Korištenje povlačne podvodne kamere za procjene škampa, hlapića i morskog pera u Jadranskom moru

Norway lobster, Nephrops norvegicus, is of great commercial importance throughout the NE Atlantic and Mediterranean, where it lives in burrows within muddy sediments. In several European countries it is assessed by means of towed underwater TV techniques. These are particularly suited to N. norvegicus because, for a number of reasons, the application of common fishery-dependent stock-assessment methods is not thorough for this species. The TV-based methodology relies on the fact that a known surface area of seabed is visually assessed and the number of N. norvegicus burrows, whose features are distinct, can be counted and their inhabitants quantified. It follows that, in theory, the same can be done for other organisms or key ecological features which appear on the footage. This study reports the results of the underwater television surveys (2009 and 2010) carried out jointly by Italy and Croatia in the Pomo/Jabuka pits, an area of the Adriatic Sea important for its N. norvegicus fishery and its hake nursery grounds. The obtained footage allowed quantification of the density of N. norvegicus in the area and the acquisition of estimates of the abundances of the squat lobster, Munida rutllanti and the sea pen Funiculina quadrangularis. The concurrent quantification of trawling activity from the footage has allowed us to place our results in the context of an ecosystem approach to fisheries management.Škamp ( Nephrops norvegicus ) je izuzetno važna gospodarska vrsta koja obitava u rupama u muljevitom sedimentu diljem sjeverno-istočnog Atlantika i Mediterana. Obzirom da uobičajene metode procjene bioloških resursa koje se zasnivaju na ribolovu nisu u potpunosti pogodne za ovu vrstu, nekoliko Europskih zemalja procjene populacije škampa obavlja korištenjem povlačne podvodne kamere. Ova metodologija bazira se na činjenici da škamp u sedimentu iskapa rupe karakterističnog izgleda koje se determiniraju i prebrojavaju vizualnim pregledom snimke dobivene povlačenjem podvodne kamere preko određene površine morskog dna. Teoretski, ova metodologija se može primijeniti i za procjene drugih vrsta ili ekoloških parametara koji su zabilježeni na snimkama. Ova studija iznosi rezultate istraživanja podvodnom kamerom (2009. i 2010. godine) koje su zajednički proveli Italija i Hrvatska na području Jabučke kotline u Jadranskom moru. Ovo područje koje se intenzivno gospodarski iskorištava značajno je kao glavno mrijestilište i rastilište većeg broja pridnenih vrsta, posebno škampa i oslića ( Merluccius merluccius ) Na osnovu dobivenih snimki izrađena je procjena brojnosti i biomase škampa, kao i procjena brojnosti hlapića ( Munida rutllanti ) i morskog pera ( Funiculina quadrangularis ). Istodobna procjena tragova koćarenja zabilježenih na snimkama omogućila nam je da ove rezultate stavimo u kontekst ekosustavnog pristupa gospodarenju bioloških resursa mora

Searching for a stock structure in <i>Sardina pilchardus</i> from the Adriatic and Ionian seas using a microsatellite DNA-based approach

En el presente trabajo se ha investigado la variabilidad genética de la sardina europea en el mar Adriático y Jónico con el objetivo de detectar la posible existencia de estructura genética entre y dentro de ambas cuencas. El análisis de la variabilidad genética en ocho loci microsatélites detectó una desviación respecto al equilibrio HW por un exceso de homocigotos en algunas de las muestras estudiadas. La estima del nivel de diferenciación interpoblacional, realizada mediante AMOVA, qST and rRST, y descriptores Bayesianos, resultó no significativa para las muestras analizadas. Estos datos concuerdan con los obtenidos en estudios previos basados en alozimas y marcadores mitocondriales y contradicen la anterior identificación de dos subpoblaciones en el mar Adriático en base a datos morfológicos y reproductivos

Korištenje povlačne podvodne kamere za procjene škampa, hlapića i morskog pera u Jadranskom moru

