Human health and well-being, and how they are affected by terrestrial and freshwater ecosystems have been the subject of numerous studies. In contrast, there are very few such studies relating to marine ecosystems. Here, in the context of the Mediterranean Sea, we assess evidence of the broad interplay of relationships between marine habitats and human health and well-being. Our review shows that the major Mediterranean marine habitats provide various provisioning, cultural and regulating services that improve physical and mental health in a number of different ways. These include: (i) the provision of seafood rich in omega-3 fatty acids, which help to reduce the risk of developing certain types of illnesses; and also, species that produce bioactive compounds that are potential sources of new drugs; (ii) the provision of blue spaces – areas of water suitable for leisure and recreational activities able to inspire, educate, and appeal to the aesthetic senses – that not only increase physical and psychological health, but also foster an individual and collective sense of place and identity and contribute to improving social relations; and (iii) the regulation of climate change, and of water quality and pollution, for example via sequestration of carbon and heavy metals, thus reducing the associated health risks. Our results show that Mediterranean marine habitats are valuable for health and well-being, thus highlighting the need to conserve as much of these habitats as possible (particularly through marine protected areas) and to carry out new studies to determine the specific causal pathways by which certain characteristics of marine habitats – including biotic (e.g. marine biodiversity) and abiotic (e.g. water quality) factors – affect human health and well-being.

Maërl habitats are composed of coralline red algae species that can live freely rolling on the seabed and forming nodules, the so-called rhodoliths, or incrusted forming coralligenous habitats. Maërl habitats are generally distributed in the Mediterranean at a depth of between 30 m and 70 m and are considered one of the most emblematic Mediterranean seabeds. In the present study, the complex structure of maërl habitats was investigated to i) characterise the relief features and classify the different sediments, ii) to estimate the abundance of the coralline red algae (both rhodoliths and encrusting ones) and iii) to analyse the biodiversity of the species inhabiting the habitat. Data were obtained from an approximately 11 km-long transect, using non-intrusive sampling methods, integrating information from video images collected using the Remotely Operated Vehicle LIROPUS (IEO_CSIC), and multibeam bathymetry and backscatter data. Video images were used to reconstruct (using GIS) the habitat structure and characteristics. Throughout the transect, a strong relationship between habitat characteristics and the effect of trawling activity and the geomorphology of the studied area was observed. The closed area to fishing activity showed a high abundance of rhodoliths in well-structured megaripples reliefs. Contrarily, the areas affected by fishing showed an important destructuring of the relief with a low density of rhodoliths. Last, the muddy bottoms showed areas with no characteristic features and no rhodoliths. All this information has allowed to reconstruct the maërl habitat in the Blanes continental shelf (NW Mediterranean) and analyse the fragmentation of the assemblages seen in the video to assess its good environmental status (GES), and finally to identify the level of ecological integrity of this vulnerable habitat.

Underwater biogenic habitats composed of unattached calcified red algae, named as rhodolith or maërl beds, may extant either alive or dead, over the seabed. The accumulation of rhodoliths constitute three-dimensional structured biogenic habitats that harbour high diversity of benthic organisms. In the Mediterranean Sea, rhodolith beds can be found between ca. 50 and 100 m, increasing diversity of the continental shelf habitats and their conservation value. Despite the remarkable relevance of these habitats, information regarding their spatial distribution in the western Mediterranean is scarce. In addition, these habitats are threatened by a range of anthropogenic activities and by climate-driven changes. In this study, we explored areas with rhodoliths' occurrence from the north to the south of the east coast of Spain. By feeding video recording data into a spatial distribution model, we assessed which biophysical drivers: (i) shape the spatial variation in the abundance of rhodoliths and (ii) define the assemblages of the biological traits and functional richness of the associated epibenthic fauna recorded by video. In addition, we examined the impact of fishing activities on these habitats. Our results evidenced that 'Depth' and 'Temperature' were important environmental factors explaining rhodoliths variation, and we defined their optimal distribution range in the western Mediterranean. The biological traits approach showed significant effects of the geographical location of rhodolith beds and their small-scale spatial heterogeneity on the functional richness index. Indeed, the lowest functional richness value was observed in the area closer to trawl fishing which could be related to habitat degradation due to trawling. This study contributes to the knowledge of deep-water rhodolith beds in the western Mediterranean and reinforce the importance of rhodolith beds in continental shelves as these constitute heterogeneous seabed habitats that harbour a high species and functional diversity.

