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Maturity is one of the most important biological parameters used in stock assessment programmes. Indeed, the macroscopic stage of gonadal development is an essential feature in estimating the maturity ogive and spawning stock biomass. It is also useful for determining the spawning season of a species and for monitoring long-term changes in the spawning cycle as well as for many other research needs related to the biology of fish. Despite the efforts made during the last few decades to standardize maturity stage data among all the researchers, marine biologists continue without a manageable and unique maturity scale to describe the reproductive development of fish gonads. For these reasons, the objectives of this article are 1) to investigate the biological parameters of five selected key species (Mullus barbatus, Galeus melastomus, Etmopterus spinax, Aristeus antennatus, Loligo vulgaris) with different reproductive strategies following the macroscopic maturity scales based on the same univocal criteria adopted in the MEDITS programme and described in this work; and 2) to compare them among some Mediterranean geographical sub-areas (GSAs) involved in the programme. Neither spawning periods nor size at first maturity (SFM50) for the studied species showed particular differences in the investigated GSAs. La madurez es uno de los parámetros biológicos más relevantes utilizados en los programas de evaluación de stock. De hecho, la etapa macroscópica del desarrollo gonadal es una característica esencial en la estimación de la madurez de la biomasa de la ojiva y del desove. También es útil para determinar la temporada de desove de una especie y para monitorear los cambios a largo plazo en el ciclo de desove, así como para muchas otras necesidades de investigación relacionadas con la biología de los peces. A pesar de los esfuerzos realizados durante las últimas décadas para estandarizar los datos de las etapas de madurez entre todos los investigadores, los biólogos marinos continúan sin una escala de madurez única y manejable para describir el desarrollo reproductivo de las gónadas de peces. Por estas razones, el objetivo de este artículo es 1) investigar los parámetros biológicos de 5 especies clave seleccionadas (Mullus barbatus, Galeus melastomus, Etmopterus spinax, Aristeus antennatus, Loligo vulgaris) con diferentes estrategias reproductivas siguiendo las escalas de madurez macroscópica basadas en criterios iguales y unívocos adoptados en el programa MEDITS y descritos en este trabajo y 2) para compararlos entre algunas sub-áreas geográficas del Mediterráneo (GSAs) involucradas en el programa. Tanto los períodos de desove como el tamaño en la primera madurez (SFM50) para las especies estudiadas no han mostrado diferencias particulares en las GSA investigadas.

The first record of the ophiuroid family Ophiohelidae from the Mediterranean Sea is reported. It consists of the description of the new record of Ophiomyces grandis from the Mallorca Channel seamounts in the Balearic Islands, western Mediterranean, where it shows high abundances. We present both the morphological description of the individuals collected and, for the first time, the cytochrome oxidase subunit I (COI) sequence of this species. The morphological traits of our specimens match the available descriptions of O. grandis. On the other hand, molecular analyses show a large genetic distance between O. grandis and Ophiomyces delata, the two species being very similar morphologically. Despite the high abundances of O. grandis reported here, previous surveys in the Mallorca Channel seamounts using ROV did not detect it, emphasizing the importance of beam trawl sampling to improving the biodiversity description of these geomorphological sea bottom features., Sí

15 pages, 8 figures, 4 tables, supplementary data https://doi.org/10.1016/j.rsma.2021.101700, Bottom trawling is the most extensive fishing activity affecting the continental shelf in Mediterranean waters. This gear has caused negative effects on the communities and topography of the seafloor. Temporal or spatial fishing closures have been proposed as strategies to reduce the disturbances caused by overfishing and for biodiversity recovery and restoration of ecosystems. The present study used various indicators to analyze and compare the differences between the demersal fish assemblages in a fishing closure area (FCA) established by the fishers of the Roses port (NW Mediterranean) and those on a fishing ground (FG) to assess the efficiency of this strategy two years after the cessation of fishing. Our findings demonstrated a noticeable increase in the abundance and biomass of all species in the FCA, especially species of small and medium size. Thus, our findings demonstrated that there were detectable shifts in the community (composition, rank abundance plots, ABC curves and diversity metrics) in a short time, evidencing slight disturbance effects on ecosystems. The present study also showed positive effects on the population structure, which had an increase in larger individuals, although the pattern varied between species. In particular, the European hake stock showed an increase in recruits, and the presence of large adults supported the suitability of this protection measure. Consequently, long time periods are not necessary to perceive noticeable benefits in terms of biodiversity recovery and ecosystem restoration in some deep marine ecosystems, and monitoring from the first year of fishing cessation is very important, Marc Farré was supported by the project CLIFISH (Ref. CTM2015-66400-C3-3-R, MINECO/FEDER, 2016–2018) and co-funded by the Ministerio de Economía y Competitividad of the Spanish government and the Fondo Europeo de Desarrollo Regional (FEDER) (European Regional Development Fund ERDF). Ulla Fernández-Arcaya was funded by a post-doctoral grant co-funded by the regional government of the Balearic Islands and the European Social Fund 2014–2020, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

