Search

This study investigated the distribution of nematode larvae of Anisakidae and Raphidascarididae (genera Anisakis and Hysterothylacium) in Trachurus trachurus (Linnaeus, 1758) in the Ligurian and central-northern Tyrrhenian Seas. The relationship between the number of parasites and the length and weight parameters of the fish was assessed, and the possible effect of the parasites on the condition factor was evaluated. A total of 190 T. trachurus specimens were collected in July 2019. Parasites were found in 70 individuals. A total of 161 visible larvae were collected in the viscera. Morphological analysis revealed the presence of Anisakis spp. in 55 fish and Hysterothylacium spp. in 15 fish, while 5 fish showed coinfection with both genera. The specimens subjected to PCR (n = 67) showed that 85% of the Anisakis larvae analyzed belonged to the species A. pegreffii, while the remaining 15% belonged to hybrids of A. pegreffii-A. simplex (s.s.). A total of 58% (n = 7) of the Hysterothylacium larvae analyzed belonged to the species H. fabri, while 42% belonged to the species H. aduncum. Our results support the hypothesis that infection with these parasites does not affect the condition of the fish host analyzed, and that body size and depth are major drivers in determining infection levels with Anisakid and Raphidascaridid nematodes.

17 pages, 7 figures, 2 tables, supplementary material https://doi.org/10.3389/fmars.2021.610241.-- Data Availability Statement: The datasets presented in this article are not readily available because some of the original raw data are protected by confidentiality. Requests to access the datasets should be directed to GM, giacomo.milisenda@szn, The recent establishment of the “landing obligation” under the reformed EU Common Fishery Policy has the twofold objective of reducing the excessive practice of discarding unwanted catch at sea and encouraging more selective and sustainable fisheries. Within this context, the awareness of the spatial distribution of potential unwanted catches is important for devising management measures aimed to decrease discards. This study analyzed the distribution of Hot Spot density areas of demersal fish and crustaceans below the Minimum Conservation Reference Size (MCRS) in four different southern European seas: continental Portuguese coast, Catalan Sea, South of Sicily, Liguria and northern Tyrrhenian Seas using both bottom trawl survey data and information on the spatial distribution of commercial fisheries. Critical areas for discarding were identified as zones where the highest densities of individuals below MCRS were consistently recorded throughout a series of years. Results clearly showed a patchy distribution of undersized individuals in each investigated area, highlighting the overlap between high density patches of both discards and fishing effort. The present findings provide a relevant knowledge for supporting the application of spatial-based management actions, such as the designation of Fisheries Restricted Areas (FRAs), in order to minimize the by-catch of undersized specimens and improve the sustainability of demersal fisheries, This work was funded by the European Commission’s Horizon 2020 Research and Innovation Program under Grant Agreement No. 634495 for the project Science, Technology, and Society Initiative to minimize Unwanted Catches in European Fisheries (MINOUW). This study received Portuguese national funds from FCT-Foundation for Science and Technology through project UIDB/04326/2020, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

20 pages, 9 figures, 5 tables, supplementary data https://doi.org/10.12681/mms.25306, The Mediterranean Sea has a long-lasting history of fishery exploitation that, together with other anthropogenic impacts, has led to declines in several marine organisms. In particular, elasmobranch populations have been severely impacted, with drastic decreases in abundance and species diversity. Based on their experience, fishers can provide information on marine species occurrence, abundance and behavioural traits on a long-term scale, therefore contributing to research on the poorly studied biological aspects of elusive or rare elasmobranch species. In this study, for the first time, the use of the Local Ecological Knowledge (LEK) of fishers was applied to study the behavioural traits of sharks, rays and skates in 12 FAO-GFCM geographical sub-areas (GSAs) of the Mediterranean Sea. This study found both new insight and proved the reliability of LEK-based catch seasonality, reflecting seasonal movements, by comparing LEK-based findings and available literature on five elasmobranch taxa (Mustelus spp., Squalus acanthias, Raja spp., Myliobatis aquila and Scyliorhinus stellaris) in the Adriatic Sea and 7 taxa (Mustelus spp., Raja spp., Prionace glauca, Scyliorhinus canicula, Torpedo spp., Pteroplatytrygon violacea and Isurus oxyrinchus) in the remaining Mediterranean GSAs. In addition, LEK provided new insights into a novel comprehensive representation of species aggregations (Mustelus spp., S. acanthias, M. aquila and S. canicula) in the sampled GSAs and supplied the first descriptions of the size, number of individuals and sex composition of the aggregations. When the limits and shortcomings of LEK-based research are considered, this methodology can be a complementary and cost-effective tool used to study elasmobranchs in either a data-poor scenario or a scenario in which a baseline is missing. LEK can also be useful for the evaluation and inclusion of fishers’ perceptions on bottom-up management and to provide important evidence for conservation plans, This work was supported by funding of Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR) to CM, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

