Reducing the impact on vulnerable species through changes in fishing practices, such as the spatial or temporal avoidance of certain areas, is key to increase the ecological sustainability of ...fisheries. However, it is often hampered by the availability of sufficiently detailed data and robust indicators. Existing trawl surveys are a cost-effective data source to assess the vulnerability of fishing areas based on the quantities of vulnerable species caught. We developed a biological traits-based approach to the vulnerability of demersal assemblages using commercial trawl catch data. An expert-based approach identified a set of biological traits that are expected to condition the species’ response to trawling impact and are combined to produce the vulnerability index ranked into four levels (low, moderate, high and very high vulnerability). The approach was tested in four southern European fishing grounds showing evidence of over-exploitation, through catches being dominated by species of relatively low vulnerability to fishing impacts. The general distribution of species’ biomass amongst vulnerability groups was highly homogenous across case studies, despite local differences in fishing fleet structure, target species and fishing depths. Within all areas the species with moderate vulnerability dominated and, in most instances, species of “very high” vulnerability were not recorded. Nevertheless, differences emerged when comparing the proportions of highly vulnerable species in the catches. Variability in vulnerability level of the catch was also observed at small spatial scales, which was principally explained by differences in habitat type and depth and, secondarily, by fishing effort. In fine mud in the shallower areas there was a higher presence of low vulnerable fauna. Furthermore, vulnerable organisms decreased in their presence in sandier substrates on the continental shelf. The spatial heterogeneity in assemblage vulnerability composition encourages the potential for adoption of this index in the spatial management of fishing grounds aiming at ensuring a sustainable exploitation by mitigating trawl impacts on the most vulnerable components of the demersal assemblages.
Among the main measures adopted to reduce anthropogenic impacts on elasmobranch communities, understanding the ecology of deep-sea sharks is of paramount importance, especially for potentially ...vulnerable species highly represented in the bycatch composition of commercial fisheries such as the blackmouth catshark
Galeus melastomus
. In the present work, we unravelled the first indication of population genetic structure of
G. melastomus
by using a novel and effective panel of nuclear, and polymorphic DNA markers and compared our results with previous findings supporting high genetic connectivity at large spatial scales. Given the lack of species-specific nuclear markers, a total of 129 microsatellite loci (Simple Sequence Repeats, SSRs) were cross-amplified on blackmouth catshark specimens collected in eight geographically distant areas in the Mediterranean Sea and North-eastern Atlantic Ocean. A total of 13 SSRs were finally selected for genotyping, based on which the species exhibited signs of weak, but tangible genetic structure. The clearcut evidence of genetic differentiation of
G. melastomus
from Scottish waters from the rest of the population samples was defined, indicating that the species is genetically structured in the Mediterranean Sea and adjacent North-eastern Atlantic. Both individual and frequency-based analyses identified a genetic unit formed by the individuals collected in the Tyrrhenian Sea and the Strait of Sicily, distinguished from the rest of the Mediterranean and Portuguese samples. In addition, Bayesian analyses resolved a certain degree of separation of the easternmost Aegean sample and the admixed nature of the other Mediterranean and the Portuguese samples. Here, our results supported the hypothesis that the interaction between the ecology and biology of the species and abiotic drivers such as water circulations, temperature and bathymetry may affect the dispersion of
G. melastomus
, adding new information to the current knowledge of the connectivity of this deep-water species and providing powerful tools for estimating its response to anthropogenic impacts.
The time series of elasmobranch catch rates off the Tuscany coasts (NW Mediterranean) were investigated by means of min/max auto-correlation factor analysis in order to estimate variations in ...population abundance and evaluate the influence of environmental and anthropogenic factors. The analyses highlighted a general decreasing trend in the catch rates of sharks and skates from 1961 to the mid-1990s, mainly influenced by the increase in fishing effort. Since the 1990s, the EU Common Fishery Policy for the Mediterranean has promoted the reduction of fishing fleets through incentives to vessel demolition. The Porto S. Stefano trawl fleet has decreased by about 50%, leading to a decrease in fishing effort which seemed to be the most relevant factor affecting the increasing trend shown by the catch rates of Galeus melastomus, Scyliorhinus canicula and skates from 1991 to 2009. The elasmobranch assemblage did not undergo major shifts but the weighted frequency of occurrence shows that elasmobranchs were more frequent in the past. Particular caution should be paid in interpreting the recent rebound of some species as an early sign of recovery: trawl survey data and landing data show that over the last 50 years elasmobranch fauna have undergone a drastic decline and that recent rebounds are still far from a recovery to historical levels.