The large-scale distribution pattern of megafauna communities along the Mediterranean middle slope was explored. The study was conducted between 500 and 800 m depth where deep-water fishery occurs. Although community studies carried out deeper than 500 m are partly available for some geographic areas, few large-scale comparative studies have been carried out. Within the framework of the MEDITS survey programme, we compared the megafauna community structure in ten geographical sub-areas (GSAs) along the Mediterranean coasts. Additionally, the spatial distribution of fishing was analysed using vessel monitoring by satellite information. Overall, the community showed a significant difference between sub-areas, with a decreasing eastward pattern in abundance and biomass. Longitude was the main factor explaining variation among sub-areas (by generalized additive models). However, we found a region which did not follow the general pattern. GSA 6 (northern Spain) showed significantly lower abundance and a different composition structure to the adjacent areas. The decrease in community descriptors (i.e. abundance and biomass) in this area is probably a symptom of population changes induced by intense fishery exploitation. Overall, a combination of environmental variables and human-induced impacts appears to influence the bentho-pelagic communities along the slope areas of the Mediterranean., En este estudio se describe la estructura y patrones de distribución de la comunidad de megafauna que habita en el margen continental medio a lo largo del Mediterráneo. El estudio se realizó entre los 500 y 800 m, coincidiendo espacialmente con las pesquerías de profundidad. A pesar de que se conoce parcialmente la estructura de las comunidades que habitan por debajo de 500 m, existe la necesidad de estudiar estas comunidades a una escala espacial más amplia. Dentro del marco del proyecto internacional MEDITS, se comparó la estructura de las comunidades en diez sub-áreas geográficas (GSAs) a lo largo de las costas mediterráneas. Además se analizó la distribución espacial del esfuerzo pesquero utilizando la información de los datos de seguimiento de buques. En general los resultados mostraron diferencias significativas entre subáreas mostrando un patrón decreciente en los valores de biomasa hacia el este, siendo la longitud el principal factor explicativo del modelo de distribución (GAMs). Sin embargo, encontramos una subárea que no seguía el patrón general, la GSA6 (norte de España). La GSA6 mostró una biomasa y estructura de la comunidad diferente a las áreas adyacentes. La disminución de la biomasa en esta área parece ser un síntoma de los cambios poblaciones causados por la elevada intensidad de pesca en la zona. Los resultados sugieren que la distribución y estructura de las comunidades bento-pelágicas parecen estar moduladas por la combinación de las variables ambientales y los impactos producidos por la actividad humana.

10 pages, 4 figures, 4 tables, The analysis of fish spillover from marine protected areas (MPA) is often based on data collected after the implementation of protection. In the present study we used a methodology based on the combination of Vessel Monitoring System (VMS) and landings data before and after the establishment of protection for spillover analysis. We defined areas of similar size to the protected zone in order to compare them over time. In addition to the no-take zone effectiveness, using this methodology, we were also able to analyze the spatiotemporal behavior of the hake population. Our results on the hake distribution were consistent with those of previous studies. The juveniles were concentrated on the continental shelf (0 - 200 m), whereas the adults were found over the shelf and the slope (300 - 500 m). We found evidence suggesting a positive spillover effect for the juveniles on the continental shelf, enhancing its fishing yields. The analysis of longer time series on the performance of the protected area combined with field sampling inside the no-take zone would lead us to confirm effective spillover effect contributing to fisheries’ long-term sustainability in this zone, This study was supported by the Government of Catalonia through FEMP (European Maritime and Fisheries Fund): ARP005/17/00174, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

