Fishery resources: between ecology and economy

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Spatio-temporal changes of Munida Rutllanti Zariquiey-Alvarez, 1952 (Decapoda: Galatheidae) in the North-Western Ionian Sea (Central Mediterranean)

The spatio-temporal pattern of Munida rutllanti distribution in the north-western Ionian Sea has been studied. Data were collected during 14 experimental trawl surveys conducted from 1997 to 2010 as part of the international MEDITS project. The hauls were carried out during day-light hours between depths of 10 and 800 m in the spring season. A progressive increase in the abundance index (N/km2) of M. rutllanti was observed from 2000 to 2008, then a sharp decrease was shown in the last two years. The greatest and lowest abundance indices were observed in the Apulian and central Calabrian sub-areas, respectively. The species was collected between 107 and 795 m in depth, with a significant increase and decrease over time in the maximum and minimum depth of finding, respectively. A highly significant increase over time in the mean carapace length was also observed in the whole study area. The widespread occurrence and increasing abundance of this species in the Ionian Sea could be related to the increase in temperature and the variation in hydrographic conditions which occurred in the Ionian basin during the EMT-BiOS phenomenon

Asociaciones de peces profundos en el Mediterráneo

[EN] Data collected during the DESEAS survey carried out in three areas of the Mediterranean Sea (Balearic Sea, western and eastern Ionian Sea) were used to describe the structure and spatial distribution of the fish assemblages at depths between 600 and 4000 m. A total of 55 species (8 chondrichthyes and 47 teleost fish) were sampled, 38 of them in the Balearic Sea, 30 in the western Ionian and 37 in the eastern Ionian. Multivariate analysis showed a clear pattern of zonation with depth and geographic area. Three main assemblages were identified across the vertical gradient investigated: on the upper slope around a depth of 600 m, on the middle slope between 800 and 1300 m, and on the lower slope below 1300 m. The geographic characterisation of the ichthyofauna structure was mainly observed on the upper and middle slope. The highest abundance and biomass values were found at depths of 1000-1200 m due to the presence of larger species with high energy requirements, such as Alepocephalusrostratus, Mora moro and Galeus melastomus. On the middle slope, significant differences in the abundance, biomass and mean fish weight were detected between the three areas. Significant differences for these parameters were also shown between the middle and lower slope assemblages. A significant decrease in species richness and diversity was shown with increasing depth, indicating an impoverishment of the megafauna with depth and a higher similarity between the Balearic Sea and the Ionian Sea with regard to the greatest depths. The dominant species on the deepest bottoms were Bathypteroismediterraneus, Chalinura mediterranea and Coryphaenoides guentheri. On the lower slope, the shark Centroscymnuscoelolepis was also found to be relatively abundant off the Balearic Islands, Etmopterusspinax in the eastern Ionian Sea and the teleost fish Cataetyx laticeps throughout the three study areas. The deepest bottoms of the Mediterranean Sea shelter an ichthyofauna dominated by small-medium species living in a food scarce environment in which some large mobile fishes are widespread. The results are discussed in relation to previous studies mostly carried out in the Atlantic and western Mediterranean[ES] A partir de datos recolectados durante la campaña DESEAS, llevada a cabo en tres áreas del mar Mediterráneo (Mar Balear y Iónico occidental y oriental), se describe la estructura y la distribución espacial de las asociaciones de peces entre 600 y 4000 m de profundidad. Se obtuvieron un total de 55 especies (8 condrictrios y 47 peces teleósteos), 38 de los cuales procedían del mar Balear, 30 del Iónico occidental y 37 del oriental. El análisis multivariante de los datos nos muestra un claro patrón en zonación tanto en profundidad como por área geográfica. Se identificaron tres asociaciones principales a través del gradiente batimétrico estudiado: en el talud superior a profundidades alrededor de los 600 m, en el talud medio entre 800 y 1300 m, y en el talud inferior por debajo de los 1300 m. La caracterización geográfica de la estructura de la ictiofauna se observó principalmente en el talud superior y medio. A profundidades comprendidas entre 1000 y 1200 m fue donde se encontraron los mayores valores de biomasa, debido a la presencia de especies más grandes y con mayores requerimientos energéticos como Alepocephalus rostratus, Mora moro y Galeus melastomus. En el talud medio se detectaron diferencias significativas en abundancia, biomasa y peso medio de los peces entre las tres áreas. También se encontraron en las asociaciones de peces diferencias significativas en estos parámetros en el talud superior e inferior. Con el aumento de profundidad se detecta una disminución de la riqueza específica y la diversidad, indicando un empobrecimiento de la magafauna con la profundidad. Sin embargo se observa alta similaridad entre las áreas de estudio y en las máximas profundidades alcanzadas. Las especies dominantes en los fondos más profundos fueron: Bathypterois mediterraneus, Chalinura mediterranea y Coryphaenoides guentheri. En el talud inferior del mar Balear, el tiburón Centroscymnus coelolepis fue también relativamente abundante. Etmopterus spinax en el Iónico oriental y el teleosteo Cataetyx laticeps en las tres áreas de estudio. Los fondos más profundos del Mediterráneo son refugio para una ictiofauna dominada por pequeñas y medianas especies que habitan en en un ambiente escaso de alimento, en el cual solo algunos grandes peces móviles pueden extenderse. Los resultados se discuten en relación a estudios previos llevados a cabo mayoritariamente en el Atlántico y Mediterráneo occidentalThis work was supported by the Directorate General of Fisheries of the European Commission as part of the project DESEAS (Exploratory survey to collect data of the exploited and virgin stocks of deep-sea shrimp A. antennatus, of interest to the CFP - Study Contract nº 2000/39, DGXIV)Peer reviewe

