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Nursery areas are essential fish habitats due to their relevance in the survival of early stages of fish populations. They are also considered as of high priority in marine conservation strategies. Here, we investigated the diet of white seabream [Diplodussargus (Linnaeus, 1758)] settlers in six nursery areas located in the shallow waters of coves in Minorca Island (Balearic Islands, Spain). Our aim was to characterize the food sources at different stages of juvenile development and their site-related variability in order to discern the importance of trophic links in cove selection during settling. The gut contents of 101 juveniles captured at different coves, three to the north of the island (N), and three in the southern coast (S), revealed a marked preference for feeding on crustaceans and, in particular, on harpacticoid copepods (>90% of gut contents). Copepods represented the main food source (80 ±4.4%; mean ±S.E.) in younger seabream individuals (10 - 15 mm length). A higher diversity in prey items was observed in the larger size-classes (s2: 16 - 23 and S3: 24 - 30 mm, respectively), which incorporated other prey items such as amphipods, isopods, foraminiferans or ostracods. Diet composition did not vary between the two surveyed locations (North vs. South of the island), but it did show significant differences among the six coves (p

The diversity of benthic communities on continental shelves is tightly linked to the diversity of habitats. Therefore, considering seascape habitat composition can help to gain insights into the spatial variability of benthic communities and move away from single-habitats approaches. This perspective needs different analytical methods, such as network analysis that enable the study of complex ecological interactions. This work explores the relationships between habitat and benthic species diversity in the Menorca Channel (the Balearic Islands, western Mediterranean). The seascape in the study area is a mosaic of alternating biogenic and sandy habitats that increases the total benthic species richness. Of the 442 benthic species included in the analyses, 286 species are shared by the six habitats identified, contributing to ecological connectivity across the seascape; 73 generalist species inhabit all six habitats simultaneously, however, 156 species are specialists and are linked to a single habitat, particularly to biogenic habitats, which increases specialization and the vulnerability of the species to habitat fragmentation. The network approach shows a tight link between epibenthic species diversity and the distribution of habitats over the continental shelf, providing essential information for optimal conservation strategies that move from a focus on protecting the most sensitive habitats to marine conservation schemes that encompass a diversity of habitats. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was funded by EU H2020 MaCoBioS (Grant Number 869710) and the original data was produced under LIFE + INDEMARES project: ‘‘Inventario y designación de la Red Natura 2000 en área marinas del Estado español’’. SdJ is supported by a Ramon y Cajal postdoctoral grant funded by the Ministry of Science and Innovation (Plan Estatal I + D + I, 2017- 2020; grant no. RyC2020-029062-I). AO was funded by the General Directorate for University Policy and Research of the Government of the Balearic Islands with a “Vicenç Mut” award Grant PD/002/2020. JM was the INDEMARES project coordinator in the Menorca Channel for the period 2009–2014.

Here, we assess whether fishery exploitation affects the trophic structure of carnivorous fish. We censused fish and analysed the stable isotope ratios of C and N of species targeted by fishermen in areas open to fishing and marine protected areas (MPAs) in the Mediterranean Sea and the north-eastern Atlantic Ocean. Results demonstrated a major impact of fishing on the biomass and size structure of nektobenthic carnivorous fish. However, those changes did not modify the diversity of the trophic resources used by the assemblage, the pattern of resource partitioning between species, or the degree of trophic redundancy. These results add to recent evidence suggesting that MPAs implemented in fished seascapes may fail to restore the original structure of the food webs that once existed in pre-fished ecosystems because regional decimation and extinction of highly mobile predators prevent recovering the original diversity of predators at local scales, even in no-take areas. If so, more strict local fishing regulations are unlikely to restore the original diversity of high trophic level carnivores and restoration goals should be reframed in terms of an objective that is less unrealistic than restoring the pre-fished condition while still recovering aspects of the historical trophic structure.

Resource partitioning in polymorphic fish species is expected to be altered by human exploitation, as individual specialization is density dependent in many vertebrates. We tested this hypothesis using the ballan wrasseLabrus bergyltaas a model species. We compared the isotope niches of the plain and spotted morphs of the species in a marine protected area (MPA) and in adjoining areas open to fishing, both off Galicia (NW Spain). Underwater visual census confirmed a 3-fold increase in the biomass of ballan wrasse off the Cíes Islands compared to areas open to recreational fishing, thus demonstrating that populations outside MPAs are well below carrying capacity. The stable isotope ratio of C revealed differences in the resource use patterns of plain and spotted ballan wrasses both in areas open and closed to fishing, as plain wrasses were always depleted in13C compared to sympatric spotted ones. The stable isotope ratio of N showed that plain ballan wrasses foraged consistently at a higher trophic level than spotted ones in areas of high population density closed to recreational fishing, whereas differences did not exist or were reversed in areas open to fishing. These results demonstrate that the pattern of trophic resource partitioning between 2 morphs of the ballan wrasse is density dependent and that plain and spotted ballan wrasses likely had different ecological niches in pristine ecosystems.

Trabajo presentado al 9th International Symposium Monitoring of Mediterranean Coastal Areas: "Problems and Measurement Techniques", celebrado en Livorno (Italia) entre el 14 y el 16 de junio de 2022., Temperate coastal ecosystems dominated by macrophytes are diverse, ranging from macroalgal forests to seagrass meadows. They provide numerous ecosystem services and are highly valuable as nursery areas for fish. However, these habitats are under increasing pressure due to anthropogenic actions. In the last decades, the use of Diver Operated Stereo-Video (stereo-DOV) systems has become popular for making accurate, precise, and repeatable measurements of fish lengths. The objective of our study is to develop an efficient video-based methodology for studying the patterns of recruitment of temperate littoral fishes at various temporal and spatial scales. We aim to evaluate our methodology compared to other non-invasive techniques used for the study of juvenile fish assemblages. In this paper, we propose a combination of habitat mapping and stereo-DOV transect methodologies and test them in two case studies to investigate the link between juvenile fish and macrophytes, considering various scales of heterogeneity of littoral habitats. Data on species composition, abundance, and mean total length of the juvenile assemblages and canopy height from each habitat can be obtained and geo-referenced in the sampling sites, mapping their distribution in space and time to understand recruitment patterns. Some benefits of using stereo-DOV transects and habitat mapping for monitoring fish assemblages in comparison with traditional non-invasive methods used for fish counts, are a) videos are permanent, they can be reanalyzed; b) divers do not have to be experts in fish and macrophyte identification; c) inter-observer variability can be controlled through quality checks; d) high accuracy and precision in fish count and length measurements; and e) image data can be used for developments of artificial intelligence (AI). However, there are also some disadvantages: a) cameras have a limited field of view; b) video processing is time-consuming; and c) experts are needed for fish identification during image processing. In conclusion, the combination of stereo-DOV and habitat mapping is an effective methodology for monitoring fish recruitment patterns and habitats at different scales. It can be also advantageous for evaluating temporal changes in the habitat structure, and therefore, in the ecosystem functions provided for the fish community.