The lack of information on age validation often affects ageing studies in cartilaginous fish, even in the most common species. Recently, the annual growth band deposition pattern has been directly validated for thornback ray in the Mediterranean Basin, thus providing a highly reliable protocol for age reading. In this regard, taking advantage of this new information, the present study aims to investigate this species growth for the first time over a wide area of the Western and Central Mediterranean Sea, involving four different FAO geographic sub-areas. In order to provide an accurate description of the species growth, different models were fitted to the age-length data obtained from the observation of vertebral centra thin sections. A total of 720 specimens were analysed (358 females and 362 males) with total length ranging between 11.5 and 86.4 cm. The corrected Akaike's Information criterion (AICc) indicated, among the tested models, the three-parameter von Bertalanffy function as the most robust in describing the species growth. Growth modelling outcomes revealed the thornback rays as capable of growing relatively fast during the first years; the growth rate gradually slows down allowing maximum sizes of about 90–100 cm in total length to be reached. Significant discrepancies in the growth pattern were found between sexes in all investigated areas with the only exception being in the Northern Tyrrhenian Sea. Differences in growth patterns were observed between areas, specifically in the estimated growth rate of the species for each sub-region. The present study, confirmed the importance of the availability of a validated ageing protocol and testing multiple growth models. Moreover, our results highlighted the urgent need to investigate a species growth in a wide geographic area, searching also for possible differences at sub-region level. Providing this information could indeed allow eventual management plans to be adapted to the exact growth pattern that the species exhibit in the region, in this way increasing their effectiveness.

The high species richness, coupled with high proportion of endemism, makes the Mediterranean one of the world’s ‘biodiversity hotspots’. However, the continuous increase in fisheries in the last few decades has led to the overexploitation of their main commercial stocks. Using fishery-independent data collected under the framework of the MEDITS trawl surveys carried out over the last 20 years, we study the demersal fish diversity pattern in the Mediterranean at a large spatial and temporal scale to determine whether it is being affected by the general fishing overexploitation of the demersal resources. The detected diversity trends are compared with the spatio-temporal variation in bottom trawl fishing effort in the Mediterranean. Our results show a stability and even recovery of demersal fish diversity in the Mediterranean together with higher diversity values on the continental shelves of the Balearic Islands, Sardinia, Sicily and the Aegean Sea. At large temporal and spatial scales, the high diversity of demersal assemblages in the Mediterranean is associated with a reduction in bottom trawl fishing effort. The inclusion of species other than target ones through diversity indices is important in the implementation of an ecosystem-based fisheries management., Sí

Variation in the numbers of pectoral fin spines and rays, pelvic fin rays, gill rakers on the first gill arch, anal fin rays, and the number of vertebrae of Silurus triostegus Heckel were examined in specimens from 16 localities that span its entire distribution range in the Tigris, Euphrates, and Shatt al-Arab rivers in Iraq. The mean number of the six meristic traits increases toward high latitudes with maximum and minimum values in the north and south of Iraq. Based on cluster analysis and PCA, the Mesopotamian river samples were clearly separated into three distinct groups. The upper Tigris populations were isolated from those of the middle and southern populations of this river and from those of the Euphrates River. Possible reasons for such differentiation among populations are discussed, and the integration of research on this species among the countries neighboring Iraq is required. CORRESPONDING AUTHOR: L.A. Jawad [+] Flat Bush, Manukau, Auckland, New Zealand e-mail: laith_jawad@hotmail.com A. Ligas CIBM, viale N. Sauro 4, 57128, Livorno, Italy M.I.G. Al-Janabi Iraq Natural History Research Centre and Museum, University of Baghdad, Baghdad, Iraq