The agricultural frontier over the arid marginal zones is steadily expanding by
means of irrigation technology. Considering the impact of bacterial population and its
biological activity on soil ...homeostasis, information on soil biodiversity and its
biological activity are a significant input to maximize the production with minimal
impact on these susceptible environments. The aim of this exploratory work was to
assess the effect of long term agricultural practices (30 years) on the activity and
structural aspects of the microbial community from arid irrigated agricultural soils.
For this, three environments were evaluated, collecting samples of a Pristine arid soil
(without irrigation and undisturbed) and two different irrigated agricultural (Alfalfa
and Corn) throughout the 2014-2015 season. For this, samples from Pristine (without
irrigation) arid soil and (Alfalfa and Corn) were collected along the 2014-2015 season.
Soil physicochemical analysis was performed, temperature and humidity were
recorded, as well as total biological activity (FDA hydrolysis test) and molecular
fingerprinting (DGGE and T-RFLP) for each treatment. Soil physicochemical
analysis show that agricultural practice improved the edaphic properties like organic
matter level, although the contribution of water in limited quantities (pressurized
irrigation) an increase in electrical conductivity. Total biological activity along the
seasons showed similar profiles for all scenarios, and the coldest/unirrigated and
hottest/irrigated-rainy months showed the lowest and highest activities respectively.
Las fronteras agrícolas se están expandiendo constantemente, por medio de la
tecnología de riego, hacia zonas áridas marginales. Considerando el impacto de la
población bacteriana y su actividad biológica en la homeostasis del suelo, la
generación de información sobre la biodiversidad del suelo y su actividad biológica
son un importante aporte para maximizar la producción con un impacto mínimo en
estos ambientes susceptibles. El objetivo de este trabajo exploratorio fue evaluar el
efecto de las prácticas agrícolas a largo plazo (30 años) sobre la actividad y los
aspectos estructurales de la comunidad microbiana de los suelos áridos con agricultura
bajo riego. Para ello, se evaluaron tres ambientes, recolectando muestras de un suelo
árido Prístino (sin riego y sin disturbar) y dos suelos agrícolas bajo riego con diferente
historial de manejo (Alfalfa y Maíz) a lo largo de la temporada 2014-2015. Se realizó
un análisis fisicoquímico de lossuelos, se registró la temperatura y humedad, así como
la actividad biológica total (hidrólisis FDA) y la huella molecular (DGGE y T-RFLP)
para cada tratamiento. Los análisis fisicoquímicos del suelo muestran que las prácticas agrícolas mejoraron algunas de las propiedades edáficas como el nivel de materia
orgánica, aunque el aporte de agua en cantidades limitadas (riego presurizado)
provocó un aumento de la conductividad eléctrica. La actividad biológica total a lo
largo de las estaciones del año mostró perfiles similares para todos los ambientes, y
los meses más fríos/sin riego y más caluroso/con riego mostraron las actividades más
bajas y más altas, respectivamente. En general, la condición Prístina presentó niveles
de actividad biológica significativamente más bajos a lo largo de la temporada. La
huella dactilar DGGE mostró un patrón discreto con bajo número de bandas y, contra
lo esperado, no mostró diferencias entre los tres ambientes evaluados. El análisis por
T-RFLP posterior confirmó que la biodiversidad bacteriana del suelo no fue
modificada por décadas de intensa actividad agrícola.
