottom trawl fisheries often catch several species simultaneously. However, most studies addressing the catch performance and selectivity of a specific trawl focus on a few commercially important or most vulnerable species requiring management measures. By contrast, the present study considers the multispecies nature of Mediterranean bottom trawl fisheries through a holistic approach that accounts for the full species community in the catches. Specifically, we evaluated and compared the catch performance of the two codends allowed for this fishery, made of 40 mm square (SM40) and 50 mm diamond (DM50) meshes. Results showed that 50 and 80% of the catch in weight and count numbers, respectively, consisted of species without commercial value, demonstrating that large proportions of the catch are not considered when using the existing approach to evaluate the ecological impact of the fishing activity. Significant differences in catch profiles between the two codends were observed, especially for two commercial flatfish species, Arnoglossus laterna and Citharus linguatula, with larger contributions in the SM40. Further, the SM40 codend had a significantly higher retention, compared to DM50 codend, for specific sizes of Merluccius merluccius and Mullus barbatus. The outcomes of the study can be useful for the Mediterranean bottom trawl fisheries management.

Smaller bar spacings in a Nordmøre grid reduces the bycatch of redfish (Sebastes spp.) in the offshore Northern shrimp (Pandalus borealis) fishery of eastern Canada

The offshore Northern shrimp (Pandalus borealis) bottom trawl fishery in eastern Canada currently uses 22 and 28 mm bar spacing Nordmøre grids to limit bycatch from using small mesh codends. However, a recent rebound of juvenile redfish (Sebastes spp.), that can pass through the grids, has greatly increased bycatch. To address this concern, this study investigated the effectiveness of 17 and 15 mm bar spacing Nordmøre grids in a twin-trawl (paired) configuration against the traditional 22 mm bar spacing grid. Size selectivity analyses showed that the 17 and 15 mm grids resulted in no significant reduction in shrimp catch across all length classes. The 17 mm grid significantly reduced redfish bycatch for all length classes and the 15 mm grid significantly reduced redfish bycatch for individuals larger than 95 mm total length. Less redfish entered the codend with the experimental grids, however, the overlap in width between redfish and Northern shrimp limits the overall sorting efficiency of the grids, leaving some redfish still vulnerable to capture.

Come, tell me how you live: Habitat suitability analysis for Ostrea edulis restoration

Abstract Against the background of the UN decade on ecosystem restoration and the new EU Biodiversity Strategy for 2030, and in the context of marine spatial planning and complex maritime user conflicts, reliable information on habitat suitability for large‐scale restoration is an important prerequisite for implementing conservation management and for supporting successful, sustainable, and ecologically efficient restoration measures. In this study, habitat suitability was assessed using multicriteria decision analysis (MCDA) for the restoration of the European oyster, Ostrea edulis, in marine protected areas (MPAs) of the German Bight in the North Sea: Borkum Reef Ground (Borkum Riffgrund, BRG) and Sylt Outer Reef – Eastern German Bight (Sylter Außenriff, SAR). Based on site selection criteria, exclusion and suitability factors for the MCDA were defined. Results were integrated with the available geodata to produce habitat suitability maps for oyster restoration in the area of interest. Suitable as well as unsuitable habitats have been successfully identified for both MPAs: several hundred square kilometres (≥97.2% of BRG) or several thousand square kilometres (≥74.5% of SAR) were classified as ecologically and logistically suitable for oyster restoration measures in the respective MPAs. As oyster restoration is significantly limited by human activities (e.g. bottom trawl fisheries), the management of fisheries is an important prerequisite for successful oyster restoration in both MPAs. Results show that designated fishery management measures will increase the possibilities for oyster restoration. In BRG, our results correspond to the known historical distribution. In SAR, our results significantly exceed the historically known distribution. The habitat suitability analysis will facilitate decision‐making regarding ocean use, and will reduce restoration costs through targeted management activities in areas of high suitability and expand species recovery by improving the survival of reintroduced individuals. The habitat suitability analysis procedure is easily adaptable for application to other areas, other species, or other habitat restoration projects, or to other conservation management settings. The software applied is open source and the suitability calculation is described in detail to inform wider applications.