Norway lobster, Nephrops norvegicus, is of great commercial importance throughout the NE Atlantic and Mediterranean, where it lives in burrows within muddy sediments. In several European countries it is assessed by means of towed underwater TV techniques. These are particularly suited to N. norvegicus because, for a number of reasons, the application of common fishery-dependent stock-assessment methods is not thorough for this species. The TV-based methodology relies on the fact that a known surface area of seabed is visually assessed and the number of N. norvegicus burrows, whose features are distinct, can be counted and their inhabitants quantified. It follows that, in theory, the same can be done for other organisms or key ecological features which appear on the footage. This study reports the results of the underwater television surveys (2009 and 2010) carried out jointly by Italy and Croatia in the Pomo/Jabuka pits, an area of the Adriatic Sea important for its N. norvegicus fishery and its hake nursery grounds. The obtained footage allowed quantification of the density of N. norvegicus in the area and the acquisition of estimates of the abundances of the squat lobster, Munida rutllanti and the sea pen Funiculina quadrangularis. The concurrent quantification of trawling activity from the footage has allowed us to place our results in the context of an ecosystem approach to fisheries management.Škamp ( Nephrops norvegicus ) je izuzetno važna gospodarska vrsta koja obitava u rupama u muljevitom sedimentu diljem sjeverno-istočnog Atlantika i Mediterana. Obzirom da uobičajene metode procjene bioloških resursa koje se zasnivaju na ribolovu nisu u potpunosti pogodne za ovu vrstu, nekoliko Europskih zemalja procjene populacije škampa obavlja korištenjem povlačne podvodne kamere. Ova metodologija bazira se na činjenici da škamp u sedimentu iskapa rupe karakterističnog izgleda koje se determiniraju i prebrojavaju vizualnim pregledom snimke dobivene povlačenjem podvodne kamere preko određene površine morskog dna. Teoretski, ova metodologija se može primijeniti i za procjene drugih vrsta ili ekoloških parametara koji su zabilježeni na snimkama. Ova studija iznosi rezultate istraživanja podvodnom kamerom (2009. i 2010. godine) koje su zajednički proveli Italija i Hrvatska na području Jabučke kotline u Jadranskom moru. Ovo područje koje se intenzivno gospodarski iskorištava značajno je kao glavno mrijestilište i rastilište većeg broja pridnenih vrsta, posebno škampa i oslića ( Merluccius merluccius ) Na osnovu dobivenih snimki izrađena je procjena brojnosti i biomase škampa, kao i procjena brojnosti hlapića ( Munida rutllanti ) i morskog pera ( Funiculina quadrangularis ). Istodobna procjena tragova koćarenja zabilježenih na snimkama omogućila nam je da ove rezultate stavimo u kontekst ekosustavnog pristupa gospodarenju bioloških resursa mora

Evaluación conjunta de la población de la anchoa del Mar Adriático septentrional y central: comparación entre dos métodos de dinámica poblacional

Anchovy (Engraulis encrasicolus, L.) is one of the most important commercial species of the northern and central Adriatic Sea, as well as one of the most productive fisheries in the whole Mediterranean. In the Adriatic Sea the stock of anchovy is shared between Italy, Croatia and Slovenia. A joint stock assessment was carried out using catch data from all the fleets for the time interval 1975-2009. Analyses were performed using estimates of natural mortality at age obtained by means of two different methods and two population dynamics methods based on the analysis of catch-at-age data: Laurec-Sheperd virtual population analysis (VPA) and integrated catch-at-age (ICA), both tuned to acoustic estimates of abundance. Gislason’s estimates for natural mortality appeared to be more realistic and were thus preferred for short-lived species. The general trend of biomass and fishing mortality is similar for the two models, highlighting the major collapse of the stock in 1987. Nevertheless, ICA has enough flexibility to combine all the data available without adding too much complexity in comparison with a VPA approach and seems to perform better in terms of the spawning stock biomass/recruitment relationship and diagnostics (i.e. the retrospective pattern). For the stock status, the exploitation rate from ICA is higher than the suggested threshold of 0.4 proposed by Patterson for small pelagic species.La anchoa (Engraulis encrasicolus, L.) es una de las especies comerciales más importantes del mar Adriático central y septentrional, a la vez que es una de las actividades pesqueras más productivas en todo el Mediterráneo. La población de anchoa en el mar Adriático es compartida por Croacia, Italia y Eslovenia: una evaluación conjunta de la población fue realizada usando los datos de captura de todas las flotas para el periodo 1975-2009. Se efectuaron análisis usando estimaciones de la mortalidad natural por edad obtenidos mediante dos métodos diferentes y dos métodos de dinámica poblacional basados en el análisis de datos de captura por edad: Análisis de Población Virtual (VPA) de Laurec-Sheperd y Análisis de Captura Integrada por Edad (ICA), ambos acordados en las estimaciones acústicas de la abundancia. Las estimaciones de mortalidad natural de Gislason aparentaban ser más realísticas y por lo tanto daba preferencia a especies de vida corta. La tendencia general de la biomasa y de la mortalidad por pesca es similar en los dos modelos, destacando la fuerte disminución de la población en 1987. Sin embargo, ICA permite una flexibilidad suficiente para combinar todos los datos disponibles sin agregar excesivas complejidades con respecto al enfoque VPA y aparenta un mejor desempeño en términos de relación de SSB-R y en términos of diagnósticos (por ejemplo: el patrón retrospectivo). En relación al estado de la población, la tasa de explotación del ICA es más alta que el umbral sugerido de 0.4 propuesto por Patterson para las especies de pequeños pelágicos