The current European Union fisheries policy encourages improving handling practices to increase the survival of discards. Trawling on the Mediterranean upper slope often generates over 30% of discards of the total catch. Among other species, Nephrops norvegicus juveniles are abundantly returned to the sea, sometimes exceeding 40% of discarded biomass. N. norvegicus discard survival probability has been recently shown to be related to vitality on board and to vary seasonally, being especially low during the summer (0.06). Environmental characteristics (especially, high on-deck temperature in summer) make it necessary to improve vitality on board in order to increase discard survival. We therefore tested new discard handling methodologies for a Mediterranean mixed trawl fishery, with N. norvegicus as the target species. The results showed a survival rate on board higher than 0.8 resulting from vitality status improvements achieved by immersing N. norvegicus in cooled seawater on board during the catch selection and discard time. The implementation of this method would make an important contribution to more sustainable Mediterranean trawl fisheries.

Highly productive and vulnerable habitats such as maerl and crinoid beds are subject to severe impacts from trawling in Mediterranean Sea. One of the most valuable target species that inhabit these habitats is the red mullet, Mullus barbatus, which can achieve there optimum feeding conditions based on infauna, which can provide some Fatty Acids (FAs) such as Polyunsaturated Fatty Acids (PUFAs) that are essential in shaping life history traits such as growth and reproduction. This study is the first one evaluating how habitat type can affect the FA profile of red mullet and that of their prey (infauna). The analysis was carried out in both habitats (maerl and crinoid beds) and compared to muddy bottom, the most common trawl fishing ground. In red mullet muscle from maerl or crinoid beds, we observed a higher concentration of PUFAs omega 3 and omega 6 such as C22:6n-3 (docosahexaenoic acid, DHA), C18:3n-3 (alfa-linolenic acid, ALA) or C18:2n-6 (linoleic acid) than in muddy bottoms. On the other hand, MUFAs such as C18:1cn-9 (oleic acid) presented higher concentrations in muddy bottoms compared to maerl habitat. Regarding infauna's FAs, there was between 30% and 35% of dissimilarity between maerl and crinoid habitats and muddy habitat respectively. In addition, differences found in infauna's PUFAs concentration were very similar to the differences found in M. barbatus PUFAs when maerl and crinoid were compared with muddy habitats. Our results support the idea of using FAs as an indicator of the quality and trophic marker of productive and sensitive benthic habitats, which can contribute to assess the good environmental status (GES) of these habitats and the goods and services they provide.

A bioeconomic model was built to assess the contribution of more selective trawl nets to the objectives of the European Multi-Annual Plan for demersal fisheries in the Western Mediterranean (WM MAP). The biological submodel was parameterized with age-structured population parameters for the five target stocks in the WM MAP (European hake, red mullet, deep-water rose shrimp, Nephrops and red shrimp) with a sixth stock combining the remaining commercial by catch and following a biomass dynamics model. The trawl fleet was composed of three fleet segments, according to Vessel Length class (VL1218, VL1824, VL2440), practicing two metiers: coastal mixed demersal fishery and deep-water crustacean fishery. The technological solutions analyzed are two simple technical modifications to the otter bottom trawl and based on i) using a panel of meshes turned 90 degrees (T90) in the extension of the trawl net, and ii) inserting a selective grid built from 40 mm square mesh (SM40) netting into the extension of the trawl net. The Results show that, in terms of policy objectives, the reduction in the values of fishing mortality achieved with these selectivity modifications would be insufficient to reach the target fishing mortality at maximum sustainable yield (Fmsy) prescribed in the WM MAP by 2025. However, model results project a substantial recovery of hake and red mullet stock biomass. The recovery of these two important stocks would help improve the evolution of the economic indicators, resulting generally in higher income, profits and salaries in the short (2025) and mid term (2030).

The catch of large quantities of sublegal-sized fish and shrimp is a pervasive feature of bottom trawl fisheries, particularly in the Mediterranean demersal mixed fisheries where regulations traditionally allow small mesh sizes. To address these concerns, two bottom trawl net selectivity trials were carried out in 2019 and 2020 on fishing grounds worked by the trawl fleet of Spanish Mediterranean, under normal commercial operating conditions with volunteer trawlers of the local fleet. The traditional otter bottom trawl employed in the demersal mixed fishery was modified with a 50-mm T90 panel on the extension piece under two different configurations (front of the extension piece and back of the extension piece). A second modification consisted of inserting a selective grid in the extension piece of the standard bottom trawl net. The species investigated in the demersal mixed fishery were European Hake Merluccius merluccius, Red Mullet Mullus barbatus, Striped Red Mullet Mullus surmuletus, and the deepwater rose shrimp Parapenaeus longirostris. Important selectivity improvements were observed for European Hake and deepwater rose shrimp, particularly in the selective grid trial, where 95% and 100%, respectively, of undersize specimens escaped through the grid. The design with the T90 panel in the back of the extension piece allowed for a reduction of 35% of sublegal-sized individuals of European Hake, but no difference was gained in the sizes of both Mullus spp. retained in the cod end. The adoption of these gear modifications might contribute to reducing discards of sublegal-sized fractions of the fisheries target species.