Explaining the mechanisms driving niche partitioning among species is of great importance in ecology. Unlike the fundamental niche, a species' realised niche can only be measured in situ, as a result of biotic and abiotic interactions defining its size. Following current methodology, the realised niche of a species is often influenced by the rare and divergent individuals of the community sampled. In this study, using fish on coral and temperate reefs as an example, behavioural empirical data were collected to estimate realised niche sizes and niche overlaps. Niche measurements were made using the total area of the convex hull (TA), but as an alternative, a metric not as strongly influenced by sample size, standard ellipse area (SEA), was also used. A comprehensive description is given, and contextdependent pros and cons of using both metrics are discussed. Additionally, an alternative sample size correction was presented for both metrics. The analyses re vealed large differences in the sizes of realised niches and their overlaps between species depending on the measurement metric used. Regardless of the species, niche size and overlap were always larger for TA than SEA. Increasing sample size re - duced niche size variability for both TA and SEA, but the variation was always smaller for SEA than TA. We successfully adapted the SEA metric for analysis of behavioural niche components and demonstrated that measuring niche sizes using the 2 metrics, each with their own strengths and weaknesses, can produce contradictory results, the ecological consequences of which are likely to be important.

In recent years, overtourism and tourism gentrification have been a central feature of public debate in the Balearic Islands, one of the most touristified regions on the planet. In this con...

By the end of 2019, more than 11,000 world scientists declared Planet Earth is facing a climate emergency, which signals the failure of the global climate agenda (GCA). Since it took off thirty years ago, emissions have continued to increase at the planetary level. We add to the literature focusing on the economic and political dimensions shaping the GCA. In particular, we examine its economic growth roots under the umbrella of sustainable development (SD) or green growth to shed some light on whether the rules driving the world economy are shaping it. Such rules are built on the growth ideology fuelling the current extractivist socioeconomic metabolism, which in turn lies behind the socioecological crisis. We review the main international climate-focused events and document a shift in the guiding principles of climate politics from the 1980s onwards under which growth is no longer viewed as a driver of climate change (CC) but as its solution. We argue that the strategy to promote growth-based SD represents the main cause of policy failure. Indeed, the result is a policy that is highly reliant on technological solutions and market-based instruments and leads to the belief that green growth is both possible and the solution to CC. Such a belief restricts the debate to the economy’s ‘decarbonisation’ and CC adaptation and overlooks other important socio-political aspects involve in climate action. A finales de 2019, más de 11.000 científicos declararon que afrontamos una emergencia climática que obliga a actuar con urgencia, lo que muestra el fracaso de la agenda climática global (ACG). Desde sus inicios hace treinta años, no se ha revertido la tendencia creciente de las emisiones globales. Este artículo contribuye al debate existente en torno al análisis de la influencia de factores económicos y políticos sobre el diseño de ACG examinando su objetivo de crecimiento económico. Buscamos aclarar si las reglas del juego económico mundial, sustentadas en la ideología del crecimiento, impulsora del actual metabolismo socioeconómico extractivista que subyace a la crisis socioecológica planetaria, determinan dicha agenda. Así, revisamos los principales eventos internacionales en torno al cambio climático (CC) y documentamos un giro en los principios de la política climática a partir de los años ochenta del siglo pasado, según el cual el crecimiento dejó de verse como la causa del CC para verse como su solución. Argumentamos que el hecho de promover un desarrollo sostenible basado en el crecimiento explica el fracaso de la política climática. Y es que esto resulta en una política demasiado optimista hacia las soluciones tecnológicas y los instrumentos de mercado que lleva a creer que el crecimiento verde es posible y la solución al CC, lo que limita la acción a la “descarbonización” de la economía y la adaptación al CC ignorando otros aspectos sociopolíticos relevantes.

Two-current choice flumes are used to measure preference and avoidance behaviour in response to chemical cues in aquatic animals. If used correctly, they produce two parallel, non-overlapping, laminar water currents in which the animal can move freely and choose between the two currents. As climate change is affecting water temperature, and altered precipitation patterns are changing water salinity, two-current choice flumes are increasingly being used to test the choice between water currents of different temperatures and salinities. This inevitably means that water currents of different densities are being used simultaneously in the flume. Here, we investigated the tolerance range for density differences due to temperature and salinity in five common flume designs. Through dye tests and stepwise modifications of temperatures and salinities we determined the limits for laminar and non-overlapping flows. We also developed an automated method for quantifying the overlap precisely and objectively. The tolerance for density differences between the water currents where laminar and non-overlapping flows were maintained was surprisingly low, withstanding ± 0.5 °C temperature differences, and ± 0.1 PSU salinity differences, i.e. a maximum density difference of 0.28 gL. Above these very narrow limits we found a range where the flumes showed partly overlapping, stratified water currents that preclude easy determination of cue preference. We conclude that two-current choice flumes are not suitable for testing the behavioural choices of aquatic animals using water currents of anything other than minor differences in temperature and/or salinity., This work was funded by the Swedish Research Council Formas (JS: 2013-947, FJ: 2009-596) and The Research Council of Norway (FJ: 262942).

Using rainbow wrasse as a model species, we evaluate the impact of protection on the relationship between body size and: i) trophic position (TP), based on δ15N; and ii) body condition (BC), based on weight-at-length. We found that the biomass of the rainbow wrasse, their predators and their competitors was higher inside the no-take marine protected area (NTA) than in the area open to fishing. The TP of rainbow wrasse was higher inside the NTA but the BC was lower. A domed relationship between TP and size was observed in both areas: the TP increased with size up to 12.6 cm total length, when all individuals shifted to terminal males, and then decreased. Although other confounding environmental variables may exist, the indirect effects of fishing on competition and predation risk are the most likely explanation for the changes in TP, BC and the ontogenetic dietary shift of the rainbow wrasse.

Concern has increased in recent decades regarding processes influencing fish juvenile density distributions; indeed, juveniles determine the replenishment of populations and their habitats are often found in shallow coastal areas, where human impacts are concentrated. We aimed to measure the relative importance of seascape attributes at various spatial scales (from seascape to microhabitat) in fish settlement and post-settlement processes. Along the coast of Minorca Island (NW Mediterranean), Diplodus sargus settlement variability was higher among the southern coast compared to the variability in the northern one. Independently of coast location, sheltered nurseries presented lower settlement intensity and recruitment levels compared to exposed ones. Such patterns suggested differential larval supply according to exposure level. Furthermore, subsequent density-dependent post-settlement mortality reduced the cove-specific variability of initial settlement. In addition, inside each cove, juveniles displayed ontogenetic changes of microhabitat use: smaller juveniles were more abundant in the most heterogeneous microhabitat. Consequently, juvenile density distributions responded to seascape attributes at different spatial scales; this suggests that both lager scale attributes and microhabitat influence both settlement and post-settlement processes, and may be limiting for recruitment. Our study demonstrated the importance of a diversified seascape to promote fish population replenishment, SI

Coral reefs are threatened by numerous global and local stressors. In the face of predicted large-scale coral degradation over the coming decades, the importance of long-term monitoring of stress-induced ecosystem changes has been widely recognised. In areas where sustained funding is unavailable, citizen science monitoring has the potential to be a powerful alternative to conventional monitoring programmes. In this study we used data collected by volunteers in Southeast Sulawesi (Indonesia), to demonstrate the potential of marine citizen science programmes to provide scientifically sound information necessary for detecting ecosystem changes in areas where no alternative data are available. Data were collected annually between 2002 and 2012 and consisted of percent benthic biotic and abiotic cover and fish counts. Analyses revealed long-term coral reef ecosystem change. We observed a continuous decline of hard coral, which in turn had a significant effect on the associated fishes, at community, family and species levels. We provide evidence of the importance of marine citizen science programmes in detecting long-term ecosystem change as an effective way of delivering conservation data to local government and national agencies. This is particularly true for areas where funding for monitoring is unavailable, resulting in an absence of ecological data. For citizen science data to contribute to ecological monitoring and local decision-making, the data collection protocols need to adhere to sound scientific standards, and protocols for data evaluation need to be available to local stakeholders. Here, we describe the monitoring design, data treatment and statistical analyses to be used as potential guidelines in future marine citizen science projects.

