Selectividad de las redes de enmalle para Solea solea (Osteichthyes: Soleidae) en el Mar Adriático

Sole juveniles concentrate along the western Adriatic coast where they are targeted from spring to autumn by small-scale gill netters. As in spring–early summer 20 to 30% of catch biomass consists of individuals smaller than MLS (TL = 20 cm), the selectivity of sole gill nets was investigated in 2004-2005 in order to obtain useful information for developing management measures aimed at reducing the retention of undersized specimens and assuring the sustainability of this fishery. Twenty-eight fishing trips were performed using sole gill nets with 5 mesh openings (64.2, 65.2, 67.8, 70.2 and 71.8 mm) simultaneously. The gill net selectivity was estimated indirectly by applying the SELECT method and between-set analysis. The log-normal curve was found to fit single set data better than other models. The catch yields did not significantly decrease with the increment of mesh size: the biomass of undersized individuals in catches noticeably decreased from 16% down to 9% in the largest mesh size, whilst the sole that were longer than the MLS increased proportionally. In view of the lower economic value of smaller specimens with respect to the larger ones, adopting the 71.8 mm mesh represents a good compromise between the need to protect juveniles and the economic profit of gill netters.Los juveniles de lenguado se concentran a lo largo de la costa oeste adriática donde son capturados desde la primavera hasta el verano con redes de enmalle de tamaño pequeño. En primavera y principios del verano el 20-30% de la biomasa capturada corresponde a individuos menores a la talla mínima legal (longitud total de 20 cm). Este trabajo ha estudiado la selectividad de las redes de enmalle para el lenguado durante 2004-2005 con el objetivo de obtener suficiente información para desarrollar medidas de gestión que reduzcan la retención de individuos demasiado pequeños y asegurar así la sostenibilidad de la pesquería. Durante este estudio se realizaron un total de veintiocho muestreos pesqueros usando simultáneamente redes de enmalle con cinco luces de malla distintas (64.2, 65.2, 67.8, 70.2 y 71.8 mm). La selectividad de la red de enmalle fue estimada indirectamente aplicando el método SELECT. El modelo que se ajustó mejor a los datos fue una curva de tipo log-normal. La captura no descendió significativamente con el incremento de la luz de malla. La biomasa de los individuos pequeños en las capturas bajó notablemente de 16% a 9% con el uso de la red de mayor luz de malla, mientras que los lenguados con mayor tamaño aumentaron proporcionalmente. Como los individuos menores tienen también un valor económico menor, el uso de la red de 71.8 mm de luz de malla es un buen compromiso entre la protección de los juveniles y la obtención de beneficios económicos para los pescadores que usan las redes de enmalle

Evaluating the unexplored recreational fishing in the Turkish Black Sea: socio-economic significance and environmental impact

Marine recreational fishing, a globally popular outdoor activity, has deep cultural roots and ecological implications. This study, conducted between 2021-2022, explores marine recreational fishing practices along the Turkish Black Sea coast. It analyzes fisher numbers and demographics, fishing effort, fishing methods, and species caught and released. Furthermore, the research sheds light on the economic dimensions, emphasizing the substantial contributions of recreational fishing to local economies. Notably, responsible practices, such as catch-and-release initiatives, demonstrate anglers’ awareness of conservation efforts. Within the Turkish Black Sea region, an observed 18.5% participation rate among a population of 24.5 million implies the presence of approximately 4.5 million marine recreational fishers. Annually, this translates to nearly 30 million fishing days, accompanied by a total expenditure of 400 million Euros. However, it’s imperative to handle these figures cautiously as the timing of the screening survey during the COVID-19 pandemic may have influenced the high participation rate, introducing a potential bias. A detailed examination of a Turkish marine recreational fisher engaged in Black Sea fishing reveals an average annual catch of 16.5 kg of retained fish and 1.2 kg of released fish biomass. When extrapolated to the larger population of 4.5 million fishers, this culminates in a noteworthy landing biomass approaching 74,000 tons. The study unveils that marine recreational fishers in the Turkish Black Sea predominantly target commercially important species, resulting in a retained biomass surpassing commercial landings in 2021. This prompts concerns about potential impacts on crucial commercial fish stocks, underscoring the imperative inclusion of recreational fisheries in stock assessments. The research, providing essential insights into the intricate dynamics of recreational fishing, lays a foundation for well-informed policies and practices that concurrently promote environmental conservation and the continuation of this valued leisure activity