A multi-annual generalized depletion (MAGD) model was applied to the data-limited Mediterranean sandeel boat seine fishery in Catalonia. The results show that catch and effort data at high temporal frequency (month), complemented with biological information on mean body weight and initial estimates of natural mortality and time of recruitment to the fishery, can be used to produce assessment results of interest to fisheries management. The estimates of fishing mortality obtained for the Mediterranean sandeel in this fishery are very low compared to natural mortality estimates (less than 10 %) and the important fluctuations in recruitment strength suggest that the dynamics of this fishery are mainly driven by density-dependent effects on the population dynamics of the species. Given the high rate of natural mortality estimated (similar to M = 2 y(-1)), its short life-span (1-2 y) and that exploitation is based on age 0 individuals, it is recommended to keep exploitation rates at current levels (<4%), which can be adapted on a short time basis, subject to the perceived availability of the stock. This low exploitation rate is compatible with a precautionary escapement biomass of 40 %. A parallel stock assessment was carried out with a surplus production model (SPiCT), which led to similar trends in biomass and fishing mortality as the MAGD model application. The parameter estimates obtained with both models have wide confidence intervals, particularly for the quantities related to population size, suggesting that these data-limited models are likely to suffer from low precision. Precision was lower for SPiCT than for MAGD, and the performance diagnostics for SPiCT were poor. The MAGD model can be used for small-scale fisheries that are unlikely to meet the requirements of standard stock assessments based on catch-at-age methods and can provide indicators (fishing mortality, vulnerable biomass) of interest to fisheries managers.

Although knowledge of the bioactive compounds produced by species inhabiting coastal waters is increasing, little is known about the bioactive potential produced by marine species occupying deeper habitats with high biodiversity and productivity. Here, we investigate about the bioactive potential of molecules produced by species that inhabit the crinoid beds, a poorly known essential fish habitat affected by trawling, wherein large amounts of commercial and noncommercial species are discarded. Based on a trawl survey conducted in 2019, 14% of the 64 species discarded on crinoid beds produce molecules with some type of bioactive potential, including; soft corals (Alcyonium palmatum); tunicates (Ascidia mentula); bony fish, such as horse mackerel (Trachurus trachurus); European hake (Merluccius merluccius); and chondrichthyans, such as small-spotted catshark (Scyliorhinus canicula). In addition, 16% of the discarded species had congeneric species that produce compounds with bioactive potential, indicating that such species might also possess similar types of bioactive molecules. Molecules with antioxidant, antitumour, antihypertensive, and antibacterial properties were the most frequent, which could provide the basis for future research aiming to discover new marine-based drugs and compounds for other human uses. Among all species or genera that produce compounds with bioactive potential, 68% presented medium or high vulnerability to trawling. Results show that the discarded catch contains many species, which produce different bioactive compounds that represent an added-value resource. These results highlight the importance of manage properly crinoid beds, to ensure that species that produce molecules with bioactive potential inhabiting these habitats are protected.

Reducing the impact on vulnerable species through changes in fishing practices, such as the spatial or temporal avoidance of certain areas, is key to increase the ecological sustainability of fisheries. However, it is often hampered by the availability of sufficiently detailed data and robust indicators. Existing trawl surveys are a cost-effective data source to assess the vulnerability of fishing areas based on the quantities of vulnerable species caught. We developed a biological traits-based approach to the vulnerability of demersal assemblages using commercial trawl catch data. An expert-based approach identified a set of biological traits that are expected to condition the species' response to trawling impact and are combined to produce the vulnerability index ranked into four levels (low, moderate, high and very high vulnerability). The approach was tested in four southern European fishing grounds showing evidence of over-exploitation, through catches being dominated by species of relatively low vulnerability to fishing impacts. The general distribution of species' biomass amongst vulnerability groups was highly homogenous across case studies, despite local differences in fishing fleet structure, target species and fishing depths. Within all areas the species with moderate vulnerability dominated and, in most instances, species of "very high" vulnerability were not recorded. Nevertheless, differences emerged when comparing the proportions of highly vulnerable species in the catches. Variability in vulnerability level of the catch was also observed at small spatial scales, which was principally explained by differences in habitat type and depth and, secondarily, by fishing effort. In fine mud in the shallower areas there was a higher presence of low vulnerable fauna. Furthermore, vulnerable organisms decreased in their presence in sandier substrates on the continental shelf. The spatial heterogeneity in assemblage vulnerability composition encourages the potential for adoption of this index in the spatial management of fishing grounds aiming at ensuring a sustainable exploitation by mitigating trawl impacts on the most vulnerable components of the demersal assemblages.