A variety of sedimentary bedforms have been identified on the continental shelf between Mallorca and Menorca (Menorca Channel). The bedforms consist of different grain sizes, ranging from very fine to coarse, predominantly bioclastic sands, and include rippled scour depressions in association with fine sand patches, sand waves, sand ridges, ribbons and furrows. The morphology and acoustic appearance of these bedforms are documented in a number of maps generated on the basis of detailed multibeam bathymetric datasets, side-scan sonar images and high-resolution reflection seismic profiles (TOPAS)., Instituto Geológico y Minero de España, España, Instituto Español de Oceanografía, España, TRAGSA, España, Centre Oceanogràfic de les Balears, Instituto Español de Oceanografía, España, TECMARIN 1990, España

Accumulating evidence shows that fishing exploitation and environmental variables can synergistically affect the population dynamics of exploited populations. Here, we document an interaction between fishing impact and climate variability that triggered a synchronic response in the population fluctuations of six exploited species in the Mediterranean from 1965–2008. Throughout this period, the fishing activity experienced a sharp increase in fishing effort, which caused all stocks to shift from an early period of underexploitation to a later period of overexploitation. This change altered the population resilience of the stocks and brought about an increase in the sensitivity of its dynamics to climate variability. Landings increased exponentially when underexploited but displayed an oscillatory behaviour once overexploited. Climatic indices, related to the Mediterranean mesoscale hydrography and large-scale north Atlantic climatic variability, seemed to affect the species with broader age structure and longer lifespan, while the global-scale El Niño Southern Oscillation index (ENSO) positively influenced the population abundances of species with a narrow age structure and short lifespan. The species affected by ENSO preferentially inhabit the continental shelf, suggesting that Mediterranean shelf ecosystems are sensitive to the hydroclimatic variability linked to global climate. (Oxford University Press)

28 pages, 6 figures, 6 tables, supplementary material in https://doi.org/10.1007/s10531-011-0210-1, Menorca Channel (Balearic Islands, western Mediterranean) comprises 98,700 Ha of continental shelf. It has been proposed to include this area in the Natura 2000 network due to the wide range of species and habitats of high conservation value found here, such as Posidonia oceanica meadows and maërl and coralligenous beds. This study aimed to establish a scientific basis for managing and protecting the continental shelf bottoms in Menorca Channel. Sampling was carried out with side-scan sonar, beam trawls, box corers, a remote-operated vehicle and an underwater drop camera. The information collected was used to map the habitat distribution between 50 and 100 m depth, as well as make an inventory and describe the spatial patterns of both the specific and functional diversity. A total of 636 species was recorded in a mosaic of habitats in which Corallinacea calcareous algae and other soft red algae (Osmundaria volubilis and Peyssonnelia spp.) were the most abundant groups. Hotspots of specific and functional diversity were located in areas with high habitat heterogeneity and complexity. Protection of Menorca Channel should not only include the habitats and species in the European directives, but also the habitats that are not currently protected, such as O. volubilis and Peyssonnelia beds, due to their biogeographical and ecological interest and their contribution to the biodiversity of shelf bottoms in the Mediterranean Sea. © 2012 Springer Science+Business Media B.V., The study was financed by the Conselleria d’Agricultura i Pesca of the Government of the Balearic Islands within the Canal Project and in the framework of LIFE+ INDEMARES project: ‘‘Inventario y designación de la Red Natura 2000 en áreas marinas del Estado español’’. Sonography was carried out by Tecmarin 1990 SL and financed by the MarViva Foundation

Many demersal fish species rely on benthic prey as food sources for part of, or in some cases, all of their life his- tory. We investigated the relationships between prey and predator abundance and prey size and predator mouth gape size for nine demersal fish species. Of the species analysed, four showed a significant positive increase in abundance with increasing prey abundance. Prey size is thought to be an important parameter for demersal fish that are limited in their feeding poten- tial by their mouth gape size, as it influences consumption rate and energy expenditure while foraging. The relationship be- tween prey size and mouth gape was investigated using both stomach content data and prey availability data. Stomach content analysis revealed positive relationships between maximum prey size and predator mouth gape size for six of the spe- cies. Indications of prey size selectivity were only seen in the environment for European hake (Merluccius merluccius), high- lighting the potential importance of prey size over prey abundance for this species. The results demonstrate that prey abundance and size are of significance for some demersal fish species feeding primarily on benthos and will help in defining habitat requirements of demersal fish species. Resume : Plusieurs poissons demersaux comptent sur les proies benthiques comme sources de nourriture durant une partie et, en certains cas, l'ensemble de leur cycle biologique. Nous etudions la relation entre l'abondance des proies et des preda- teurs, ainsi qu'entre la taille des proies et l'ouverture de la bouche des predateurs, chez neuf especes de poissons demersaux. Parmi les especes analysees, quatre montrent une augmentation positive d'abondance en fonction de l'augmentation de l'a- bondance des proies. On croit que la taille des proies est une variable importante chez les poissons demersaux dont le po- tentiel alimentaire est limite par la taille de l'ouverture de leur bouche, puisqu'elle va influencer le taux de consommation et la depense d'energie durant la recherche de nourriture. Nous examinons la relation entre la taille des proies et l'ouverture de la bouche en utilisant a la fois des donnees sur les contenus stomacaux et des donnees de disponibilite des proies. L'analyse des contenus stomacaux montre une relation positive entre la taille maximale des proies et l'ouverture de la bouche chez six des especes. Nous n'observons d'indications de selection des proies en fonction de la taille dans le milieu que chez le merlu (Merluccius merluccius), ce qui souligne le role plus grand de la taille que de l'abondance des proies chez cette espece. Nos resultats demontrent que l'abondance et la taille des proies sont d'importance pour certains poissons demersaux qui se nour- rissent principalement de benthos et qu'elles pourront servir a definir les besoins d'habitat des especes de poissons demer- saux. (Traduit par la Redaction)

Irregular sea urchins such as the spatangoid Spatangus purpureus are important bioturbators that contribute to natural biogenic disturbance and the functioning of biogeochemical cycles in soft sediments. In the coastal waters of the Balearic Islands S. purpureus occurs in soft red algal beds, and can reach high densities. The diet of S. purpureus is unknown and it is particularly difficult to analyze the stomach contents of this group; therefore, we analyzed the fatty acid (FA) composition of the gonads and potential food resources in order to assess the trophic relationships of this species. The FA profiles of the gonads of S. purpureus agree well with the FA composition of the potential trophic resources (algae and sediment) and reveals changes between localities with different available resources. Three polyunsaturated FAs mainly contributes in the composition in the S. purpureus gonads: eicosapentaenoic acid (C20:5n-3) and arachidonic acid (C20:4n-6), both abundant in the macroalgal material, and palmitoleic acid (C16:1n-7), which is characteristic of sediment samples. Trophic markers of bacterial input and carnivorous feeding were significantly more abundant in sea urchins caught on bottoms with less vegetation. The current study demonstrates that the FA content of S. purpureus gonads is a useful marker of diet, as differences in the profiles reflected the variations in detritus composition. The results of this study show that this species has omnivorous feeding behavior; however, viewed in conjunction with available abundance data the results suggest that phytodetritus found within algal beds is an important carbon source for this species.