Edad y crecimiento del rascacio, Scorpaena porcus (Pisces: Scorpaenidae) en estructuras artificiales y arrecifes naturales en el mar Adriático

Age and growth of the black scorpionfish, Scorpaena porcus, were estimated for different populations inhabiting natural reefs and artificial structures (artificial reefs and offshore gas platforms) in the northwestern Adriatic Sea. Annual growth increment counts were carried out on sagittal otoliths of 415 specimens ranging from 80 to 280 mm TL. The accuracy of age estimates was assessed by testing the annual deposition of annuli and the location of the first annulus by marginal increment analysis and daily growth increment counts, respectively. As commonly observed in other scorpaenids, annuli consisted of an alternating pattern of opaque and translucent zones. Marginal increment analysis confirmed that annuli are formed once a year, with opaque zones laid down in spring-summer and translucent zones laid down in autumn-winter. The precision of age estimates was tested by applying both the average percent error (APE) and the mean coefficient of variation (CV). The maximum age estimated for the whole sampled populations was 8 years. The von Bertalanffy growth curves were separately fitted for natural and artificial reef populations of S. porcus. The likelihood ratio test indicated that the overall von Bertalanffy growth curves differed significantly between the two populations. The instantaneous growth rate (k, year-1) and asymptotic length (L∞, cm) were 0.23 and 22.30 and 0.53 and 20.13 for natural and artificial reef populations, respectively. Compared with natural reef population, populations of S. porcus inhabiting artificial reefs and, particularly, offshore platforms, were characterized by larger and older fish. However, young-of-the-year were completely absent from the platform habitats. The effects of artificial structures on S. porcus populations in the study area are discussed in the light of previous results on scorpionfish living in other areas.Se estimó la edad y crecimiento del rascacio, Scorpaena porcus, de diferentes poblaciones de arrecifes naturales y estructuras artificiales (arrecifes artificiales y plataformas de gas a mar abierto) en el noroeste del mar Adriático. Los contajes de los incrementos de crecimiento anuales se realizaron en otolitos sagitta de 415 especímenes entre 80 y 280 mm de longitud total. La precisión de la estima de la edad se evaluó comprobando la formación anual de los anillos, y la localización del primer anillo mediante análisis de incrementos marginales y contajes de incrementos diarios, respectivamente. Tal como es comúnmente observado, los anillos presentan un patrón de zonas opacas y translúcidas que van alternando. El análisis de incrementos marginales confirmó que los anillos se forman una vez al año, con las zonas opacas que se depositan en primavera-verano y las translúcidas en otoño-invierno. La precisión en la estima de las edades se comprobó aplicando el porcentaje de error promedio y el coeficiente promedio de variación (CV). La edad máxima estimada para todas las poblaciones muestreadas fue de ocho años. Las curvas de crecimiento de von Bertalanffy growth se ajustaron separadamente para las poblaciones de S. porcus de arrecifes naturales y artificiales. El test de verosimilitud indicó que las curvas de crecimiento de von Bertalanffy diferían significativamente entre las dos poblaciones. La tasa instantánea de crecimiento (k, año-1) y la longitud asintótica (L∞, cm) fueron 0.23 y 22.30 y 0.53 y 20.13 para poblaciones de arrecifes naturales y artificiales, respectivamente. En comparación con las poblaciones de S. porcus de arrecifes naturales, las que se encuentran en arrecifes artificiales y, en particular en plataformas a mar abierto, se caracterizaron por peces más grandes y de más edad. No obstante, los individuos de edad inferior a un año están completamente ausentes en dichas plataformas. El efecto de estructuras artificiales en las poblaciones de S. porcus en el área de estudio se discuten en función de resultados previos de scorpeniformes de otras áreas