Improving seabed substrate mapping with high-resolution bottom trawl data

Accurate seabed substrate maps are essential for marine management, as substrate is an important component of the habitat type and used as a proxy for the prevailing benthic community. The provision of substrate maps, however, is hampered by the excessive costs of at-sea observations and, consequently, the uncertainty associated with spatial models used to interpolate these observations to full-coverage maps. Here, we tested whether high-resolution distributions of bottom trawling activity, readily collected under EU law, could improve the accuracy of substrate interpolations. Fishing distributions contain indirect information of the substrate type, as targeted species often show habitat preferences and gear types are designed for particular substrates. For two study areas in the Danish North Sea, we demonstrate that including spatial distributions of bottom trawl fisheries in substrate interpolation models results in more accurate substrate predictions. This potentially opens a novel source of previously unused information for improved seabed substrate interpolation.

Minimising discards while taking revenue into account: Spatio-temporal assessment of catches in an artisanal shrimp trawl fishery in Peru

Around 4.2 million tonnes of fish and other species, some of which are of conservation concern, are discarded every year in bottom trawl fisheries. This study focusses on a small-scale shrimp trawl fishery located in northern Peru that operates with high level of discards which causes conflict with other local fishers. Despite trawling being an illegal activity within the 5NM off the coast, this fishery has been operating in these inshore areas for over 40 years because it sustains the well-being of hundreds of fishers. This study aimed to identify the factors that affect the spatio-temporal variation in catches in order to propose recommendations that can be adopted by fishers to minimise their impact on the ecosystem while still providing economic opportunities. The spatial distributions of shrimp, main commercial species and discards were modelled over time using hierarchical generalised additive models. Strong spatio-temporal variation was observed for all catch components and moon phase affected commercial species and discards differently. The results show that, to reduce the environmental impacts of this fishery in the short-term, the fishing area could be divided into north and south and that fishing activities should be limited to the southern area in the autumn. Other recommendations rely on temporal closures during the week of the first quarter of the moon phase. Finally, considering the institutional weaknesses in monitoring, control and surveillance, we suggest that the only realistic approach to reduce the fishery's environmental impacts in the short-term is to foster the willingness of fishers to adopt responsible fishing practices. Yet, long-term solutions will require comprehensive co-management efforts.

Variability in catch composition and CPUE of bottom trawl fishery along Parangipettai, Cuddalore and Pazhayar, Southeast coast of India, Bay of Bengal

Variability in catch composition and CPUE of bottom trawl fishery along Parangipettai, Cuddalore and Pazhayar, Southeast coast of India, Bay of Bengal

The effect of habitat and fishing-effort data resolution on the outcome of seabed status assessment in bottom trawl fisheries

Mobile bottom fishing is widespread and is known to impact seabed habitats. Risk assessments can evaluate these impacts and inform decisions about the certification of sustainable fisheries by bodies like the Marine Stewardship Council. Spatial risk assessments require input data layers of seabed habitats and fishing effort, and when available, they are often available at different resolutions (number of different habitat categories for seabed habitats, spatial cell size for fishing effort). Here we evaluate how the outcome of risk assessments of the impact of bottom trawling depends on resolution of these data layers. We evaluate the relative benthic state, recovery time and the resulting indicative score for the ‘habitats outcome’ of the Marine Stewardship Council (MSC) Fisheries Standard using three different levels of habitat categorisation and four different fishing effort resolutions for 14 areas in the North Sea that are intensely fished by different trawl gears. In this framework outcomes are reported by habitat category. The assessments show that when fishing effort is low, choices about effort and habitat resolution do not affect the scores. Fine and medium resolution habitat maps results in a larger range of seabed status and recovery times than coarse resolution maps, and worse predicted habitat outcomes. In MSC fishery assessments, both mean and minimum scores are important to achieving certification. The mean score for each Principle must be ≥ 80 for a fishery to be certified, with any score below 80 triggering conditions that must be addressed by the fishery within five years of certification. A single score below 60 prevents a fishery being certified. Coarser fishing effort resolution layers lead to higher seabed status and faster recovery times. As a result, more detailed data layers result in a larger range of MSC scores, including more scores that would result in conditions on certification and modifications to fishing practices. In conclusion, for intensely fished areas, more detailed data layers provide a more stringent assessment of the sustainability of bottom trawl fisheries and it is recommended that the most-detailed available fishing effort data and fine or medium scale habitat data is used in assessments.