The bottom trawl fishery developed on the slope off Balearic Islands (western Mediterranean) has been analysed from different sources of information: (i) data obtained during experimental bottom trawl surveys developed annually since 2001; (ii) daily sale bills from the bottom trawl fleet, available since 2000. Considering both hydrographical and geomorphologic conditions, the study area was divided in four geographical sectors. Multivariate techniques were applied to identify assemblages and their main species, and to investigate the influence of environmental variables in the slope communities. Fishery-independent and fishery-dependent indicators were calculated, both at specific and community level, for the assemblages identified. In all cases, they were summarised using the Traffic Light approach. Three assemblages have been identified in the slope trawl fishing grounds off the Balearic Islands: (1) the almost unexploited shelf break, where teleosts predominate; (2) the upper slope, where teleosts still predominate but crustaceans are also very important (with Nephrops norvegicus as target species); (3) and the middle slope, where crustaceans predominate (with Aristeus antennatus as target species). Depth was the main factor affecting the species composition of the assemblages, although other factors such as area, year and effort level also affect. Indicators estimated from both sets of data suggested an improvement in the state of N. norvegicus, although the results suggest the influence of other factors than fishing impact in the state of this resource. For A. antennatus, marked differences have been found depending on the data source. In the upper slope, indicators suggested an improvement in the state of this assemblage, which can be related to a decreasing trend found in the fishing effort exerted in this depth range. Indicators from the middle slope showed differences for both sets of data. The characteristics of both data sources and of the species analysed are discussed as responsible of these differences, Sí

Short-term temporal variability in deep-sea demersal fish assemblages is described for two slope areas characterised by different oceanographic conditions, which are situated north (Balearic sub-basin, BsB) and south (Algerian sub-basin, AsB) of the Balearic Islands (western Mediterranean). A total of 75 hauls were analysed from six bottom trawl surveys carried out in the two sub-basins. At BsB, surveys were designed for sampling different slope habitats during April 1991, December 1991, March 1992 and July 1992: (i) a submarine canyon at a depth of around 450 m, (ii) the upper slope at a depth of 600-650 m, and (iii) the middle slope at a depth of around 1200 m. At AsB, surveys were carried out during October 1996 and May 1998, along a continuous transect on the upper, middle and lower slope. The taxonomic composition, ecological parameters (number of species, abundance and biomass) and biomass spectra of the assemblages, as well as the length frequency distribution of the main species, were compared for different seasons and bathymetric ranges. Forty-four demersal species were captured in BsB and 38 in AsB. Helicolenus dactylopterus and Trachyrinchus scabrus were more abundant in BsB, and Hoplostethus mediterraneus, Galeus melastomus and Centroscymnus coelolepis in AsB. Depth was the determinant factor in all the analyses. Species-specific densities (abundance and biomass) showed significant differences between surveys, depth strata and their interaction in BsB. However, survey and its interaction with depth, were not significant in AsB. We also found significant differences in relation to depth and season for the three ecological parameters tested in BsB, but only significant differences in relation to depth in AsB. Biomass spectra showed large differences in relation to depth but only slight between-survey differences, which mainly occurred in the upper slope. The length frequency distributions of single species presented short-term temporal variations, mainly due to the varying presence of a larger proportion of small or large individuals. Depth, geographic area and sampling time were the main factors determining the species composition and structure of deep-sea slope demersal fish assemblages. The effects of short-term temporal variations were observed in both the replacement and the size structure of some dominant and subdominant species throughout the year. The different temporal variation effects observed between the two sub-basins might be related to differences in productivity and its transport to the benthos. © 2008 Elsevier Ltd. All rights reserved.

The red shrimp Aristeus antennatus is one of the target species of the bottom trawl fishery of the Balearic Islands. The objective of the present paper is to study the short spatial and temporal differences of this important economic resource between two different locations off Mallorca (Cabrera: CA; Soller: SO), where a fleet mobility pattern has been detected, and to study the influence of environmental conditions on this species. Six simultaneous bottom-trawl and oceanographic surveys were carried out at these two locations in order to collect data from the demersal species, hydrography (temperature and salinity), trophic resources and sediment characteristics. The commercial fleet from both locations was monitored by monthly on-board sampling, log-books and daily landings obtained from sales slips. Additional data was obtained from other fishing surveys. Short spatial and temporal differences have been detected between both locations. The population at CA was more demographically homogeneous, while that at SO showed important variations, like high abundance of juveniles recruiting to fishing grounds in autumn–winter and high abundance of large females during summer. Several differences have also been found in the biology of the species between locations, such as males were more abundant in SO than in CA. Also, the reproductive period started sooner in SO than in CA, and the condition of pre-spawning females was better in SO. The percentage of total lipids in the hepatopancreas was minimal during the spawning period, showing their importance as a reserve of energy for the ovary ripening. Water masses could play an important role in these differences, the characteristics of water masses being more stable in CA than in SO. Red shrimp adult females seemed to be more correlated with the warmer and more saline Levantine Intermediate Waters, while juveniles (males and females) and adult males were more correlated with the colder Western Mediterranean Deep Waters, detected only in SO during autumn–winter. Two different hypothesis of mobility patterns for the species are discussed in relation to these observed differences.

Seasonal abundance and biomass of littoral fish at Posidonia oceanica seagrass meadows were characterized throughout an annual cycle in Mediterranean waters. Bimonthly beam trawl hauls were performed between 18 and 38 m depth at 4 sites sampling from 2 locations. Approximately 8230 littoral fish were collected belonging to 25 families and 51 species with Labridae and Sparidae families being predominant in terms of abundance. Mean fish abundance was 92 ± 7.5 individuals · 1000 m− 2 peaking in March, April and September and total abundance showed significant statistical differences between May and October. Densities of Diplodus annularis, Gobius sp., Mullus surmuletus, Parablennius tentacularis, Sarpa salpa, Sciaena umbra, Scorpaena porcus, Serranus cabrilla, Symphodus ocellatus, Symphodus rostratus, Symphodus tinca and Synodus saurus differed significantly between seasons. Total community biomass varied significantly along the year with maximum values observed in July (1500 g · 1000 m− 2) and minimum biomass recorded in October. The number of species ranged between 5 in January and 21 in July while the total number of individuals was 293 in July and 21 in September, and Margalef diversity index differed between 4.11 in July and 1.3 in January. Biomass peaked in summer linked mainly to the increase of S. porcus, Serranus scriba and some Symphodus species. Diversity was maximal in July and the larger mean size for most of the fish species was achieved from May to July corresponding to the recruitment peaks of some of the fish species. The SIMPER analysis showed that there are seasonal differences in the trophic roles of the fish communities at seagrass meadows. The temporal patterns observed highlight the multifunctional role of deep seagrass meadows during the summer months when all the measured parameters are maximal. Those observations point out the need for conservation measures to be intensified in the warm season.