Most studies on European hake focus on the recruitment process and nursery areas, whereas the information is comparatively limited on the ecology of the juvenile stage (ca. second year of life)—the one most exploited by the Mediterranean trawl fisheries. Using information of the MEDITS programme, we provide a spatial and temporal assessment of the influence of body size and growth on hake survival from recruits (age 0) to juveniles (age 1), along with the impact of surface temperature and chlorophyll variability. At a biogeographic scale, size-dependent survival is supported, with areas with higher mean length of recruits and juveniles yielding higher survival. A similar pattern was observed at interannual level in some western Mediterranean areas, also mediated by a density-dependent effect on growth. However, the most recurrent inter-annual pattern was a negative effect of size on survival, which could be attributed to potential ontogenetic changes in catchability and underrepresentation of intra-annual recruitment pulses that are seasonally inaccessible to the MEDITS sur- vey. Results also evidence that survival in the Alboran and Adriatic seas is dependent on the primary production variability, and that Corsica and Sardinia could be potential feeding grounds receiving juveniles from neighbouring areas. The present study reveals the importance of size- and growth-dependent survival in the juvenile stage of European hake in the Mediter- ranean Sea., Sí

The uncertainty in age estimation by otolith reading may be at the root of the large variability in red mullet (Mullus barbatus) growth models in the Mediterranean. In the MEDITS survey, red mullet age data are produced following the same sampling protocol and otolith reading methodology. However, ageing is assigned using different interpretation schemes, including variations in theoretical birthdate and number of false rings considered, in addition to differences in the experience level of readers. The present work analysed the influence of these variations and the geographical location of sampling on red mullet ageing using a multivariate approach (principal component analysis). Reader experience was the most important parameter correlated with the variability. The number of rings considered false showed a significant effect on the variability in the first age groups but had less influence on the older ones. The effect of the theoretical birthdate was low in all age groups. Geographical location had a significant influence, with longitude showing greater effects than latitude. In light of these results, workshops, exchanges and the adoption of a common ageing protocol based on age validation studies are considered fundamental tools for improving precision in red mullet ageing.

The main characteristics concerning the distribution of two of the most important decapod crustaceans of commercial interest in the Mediterranean Sea, the deep-water rose shrimp, Parapenaeus longirostris, and the Norway lobster, Nephrops norvegicus, are studied in the European Mediterranean waters. The study is based on data collected under the MEDITS trawl surveys from 1994 to 2015 from the Gibraltar Straits to the northeastern Levantine Basin (Cyprus waters). The observed differences can be interpreted as different responses to environmental drivers related to the differing life history traits of the two species. In fact, N. norvegicus is a long-living, benthic burrowing species with low growth and mortality rates, while P. longirostris is an epibenthic, short-living species characterized by higher rates of growth and mortality.

The present study provides updated information on the occurrence, abundance and biomass distribution patterns and length frequencies of Merluccius merluccius in the Mediterranean Sea, by analysing a time series of data from the Mediterranean International Trawl Surveys (MEDITS) from 1994 to 2015. The highest values of abundance and biomass were observed in the Sardinian Seas. The use of a generalized additive model, in which standardized biomass indices (kg km–2) were analysed as a function of environmental variables, explained how ecological factors could affect the spatio-temporal distribution of European hake biomass in the basin. High biomass levels predicted by the model were observed especially at 200 m depth and between 14°C and 18°C, highlighting the preference of the species for colder waters. A strong reduction of biomass was observed since the year 2009, probably due to the strengthening of the seasonal thermocline that had greatly reduced the availability of food. The general decrease in biomass of several stocks of anchovy and sardine, preys of European hake, might be indirectly connected to the decreasing biomass detected in the present study. The length analysis shows median values lower than 200 mm total length of most of the investigated areas.

In this study, we analysed the variability of reserve storage in juvenile European hake (Merluccius merluccius) off the western coasts of Italy (Central Mediterranean Sea). Reserve storage was measured by the hepatosomatic index (HSI), in relation to environmental and population covariates. HSI has been proved to be a consistent measure of energy storage in gadoids, thus reflecting quantity and quality of food availability for growth. Generalized Additive Models for Location, Scale and Shape (GAMLSS) were used to model the effect of depth, bottom temperature, bottom currents, fish density and fish body size on HSI of juvenile European hake. The results revealed that reserve storage in the liver appears to be maximized for juveniles living on the shelf break, between 120 and 170 m depth, with bottom temperature and current speed not exceeding 14 °C and 0.04 m s−1 respectively. Furthermore, HSI significantly increased with fish density up to about 6000 individuals per km−2 and decreased at higher densities indicating that reserve accumulation in the liver might be subject to density-dependent mechanisms (e.g. competition for food) as well. These findings suggest that the use of density as measure of nursery importance need to be further investigated. Finally, we found that HSI increased with fish size up to about 14 cm total length. Based on these results, HSI appears a reasonable index to indirectly measure the quality of habitats where juvenile European hake aggregate after their settlement on the bottom, and to potentially monitor habitat suitability as nursery across the spatial-temporal gradient.