The objective of this study was to determine the population distribution and some biological aspects for fish stock assessment of the greater forkbeardPhycis blennoidesalong the Algerian basin. The distribution ofP. blennoides(3418 individuals) was studied using data collected between 170–779 m depth during two bottom trawl surveys developed on 2003 and 2004. Additionally, some biological parameters were obtained from 1050 individuals sampled from commercial fisheries in Algerian ports (i.e. Annaba, Azeffoun, Dellys, Cap Djinet, Zemmouri, Bouharoun, Algiers, La Madrague, Cherchell, Tenes and Mostaganem) during the period 2013–2017.P. blennoidessampled from bottom trawl surveys showed a depth related distribution with the largest individuals being found at 600–800 m depth and the smallest at shallower depths. Density and biomass varied with depth and density also with longitude, while biomass showed no pattern with longitude. Recruitment was recorded in the eastern sector of Algeria during winter, for individuals sampled by bottom trawl surveys. YoungP. blennoidesentered commercial fisheries in summer, with an overall sex ratio skewed towards males (1F:2.18M). The size at first maturity (L50) was 24.30 cm and 30.39 cm for males and females, respectively. The age at 50% maturity was 2–3 years for specimens collected by a bottom trawl survey in 2003 and commercial fisheries, but 3–4 years for the bottom trawl survey in 2004.

Matabos, M. ... et al.-- 9 pages, 4 figures, 1 table, data accessibility https://doi.org/10. 5061/dryad.98 g01, Recent technological development has increased our capacity to study the deep sea and the marine benthic realm, particularly with the development of multidisciplinary seafloor observatories. Since 2006, Ocean Networks Canada cabled observatories, have acquired nearly 65 TB and over 90 000 h of video data from seafloor cameras and remotely operated vehicles. Manual processing of these data is time-consuming and highly labour-intensive, and cannot be comprehensively undertaken by individual researchers. These videos are a crucial source of information for assessing natural variability and ecosystem responses to increasing human activity in the deep sea. We compared the performance of three groups of humans and one computer vision algorithm in counting individuals of the commercially important sablefish (or black cod) Anoplopoma fimbria, in recorded video from a cabled camera platform at 900 m depth in a submarine canyon in the Northeast Pacific. The first group of human observers were untrained volunteers recruited via a crowdsourcing platform and the second were experienced university students, who performed the task for their ichthyology class. Results were validated against counts obtained from a scientific expert. All groups produced relatively accurate results in comparison to the expert and all succeeded in detecting patterns and periodicities in fish abundance data. Trained volunteers displayed the highest accuracy and the algorithm the lowest. As seafloor observatories increase in number around the world, this study demonstrates the value of a hybrid combination of crowdsourcing and computer vision techniques as a tool to help process large volumes of imagery to support basic research and environmental monitoring. Reciprocally, by engaging large numbers of online participants in deep-sea research, this approach can contribute significantly to ocean literacy and informed citizen input to policy development.

26 pages, 7 figures, 2 tables, supplementary material https://www.frontiersin.org/article/10.3389/fmars.2017.00005/full#supplementary-material, Submarine canyons are major geomorphic features of continental margins around the world. Several recent multidisciplinary projects focused on the study of canyons have considerably increased our understanding of their ecological role, the goods, and services they provide to human populations, and the impacts that human activities have on their overall ecological condition. Pressures from human activities include fishing, dumping of land-based mine tailings, and oil and gas extraction. Moreover, hydrodynamic processes of canyons enhance the down-canyon transport of litter. The effects of climate change may modify the intensity of currents. This potential hydrographic change is predicted to impact the structure and functioning of canyon communities as well as affect nutrient supply to the deep-ocean ecosystem. This review not only identifies the ecological status of canyons, and current and future issues for canyon conservation, but also highlights the need for a better understanding of anthropogenic impacts on canyon ecosystems and proposes other research required to inform management measures to protect canyon ecosystems, UF was funded by the Balearic Government post-doctoral grant 2016, co-financed by European Social Plan; VH was supported by the CODEMAP project (ERC Starting Grant no 258482) and the NERC MAREMAP programme; PP has been funded by the ABIDES project (CTM2015-65142-R); AR was supported by NIWA research project “Impact of resource use on vulnerable deep-sea communities” (MBIE contract CO1X0906). IV was funded by Ifremer and Région Bretagne. ALA is supported by Science Foundation Ireland / Marine Institute IvP award 15/IA/3100