Fish assemblages associated with Posidonia oceanica from three locations of the western Mediterranean (Mallorca, Formentera and Alacant, Spain) were sampled in order to assess their spatial variability at three different scales ranging from 100 km. Sampling was carried out using a beam trawl. Simultaneous sampling at these three spatial scales with the appropriate number of replicates implies a huge effort which is rarely possible to achieve. Consequently, we propose an arrangement of data coming from different sampling programs, after testing and making sure the specificities of each program cannot be confounded with the spatial variability. The two preliminary experimental designs adopted in order to combine the datasets were: (1) differences between two consecutive years were tested by sampling the same meadow (Formentera) in June 2001 and June 2002; and (2) differences attributable to the meadow structure were evaluated by sampling two meadows (Mallorca 2000 and Formentera 2001). The absence of any significant correlation pattern for univariate community descriptors and multivariate species-specific densities (i.e. individuals per hour) related to both between-year and within-location structural differences of the meadows, allow us to combine data from the three locations (Formentera 2001, Mallorca 2000 and Alacant 2000) in a single analysis aimed at determining how much variability is explained by the three spatial scales considered. The between-location scale (>100 km) is the most variable scale for species-specific densities (multivariate approach). Spatial variability at the smallest scale (

Young-of-the-year European hake (Merluccius merluccius) were sampled during four seasonal cruises between November 1998 and September 1999. The greatest numbers and biomass were found in spring 1999. Some 73% of juvenile fish in terms of number, and 81% in terms of biomass, were caught at depths between 60 and 160 m on the outer western Mediterranean shelf, where the water temperature ranged between 13.5 and 14°C. The length composition of samples showed there to be small hake all year around, with modes between 7 and 11 cm total length depending on the season. Otolith analysis was used to establish age at settlement (62.7 days) and to determine seasonal growth. The monthly growth rates ranged from 1.2 cm month-1 for juvenile hake captured on February 1999 to 2.5 cm month-1 for ones captured in June. The growth rates are related to survival, as was shown by the calculated hatch dates and relative abundances of recruits. This work provides information on the first year of life, recruitment and growth processes in an important species of the Mediterranean demersal ecosystem which is heavily exploited by a recruitment fishery.

The regular presence of the white shark, Carcharodon carcharias, off the Balearic Islands (western Mediterranean) is shown from 27 captures carried out with trap nets between the 1920s and 1970s and from eight attacks on cetaceans and marine turtles from the 1990s to the present. The geographic distribution, seasonality and population structure of the species in the area are analysed and discussed in relation to environmental conditions and to the proposed distribution of this species in the Mediterranean Sea.

Weight-length relationships (WLRs) are presented for 103 fish species inhabiting littoral to lower slope habitats of the Balearic Islands and the Iberian coast (western Mediterranean). Samples were collected using seven types of fishing gear and at depths ranging from 0.5 to 1713 m. Captures were made between the years 1991 and 2001. The b values in the WLR W = aLb varied between 2.072 and 3.847 and showed a mean value of 3.03 (S.E. = ±0.03). Whenever possible, the b values for the species obtained both in this study and some of the previously reported in the Mediterranean Sea were compared, showing the existence of spatial variation whose causes are discussed. © 2002 Elsevier Science B.V. All rights reserved.

The analysis of 131 hauls from four bottom trawl fishing surveys carried out between depths of 46 and 1713 m in two different areas off the Balearic Islands yielded a total of 23 elasmobranch species belonging to eight families. Cluster analysis and multidimensional scaling (MDS) ordination were applied to detect zonation patterns and some ecological parameters (e.g. species richness, abundance and biomass, mean weight, diversity and evenness) were calculated for each assemblage. For each area, analysis of similitude (ANOSIM) and similarity percentage analysis (SIMPER) were also applied to detect differences between seasons and depths. For the most important species (Galeus melastomus, Scyliorhinus canicula, Centroscymnus coelolepis, Etmopterus spinax, Squalus blainvillei, Raja naevus, Raja asterias, Raja clavata, Raja miraletus and Raja oxyrhinchus), abundance and size distributions were analysed by depth.

Fishes and invertebrates were collected from the continental slope southwest of the Balearic Islands, Mediterranean, in October 1996 and May 1998 from 3 faunally-distinct depth zones: 200 to 800 m (upper slope), 800 to 1425 m (middle slope) and 1425 to 1800 m (lower slope). Differ- ences in δ 15 N and δ 13 C between October 1996 and May 1998 were observed only in the crustaceans Aristeus antennatus and Nematocarcinus exilis. There were few differences among depths in δ 15 N or δ 13 C of benthic fishes or crustaceans: the shrimps A. antennatus and Acanthephyra eximia showed higher δ 15 N values at greater depth, and δ 13 C values of the fishes Alepocephalus rostratus (Ale- pocephalidae) and Coelorhynchus coelorhynchus (Macrouridae) also tended to increase with in- creasing depth. Differences in plankton and suprabenthos were also observed among zones (at depth, greater δ 15 N values of gelatinous plankton, calanoid copepods and peracarids were recorded, along with smaller δ 13 C values of gelatinous plankton and peracarids). These are attributed to a microbially-mediated increase in δ 15 N and a reduction in δ 13 C of the particulate material remaining after preferential utilization of labile organic matter in the stable and relatively high (13°C) tem- perature of the Mediterranean water column. Strong positive correlations between δ 15 N and δ 13 C data for plankton, fishes and crustaceans indicated a single primary source material for these com- munities, which is attributed to marine snow.

The Migjorn artificial reef (MAR) was deployed in the summer of 1990 and is made by 48 concrete blocks set 30 m deep on a sea bed of sand with a small proportion of Posidonia oceanica (L.) Delile meadow. Visual censuses of blocks on both substrata were carried out during the months of February, May and September in 1992 and 1993. The MAR fish assemblages were influenced by the surronding substrate. Thus, a group of ubiquitous species, frequent on both substrata and typical of natural rocky habitats (mostly Sparidae) and a group associated with the samples recorded on the Posidonia meadow (mostly Labridae) could be distinguished. Season had only a secondary and slight effect on fish assemblages. The MAR was colonized by 74% of the species in the first two years after deployment. Positive and lineal relationships between species richness, diversity, abundance of necto-benthic species and time since deployment on sandy substrata were found. On Posidonia oceanica deployment time has only increased very sedentary and cryptic species. Although some ways in which the MAR would have a productive function are not rejected, the most obvious MAR working pattern is that of fish aggregation.