A medium-term (10 year) stochastic forecast model is developed and presented for mixed fisheries that can provide estimations of age-specific parameters for a maximum of 10 stocks and 10 fisheries. Designed to support fishery managers dealing with complex, multi-annual management plans, the model can be used to quantitatively test the consequences of various stock-specific and fishery-specific decisions, using non-equilibrium stock dynamics. Such decisions include fishing restrictions and other strategies aimed at achieving sustainable mixed fisheries consistent with the concept of maximum sustainable yield (MSY). In order to test the model, recently gathered data on seven stocks and four fisheries operating in the Ligurian and North Tyrrhenian Seas are used to generate quantitative, 10 year predictions of biomass and catch trends under four different management scenarios. The results show that using the fishing mortality at MSY as the biological reference point for the management of all stocks would be a strong incentive to reduce the technical interactions among concurrent fishing strategies. This would optimize the stock-specific exploitation and be consistent with sustainability criteria.

Temporal variation in the population abundance of the deep-water rose shrimp, Parapenaeus longirostris (Lucas, 1846) (Decapoda, Penaeidae), and the Norway lobster, Nephrops norvegicus (Linnaeus, 1758) (Decapoda, Nephropidae), in the Tyrrhenian Sea (NW Mediterranean), were evaluated using time-series data (1994–2008) from experimental trawl surveys and commercial landings. The influence of several environmental variables (sea surface temperature, wind-mixing index and NAO index) and fishing effort indices (number of days at sea per month and mean engine power of the trawl fleet) were investigated. The time series were analysed by means of min ⁄ max auto-correlation factor analysis (MAFA) and dynamic factor analysis (DFA). The abundance of P. longirostris showed a clear increasing trend, significantly correlated with the fishing effort index (number of days at sea per month), the sea surface temperature and the wind-mixing index. The temporal variations in the stock of P. longirostris, which has a preference for warm waters, were positively correlated with the rise of the sea surface temperature and the decrease of wind circulation. For N. norvegicus, an increasing trend of landings per unit of effort and recruitment index contrasted with a decreasing trend of relative population abundance (biomass and density indices).

The present study aimed to evaluate the variation over time of the abundance of the populations of five demersal species in the Tyrrhenian Sea (NW Mediterranean) analysing data obtained from trawl surveys and commercial landing monitoring. The influence of some environmental variables (sea surface temperature, wind speed, NAO index) and some fishing effort indices (fishing days, mean size and mean engine power of the trawl vessels) was analysed as well. The species considered for the study were Eledone cirrhosa, Merluccius merluccius, Mullus barbatus, Nephrops norvegicus and Parapenaeus longirostris. From 1991 to 2006, the mean monthly landing rates were computed from the data collected at the auction of Porto Santo Stefano, the most important fishing harbour in the area. A second data set was represented by trawl survey data: two experimental trawl surveys per year have been carried out in the framework of national and international programs on the assessment of demersal resources. The mean biomass (kg/km 2 ) indices were calculated. The time series analyses were carried out by means of Min/Max Auto-correlation Factor Analysis (MAFA) and Dynamic Factor Analysis (DFA). The two techniques provided coherent results, indicating that the two most important trends in the response variables are an increase in terms of both LPUE and survey biomass index, and a fluctuating pattern, even though characterized by a general increasing tendency. What drove these trends is less clear, even though the available evidence suggests that the reduction of fishing effort has been more important than environmental factors.

The presence and continuity of naturalized populations of the red swamp crayfish, Procambarus clarkii (Girard, 1852) (Decapoda, Astacidea, Cambaridae), were investigated in the Salica River, in the southern part of Tuscany (Italy), from where no previous information on this species was available. Seasonal samplings were conducted using baited traps. A total of 747 crayfish, including three gravid females, was caught in the framework of the investigation. Information on some population dynamic features (size-frequency distributions, sex-ratio, growth of juveniles, etc.) can now be provided. La presenza e la consistenza di popolazioni naturalizzate di gambero rosso della Louisiana, Procambarus clarkii (Girard, 1852) (Decapoda, Astacidea, Cambaridae), e stata investigata nel torrente Salica, nella parte meridionale della Toscana (Italia), area nella quale non erano disponibili informazioni precedenti su questa specie. Campionamenti stagionali sono stati condotti utilizzando nasse con esca. Un totale di 747 esemplari di gambero rosso della Louisiana, tra i quali tre femmine gravide, e stato catturato nel corso dell'indagine. Alcune informazioni sulla struttura e sulla dinamica (distribuzioni di taglia-frequenza, rapporto sessi, accrescimento dei giovanili, ecc.) sono state ricavate.