VII International Symposium on Marine Sciences (ISMS 2020), 1-3 July 2020 (Barcelona).-- 3 pages

The landing obligation in the revised European Union Common Fisheries Policy allows for exemptions to obligatory landing of the entire catch for species for which "high survival" of discards can be demonstrated. Nephrops norvegicus is an important target species in many fisheries across Europe in the Mediterranean Sea, NE Atlantic Ocean and North Sea. Historically, Mediterranean fisheries have had a high discard rate of small-sized Nephrops, and it is suspected that this unwanted component of the catch may have a high survival potential that is comparable to those of other EU fisheries, where survival rates of up to 0.56 have been demonstrated. However, to date, no investigations have confirmed a high discard survival rate for Nephrops in the Mediterranean Sea. Furthermore, the environmental, technical and biological characteristics that could affect Nephrops survival have been shown to be substantially different from those in the survival assessments conducted in the NE Atlantic and the North Sea. To address this knowledge gap, this study was conducted to determine the survival of Nephrops discarded from trawls in the Mediterranean Sea. The survival and vitality status of the discarded Nephrops removed from trawl catches were monitored onboard and for 14 days in the laboratory. The results showed seasonality in survival, with the highest survival rate in winter (0.74; CI: 0.7 - 0.78), lower survival in spring (0.36; CI: 0.31 -0.41) and the lowest survival in summer (0.06; CI: 0.04 - 0.09). Survival was monitored to the asymptote in all cases, and season and vitality status were shown to have statistically significant relationships with survival.

Involving and engaging stakeholders is crucial for studying and managing the complex interactions between marine ecosystems and human health and wellbeing. The Oceans and Human Health Chair was founded in the town of Roses (Catalonia, Spain, NW Mediterranean) in 2018, the fruit of a regional partnership between various stakeholders, and for the purpose of leading the way to better health and wellbeing through ocean research and conservation. The Chair is located in an area of the Mediterranean with a notable fishing, tourist, and seafaring tradition and is close to a marine reserve, providing the opportunity to observe diverse environmental conditions and coastal and maritime activities. The Chair is a case study demonstrating that local, collaborative, transdisciplinary, trans-sector, and bottom-up approaches offer tremendous opportunities for engaging coastal communities to help support long-lasting solutions that benefit everyone, and especially those living by the sea or making their living from the goods and services provided by the sea. Furthermore, the Chair has successfully integrated most of its experts in oceans and human health from the most prestigious institutions in Catalonia. The Chair focuses on three main topics identified by local stakeholders: Fish and Health; Leisure, Health, and Wellbeing; and Medicines from the Sea. Led by stakeholder engagement, the Chair can serve as a novel approach within the oceans and human health field of study to tackle a variety of environmental and public health challenges related to both communicable and non-communicable diseases, within the context of sociocultural issues. Drawing on the example provided by the Chair, four principles are established to encourage improved participatory processes in the oceans and human health field: bottom-up, "think local", transdisciplinary and trans-sectorial, and "balance the many voices".

Assessments of small-scale, coastal fisheries are often hindered by the lack of complete data sets fulfilling the requirements of conventional stock assessment methods In contrast, existing information from the regular monitoring of fisheries coupled with data-limited assessment methods can help provide the information needed for effective management of fisheries. We investigated the year-to-year length-based estimates of the spawning potential ratio (SPR) of European hake, a species with moderate data availability (i.e., reasonable knowledge of the life-history traits and temporal length structures of the population). We explore the effects of considering fast- vs. slow-growth hypotheses and the uncertainties of input parameters on the annual estimates of the SPR (1998-2010) in a bottom trawl fishery in the SW Mediterranean (Murcia region). The SPR estimates under four life-history scenarios were sensitive to the quality (sample size) of the length frequencies. Consequently, comparable and more accurate SPR estimates were often found for annual samples larger than 2000 individuals. The F/M ratio varied less when size compositions were grouped by period, suggesting there are transitory-population size structures. The SPR estimates were insensitive to the underlying growth hypothesis since similar M/k ratios > 2.3 were derived from the four sets of von Bertalanffy growth parameters. The assessment indicated overexploitation of hake (F/M > 2, SPR < 10%) that is comparable with that derived from conventional assessments for this species elsewhere in the Mediterranean Sea. According to our findings, the LB-SPR method can provide reliable stock assessments and allows population trends to be calculated for data-limited species. However, this method requires a good understanding of the input data and their possible sources of bias.