Age, growth, mortality, maturity and diet were analysed for 210 common dentex from 17 to 83 cm TL collected off the island of Mallorca from 1993 to 1995. The length composition by sex showed no differences between females and males. The length-weight relationship was identical for both sexes: W = 0.011 TL 3.06 . Age at 50% maturity was reached between 2 and 4 years old. The reproductive period was centred in the second quarter of the year. Ages were estimated from whole sagittal otoliths. Marginal-increment analysis showed that a single annuli formed each year during autumn-winter. Common dentex ages ranged from 0 to 28 years. The von Bertalanffy growth equation for males was TL = 844 (1 − e( −0.1(t + 2.854) ) and for females was TL = 856 (1 − e( −0.1(t + 2.874) ). The estimate of the instantaneous rate of total mortality ( Z ) was 0.24. Empirically derived estimates of natural mortality were similar to total mortality estimates suggesting that fishing mortality is low.

We assessed the elasmobranch communities exploited by the bottom trawl fishery off the Balearic Islands (northwestern Mediterranean) by analysing two time series containing information with different levels of detail: 1) a long-term series containing the abundance indices of the whole elasmobranch community landed from 1965 to 2009; and 2) a shorter time series from 2000 to 2009 from two different data sources (daily sales records: 2000-2009; bottom trawl surveys: 2001-2009), with information that allowed the shelf and slope to be analysed separately and different community parameters and abundance indices to be studied. Temporal trends of all these variables were used as ecological status indicators and tested with generalized additive models and analysis of variance. They were finally summarised using the Traffic Light methodology. The long-term series showed two marked trends, an inter-annual decreasing trend that would be a consequence of the large increase in fishing effort, and an intra-annual trend with a clear peak in May in accordance with the seasonal biological cycle of these species. However, data from the last ten years revealed differences between the shelf and slope, as some parameters increased significantly over time on the shelf but did not follow any trend on the slope. The Traffic Light methodology captured these differences well, demonstrating its usefulness for interpreting ecological transitions at a glance. Se han evaluado las poblaciones de elasmobranquios explotadas por la pesca de arrastre de las Islas Baleares (Mediterráneo noroccidental) analizando dos series temporales con información a distinto nivel de detalle: 1) una serie larga que contiene únicamente el índice de abundancia de toda la población de elasmobranquios desembarcada entre 1965 y 2009 y 2) una serie corta a lo largo de la primera década del siglo XXI proveniente de dos fuentes de datos diferentes (hojas de venta diarias: 2000-2009; campañas de arrastre de fondo: 2001-2009), que permitieron el análisis, para la plataforma y el talud por separado, de diferentes parámetros de la comunidad además de índices de abundancia. Las tendencias temporales de todas estas variables se usaron como indicadores ecológicos de estado y se testaron aplicando modelos generales aditivos y análisis de la varianza y finalmente se han resumido usando la metodología de los Semáforos. La serie larga mostró dos señales claras, un decrecimiento interanual que podría ser consecuencia del importante incremento del esfuerzo pesquero, y una tendencia intra-anual con un claro pico en mayo, relacionado con el ciclo biológico estacional de estas especies. Así y todo, los datos del primer decenio del siglo XXI revelaron diferencias entre la plataforma y el talud, porque algunos parámetros aumentaron significativamente con el tiempo en el primer caso, pero no siguieron ninguna tendencia en el segundo. Estas diferencias quedaron bien reflejadas en los Semáforos, demostrando su utilidad en reflejar las transiciones ecológicas.

Seasonal pattern of fish recruitment can vary over years, and the coupling of such pattern with favourable trophic-environmental conditions may trigger non-stationary and non-linear effects on the yearly recruitment variability. The relative contribution of intra-annual discrete recruitment events (REs) to recruitment is often the basis of the inter-annual fluctuations in abundance and biomass of exploited fish populations which are based on a small number of age classes. In this study, REs of European hake (Merluccius merluccius L.) were identified in the north and south of the Balearic Islands (NW Mediterranean) during the 2004 recruitment season and investigated for growth and physiological and morphological condition. Five REs were identified with different contributions in abundance to the annual recruitment in each area coming from different intra-annual spawning batches. Growth rates were similar between the REs with the exception of the last event of the season. Conversely, large differences in morphological and physiological condition were observed between REs and were due to: different environmental-trophic scenarios encountered, and ontogenetic changes related to the recruitment to the shelf-break grounds (ca. 11 cm, 5-6 months of life) which triggered a trade-off in the energy allocation strategy. The spatial-temporal variability in the physiological condition among REs at the beginning of the recruitment season might be explained in the basis on a 'condition expanded match-mismatch hypothesis'. We advance that individuals recruiting in the north, which were in better condition and temporally and spatially differenced from the south, have most probably hatched in separated locations with different food availability for larvae and early life stages. We propose that hake recruiting to the north and south of the island are from different origins, mainland and the islands respectively, and have benefited from different environmental conditions. This results in a different condition but not in different growth rates. © 2009 Elsevier Ltd. All rights reserved.

The aim of the present paper is to study the relationships between some climatic indices and parental stock, recruitment and accessibility to trawl fishery of hake (Merluccius merluccius) and red shrimp (Aristeus antennatus) off Balearic Islands (western Mediterranean). Available annual catch per unit effort, recruitment and spawning stock biomass have been used as biological data. As environmental data, the meso-scale IDEA index and the large-scale North Atlantic Oscillation (NAO) and Mediterranean Oscillation (MO) indices have been used. To analyze possible links between these indices with the population dynamics of demersal resources, two non-linear approaches have been applied: (i) stock-recruitment relationships from Ricker and Beverton-Holt models, by sequentially incorporating environment factors; (ii) generalized additive modelling, both classical general and threshold non-additive models were considered. The latter simulate an abrupt change in explicative variables across different phases (time periods or climatic index values). The results have shown that two oceanographic scenarios around the Balearic Islands, associated with macro and meso-scale climate regimes, can influence the population dynamics of hake and red shrimp. This is especially true for recruitment, which seems to be enhanced during low NAO and IDEA indices periods. During these periods, colder-than-normal winters generate high amounts of cold Western Mediterranean Intermediate Waters (WIW) in the Gulf of Lions, which flow southwards and reach the Balearic Islands channels in spring, increasing the productivity in the area. This oceanographic scenario could also be favourable to the distribution of hake on the fishing grounds where the trawl fleet targets this species, increasing its accessibility to the fishery. Both spawning stock and abundance of red shrimp seems to be also enhanced by high MO index periods, which could reflect the increased presence of the saline and warm Levantine Intermediate Waters (LIW) in the study area, extending over the fishing grounds of this species. The proposed interactions can be useful to assess and manage these important demersal resources. © 2007 Elsevier B.V. All rights reserved., The IDEA project has been funded by the Spanish Ministry of Education and Science (Plan Nacional I+D+i 2000-2003, REN2002-04535-C01-02/MAR)