Characterization of discards along a wide bathymetric range from a trawl fishery in the NW Mediterranean

Discards represent a loss of natural resources and negatively affect the sustainability of fisheries. Information on discards, such as diversity and size of the species discarded is essential to better manage trawl fisheries. Thus, this study aims to gain knowledge on discards from the Catalan bottom trawl fisheries in the NW Mediterranean Sea to offer information needed for fisheries management. Discard ratios, species composition of discards and lengths of the discards were analyzed from data collected on board commercial trawlers, from November 2018 to December 2020 and analyzed by depth, zone, and season. Discard ratio varied among depths from 30.5% in the shallowest depth (20 – 70 m) to 14.3% in the deepest (400–700 m), with depth being the main factor determining the species composition of discards. This study also focused on the discards of six main commercial species, i.e. European hake (Merluccius merluccius), red mullet (Mullus barbatus), black-bellied angler (Lophius budegassa), poor cod (Trisopterus capelanus), deep-water pink shrimp (Parapenaeus longirostris) and Norway lobster (Nephrops norvegicus). The length at which 50% of individuals were discarded (L50d) was lower than the Length at First Maturity (LFM) and the Minimum Conservation Reference Size (MCRS) for the six species. These findings provide relevant information to comply with the Marine Strategy Framework Directive’s (EU Directive 2008/56/EC) ecosystem approach to fisheries and to evaluate the implementation of measures for fisheries’ best management practices, such as gear selectivity and spatial planning.

Biodiversity of bottom trawl fishery and left-over marine resources along the Cameroonian coast

The objective of this study was to provide information on the diversity of catches, by-catches and discards by trawlers in the mouths of Sanaga (MSR) and Nyong (MNR) rivers along the coast of Cameroon. Samples were collected on board of a fishing vessel using the bottom trawling technique. Specimens were identified using 2104 and 2016 FAO identification keys. A total of 58 species belonging to 38 families and 5 super-classes were identified. Amongst, 72%, 14%, 10%, 2% and 2% were fish, mollusks, reptiles, crustaceans and cnidarians, respectively. We found 67.1% of marketable fish and shrimp and 32.9% of discards consisting of immature fishes. The MNR was richer in marketable fish species (p=0.0001) and discards (p=0.019) than MSR. The Cameroon coast is rich in biodiversity. However, it is today threatened by marine pollution and the non-respect of trawling which jeopardizes the sustainability of the fishing industry in Cameroon.

First known observations of brooding, development, and hatching of fertilized eggs for the North Pacific bigeye octopus, Octopus californicus.

The North Pacific bigeye octopus, Octopus californicus (Berry, 1911) is a cold-water, deep-sea octopod. Little is known about their biology due to difficulty accessing their natural habitat and obtaining live specimens. Although they are a frequent bycatch product in commercial bottom trawl fisheries, individuals of this species have rarely been raised in captivity and their embryonic development has not yet been documented. Considering these limitations, we were fortunate to have witnessed this process leading to successful hatching in an aquarium setting. Here, we present a brief observational account of the first-known record of brooding, development, and hatching of fertilized eggs for O.californicus. The incubation time was a maximum of 10months at a temperature between 8-10°C and embryos hatched over a period of 2.5months. While more detailed research is needed, this preliminary information contributes to our limited knowledge of this species and supports life history theories of prolonged embryonic development under colder temperatures.

Managing size selectivity: the relevance of compulsory and alternative selection devices in the Northeast Atlantic bottom trawl fishery

AbstractTwo decades of use of the compulsory selectivity gear configuration in the Northeast Atlantic bottom trawl fishery, which consists of a rigid sorting grid followed by a diamond mesh codend, have revealed problems with performance and efficiency. Size selectivity gear alternatives to this configuration are being pursued, and recent studies of codends with shortened lastridges have reported promising results. In this study, we compared the size selectivity and catch efficiency for cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) caught using a sorting grid with 55 mm bar spacing followed by a 130 mm knotted diamond mesh codend (i.e. the compulsory gear) that same configuration but considering only the catch in the 130 mm diamond mesh codend (regular codend), and an alternative knotless codend with shortened lastridge ropes and a thinner twine. We also addressed the question of whether size-selective gear is even needed to avoid exceeding the bycatch limits of the fishery. Our results demonstrated that the alternative codend improved size selectivity by reducing the loss of fish above minimum legal size (MLS), with a minor increase in the retention of fish below MLS, compared to the compulsory combined grid and codend configuration. The regular codend also reduced the loss of fish above MLS, but the retention of haddock below MLS approached the legal limit of 15% by number. Our results also showed that the abundance of cod below MLS in the fishing area during the trials was low. They also suggested that spatial and seasonal closures in combination with a flexible choice of selection device and modern monitoring tools could be an alternative to rigid enforcement of the use of selective fishing gear.