Biometrijska i biološka integrativna studija o boljem gospodarskom upravljanju morskim pužem, Nassarius mutabilis (Linnaeus, 1758)

Fishing of Nassarius mutabilis is by far the most important activity carried out by artisanal fisheries in the central and northern Adriatic Sea, accounting for more than 35% of total fishing effort and yielding from 2000 to 3000 t of landings each year. This gastropod is targeted from the beginning of autumn to the end of spring using basket traps. Despite its importance under a socio-economic point of view, the scientific studies on the biology and ecology of this species are very scarce and the failure of the current management measures could also be attributed to the scarce knowledge on the biology of this species in the area. Taking this statement into consideration, the results of the present study contribute to fill a few existing gaps and may be useful to improve the management measures currently in force. Samples were collected from March 2006– March 2008 during monthly fishing surveys and carried out using basket traps in the central Adriatic Sea. A total of 383 males (size range 7–29 mm SH) and 504 females (size range 15-32 mm SH) were caught. Mean SH (± SD) of males was 15.84±3.57 mm and mean SH of females was 25.31±3.06 mm. A significant difference in the biometric characteristics between the two sexes was discovered. The condition index (CI) showed similar seasonal trends for both sexes, with a decrease from late winter to spring followed by an increase from summer to fall - early winter. The minimum values were recorded in summer and the maximum ones in winter, following an opposite trend in respect to water temperature. In the males this trend was observed starting from size classes larger than 11 mm SH, hence this size might be very close to the size at first sexual maturity. The size at first maturity hypothesized for females (16-20 mm SH) agrees with the minimum landing size (MLS) currently established for this species (20 mm SH). The absence of small females (SH 23 mm) leads to suppose a sex reversal from male to female at around 20 mm SH. On this basis, the management measure of MLS leads to the selective retention of females and, hence, to a sexual gap between the two sexes with possible consequences on the biology of the species and the resilience of the stock. The peaks of CI observed for males and females confirmed that the spawning season of this gastropod occurs in late winter – early spring, according to the abundant presence of egg capsules attached to submerged substrates in that period at sea. Consequently, from a management point of view, it would be advisable to shorten the fishing season that at present extends from fall to later spring.Lovljenje morskog puža Nassarius mutabilis je daleko najvažnija djelatnost malog priobalnog ribolova u središnjem i sjevernom Jadranu, što čini više od 35% ukupnog ribolovnog napora s prinosom od 2000 do 3000 tone svake godine. Ovaj puž se lovi od početka jeseni do kraja proljeća pomoću vrše. Unatoč njegovoj društveno-ekonomskoj važnosti, znanstvene studije o biologiji i ekologiji ove vrste su vrlo rijetke, stoga se neuspjeh trenutnih mjera upravljanja također može pripisati oskudnom znanju o biologiji ove vrste u navedenom području. Rezultati ovog istraživanja pridonose rješavanju nekoliko postojećih nedostataka i mogu biti korisni za poboljšanje mjera upravljanja koje su trenutno na snazi. Uzorci su prikupljeni pomoću vrše (košare; pletene stupice) u razdoblju od ožujka 2006. do ožujka 2008. godine tijekom mjesečnih istraživanja u središnjem Jadranu. Ukupno su uhvaćena 383 mužjaka (raspon veličina 7-29 mm SH) i 504 ženke (raspon veličina 15 - 32 mm, SH- visina školjke-puža). Srednja visina puža (± SD - značajna razlika) mužjaka iznosila je 15,84 ± 3,57 mm, a srednja visina kućice ženki je iznosila 25.31 ± 3.06 mm. Otkrivena je značajna razlika biometrijskih karakteristika između dva spola. Indeks stanja (CI) pokazao je slične sezonske trendove za oba spola, s padom od kraja zime do proljeća, nakon čega slijedi porast od ljeta do jeseni odnosno početkom zime. Najmanje vrijednosti zabilježene su u ljeto, a maksimalne zimi, što predstavlja suprotni trend u odnosu na temperaturu vode. Kod mužjaka je ovaj trend uočen počevši od kategorije visine kućice veće od 11 mm, pa bi stoga ove veličine mogle biti vrlo blizu veličini puža kod prve spolne zrelosti. Hipotetski veličina ženki kod prve spolne zrelosti (visina kućice 16-20 mm) se slaže s veličinom minimalnog ulova (MLS) trenutno uspostavljenog za ovu vrstu morskog puža (visina kućice 20 mm). Odsutnost malih ženki (visina kućice <15 mm) i velikih mužjaka (visina kućice > 23 mm) dovodi do pretpostavke da se preokret kod muškog i ženskog spola odvija kada kućica dosegne visinu od oko 20 mm. Na temelju toga, mjera upravljanja bi trebala dovesti do selektivnog zadržavanja ženki, a time i do spolnog razdvajanja s mogućim posljedicama na biologiju vrste i održivost stocka. Vrhunac indeksa stanja uočenog kod mužjaka i ženki je potvrdio da se mriještenje ovog mekušca javlja krajem zime - početkom proljeća, u skladu s obilnom prisutnošću kapsula jajašaca pričvršćenih na potopljene supstrate u tom razdoblju. Prema tome, s gledišta gospodarskog upravljanja, bilo bi poželjno da se skrati ribolovna sezona koja se u ovom trenutku proteže od jeseni do kasnog proljeća