The present study is a mesoscale analysis of latitude and depth related trends in abundance, biomass and body size of the four grenadier species Caelorinchus caelorhincus, Hymenocephalus italicus, Nezumia aequalis and Trachyrinchus scabrus inhabiting the deep western Mediterranean. We have analysed data from seven annual bottom trawl surveys, carried out down to 800 m depth along the Iberian Mediterranean coast covering a distance of approximately 1200 km. The objectives were to establish general patterns in the mesoscale distribution of abundance, biomass and body size of deep-water grenadier fishes and also analyse the consistency of the bathymetric distribution of these parameters along a large latitudinal gradient. Five complementary series of analyses have been completed. The first focussed on describing the general patterns of abundance and size by correspondence canonical analysis, CCA, in the area. The second and third series focussed on the existence of temporal, geographical and bathymetric trends of abundance, weight and mean size by analysis of covariance, ANCOVA and multiple regression analysis. The fourth series compared the frequency distributions of body length. Finally, the last series focussed on the patterns of abundance versus size. The total number of individuals of all four grenadier species captured in 260 bottom trawls amounted to 27,435 and their weight was 1404 kg. No general trends for the four species have been observed between years. All four species showed a general pattern of increasing size with depth, which, except in the case of C. caelorhincus, was consistent along a large latitudinal gradient. Nezumia aequalis was unique in showing the same noticeable trend of increasing abundance with depth along the entire latitudinal range, but with clear differences in the intercepts. The abundance of N. aequalis and C. caelorhincus decreased significantly northwards. Hymenocephalus italicus was the least abundant species and had a homogeneous distribution without any specific trend along the entire latitudinal range analysed. The distribution of T. scabrus in the Mediterranean seemed to be more localised. Higher abundances were found to the north and south of the latitudinal gradient with lower values between. The grenadiers studied also showed a general trend of decreasing mean size northwards, except in the case of the smallest species, H. italicus. The relation between abundance and body size differed between sectors for the whole grenadier population and species-specific variations were also observed. The relationship between individual body mass and population density fit well to a second-order polynomial function rather than to a linear regression, showing a significant trend for density to increase with increasing size until some mid-point, then to decline with increasing size thereafter. The observed latitudinal gradient in the distribution patterns of grenadiers along the upper slope of the western Mediterranean can be discussed in relation to direct and indirect factors of biogeographic, environmental and anthropogenic origin. © 2006 Elsevier Ltd. All rights reserved., This paper is a result of the Spanish MEDITS project (DGXIV/IEO/054)

The sociology and habits of recreational anglers on the Island of Majorca (western Mediterranean) were evaluated using telephone and on-site surveys, as well as fishing logbooks and recreational fishing competitions. The recreational fishery is one of the island's main leisure activities, 5.14% of the population (37 265 people) participating. Enthusiasts tend to be mainly middle class (most anglers own boats moored at marinas), middle-aged males (90% male, mean age 46 ± 2 years). The most popular fishing method is from a boat (62.9%), followed by fishing from shore (32.4%), and spearfishing (3.6%). The mean time spent fishing is 3.86 ± 0.03 h d-1, and more than one type of gear (mean 1.27 ± 0.21) is used simultaneously by a single angler. The frequency of fishing is 4-6 times per month, mainly on holidays and weekends, increasing in summer. The activity has a sizeable impact on the coastal fauna, with diverse catches of at least 1209.25 t year-1 (about 615 000 fishing outings year-1). Thus, the amount of carbon extracted annually is at least 137.34 kg C km-2 year-1, and the recreational fishery removes about 31% of production at trophic level 4. Although these are gross estimates and more detailed study of the effect on trophic level and local production is needed, the values do highlight the pressure the recreational fishery exerts on coastal fish communities. Assuming that this level of exploitation is common to north-shore Mediterranean countries, there may be cause for concern about sustainable exploitation in the recreational fishery, and the effectiveness of current protection measures is discussed. Despite the limitations of the study, recreational fisheries clearly should be taken into account when considering measures for fisheries management. Moreover, fishing has considerable social import, and the benefits must be taken into account when investments to protect exploited resources are being contemplated. © 2005 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.

Young-of-the-year European hake (Merluccius merluccius) were sampled during four seasonal cruises between November 1998 and September 1999. The greatest numbers and biomass were found in spring 1999. Some 73% of juvenile fish in terms of number, and 81% in terms of biomass, were caught at depths between 60 and 160 m on the outer western Mediterranean shelf, where the water temperature ranged between 13.5 and 14°C. The length composition of samples showed there to be small hake all year around, with modes between 7 and 11 cm total length depending on the season. Otolith analysis was used to establish age at settlement (62.7 days) and to determine seasonal growth. The monthly growth rates ranged from 1.2 cm month-1 for juvenile hake captured on February 1999 to 2.5 cm month-1 for ones captured in June. The growth rates are related to survival, as was shown by the calculated hatch dates and relative abundances of recruits. This work provides information on the first year of life, recruitment and growth processes in an important species of the Mediterranean demersal ecosystem which is heavily exploited by a recruitment fishery., Juveniles de la merluza europea fueron muestreados durante cuatro cruceros estacionales realizados entre 1998 y 1999, la mayor biomasa se encontró en la primera de 1999 y entre 60 y 160 m. de profundidad. Las tasas de crecimiento están relacionadas con la supervivencia. Este trabajo provee por primera vez información sobre el primer año de vida.

Knowledge of deep-sea reproductive biology is slight and interpretations of reproductive strategies in deep-sea fishes are controversial. Since the Mediterranean is a fairly stable and constant sea, we might expect a consistent pattern of reproduction of deep-sea species. Three gadiforms species with a succesive bathymetric and an ecological and economical importance in the Mediterranean fishing industry, Phycis blennoides, Mora moro and Lepidion lepidion, were selected for the present study. These three species of gadiforms are sexually dimorphic and their reproductive population is located at the lower zone of their bathymetric range. Females were always bigger than males. The smallest mature male was observed at 19, 32 and 18 cm TL (total length) and the smallest mature female at 20, 34 and 20 cm TL for P. blennoides, M. moro and L. lepidion respectively. The three species are iteroparous and females could be all-at-once or batch-spawners. An autumn mature season was observed for P. blennoides, whereas M. moro and L. lepidion had mature individuals all year round except in summer. Hence, physical constancy at greater depths is able to lengthen the reproductive season and the deepest species has a quasi-continuous reproductive pattern. Similar reproductive tissues have been found in the three species studied, and they show analogous structure with other deep-sea gadiforms and their shallow-water congeners, This paper is a result of the Spanish CICYT Projects RETRO (MAR90-757), ZONAP (PB90-O166) and BATMAN (AMB93/0283) and the European Commission project EU FAIR (CT 95-0655)

13 pages, 9 figures, 3 tables, During 2 deep-sea oceanographic cruises carried out in October 1996 and May 1998, megafauna (fish and decapod crustaceans), suprabenthos, zooplankton, and environmental variables from the water column (fluorescence and light transmission) were simultaneously collected between 210 and 1752 m depth. Fish were the dominant megafaunal taxon in biomass along the slope; decapod crustaceans were co-dominants at intermediate depths (between 402 and 710 m). Suprabenthos and zooplankton attained their maximal biomass at intermediate depths, with deeper maxima detected for suprabenthos (between 802 and 1322 m) than for zooplankton (between 402 and 802 m). Fish and decapod biomass were weakly correlated with each other, and with the suprabenthos-zooplankton biomass, fluorescence and light transmission. Significant correlations were, however, detected between the suprabenthos and zooplankton and their possible food-sources deduced from fluorometer and light transmission data, with different patterns depending on the distribution of each compartment (trophic level) in the water column and the sediment-water interface. Within a single taxon (crustaceans), size distribution for suprabenthos-zooplankton and megafaunal species followed opposite temporal patterns in our study. Among suprabenthos-zooplankton species, smaller specimens (recruitment) were detected in October 1996, coinciding with the highest fluorometer signals in the water column. The dominant phytoplankton/phytodetritus consumers (the euphausiid Euphausia krohni and the mysid Boreomysis arctica) showed clearer recruitment peaks during October than those species preying upon meiofaunal taxa (the amphipod Rhachotropis caeca, and the isopod Munnopsurus atlanticus). These results suggest that the influence of food input signals progressively decreases with increasing trophic level, and therefore the indirect effect of superficial production on top trophic levels is difficult to establish at least for the short time scales of our oceanographic surveys