A critical review was carried out involving experts from 17 countries, to identify, summarize and evaluate the current understanding related to the Ecosystem Approach to Fisheries management (EAF) in ...the Mediterranean and Black Seas. The existing information available at country level, coming from research and monitoring projects and other types of activities, was explored. The evaluation was done following a standardized protocol and using simple semi-quantitative methods. The results highlighted an overall low-medium degree of fulfilment of the requirements of the EAF, with some dif-ferences related to the different issues considered. The highest scores were reported for the knowledge related to fleet struc-ture/behaviour and species/habitat distribution, whereas the lowest scores were reported for modelling, and socio-economic and management issues. Although only semi-quantitative, these results provided an initial picture at a broad regional level on the state of knowledge with a view to a proper implementation of the EAF in the Mediterranean and Black Seas, and identi-fied gaps in scientific knowledge that should be covered.Original Abstract: Se llevo a cabo una revision critica con la intervencion de expertos de 17 paises para la identificacion, resumen y evaluacion del conocimiento actual en relacion a la Aproximacion Ecosistemica a la Gestion Pesquera (EAF) en el Mar Me-diterraneo y el Mar Negro. Se explora la informacion existente a nivel de cada pais, derivada de proyectos de investigacion y seguimiento, asi como otros tipos de actividades. Se llevo a cabo una evaluacion siguiendo un protocolo estandardizado y el uso de metodos semi-cuantitativos. Los resultados muestran que en general el grado de cumplimiento con los requerimien-tos de EAF es bajo-medio, con algunas diferencias relacionadas con los distintos aspectos considerados. Las puntuaciones mas elevadas correspondieron al conocimiento relacionado con la estructura de flota y su comportamiento, asi como con la distribucion espacial de habitats y especies. Las puntuaciones mas bajas correspondieron a aspectos relacionados con la modelizacion, la socio-economia y la gestion. A pesar de su caracter semi-cuantitativo, estos resultados proporcionan una primera imagen a nivel regional del estado de conocimiento del que se parte para una implementacion adecuada de EAF en el Mar Mediterraneo y el Mar Negro y ayuda a identificar las carencias en el conocimiento cientifico que deben ser corregidas.
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<0.05) only for the Adriatic Sea.
The deep-sea can act as a sink for legacy contaminants such as organochlorines (OCs), causing damages in its inhabitants for their persistence and their prolonged effects in the organisms. HCB, DDT ...and its isomers, and 28 PCBs congeners were detected in muscle and embryonic tissues of three deep-sea chondrichthyes Chimaera monstrosa (n = 16), Dalatias licha (n = 12) and Etmopterus spinax (n = 51) sampled in Ligurian and Tyrrhenian Sea (Mediterranean Sea). Contaminant distribution in E. spinax and C. monstrosa was PCBs > DDTs ≫ HCB while in D. licha was DDTs > PCBs ≫ HCB. Statistically significant differences were highlighted in OC levels among the species, but no such differences were found among sexes. Ratios between DDT isomers highlighted an historical input of the pesticide in the environment. For the first time was also demonstrated maternal transfer in deep water chondrichthyes, specifically in E. spinax where was highlighted that transfer of contaminants increases with increasing compound's Log Kow.
•OC pattern in sampled species was HCB < DDTs < PCBs.•OC burden in the species was made up of OCs with EDC properties.•OCs maternal transfer was documented for the first time in deep sea chondrichthyes.•OCs with higher LogKow showed greater maternal transfer in E. spinax.•Legacy contaminants are still a threat to deep-sea biodiversity conservation.
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Small-scale driftnets provide a high degree of size and species selection, chiefly through their mesh size. The main environmental impact of driftnets is due to the bycatch of non-target species. At ...present, few alternative methods to catch target species are available, and there is disagreement on the impact of some of them. The aim of the present study is to analyse and review the literature to find and explore alternative technical solutions to a complete ban on European small-scale driftnet fisheries, taking into account the scientific evidence of the damage that driftnets may cause to the environment in the different regions. Environmental impact on non-target species, including protected species, of current small-scale driftnet fisheries is similar to that of other passive fishing gears, such as purse seines, boat seines, trammel nets, set gillnets, and set- and drifting-longlines. Proposals are advanced to reduce the environmental impact of small-scale driftnet fisheries both in terms of conversion to other activities and improvement of selectivity. The study provides recommendations for policymakers to base their decisions on the circumstances in which driftnets use are not acceptable. It examines the effectiveness of mesh size and twine thickness limits of 90 mm and 0.6 mm, respectively in all driftnet fisheries, the restrictions on the fishing gear types and dimensions, and then the possible selective ban on those driftnet fisheries that are more harmful to protected species and/or are unable to avoid unwanted bycatch of unauthorised species.
