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Background. Microichthys coccoi Rüppell, 1852 was originally described based on a stranded individual collected in the Strait of Messina, Sicily, central Mediterranean. The distribution range of the species is poorly known, as very few individuals have been recorded from Italy, Greece, and Turkey in the Mediterranean, and from the Azores in the north eastern Atlantic. The aim of this study was to report the presence of M. coccoi from the Balearic Islands (western Mediterranean). The history of species’ known records is compiled and its presence in the Atlantic is discussed. Materials and methods. A specimen of M. coccoi was collected from a bottom trawl sampling, carried out at 591 m depth in the south of Mallorca (Balearic Islands) during the survey MEDITS_ES05_17 in June 2017. The fish (a female) was subjected to standard descriptive procedures and subsequently deposited in the collection of the Hebrew University of Jerusalem. Results. Microichthys coccoi is recorded for the first time from the Balearic Islands, which expands its distributional range inside the Mediterranean more than 1000 km westwards. Conclusion. Like the other known specimens, except for those collected in the Strait of Messina, the presently described individual was caught on the slope, confirming that M. coccoi is a deep-water species. The comparison of this fish with Azorean specimens indicated differences in the number of pectoral-fin rays, the most important character distinguishing the species of Microichthys. Hence, further work is necessary to classify the Azorean population, which if confirmed as M. coccoi, would make necessary a modification of the species’ description and if rejected, an additional Atlantic species should be described.

Two groups of six fish aggregating devices (FADs) were deployed at two locations off the eastern coast of Majorca (Western Mediterranean). Samples were obtained fortnightly throughout a two-year period by means of hauls performed with an experimental purse seine. Two control areas were established to check the aggregation efficiency of the FADs. A total of 16 families and 26 species of fishes were recorded beneath FADs. Pelagic fishes, largely Trachurus picturatus, T. mediterraneus, T. trachurus, Naucrates ductor, Seriola dumerili and Coryphaena hippurus, dominated the fauna. The total fish abundance, number of species and length range of the species confirmed that the FAD community was significantly related to season (recruitment period), resulting in a sequential fish colonisation of the FADs during the study period. Some of the species were present only during a particular period, such as Trachurus spp. in spring and summer. Other species, although evident for a longer period, were more occasional in catches (Schedophilus ovalis, Balistes carolinensis and Polyprion americanus), and some others were also present in small quantities. Diversity and equitability of the fish community associated with FADs were higher in summer than in winter. Many species were more abundant around FADs than in open water controls. The species that showed the most distinct recruitment phase beneath the FADs were N. ductor, S. ovalis, Trachurus spp., P. americanus, S. dumerili, C. hippurus and B. carolinensis. FADs can be considered nursery structures for many pelagic and demersal species, thus having an effect on the redistribution of juveniles. In the deployment of artificial structures as aggregators for fishing purposes one should consider the patchiness and seasonal characteristics of these communities as well as the redistribution aspect for fishery management.

The sponge fauna of the Western Mediterranean stands as one of the most studied in the world. Yet sampling new habitats and a poorly studied region like the Balearic Islands highlights once again our limited knowledge of this group of animals. This work focused on demosponges of the order Tetractinellida collected in several research surveys (2016-2021) on a variety of ecosystems of the Balearic Islands, including shallow caves, seamounts and trawl fishing grounds, in a broad depth range (0-725 m). Tetractinellid material from the North Atlantic and more than twenty type specimens were also examined and, for some, re-described in this work. All species were barcoded with the traditional molecular markers COI (Folmer fragment) and 28S (C1-C2 or C1-D2 fragment). A total of 36 species were identified, mostly belonging to the family Geodiidae (15 species), thereby bringing the number of tetractinellids recorded in the Balearic Islands from 15 to 39. Eight species from this study are new: Stelletta mortarium sp. nov., Penares cavernensis sp. nov., Penares isabellae sp. nov., Geodia bibilonae sp. nov., Geodia microsphaera sp. nov. and Geodia matrix sp. nov. from the Balearic Islands; Geodia phlegraeioides sp. nov. and C aminus xavierae sp. nov. from the North East Atlantic. Stelletta dichoclada and Erylus corsicus are reported for the first time since their description in Corsica in 1983. Pachastrella ovisternata is documented for the first time in the Mediterranean Sea. Finally, after comparisons of type material, we propose new synonymies: Geodia anceps as a junior synonym of Geodia geodina, Erylus cantabricus as a junior synonym of Erylus discophorus and Spongosorites maximus as a junior synonym of Characella pachastrelloides ., Competing Interests: The authors declare there are no competing interests., (©2024 Díaz et al.)