Comparison of growth rates estimated by otolith reading of Scorpaena porcus and Scorpaena notata caught on artificial and natural reefs of the northern Adriatic sea

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Novi nalaz šaruna golemog, Trachurus picturatus T. E. Bowdich, 1825 (Osteichthyes: Carangidae) u sjevernom Jadranu

The observation of a new species in a new area represents the first opportunity to follow and study the dynamics of colonization and understand how a new species arrives, what are its movements and its potential impact. The discovery of a large number of species outside their usual area of distribution is probably the most important reason for the increase in perceived biodiversity of the Adriatic ichthyofauna. A total of 4 specimens of T. picturatus were caught in the period May-June 2011 in the surroundings of an offshore gas platform in the Northern Adriatic Sea. Scientific literature depicts this species as rare in the Adriatic Sea, indicating and suggesting the Pomo Pit (Central Adriatic Sea) as the Northern latitudinal limit of its distribution. On this basis, this paper reports the first record of T. picturatus in the Northern Adriatic basin, suggesting an expansion of its spatial distribution.Promatranje nove vrste u novom prostoru predstavlja prvu priliku praćenja i proučavanja dinamike kolonizacije, te razumijevanje kako nova vrsta pristiže u prostor, kako se u njemu kreće i njen potencijalni utjecaj na prostor. Otkriće velikog broja vrsta izvan njihovog uobičajenog područja raspodjele je vjerojatno najvažniji razlog za povećanje percipirane bioraznolikosti Jadranske ihtiofaune. Ukupno 4 primjerka šaruna golemog, T. picturatus, su ulovljeni u razdoblju od svibnja do lipnja 2011. u okolici platformi plina u sjevernom Jadranu. Znanstvena literatura opisuje ove vrste kao rijetke u Jadranu, što potvrđuje Jabučku kotlinu (srednjeg Jadrana) kao sjevernu granicu njegove raspodjele. Na temelju toga, u ovom radu se iznosi prvi nalaz šaruna golemog, T. picturatus, u sjevernom jadranskom slivu, što ukazuje na širenje njegove prostorne raspodjele