A trophic model of the benthopelagic fauna distributed in the Santa Maria di Leuca cold-water coral province (Mediterranean Sea)

The benthopelagic fauna distributed in and around the Santa Maria di Leuca (SML) cold-water coral (CWC) province (Northern Ionian Sea–Central Mediterranean Sea) was analyzed through the development of a mass-balanced ecosystem model. A total of nine balanced simulations were provided taking into account the biomass data collected during several experimental bottom trawl surveys carried out from 2005 to 2010 in a depth range between 101 and 541 m. A total of 100 species were included in the analysis corresponding to 15 cephalopods, 25 crustaceans, 7 chondrichthyes and 54 osteichthyes. Simulations were developed maintaining the species-level detail. The total system throughput estimated in the SML CWC province trophic web resulted mainly due to consumption and about 80% of it was maintained by species with trophic level between 2 and 4. Results highlighted important features in terms of the structure and functioning of the system, such as the high level of activity maintained by intermediate trophic levels and the important role of top-down control in the faunal assemblage due to both vertebrate and invertebrate species

Does the Bari Canyon (Central Mediterranean) influence the fish distribution and abundance

Abstract The objective of this study was to evaluate whether the Bari Canyon influences the distribution and abundance of fish fauna in the southern Adriatic Sea. Data were collected in the Bari Canyon and in an adjacent area on the continental slope during an experimental longline survey carried out in June 2015. A total of 19 fish species were collected (16 inside and 13 outside the canyon). Differences between the sites were evaluated by means of a set of univariate and multivariate methods (analysis of variance, permutational multivariate analysis of variance, non-metric multidimensional scaling). The abundance and biomass of the whole catch were significantly greater inside than outside the canyon. The most abundant species were the shark Galeus melastomus and the teleost fishes Conger conger, Helicolenus dactylopterus, Merluccius merluccius, Pagellus bogaraveo and Phycis blennoides. All these species were found to be more abundant in the canyon than in the adjacent area. However, a significantly greater abundance inside the canyon than outside was detected for C. conger, while P. blennoides showed both significantly greater abundance and biomass in the canyon than outside. P. bogaraveo was exclusively caught inside the canyon. C. conger and P. blennoides exhibited significant differences in their sizes between the canyon and the adjacent area: a greater number of both smaller and larger individuals were found in the canyon than on the open slope. Mature females and males were mostly observed in the canyon in all the most abundant species, with the exception of P. blennoides due to its autumn-winter spawning. The present study corroborates the role of the Bari Canyon as a refuge area and an Essential Fish Habitat for fish species exploited in the neighbouring fishing grounds, highlighting the need for conservation measures

Assessment of cetacean–fishery interactions in the marine food web of the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

AbstractThe exploitation of fishery resources acts as a driving force on cetaceans both directly, by determining their fishing mortality or injury as by-catch species, and indirectly, through the lowering the availability of their prey. This competitive overlap between fishing and cetaceans often results in inadequate solutions so that in some cases there have been cases of intentional cetacean culling to maximize fishing production. A modelling approach applied to investigate the ecological roles of cetaceans in the food web could prove more effective to integrate ecological and fishing aspects and to provide suggestions for management. The comparative analysis carried out in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) showed that fishing exploitation provides impacts on the investigated food web greater than those due to cetacean predation. Trawling was estimated to be the most negatively impacting fishing gear considering the mortality rates and consumption flows. On the other hand, the striped dolphin was the main impact on the food web due to its highest consumption flows. Analysis showed a negative and non-selective impact on the exploited species due to the fishing gears, while the odontocetes proved to select their prey species and provide a positive impact in the assemblage. In particular, while the fishing gears are primarily size selective, targeting mostly large and economically valuable fish, the odontocetes seem to follow a co-evolution process with their prey, developing a specialization in their resources, providing control of the meso-consumers and ensuring a trophic stability in the ecosystem

Macro- and megafauna recorded in the submarine Bari Canyon (southern Adriatic, Mediterranean Sea) using different tools

Macro- and megafauna were recorded in the submarine Bari Canyon, located in the southern Adriatic Sea (Mediterranean Sea) during an oceanographic cruise carried out in May-June 2012 and an experimental fishing survey conducted in November 2013. During the former, 20 benthic samples were taken using a Van Veen grab at depths between 268 and 770 m and four deployments of a baited lander, for approximately 43 hours of video records, were carried out at depths between 443 and 788 m. During the latter, eight longline fishing operations were conducted from 338 m down to 612 m. Eighty-five living benthic and bentho-pelagic species were recorded: 29 Porifera, 1 Cnidaria, 2 Mollusca, 11 Annelida, 1 Arthropoda, 19 Bryozoa, 3 Echinodermata, and 19 Chordata. Fifty-one species are new records for the Bari Canyon, and 29 species are new records for the Adriatic Sea. Among the Porifera Cerbaris curvispiculifer is a new addition for the Italian sponge fauna. The first confirmed record of living specimens of the bryozoan Crisia tenella longinodata is reported. A total of six Mediterranean endemic species have been identified, four Porifera and two Annelida. The bathymetric range of some species has been extended. New information acquired for deep sea species confirms their importance in the structure of cold-water coral communities. This study has updated knowledge on the biodiversity of the Adriatic Sea, as well as of the Bari Canyon in particular, one of the sites designated as “jewels of the Mediterranean” for which urgent conservation measures are needed