Juvenile redfish (Sebastes spp.) behavior in response to Nordmøre grid systems in the offshore northern shrimp (Pandalus borealis) fishery of Eastern Canada

A recent rebound of juvenile redfish (Sebastes spp.) in areas where the northern shrimp (Pandalus borealis) bottom trawl fishery in eastern Canada occurs has been challenging the fishing industry to maintain bycatch of this species within acceptable levels. Using self-contained underwater cameras and red lights, this study investigated the behavior of juvenile redfish in response to bycatch reduction devices (BRDs), called Nordmøre grids. Fish behavior was analyzed in grid systems with different bar spacings, including 22- and 19-mm bar spacings. A total of 10.3 h of useable underwater video was collected during commercial fishing conditions, which yielded individual observations of 931 redfish. Generalized linear models (GLMs) and behavioral trees were used to analyze the data. We observed that 52.5% of all redfish passed through the bar spacings and were retained. The duration of the selection process was relatively short (~1.9 s mean), and 57.8% of redfish reacted to the grids by swimming upwards, forward, or towards with respect to the grids. Behaviors exhibited by redfish and redfish retention were similar for both grids. GLM results suggested that as time in front of the grid increased and redfish had upwards or steady grid reactions, retention was drastically reduced. These were important variables that significantly explained the capture fate of redfish. The behavioral sequence that led to higher escape probability was redfish that approached upwards, had no contact with the grid, and reacted to the grid by continuing to move upwards to finally exit through the escape opening. GLM and behavioral trees gave a comprehensive view of redfish behavior, which is extremely useful for perfecting or developing any BRD to address juvenile redfish bycatch.

Resources and population traits modulate the association patterns in the common bottlenose dolphin living nearby the Tiber River estuary (Mediterranean Sea)

Sociality and ecological drivers that can influence individual association patterns are infrequently considered in wildlife management, although they are essential aspects affecting animals’ responses to both human-related pressures and conservation strategies. In common bottlenose dolphins (Tursiops truncatus), sex-specific social dynamics and interactions with anthropogenic activities may affect grouping and induce changes in relationships between individuals. Out of a total of 347 individuals, we assessed the level of association among 68 bottlenose dolphins that have been sighted more than five times near the Roman coast (central Mediterranean Sea, Italy). The half-weight index (HWI) of dyadic associations, their network relations, and stability over time were investigated by using the SOCPROG software. Outcomes showed that females were more strongly associated than other individuals, with both preferred constant short-term associations and random long-term associations, possibly resulting in greater success in rearing young. Individuals interacting with the bottom trawl fishery showed weaker and short-term associations. Temporary disruption of individual associations during interaction with fishery and the relatively low number of females with calves participating in depredation seem to denote both the opportunistic nature of interactions with fishing vessels and the offspring-related protection strategy. The results show that the dolphins in this region maintain a complex but flexible social structure that varies with local biological requirements and is resilient to anthropogenic pressures.

Critical evaluation of ecosystem changes from an offshore wind farm: producing natural capital asset and risk registers

Offshore wind infrastructure modifies benthic habitats, affecting ecosystem services. A natural capital approach allows risks to nature-based assets and ecosystem benefits to be assessed. The UK Natural Capital Committee produced guidance for conducting natural capital assessments to aid decision making processes. Development of an asset register and risk register are key components of this methodology. The former provides an inventory of NC stocks, and the latter considers the likelihood of changes and the scale of their impact on delivery of ecosystem services. In this study, suitability of the methodology in a marine environment context was critically evaluated. Natural capital stocks before and after installation of Greater Gabbard offshore wind farm were compared and risks to delivery of ecosystem services were assessed. It was demonstrated that incorporating an assessment of impacts on natural capital assets in planning and management decisions (as an extension to traditional environmental impact assessment approaches) could further facilitate sustainable use of marine ecosystems. For example, by preventing access to bottom-trawl fisheries activities, wind farms may promote recovery and increase value of seabed natural capital assets. By also introducing aquaculture systems loss of food provision (from reduced fishing activity) could be offset whilst allowing benthic natural capital assets to recover. Natural capital assessment is relevant to the marine context. However, application of the Natural Capital Committee’s methodology was constrained by the limited coverage of standard benthic sampling tools. Given the scale of wind energy plans across the marine environment it is recommended that these shortcomings are appropriately addressed.