The catch composition of two commercial vessels of the trawl fleet operating from Mallorca (Balearic Islands, western Mediterranean) was analysed. A total of 4959 kg resulting from 144 fishing hours was sampled from October 1996 to December 1997. The fishes represented the major proportion with respect to the total catch. The analysis of the fish discards assembled them in three depth related groups: group A (mean depth 300 m); group B (mean depth 489 m); and group C (mean depth 616 m). Species richness, number of individuals and biomass decreased with depth. The diversity and evenness indices also varied with depth, but no significant differences were found. Fishes, with around 70%, dominated the biomass discarded in the three depth groups. Within the landings, fish biomass also represented the major proportion in groups A and B, but in group C the crustaceans biomass dominated. Our results confirm that an important fraction of the catch of the two deep-sea decapod crustacean fisheries is discarded., This paper is a result of the European Project Developing deep-water fisheries: data for their assessment and for understanding their interaction with and impact on a fragile ecosystem (EU FAIR PORJECT CT 95-0655; European commission DG-XIV, Fisheries).

δ15N and δ13C were determined for plants, invertebrates and fishes collected from 3 sites on the southern coast of the Mediterranean island of Mallorca, Spain. The sites were separated by distances of 1250 to 3750 m. The mean δ15N of plants was 1.1 to 4.1‰, benthic invertebrates 5.9 to 6.9‰, planktonic invertebrates 5.5 to 5.8‰ and fishes 84 to 13.8‰. δ15N became enriched with increasing trophic level. The mean δ13C of plants was -11.4 to -16.3‰, benthic invertebrates -14.8 to -16.8‰, planktonic invertebrates -19.3 to -19.8‰ and fishes -16.1 to -19.2‰. There were significant differences in the isotopic composition of individual species within the plant, invertebrate or fish groupings at each site and there were significant differences in the isotopic composition of the same species at different sites. Depleted 13C was associated with benthic food chains and enriched 13C with planktonic chains. The data suggest that benthic food chains are important to the rocky reel associated fishes studied, as might be expected in a nutrient poor system where planktonic production is relatively low. However, the variance in δ13C composition between sites was such that the relative significance of the 2 pathways could not be determined. 15N measurements indicated that some of the fish species studied had adopted different feeding strategies at different sites and, as a result, individuals of the same species could sometimes be assigned to different trophic groups at different sites. The data suggest that these fishes exhibit plasticity in their feeding strategies and this may provide them with greater adaptive flexibility to respond to site-specific changes in food availability. Moreover, the data provide empirical support for current theories of food web dynamics which suggest that trophic 'levels' are dynamic rather than fixed and that 'multichannel omnivory' is an important feature of food webs.

11 pages, 2 figures, 5 tables, Fishes and invertebrates were collected from the continental slope southwest of the Balearic Islands, Mediterranean, in October 1996 and May 1998 from 3 faunally-distinct depth zones: 200 to 800 m (upper slope), 800 to 1425 m (middle slope) and 1425 to 1800 m (lower slope). Differences in δ15N and δ13C between October 1996 and May 1998 were observed only in the crustaceans Aristeus antennatus and Nematocarcinus exilis. There were few differences among depths in δ15N or δ13C of benthic fishes or crustaceans: the shrimps A. antennatus and Acanthephyra eximia showed higher δ15N values at greater depth, and δ13C values of the fishes Alepocephalus rostratus (Alepocephalidae) and Coelorhynchus coelorhynchus (Macrouridae) also tended to increase with increasing depth. Differences in plankton and suprabenthos were also observed among zones (at depth, greater δ15N values of gelatinous plankton, calanoid copepods and peracarids were recorded, along with smaller δ13C values of gelatinous plankton and peracarids). These are attributed to a microbially-mediated increase in δ15N and a reduction in δ13C of the particulate material remaining after preferential utilization of labile organic matter in the stable and relatively high (13°C) temperature of the Mediterranean water column. Strong positive correlations between δ15N and δ13C data for plankton, fishes and crustaceans indicated a single primary source material for these communities, which is attributed to marine snow

Comparativa de abundancias y biomasa de la ictiofauna profunda (200-1800 metros)de las proximidades de las islas Baleares. Mapas, gráficos y listado de especies, A total of 13 026 fishes belonging to 82 species and 43 famllies were collected in a continuous transect between depths of 200 and 1800 m south of the Baleanc Islands (Algerian basin, western Mediterranean). The analysis of 32 bottom trawls showed the existence of 4 groups associated with the upper slope (groups 1 and 2, from 200 to 400 and 400 to 800 m, respectivelv), middle slope (group 3, from 800 to 1400 m) and lower slope (group 4, below a depth of 1400 m) Thc differcnces in the mean values of the ecological parameters species richness, abundance, biomass and mean fish weight were also indicative of distinctive characteristics between these fish assemblages. Species richness decreased significantly with depth. The highest values of diversity corresponded to the samples from group 2. Biomass did not show any specific trend throughout the whole bathymetric range. Mean fish weight show 2 different trends along the continental slope: a bigger-deeper phenomenon at the upper 1000 to 1200 m depth. and a smaller-deeper phenomenon below this depth. Our results are compared with those obtained in the north Atlantic basin and in the western Mediterranean (Balearic basin), and the main factol-s affecting these deep-sea fish assemblages are discussed, EU FAIR PROJECT CT 95-0655. European Commission DC;-XIV, Fisheries

The growth of three demersal species dominant in biomass and abundance in the Weddell Sea, Chionodraco myersi (channichthyid), Trematomus eulepidotus (nototheniid) and Dolloidraco longedorsalis (artedidraconid), was studied on specimens caught in summer. Ages were determined using ground and polished otolith sections and an image analysis system to measure the otolith radius and distances of each growth increment to the otolith core. Ageing precision and accuracy have been estimated. Indirect validation methods, based on the increment growth pattern, were applied to support the annual periodicity of the increments. Due to the lack of some age classes, back-calculated age-length keys were determined and used to fit the von Bertalanffy growth parameters by sex and species. The determined values showed sexual dimorphism, with females having faster growth rates, except in D. longedorsalis. The growth performance index was between 1 and 2, as in other high-Antarctic fish. For T. eulepidotus, age and growth data were available, but this is the first report for C. myersi and D. longedorsalis. Moreover, this is the first time that accuracy and precision have been estimated for high-Antarctic fish age determination.