Special issue Deep-Sea Biodiversity and Life History Processes.-- 10 pages, 7 figures, 5 tables, Nezumia aequalis and Coelorinchus mediterraneus are abundant species on the upper and lower continental slopes, respectively, in the Mediterranean Sea. A study on the reproductive strategy of the two species was conducted on the Catalan margin (NW Mediterranean). The reproductive cycle of both species was investigated using visual analyses of gonads and histological screening. The shallower species, N. aequalis, showed continuous reproduction with a peak of spawning females in winter months. In contrast, the deeper-living species, C. mediterraneus, showed semi-continuous reproduction with a regression period during the spring. Juveniles of N. aequalis were present in all seasons, but most abundant in the spring. Only two juveniles of C. mediterraneus were found. Both species had asynchronous oocyte development. The average fecundity of N. aequalis was 10,630 oocytes per individual, lower than known for the same species in the Atlantic Ocean. The fecundity of C. mediterraneus was measured for the first time in this study, with an average of 7693 oocytes per individual. Males of both species appear to have semi-cystic spermatogenesis. © 2013 Elsevier Ltd., This study was conducted in the framework of the RECS II, PROMETEO and DOS MARES projects funded by the Spanish Science and Innovation Ministry (CICYT: REN02/04556/C02/MAR; CTM2007-66316-C02/MAR; CTM2010- 21810-C03-03/MAR respectively, to JBC) and the European Community’s Seventh Framework Program under the HERMIONE project (Grant agreement 226354, to ERLL). UF-A is funded by a Spanish doctoral fellowship FPI-2008. ERLL is funded by a Spanish JAE-CSIC postdoctoral grant with co-funding of the European Social Fund. This paper is contribution no. 619 from AZTI- Tecnalia (Marine Research Division)

12 pages, 10 figures, 6 tables, Macrourid fish are one of the most abundant marine species on continental margins worldwide. Although they play an important role in the ecosystem, little is known about their overall biology. We report here a large data set of the most abundant macrourid in Mediterranean waters, Trachyrincus scabrus, showing the main population and reproductive characteristics. The study was based on 3,239 specimens collected between 300 and 1,500 m depth on the northwestern Mediterranean in 2003–2004 and 2008–2009. The population showed a depth-related structure with the largest individuals at 1,100 m depth and the smallest (i.e., immature) at shallower depths. Macroscopic and microscopic analyses of the gonads showed that T. scabrus has a highly seasonal reproductive pattern. Spawning females were found during winter when the organic matter fluxes were highest on the continental slope. T. scabrus is a batch spawner with group-synchronous oocyte development and present low average fecundity of 14,191 oocytes, The authors would like to thank the Officers and crews of the R/V Garcia del Cid, F/V Montse III and Virgen del Vilar for helping to provide samples and the data necessary for our study. We also thank I Quagio-Grassiotto, M Metaksakis and C Cerviño for helping with the histological analyses and JA Garcia for developing the study area map. This study was conducted within the RECS, PROMETEO and DOS MARES projects by the Spanish Science and Innovation Ministry CICYT (REN02/04556/C02/MAR; CTM2007-66316-C02/MAR; CTM2010-21810-C03-03/MAR, respectively, to JBC) and European Community’s Seventh Framework Programme under the HERMIONE project (Grant Agreement 226354, to ERLL). UF-A is funded by a Spanish PhD doctoral fellowship FPI-2008. ERLL is funded by a Spanish JAE-CSIC postdoctoral grant. This paper is a contribution number 580 from AZTI Tecnalia (Marine Research Division)