The study was carried out in two fishing grounds on the Mediterranean continental shelf: one in the Adriatic Sea and one in the Catalan Sea. Samplings on board otter trawlers were performed from November 2002 to December 2003 in the Catalan Sea and from February 2003 to January 2004 in the Adriatic Sea. The Adriatic fishing ground was affected by high fishing intensity from January to June, while the Catalan area was highly exploited from September to February. Fishing activity in the Adriatic area was closed for 45 days, and 62 days in the Catalan area; both periods were in summer. Totals of 92 and 88 species were collected in the Adriatic and Catalan fishing grounds respectively. The species composition of the retained and discarded fractions showed close agreement between the two areas. Mullus barbatus showed very low discard rates in both areas, as well as Loligo vulgaris in the Catalan Sea and Merluccius merluccius in the Adriatic Sea. In both fishing grounds Squilla mantis showed high catch rates with low discards, except in March in the Catalan area. In the Adriatic Sea Liocarcinus depurator was characterized by large discard fractions. In both fishing grounds the retained fraction was slightly higher in the high fishing intensity periods than in the low intensity ones (Adriatic Sea: 0.613 vs 0.524; Catalan Sea: 0.597 vs 0.539), even though the Kruskall Wallis test revealed significant differences (p Este estudio se realizó en dos caladeros de la plataforma continental: uno en el mar Adriático y el otro en el Catalán. El muestreo se llevo a cabo a bordo de arrastreros comerciales desde noviembre 2002 a diciembre 2003 en el mar Catalán y desde febrero 2003 hasta enero 2004 en el Adriático. En este último caladero se detectó un periodo de alta intensidad de pesca que abarca desde enero a junio, mientras que la explotación más alta se produce de septiembre a febrero en el mar Catalán. En el Adriático se realiza una veda estival de 45 días, mientras que en la zona catalana el paro es de 62 días, también en verano. Se recolectó un total de 92 y 88 especies en los caladeros del Adriático y del mar Catalán, respectivamente. La composición específica de las fracciones retenida y descartada fue similar en ambas áreas. La proporción de descarte de Mullus barbatus fue muy baja en las dos áreas, así como la de Loligo vulgaris en el mar Catalán y Merluccius merluccius en el Adriático. En ambos caladeros, Squilla mantis mostró proporciones de captura altas con descartes bajos, excepto en marzo en el área catalana. Liocarcinus depurator se caracterizó por proporciones de descarte grandes en Adriático. La proporción comercializada fue ligeramente mayor en las épocas de alta intensidad de pesca en ambos caladeros (Adriático: 0.613 vs 0.524; Catalán: 0.597 vs 0.539). Sin embargo, únicamente se hallaron diferencias significativas (p

The aim of the present study was to provide an estimation of growth of juvenile European hake, Merluccius merluccius (L., 1758) (OSTEICHTHYES; MERLUCCIIDAE), by means of the analysis of otolith daily increments. Hake specimens were collected during trawl surveys carried out in the northern Tyrrhenian Sea (NW Mediterranean). The sagittae were removed from hakes ≤20 cm total length. Left otoliths were ground and polished to obtain thin frontal sections. Otolith microstructure was analysed under a compound green light-polarising microscope. A power curve with intercept was fitted to the length-age data to describe the growth of M. merluccius. According to the growth curve, a mean length of 18 cm was reached at the end of the first year of life. The validation of the otolith increment periodicity was performed by means of two indirect methods.