Chondrichthyans are a vulnerable group that has been overexploited for almost half a century in the Mediterranean. Since in this area most chondrichthyans are rarely incorporated into international statistics, the impact of fishing on their populations is difficult to assess. Here, we evaluate temporal trends in order to understand the recent history of chondrichthyans in the western Mediterranean. Fishery-independent data were obtained from scientific surveys carried out from 1994 to 2015 in three geographical sub-areas. Our results reflect fairly stable populations in terms of diversity, with some increase in density and standardized biomass of some species dwelling on the continental shelf, and even for some species dwelling on the slope. In contrast, decreasing trends were observed in some deep-water species. This can be explained by the reduction of the trawling effort on the continental shelf over the last few decades, and the shift of the fleet towards deep waters, along with the greater resilience displayed by some species. Furthermore, a decreasing trend in maturity of Scyliorhinus canicula was detected, suggesting an evolutionary response to overfishing. These results improve scientific knowledge for developing true adaptive management in the Mediterranean that will implement measures to strengthen or initiate the recovery of chondrichthyans.

Marine resources stewardships are progressively becoming more receptive to an effective incorporation of both ecosystem and environmental complexities into the analytical frameworks of fisheries assessment. Understanding and predicting marine fish production for spatially and demographically complex populations in changing environmental conditions is however still a difficult task. Indeed, fisheries assessment is mostly based on deterministic models that lack realistic parameterizations of the intricate biological and physical processes shaping recruitment, a cornerstone in population dynamics. We use here a large metapopulation of a harvested fish, the European hake (Merluccius merluccius), managed across transnational boundaries in the northwestern Mediterranean, to model fish recruitment dynamics in terms of physics-dependent drivers related to dispersal and survival. The connectivity among nearby subpopulations is evaluated by simulating multi-annual Lagrangian indices of larval retention, imports, and self-recruitment. Along with a proxy of the regional hydroclimate influencing early life stages survival, we then statistically determine the relative contribution of dispersal and hydroclimate for recruitment across contiguous management units. We show that inter-annual variability of recruitment is well reproduced by hydroclimatic influences and synthetic connectivity estimates. Self-recruitment (i.e., the ratio of retained locally produced larvae to the total number of incoming larvae) is the most powerful metric as it integrates the roles of retained local recruits and immigrants from surrounding subpopulations and is able to capture circulation patterns affecting recruitment at the scale of management units. We also reveal that the climatic impact on recruitment is spatially structured at regional scale due to contrasting biophysical processes not related to dispersal. Self-recruitment calculated for each management unit explains between 19% and 32.9% of the variance of recruitment variability, that is much larger than the one explained by spawning stock biomass alone, supporting an increase of consideration of connectivity processes into stocks assessment. By acknowledging the structural and ecological complexity of marine populations, this study provides the scientific basis to link spatial management and temporal assessment within large marine metapopulations. Our results suggest that fisheries management could be improved by combining information of physical oceanography (from observing systems and operational models), opening new opportunities such as the development of short-term projections and dynamic spatial management., (© 2019 by the Ecological Society of America.)

According to their main life history traits, organisms can be arranged in a continuum from fast (species with small body size, short lifespan and high fecundity) to slow (species with opposite characteristics). Life history determines the responses of organisms to natural and anthropogenic factors, as slow species are expected to be more sensitive than fast species to perturbations. Owing to their contrasting traits, cephalopods and elasmobranchs are typical examples of fast and slow strategies, respectively. We investigated the responses of these two contrasting strategies to fishing exploitation and environmental conditions (temperature, productivity and depth) using generalized additive models. Our results confirmed the foreseen contrasting responses of cephalopods and elasmobranchs to natural (environment) and anthropogenic (harvesting) influences. Even though a priori foreseen, we did expect neither the clear-cut differential responses between groups nor the homogeneous sensitivity to the same factors within the two taxonomic groups. Apart from depth, which affected both groups equally, cephalopods and elasmobranchs were exclusively affected by environmental conditions and fishing exploitation, respectively. Owing to its short, annual cycle, cephalopods do not have overlapping generations and consequently lack the buffering effects conferred by different age classes observed in multi-aged species such as elasmobranchs. We suggest that cephalopods are sensitive to short-term perturbations, such as seasonal environmental changes, because they lack this buffering effect but they are in turn not influenced by continuous, long-term moderate disturbances such as fishing because of its high population growth and turnover. The contrary would apply to elasmobranchs, whose multi-aged population structure would buffer the seasonal environmental effects, but they would display strong responses to uninterrupted harvesting due to its low population resilience. Besides providing empirical evidence to the theoretically predicted contrasting responses of cephalopods and elasmobranchs to disturbances, our results are useful for the sustainable exploitation of these resources.