•Small-scale driftnets provide a high degree of size selection, chiefly through their mesh size and twine thickness.•Environmental impact of other passive fishing gears is similar to that of small-scale driftnets.•Large-scale driftnets with much larger mesh sizes and greater length (driftnet longer than 2.5 km) should continue to be banned because they are not selective.•Enforcement of mesh size and twine thickness limits would be more successful than the adoption of alternative fishing gears.•Revision of driftnet fisheries regulations is essential and should include technical parameters (e.g. maximum mesh size, twine thickness).
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Sustainable management of living resources must reconcile biodiversity conservation and socioeconomic viability of human activities. In the case of fisheries, sustainable management design is made ...challenging by the complex spatiotemporal interactions between fish and fisheries. We develop a comprehensive metapopulation framework integrating data on species life‐history traits, connectivity and habitat distribution to identify priority areas for fishing regulation and assess how management impacts are spatially distributed. We trial this approach on European hake fisheries in the north‐western Mediterranean, where we assess area‐based management scenarios in terms of stock status and fishery productivity to prioritize areas for protection. Model simulations show that local fishery closures have the potential to enhance both spawning stock biomass and landings on a regional scale compared to a status quo scenario, but that improving protection is easier than increasing productivity. Moreover, the interaction between metapopulation dynamics and the redistribution of fishing effort following local closures implies that benefits and drawbacks are heterogeneously distributed in space, the former being concentrated in the proximity of the protected site. A network analysis shows that priority areas for protection are those with the highest connectivity (as expressed by network metrics) if the objective is to improve the spawning stock, while no significant relationship emerges between connectivity and potential for increased landings. Synthesis and applications . Our framework provides a tool for (1) assessing area‐based management measures aimed at improving fisheries outcomes in terms of both conservation and socioeconomic viability and (2) describing the spatial distribution of costs and benefits, which can help guide effective management and gain stakeholder support. Adult dispersal remains the main source of uncertainty that needs to be investigated to effectively apply our model to fisheries regulation.
Riassunto La gestione delle risorse biologiche deve conciliare la conservazione della biodiversità e la sostenibilità socioeconomica delle attività umane. Nel caso delle risorse alieutiche, l'elaborazione di strategie di gestione sostenibili è resa difficile dalle complesse interazioni spazio‐temporali tra pesci e pesca. Abbiamo sviluppato un modello di metapopolazione che integra informazioni sui tratti vitali, sulla connettività oceanografica e sulla distribuzione degli habitat per studiare gli impatti spaziali della regolamentazione della pesca. Abbiamo applicato questo approccio alla pesca del nasello comune nel Mediterraneo nord‐occidentale, per il quale abbiamo valutato scenari di gestione spaziale in termini di stato dello stock e produttività della pesca per identificare le aree a massima priorità di protezione. Le simulazioni del modello dimostrano che attraverso chiusure locali della pesca è possibile aumentare sia la biomassa dello stock riproduttivo sia gli sbarchi a scala regionale rispetto a uno scenario status quo, ma che migliorare la protezione è un obiettivo più facilmente perseguibile che aumentare la produttività. Inoltre, l'interazione tra le dinamiche di metapopolazione e la redistribuzione dello sforzo a seguito della chiusura locale della pesca determina benefici e svantaggi distribuiti in modo eterogeneo nello spazio, con i primi che si concentrano in prossimità delle aree protette. Un'analisi di rete mostra che le aree a massima priorità di protezione sono quelle con la più alta connettività se l'obiettivo è quello di incrementare lo stock riproduttivo, mentre non emerge alcuna relazione significativa tra connettività e potenziale aumento degli sbarchi. Sintesi e applicazioni. L’approccio proposto fornisce uno strumento per (1) valutare misure di protezione spaziale che mirano a migliorare le prestazioni della pesca in termini di conservazione e sostenibilità socioeconomica e (2) descrivere la distribuzione spaziale dei costi e dei benefici, la cui conoscenza può aiutare a guidare una gestione efficace e a ottenere il sostegno delle parti interessate. La dispersione spaziale degli adulti rimane la principale fonte di incertezza del modello, che richiede ulteriori indagini per applicare efficacemente il nostro approccio alla regolamentazione della pesca.
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