6 pages, 2 figures, 2 tables, The diversity of chondrichthyans in the Mediterranean Sea is relatively high; however, available data indicate that this group is declining in abundance and several species are becoming rare. As a result, the collection of biological data is a priority for demographic models, stock assessments, and food web analysis. In the present study, we report morphological parameters and length–weight relationships of several chondrichthyan species, both abundant and threatened, from the western Mediterranean Sea. Samples were obtained with commercial and scientific bottom trawl vessels between 2001 and 2013. A total of 893 individuals belonging to 11 families and 20 species were weighed and total lengths measured. In addition, seven species of large demersal sharks were measured and length–length relationships obtained to study the relationships between different body length measurements. All species showed positive allometric or isometric growth, except for Centroscymnus coelolepis. The results of the length–weight relationships reveal differences between the western Mediterranean and nearby areas, depending on the species studied, CB was supported by a predoctoral fellowship CONICYT- Becas Chile. JN and MC were supported by a research contract of the Marie Curie Career Integration Grant Fellowships to the BIOWEB project. MC was also funded by a postdoctoral contract of the Ramon y Cajal Program (Spanish Ministry of Economy and Competiveness). This study forms a contribution to the project ECOTRANS (CTM2011-26333, Spanish Ministry of Economy and Competiveness, Spain)

11 pages, 8 figures, 5 tables, Ceramaster grenadensis is one of the most abundant bathyal seastars in the north-western Mediterranean Sea and also presents a wide geographic distribution in the Atlantic Ocean. As with other species in this genus, little information is available on the biology and reproductive strategy of C. grenadensis. In this context, we describe for the first time the reproductive cycle of this species from bathyal depths in the north-western Mediterranean Sea. Specimens (NA = 141) were collected seasonally from 194 benthic trawls (141 Otter Trawls and 53 Agassiz trawls) conducted during 10 cruises from October 2008 to April 2013. Open slope and canyon systems were sampled at depths between 900 and 2250 m. The population distribution of C. grenadensis showed a depth-related structure, with the smaller adult specimens and juveniles present at greater depths. Sex ratio was 2:1 females per male, constant among seasons and depths. Histological analyses of the gonads showed an asynchronous ovarian organization, with previtellogenic and vitellogenic oocytes throughout the year. These oogenesis patterns suggest a continuous reproduction. However, the Pyloric Caeca Index (PCI) decreased in summer while the Gonad Index (GI) increased in autumn in males, suggesting a higher spawning capacity in autumn. In both sexes, an increasing GI and PCI trend was observed with increasing depth. © Marine Biological Association of the United Kingdom 2015, This study was supported by three projects funded by the Spanish Government: PROMETEO (CTM2007-66316-C02/MAR), PROMARES – OASIS DEL MAR (Obra Social ‘la Caixa’) and DOSMARES (CTM2010-21810-C03-03). JA was a fellow of the Spanish Ramo´n y Cajal Programme. ERLL was partially funded by a Spanish Ramón y Cajal Programme

9 pages, 6 figures, 3 tables, The population structure and reproductive biology of deep-water continental margin Cynoglossidae is poorly known. Here, we focused on two highly abundant species of the upper slope of the NW Mediterranean Sea, Symphurus nigrescens and S. ligulatus. Megafaunal sampling of 37 hauls was conducted between April 2003 and May 2004 in the Blanes canyon and the adjacent open slope between 300-1500 m depth. The differential bathymetric distribution between the two species was surveyed by standardizing catch data per unit of swept surface and by pooling resulting densities by 100 m depth interval. Females of both species were classified into a five-stage maturity scale according to their external appearance and their gonads dissected for histological analysis. The analysis of the species' bathymetric distribution revealed a differential and only partial overlap. In both species, an increase in size with depth was observed coinciding with the dominance of females in deeper depth strata. The shallower species, S. nigrescens showed a marked spawning period with a peak in summer. In contrast, the deeper-living species, S. ligulatus, presented a longer spawning period ranging from spring to autumn. Moreover, histological examination demonstrated that the ovaries of both species had an asynchronous organization. Present results on spatial-temporal size frequency distribution, spawning temporality and oocyte size are discussed assuming interspecific competition and the different environmental conditions related to their bathymetric distribution. Copyright © Marine Biological Association of the United Kingdom 2015, This study was conducted within the RECS projects funded by the Spanish Science and Innovation Ministry CICYT (REN02/04556/C02/MAR to JBC) and the EU-FP7 project HERMIONE (Grant Agreement 226354)