13 pages, 5 figures, 5 tables, The trophic ecology, energy and reproductive states of the deep-water shrimp Aristaeomorpha foliacea, widely distributed along the slopes of the Mediterranean Sea Basins, were analysed in eight areas spread along ca. 3000km in order to identify patterns in the habitat conditions supporting the species. From W to E the areas were situated between the north side of Eivissa (39°12'N, 1°20'E, in the Balearic Basin) and off Mersin, Turkey (36°15'N, 34°19'E, in the Levantine Sea). Trends identified mainly as a function of longitude from west to east were: (i) higher δ15N, parallel to δ15N shifts in the top 200m of the water column for particulate organic N (Pantoja et al., 2002). The δ15N trend indicates that the deep trophic web, i.e. A. foliacea at 400-600m, reflects the δ15N signal of the photic zone; (ii) a similar significant trend of δ13C, related with exploitation of pelagic versus benthic resources by A. foliacea in each area (i.e. by local variability of terrigenous inputs via submarine canyons). More depleted δ13C was found at mid-longitudes (Tyrrhenian Sea and Sicily Channel) linked to higher consumption of macroplankton prey (Pasiphaea spp., euphausiids and mesopelagic fishes). The feeding intensity (gut fullness, F) and prey diversity (J) of A. foliacea were related, according to generalized linear models, with the temperature and salinity of intermediate waters, variables in turn associated with latitude and longitude. Both F and J were higher in areas with greater shrimp density. The optimal ecological habitat of A. foliacea appears to be located in the Tyrrhenian Sea and the Sicily Channel, where we found the highest F, the greatest trophic diversity and A. foliacea in the best biological condition (i.e. with higher hepato-somatic index, HSI). These are also the areas with the highest densities of A. foliacea. In contrast, in the western Mediterranean Sea (Balearic Basin and the southern Balearic Islands), where A. foliacea has low densities, the shrimp showed generally lower values of trophic indicators and biological condition. © 2014 Elsevier Ltd., This research was performed and financed within the framework of the MICYT project ANTROMARE (CTM2009-12214-C02-01-MAR). In addition, this study was possible thanks to some material collected on oceanographic cruises (MEDITS_IT10 and 11, IDEADOS09, IDEADOS10) and by commercial trawlers

The effect of temperature increase on the stock of the deep-sea pink shrimp (Parapenaeus longirostris) was analysed along the western coasts of Italy (North Tyrrhenian–Ligurian Sea: Geographical Sub-Area 9). This crustacean is currently one of the most important commercial species of the trawl fisheries in the Mediterranean Sea. Landings of the species in the North Tyrrhenian–Ligurian Sea have grown consistently during the last years following a rapid increase in the stock size. Since the deep-sea pink shrimp stock is exploited on the same fishing ground of other heavily overexploited stocks in a full mixed and poorly selective fishery, its condition seems to be largely independent of the current fishing exploitation pattern suggesting a positive role of climate change on the dynamic of the stock. To test this hypothesis we investigated the effect of sea surface temperature (SST) on density and distribution of P. longirostris by means of general additive models (GAMs). Two different models were developed for the whole stock and for the recruits (CL The best GAM for the whole stock explained 67.1% of the total deviance, showing a clear increase in density in concomitance with the expansion of the stock northward. We found a significant positive effect of the min SST of all seasons, as expected considering that P. longirostris spawn all year round, with the highest influence played by summer min SST, either in the same or previous year. The best model for recruits explained 64.9% of the total deviance. Recruitment increased linearly with the density of spawners showing a positive temporal trend and an expansion northward. The observed trend in recruitment appeared significantly linked to minimum SST in summer and during the autumn of the previous year, with a positive effect on shrimp density over 23.5 °C and 14 °C respectively. The climate-related changes in recruitment appeared to be the key process driving the dynamics of the stock, involving either higher production or survival in the planktonic stages, or owing to changes in the quality/quantity of nursery habitats.

Summary Relationships between otolith major axis length (mm) and fish size (total length, cm) were described by means of linear regression analysis for six demersal fish species from the NW Mediterranean: blue whiting (Micromesistius poutassou), greater forkbeard (Phycis blennoides), red mullet (Mullus barbatus), poor cod (Trisopetus minutus capelanus), horse mackerel (Trachurus trachurus), and Mediterranean mackerel (Trachurus mediterraneus). Results show that reconstruction of body size from otolith measurement is possible by applying this approach based on the relationship of otolith length – fish length.