With the full implementation of the landing obligation on 1 January 2019, In European waters it will become mandatory for the trawling fleet to land at port all catches of certain species because, according to Article 15 of the new European Common Fisheries Policy, the species subject to the minimum conservation reference size (MCRS) cannot be discarded. Additionally, since 2005, trawlers over 15 m in length are required to carry an onboard vessel monitoring system (VMS), which generates information on fleet dynamics. The objective of this work was to provide a tool for avoiding unwanted catches by integrating the catch study of trawlers operating in the port of Blanes together with VMS data. To achieve this objective, the catches of 40 hauls were monitored, sampled and analysed together with VMS data for the years 2012-2014 integrated in a geographical information system. The results show that specimens below the MCRS were often captured in crinoid aggregation habitats, bottoms with maërl and muddy bottoms that were identified as nursery habitats of commercial species, e.g. Merluccius merluccius, Pagellus spp. and Mullus spp. VMS data showed considerable fishing pressure on areas with maërl and muddy habitats during the recruitment periods of these and other commercially relevant species. Implementing spatial or seasonal closures in habitats where species regulated by the MCRS are subject to catches could be a useful tool for preventing unwanted catches.

There is currently very little information on the survival of discards of unwanted and unregulated catches of invertebrates after the stresses caused by capture. A great number of the unregulated invertebrate species form the basis of essential fish habitats for important fisheries resources such as hake, red mullet and cuttlefish. Thus, data on their survival after discarding may help to interpret the role of these species within the benthic ecosystems. Furthermore, descriptor 6 of the Marine Strategy Framework Directive (EU Directive 2008/56/E) foresees maintaining sea floor integrity at a level that ensures that the structure and functions of the ecosystems are safeguarded, and Article 7(d) of the Common Fisheries Policy (EU Reg. 1380/2013) foresees the implementation of management measures for fishing with low impact on the marine ecosystem and fishery resources. Survival measurements by direct recovery of tagged discarded species are not effective in bottom trawl fisheries, for which alternative studies such as semi-quantitative measures obtained on board prior to discarding can be considered as appropriate for mortality estimation. The present work assessed the survival of unwanted species using a semi-quantitative assessment on the deck of trawlers and at the laboratory for a period of 96 hours in two Mediterranean areas (the Catalan coast and the Ligurian and Northern Tyrrhenian seas). A high number of discarded invertebrates showed a high percentage of survival (>70%) in both assessments. The results can be used to provide information that can help to achieve higher survival levels of discarded specimens and enhance the productivity of fishing grounds by increasing the health of benthic ecosystems.

For a successful implementation of an Ecosystem Approach to Fisheries (EAF) management, it is necessary that all stakeholders involved in fisheries management are aware of the implications of fishing impacts on ecosystems and agree with the adopted measures to mitigate these impacts. In this context, there is a need for tools to share knowledge on the ecosystem effects of fisheries among these stakeholders. When managing bottom trawl fisheries under an EAF framework, one of the main concerns is the direct and indirect consequences of trawling impacts on benthic ecosystems. We developed a platform using the ExtendSim® software with a user-friendly interface that combines a simulation model based on existing knowledge, data collection and representation of predicted trawling impacts on the seabed. The platform aims to be a deliberation support tool for fisheries’ stakeholders and, simultaneously, raise public awareness of the need for good benthic community knowledge to appropriately inform EAF management plans. The simulation procedure assumes that trawling affects benthic communities with an intensity that depends on the level of fishing effort exerted on benthic communities and on the habitat characteristics (i.e. sediment grain size). Data to build the simulation comes from epifaunal samples from 18 study sites located in Mediterranean continental shelves subjected to different levels of fishing effort. In this work, we present the simulation outputs of a 50% fishing effort increase (and decrease) in four of the study sites which cover different habitats and different levels of fishing effort. We discuss the platform strengths and weaknesses and potential future developments.