Special issue Integrated study of a deep submarine canyon and adjacent open slopes in the Western Mediterranean Sea: an essential habitat.-- 13 pages, 10 figures, 3 tables, Temporal patterns in deep-sea fish reproduction are presently unknown for the majority of deep continental margins. A series of seasonal trawling surveys between depths of 300 to 1750. m in the Blanes submarine canyon and its adjacent open slope (NW Mediterranean) were conducted. The bathymetric size distributions and reproductive cycles of the most abundant species along the NW Mediterranean margin were analyzed to assess the occurrence of (i) temporal patterns in reproduction (i.e., spawning season) along a bathymetric gradient and (ii) preferential depth strata for recruitment. The fish assemblages were grouped in relation to their bathymetric distribution: upper slope, middle slope and lower slope species. Middle-slope species (i.e., 800-1350. m) showed short (i.e., highly seasonal) reproductive activity compared to the upper (300-800. m) and lower (1350-1750. m) ones. Our results, together with those previously published for megabenthic crustacean decapods in the area, suggest a cross-phyla depth-related trend of seasonality in reproduction. In the middle and lower slope species, the reproductive activity reached a maximum in the autumn-winter months and decreased in the spring. The observed seasonal spawning patterns appear to be ultimately correlated with changes in the downward transport of organic particles and with seasonal changes in the physicochemical characteristics of the surrounding water masses. The distribution of juveniles was associated with the bathymetric stratum where intermediate nepheloid layers interact with the continental margins, indicating that this stratum acts as a deep-sea fish nursery area. © 2013 Elsevier Ltd., This study was conducted within the framework of the RECSII, PROMETEO and DOSMARES projects by the Spanish Science and Innovation Agency (REN02/04556/C02/MAR; CTM2007-66316-C02/MAR; CTM2010-21810-C03-03/MAR respectively, to JBC) and European Community’s Seventh Framework Program under the HERMIONE project (Grant Agreement 226354, to ERLL). UF-A is funded by a Spanish doctoral fellowship FPI-2008. ERLL is funded by a Spanish JAE-CSIC postdoctoral grant with co-funding of the European Social Fund

12 páginas, 7 figuras, 4 tablas., Seasonal variations in the photophase length seem to drive migrations of marine animals, a phenomenon still largely unknown in deep-sea fishes and decapod crustaceans. Here, we report depth-oriented migrations of species living in the continental slope of the NW Mediterranean after repeated trawl sampling between 900 and 1500 m depths in four seasons. To understand the variations in the catchability of animals as a function of water depth, we analysed the relationship between population depth shifts and environmental factors by performing a multiparametric habitat monitoring at sea surface (PAR), in the water column (temperature and salinity), and on the seabed (organic matter flux and total mass flux). Significant connections are studied by NMDS and GAM analyses. Bathymetric changes in most targeted species are identified from winter, when distribution was the deepest, to spring and summer, and finally autumn, when the shallowest distribution was observed prior to a sudden bathymetric retreat. The analysis of size-class frequency distributions (Kolmogorov–Smirnov test) discards an effect of the juvenile recruitment on these bathymetric changes. Which environmental factor imparts seasonality to these depth-oriented migrations has not yet been clarified. A strong connection is found with water temperature and salinity, associated to flow of the Levantine Intermediate Water (LIW) and the Western Mediterranean Deep Water (WMDW). The studied depth range was affected by seasonal fluctuations of both water masses and the interphase amongst them. LIW showed a stronger seasonal pattern, getting warmer, saltier in autumn and fresher in winter. The migration of most species towards shallower depths in spring, summer and autumn, and the sudden migration to deeper grounds in winter could therefore be related to changes in LIW temperature and salinity., The present work was developed within the framework of PROMETEO (CTM 2007-66316-C02/MAR) and DOS MARES (CTM2010-21810/MAR) research projects funded to MC and JBC by the Spanish “Ministerio de Ciencia e Innovación” (MICINN; actual Ministerio de Economia y Competividad). The OOCS was supported by MICINN project “Observation, analysis and modelling of the Mediterranean Sea—OAMMS” (CTM2008-03983) from January 2009 to December 2011. Jacopo Aguzzi is a Postdoctoral Fellow of the “Ramon y Cajal” Program (MICINN).