Species diversity is widely recognized as an important trait of ecosystems' functioning and resilience. Understanding the causes of diversity patterns and their interaction with the environmental conditions is essential in order to effectively assess and preserve existing diversity. While diversity patterns of most recurrent groups such as fish are commonly studied, other important taxa such as cephalopods have received less attention. In this work we present spatio-temporal trends of cephalopod diversity across the entire Mediterranean Sea during the last 19 years, analysing data from the annual bottom trawl survey MEDITS conducted by 5 different Mediterranean countries using standardized gears and sampling protocols. The influence of local and regional environmental variability in different Mediterranean regions is analysed applying generalized additive models, using species richness and the Shannon Wiener index as diversity descriptors. While the western basin showed a high diversity, our analyses do not support a steady eastward decrease of diversity as proposed in some previous studies. Instead, high Shannon diversity was also found in the Adriatic and Aegean Seas, and high species richness in the eastern Ionian Sea. Overall diversity did not show any consistent trend over the last two decades. Except in the Adriatic Sea, diversity showed a hump-shaped trend with depth in all regions, being highest between 200-400 m depth. Our results indicate that high Chlorophyll a concentrations and warmer temperatures seem to enhance species diversity, and the influence of these parameters is stronger for richness than for Shannon diversity.

The identification of nursery grounds and other essential fish habitats of exploited stocks is a key requirement for the development of spatial conservation planning aimed at reducing the adverse impact of fishing on the exploited populations and ecosystems. The reduction in juvenile mortality is particularly relevant in the Mediterranean and is considered as one of the main prerequisites for the future sustainability of trawl fisheries. The distribution of nursery areas of 11 important commercial species of demersal fish and shellfish was analysed in the European Union Mediterranean waters using time series of bottom trawl survey data with the aim of identifying the most persistent recruitment areas. A high interspecific spatial overlap between nursery areas was mainly found along the shelf break of many different sectors of the Northern Mediterranean indicating a high potential for the implementation of conservation measures. Overlap of the nursery grounds with existing spatial fisheries management measures and trawl fisheries restricted areas was also investigated. Spatial analyses revealed considerable variation depending on species and associated habitat/depth preferences with increased protection seen in coastal nurseries and minimal protection seen for deeper nurseries (e.g. Parapenaeus longirostris 6%). This is partly attributed to existing environmental policy instruments (e.g. Habitats Directive and Mediterranean Regulation EC 1967/2006) aiming at minimising impacts on coastal priority habitats such as seagrass, coralligenous and maerl beds. The new knowledge on the distribution and persistence of demersal nurseries provided in this study can support the application of spatial conservation measures, such as the designation of no-take Marine Protected Areas in EU Mediterranean waters and their inclusion in a conservation network. The establishment of no-take zones will be consistent with the objectives of the Common Fisheries Policy applying the ecosystem approach to fisheries management and with the requirements of the Marine Strategy Framework Directive to maintain or achieve seafloor integrity and good environmental status.

A study of the plerocerci of Floriceps saccatus from the abdominal cavity of dolphin fish (Coryphaena hippurus) and pompano dolphin (Coryphaena equiselis) was conducted. In all, 565 dolphin fishes were collected from Majorcan waters (Balearic Islands, western Mediterranean) during 3 summer and autumn seasons (1990, 1991, and 1995). From the Canary Islands (eastern Atlantic), 41 specimens of dolphin fish were caught during 1994 and 49 specimens of pompano dolphin during 1995. Cysts of different shapes and sizes appeared in the conjunctive tissues of the abdomen and viscera, mainly in the liver, gonads, and pancreas. A larva was found inside every cyst examined. Small, medium size, and large larvae were found. The largest larvae correspond to Floriceps saccatus plerocercoids. Stomach contents indicated that crustaceans and fish larvae were the main prey items of juvenile C. hippurus, whereas teleosts and cephalopods were the only food found in adult dolphin fishes. Infection of F. saccatus plerocercoids takes place in preadult dolphin fishes. Prevalence increases as fishes grow and change to a diet of teleosts. Coryphaena equiselis was not infected.