Identifying priority areas for spatial management of mixed fisheries using ensemble of multi‐species distribution models

Spatial fisheries management is widely used to reduce overfishing, rebuild stocks, and protect biodiversity. However, the effectiveness and optimization of spatial measures depend on accurately identifying ecologically meaningful areas, which can be difficult in mixed fisheries. To apply a method generally to a range of target species, we devel- oped an ensemble of species distribution models (e-SDM) that combines general ad- ditive models, generalized linear mixed models, random forest, and gradient-boosting machine methods in a training and testing protocol. The e-SDM was used to integrate density indices from two scientific bottom trawl surveys with the geopositional data, relevant oceanographic variables from the three-dimensional physical-biogeochemi- cal operational model, and fishing effort from the vessel monitoring system. The de- termined best distributions for juveniles and adults are used to determine hot spots of aggregation based on single or multiple target species. We applied e-SDM to juvenile and adult stages of 10 marine demersal species representing 60% of the total demer- sal landings in the central areas of the Mediterranean Sea. Using the e-SDM results, hot spots of aggregation and grounds potentially more selective were identified for each species and for the target species group of otter trawl and beam trawl fisheries. The results confirm the ecological appropriateness of existing fishery restriction areas and support the identification of locations for new spatial management measures

Identifying priority areas for spatial management of mixed fisheries using ensemble of multi‐species distribution models

Spatial fisheries management is widely used to reduce overfishing, rebuild stocks, and protect biodiversity. However, the effectiveness and optimization of spatial measures depend on accurately identifying ecologically meaningful areas, which can be difficult in mixed fisheries. To apply a method generally to a range of target species, we developed an ensemble of species distribution models (e-SDM) that combines general additive models, generalized linear mixed models, random forest, and gradient-boosting machine methods in a training and testing protocol. The e-SDM was used to integrate density indices from two scientific bottom trawl surveys with the geopositional data, relevant oceanographic variables from the three-dimensional physical-biogeochemical operational model, and fishing effort from the vessel monitoring system. The determined best distributions for juveniles and adults are used to determine hot spots of aggregation based on single or multiple target species. We applied e-SDM to juvenile and adult stages of 10 marine demersal species representing 60% of the total demersal landings in the central areas of the Mediterranean Sea. Using the e-SDM results, hot spots of aggregation and grounds potentially more selective were identified for each species and for the target species group of otter trawl and beam trawl fisheries. The results confirm the ecological appropriateness of existing fishery restriction areas and support the identification of locations for new spatial management measures

Food-web changes in the Adriatic Sea over the last three decades

21 pages, 9 figures, 5 tablesWe used a process-oriented model (Ecosim) to characterize changes in marine resources in the north-central (NC) Adriatic Sea (Mediterranean) from 1975 to 2002, and to explore the extent to which these changes were driven by trophic interactions, environment and fishing. Fishing efforts and fishing mortalities were used to drive the ecosystem model, and available biomass and catch data were compared to the model predictions. We calibrated and assessed the fit of the model using the sum of the squared deviations of the observed and predicted biomass values. Trophodynamic indicators were then calculated and used to analyse changes to the ecosystem. Trophic interactions, fishing, and environmental conditions were important driving factors of the ecosystem. Predictions from the model adequately matched observed biomass and catch data for each year. Observed trends and predicted data for biomasses decreased with time for several species, including Norway lobster, hake, red mullets, flatfish, and anchovy. The environmental functions resulting from the fitting procedure predicted that primary production and nutrients increased beyond the baseline from 1975 level, and then showed a decrease. They were negatively correlated with mean sea surface temperature and positively correlated with the Mediterranean Oscillation Index. Our results suggested that the NC Adriatic ecosystem became more degraded over time due to expanding fishing effort, bottom-up effects, and climatic anomalies. Possible mechanisms involved are discussed. Comparing our findings with descriptions of the south Catalan Sea ecosystem showed certain similarities between these 2 Mediterranean ecosystems and revealed unique features of the Adriatic SeaThis work was made possible by a bilateral co-operative-agreement between the Istituto di Scienze Marine (CNR), Italy, and the Consejo Superior de Investigaciones Científicas, Ciencia e Investigación (CSIC), Spain. The integrated project ’Site Effect Assessment Using Ambient Excitations’ (SESAME) contract no. 036949-2, supported by the European Commission’s Sixth Framework Programme, Sustainable Development, Global Change and Ecosystems, which allowed the continuation of this work, is greatly acknowledged. During part of the work, M.C. was supported financially by doctoral and postdoctoral fellowships from the Spanish Ministry of Science and Technology and the Ministry of Education and Science, and by Dalhousie University (Canada)Peer reviewe