13 pages, 6 figures, [EN] Towing gears are known to produce several kinds of effects on benthic ecosystems. As small organisms and benthic species with faster growth rates and shorter life histories can withstand the fishing mortality and benefit from reduced competition or predation, trawl fishing can enhance their proliferation. Thus, trawl fishing can lead to biomass loss and production increase, since smaller specimens are more productive than bigger ones. In the present study we evaluate the effects, if any, of trawling on benthic crustacean macrofaunal production rates. Sampling was carried out in two neighbouring sites in the central Adriatic Sea (central Mediterranean), one affected by fishing activity and one not. Production and production/biomass (P/B) ratio of 13 species of peracarid and eucarid crustaceans were estimated using the Hynes size-frequency method. Estimates measured at both sites were compared in order to test the hypothesis that higher production and P/B values should occur in the fished area rather than in the unfished one. Our results indicated that the effects on the species are more complex than expected in regard to this hypothesis, and that they depend on the ecological and behavioural characteristics of the selected species. [ES] Las artes de pesca de arrastre pueden tener varios tipos de efectos sobre los ecosistemas bénticos. Considerando que los organismos pequeños y las especies bénticas con mayores tasas de crecimiento y menores expectativas de vida pueden soportar la mortalidad por pesca y beneficiarse de una reducción en la competencia o depredación, la pesca de arrastre puede propiciar su proliferación y, por ende, resultar en una pérdida de biomasa y un incremento en producción, ya que las especies de menor talla son más productivas que las de mayor tamaño. En el presente estudio se evalúan los efectos, si es que los hay, de la pesca de arrastre sobre las tasas de producción de la macrofauna béntica. Los muestreos se realizaron en dos sitios adyacentes en la parte central del Mar Adriático (Mediterráneo central), uno impactado por actividad de pesca y otro no. Se estimaron la producción y la razón producción/biomasa (P/B) de 13 especies de crustáceos peracáridos y eucáridos mediante el método de frecuencia de tallas de Hynes. Las estimaciones para ambios sitios se compararon para probar la hipótesis de que los valores de producción y P/B deberían de ser mayores en la zona de pesca que en la zona de exclusión a la pesca. Los resultados indican que los efectos sobre las especies son más complejos que los esperados en relación a esta hipótesis, y que dependen de las características ecológicas y el comportamiento de las especies seleccionadas., [en] This study is part of the EU project (Q5RS-2002-00787) "Response of benthic communities and sediment to different regimens of fishing disturbance in European coastal waters (RESPONSE)". [es] Este estudio es parte del proyecto de la Unión Europea (Q5RS-2002-00787) "Respuesta de diferentes comunidades bénticas y el sedimento a distintos regímenes de perturbaciones pesqueras en aguas costeras europeas (RESPONSE)".

9 pages, 5 figures, 2 tables, Species composition, distribution, and spatio temporal dynamics of hyperbenthic Mysidae Haworth, 1825 (Peracarida, Mysida) were studied on the continental shelf of the northern Adriatic Sea. A total of seven species was collected: Anchialina agilis, Erythrops elegans, Haplostylus lobatus, Leptomysis gracilis, Mysidopsis angusta, Mysidopsis gibbosa, and Paraleptomysis banyulensis. The hyperbenthic mysid assemblage was dominated by A. agilis, E. elegans, and L. gracilis, in terms of frequency of occurrence, abundance, and biomass. Notable seasonal fluctuations in the abundance of the catches were observed, with a minimum reached in the period July-September, probably due to the species’ life cycles as well as to environmental factors, such as the presence of mucilaginous aggregates close to the bottom., Se estudiaron la composición en especies, la distribución y la dinámica espacio-temporal de los crustaceos suprabentonicos de la familia Mysidae Haworth, 1825 (Peracarida, Mysida), en un area de la plataforma continental del Mar Adriatico del Norte. Siete especies fueron capturadas: Anchialina agilis, Erythrops elegans, Haplostylus lobatus, Leptomysis gracilis, Mysidopsis angusta, Mysidopsis gibbosa, Paraleptomysis banyulensis. A. agilis, E. elegans y L. gracilis dominaron las capturas, por lo que concierne la frecuencia de captura, los valores de abundancia y biomasa. Las capturas mostraron amplias fluctuaciones temporales, con un mínimo en Julio-Septiembre, probablemente debido tanto a las caracteristicas del ciclo biológico de las especies como a factores ambientales, en este caso a la presencia de agregados mucilaginosos cerca del fondo., The authors would like to thank Dr. Montserrat Demestre, Institut de Ciències del Mar (CMIMA-CSIC), Barcelona, coordinator of the EU Project RESPONSE (Q5RS-2001-00787), for her support and scientific assistance.