Estimation of CPUE and CPUA of pufferfish (Tetraodontidae) caught by the Bottom Trawl Fishery in the eastern Mediterranean Coasts

Two indicators of pufferfish communities, catch per unit effort (CPUE) and catch per unit area (CPUA), were used with surveys of bottom trawl fishery to elucidate the level of the catch of each pufferfish species in the Mediterranean coasts of Turkey, comprising the Iskenderun Bay, Mersin Bay, and Antalya Bay. The surveys were conducted seasonally in 2019. The average rate of CPUE for Lagocephalus sceleratus, L. suezensis, L. spadiceus, and Torquigener flavimaculosus were 2.2, 0.8, 0.5, and 0.2 kg km-2, respectively that the highest CPUE values were in winter (8.0 kg km-2) for L. sceleratus and also lowest was in winter (0.08 kg km-2) for L. spadiceus. The highest and lowest CPUE values were at the depth of 20-50 m (2.7 kg km-2) for L. sceleratus and 50-80 m (0.08 kg km-2) for T. flavimaculosus, respectively. The highest CPUE values (3.5 kg km-2) were found at the sandy bottom for L. sceleratus, and the lowest one (0.01 kg km-2) was at the hardy-ground for T. flavimaculosus. The average annual CPUA of pufferfish species at the Iskenderun, Mersin, and Antalya bays was estimated as 15.6, 28.4, and 6.81 kg, respectively, with a mean value of 17.3 kg/day/boat. In multiple correspondence analysis, L. sceleratus showed a great contribution to CPUE and CPUA data. However, T. flavimaculosus revealed contribution, especially in catch numbers which were positively affected by precipitation. L. spadiceus, L. suezensis, and T. flavimaculosus were positively affected by depth, temperature, month, season, and bottom structure.

Spatio-temporal trends of the bottom trawling activity in a mud volcano field of the north-eastern Gulf of Cádiz (south-western Iberian Peninsula)

Multi-species bottom trawl fisheries are one of the human activities with a great impact on the benthic habitats and their associated biota. This study provides estimates of the bottom trawling activity (effort), catches and landings of the main commercial species as well as an estimation of the total revenue (TR) generated inside a mud volcano field located in the Spanish margin of the Gulf of Cádiz, during a time series from 2007 to 2012. To date, no studies have been carried out to analyse the temporal evolution of bottom trawling activity and TR in a mud volcano fied, or the economic consequences of possible potential bottom trawling regulation of certain sectors harbouring vulnerable and/or threatened habitats. In this study, Vessel Monitoring System data, logbooks and sales slips were used. The spatial distribution of the bottom trawling activity, catches and TR were related to the seafloor morphology and specific bottom types of the mud volcano field. During the time series, a high bottom trawling activity and associated catches was detected in flat sandy and muddy bottoms, including the Anastasya sector and between the Guadalquivir and Cádiz Diapiric Ridges. Low bottom trawling activity and catches were detected in the deepest areas but also in areas with hard and detritic bottoms such as Gazul and Chica sectors as well as in the Diapiric Ridges. A similar spatial pattern was detected for the TR asociated with these bottom trawling fisheries. An increase in bottom trawling activity was detected during the time series, mainly at the end, probably for increasing the TR and mantaining the economic profit due to the instability and increases in fuel prices and offset the increased costs. Based on the obtained information, bottom trawling regulations should be implemented in certain sectors harboring singular and/or threatened habitats and species. In some of these sectors, a low TR from bottom trawling was detected and, bottom trawling regulation may potentially have a low socioeconomic impact. This specific bottom trawling regulation could provide a sustainable balance between bottom trawling activities and habitat conservation in this mud volcano field according to the aims of the Habitats Directive (92/43/EEC) and the European Marine Strategy Framework Directive (2008/56/EEC).