Fishing management scenarios to rebuild exploited resources and ecosystems of the Northern-Central Adriatic (Mediterranean Sea)

13 pages, 6 figures, 6 tablesWe examined various fishing management options to recover exploited marine resources and ecosystems of the Northern-Central Adriatic Sea. Dynamic simulations were based on a spatial ecological model previously calibrated with time series of data. Scenarios regarding spatial management were evaluated with the establishment of two marine protected areas, respectively, in the Pomo pit and the northern region. In addition, three temporal simulations of temporary closures and overall reduction of fishing effort of demersal and pelagic fleets (bottom, mid-water trawls and purse seines) were also considered. Simulations were run for 45 years (1975–2020), including the calibration period (1975–2002), and changes in biomass and catch of marine resources were analyzed. Our results confirm that current fishing management in the Adriatic Sea does not have clear beneficial impacts for the recovery of exploited resources, which will remain depleted in 2020 if “business as usual” continues. Simulations of alternative management suggest that both protected areas could be beneficial for fish population recovery predicting an increase in the biomass of commercial fish and predatory organisms. Simulations of temporary closures and overall reduction of fishing effort also show significant benefits for several commercial resources. We argue that both management measures may be effective tools to recover exploited ecosystems of the Northern-Central Adriatic Sea and halt the decline of marine resourcesDuring the work, N.F. was supported financially by a fellowship from the International Centre for Advanced Mediterranean Agronomic studies (CIHEAM). M.C. was supported financially by postdoctoral fellowships from the Spanish Ministry of Science and Technology and by the European Community Marie-Curie OIF Post-doctoral Fellowship to the ECOFUN project. This work was developed within the context of the SESAME project—EC Contract No. GOCE-036949, funded by the Sixth Framework ProgrammePeer reviewe

Ecosystem assessment of the North-Central Adriatic Sea: towards a multivariate reference framework

We analyzed data from catch statistics, scientific surveys and results from ecosystem models to assess main changes in marine resources of the North-Central Adriatic Sea (Central Mediterranean) from the mid 1970s to the early 2000s. We then quantified food-web changes using these datasets and trophodynamic indicators. We applied time series trends and a Principal Component Analysis (PCA) to reduce the number of multivariate dimensions and to define ecosystem reference directions. To assess the correlation between ecological indicators and abiotic (human or environmental) factors, we used the non-parametric BIO-ENV procedure. Results illustrated a general decrease in the biomass and catch of target species with time, with a first phase of increasing catch and biomass of some organisms from the 1970s to the 1980s, a 'fishing down the food web' process during the 1980s, and a clear trend towards biomass and catch reductions during the late 1990s and early 2000s. These changes occurred in parallel with an increase in fishing effort and human development in the basin and changes in environmental factors such as an increase in the average annual sea water temperature, a decrease in the inflow of highly saline Mediterranean water into the Adriatic Sea, and changes in the atmospheric pressure at sea level. We found a high and significant correlation between ecological indicators and abiotic factors (in particular with human factors: fishing effort and the human development index). Results from the PCA summarized main ecosystem trends and could be used as a reference framework. These results complement traditional single-species fisheries assessments and inform on past trajectories and present ecological status of the North-Central Adriatic SeaThis work was made possible by a bilateral Cooperative-Agreement between the CNR (Italy) and the CSIC (Spain). The EU project SESAME contract no. 036949-2 that allowed the continuation of this work is greatly acknowledged. M.C. was supported financially by a postdoctoral fellowship from the Spanish Ministry of Science and Technology, and by the European Community Marie-Curie Postdoctoral Fellowship through the International Outgoing Fellowships (Call: FP7-PEOPLE-2007-4-1-IOF) to ECOFUNPeer Reviewe

An ecosystem model of the northern and central Adriatic Sea : anasisys of ecosystem structure and fhishing impacts

5 pages, 1 figure, 2 tablesA trophic mass-balance model of the Northern and Central Adriatic Sea was developed to characterice the classical food web functioning and structure and to describe the ecosystem impacts of fishing. Important features of the ecosystem were highlighed, such as the key role of coupled pelagic-benthic production of plankton, benthic invertebrates and detritus, and the importance of small pelagic fishes within the system. Fishing impacts are higt in the ecosystem.Peer reviewe