Analysis of spatial conflicts of large scale salmonid aquaculture with coastal fisheries and other interests in a Norwegian fjord environment, using the novel GIS-tool SEAGRID and stakeholder surveys

The expansion of the Norwegian aquaculture industry has generated a need for balancing aquaculture with other societal interests in the coastal zone. The interactions, conflicts and synergies of different uses of a Norwegian coastal region heavily influenced by large-scale salmonid aquaculture was analyzed and mapped by means of systematic stakeholder participatory approach and a GIS-based spatial interaction analysis tool, SEAGRID. Our study focused on spatial conflicts/synergies, whereas non-spatial interactions were taken into account in order to elucidate the spatial effects. The questionnaire analysis showed that there was a large agreement across the respondents that aquaculture and fisheries compete for access to sea areas, which is also in agreement with the SEAGRID analysis. All but one of the interviewees thought that conservation issues will become more important in the future. We found that societal interests and infrastructure obstruct or displace private enterprises and economic interests, whereas environmental protection measures do so to a lesser extent; an exception are coral reefs which seem to be well protected against both fishing operations as well as new aquaculture facilities. Nature protection was not found to affect fisheries nor aquaculture to a large extent, with the exception of the single salmon fjord, which is protected from salmonid aquaculture, but otherwise open to other activities, such as fisheries, tourist fisheries and tourism in general. The restricted military areas had a limited extent, and were not viewed as a cause of conflicts. Stakeholder consultations, like our participatory GIS approach, combined with GIS-based tools for analysis of spatial conflicts/synergies may be useful in identifying areas where aquaculture production can increase with little increase in degree of conflict with fisheries, although some interactions are not strictly spatial. Our results indicated a certain degree of mistrust of management authorities since neither fishermen nor aquaculturists perceived that their own sector was given priority by management authorities, but thought the other sector was prioritized.Analysis of spatial conflicts of large scale salmonid aquaculture with coastal fisheries and other interests in a Norwegian fjord environment, using the novel GIS-tool SEAGRID and stakeholder surveyspublishedVersio

Ecosystem-Based MSP for Enhanced Fisheries Sustainability: An Example from the Northern Adriatic (Chioggia\u2014Venice and Rovigo, Italy)

Human pressures on marine ecosystems significantly increased during last decades. Among the intense anthropic activities, industrial fisheries have caused the alteration of habitats, the reduction of biodiversity and the main fish stocks. The aim of this research, carried out in the Adriatic Sea, was to test a repeatable Marine Spatial Planning framework aimed at enhancing fisheries sustainability through the application of Decision Support Tools and the composition of a catalog of possible measures. The use of these tools proved very useful to identify possible criticalities and facilitate an effective exchange with fisheries stakeholders, local authorities, and fishermen, whose involvement was an indispensable step in the process. Tool-based analyses allowed to assess the spatial footprint of a range of anthropogenic pressures from human activities (e.g., fisheries, maritime traffic, and aquaculture). Within this multi-pressure scenario, special attention was paid to fishing-related disturbances and potential conflicts across different fishing m\ue9tier and with other sectors. Specifically, results highlighted the spatial features of the major fishing pressures (e.g., abrasion from trawling) affecting essential fish habitats, marine mammals and turtles in the study area. A portfolio of possible management measures is identified for the study area. It provides clear evidence that, in order to mitigate emerging conflicts and cumulative impacts, it is necessary to combine and integrate different types of measures: spatial measures modulated over time, monitoring and control, actions to fill knowledge gaps, concertation\u2014involvement\u2014co-management actions, improvement of governance systems, actions to support innovation in the sector, etc. Given the complex set of measures discussed, this work can provide a useful contribution to the management of fisheries both at local and regional level, fostering the transition to sustainable fisheries

The Seascape of Demersal Fish Nursery Areas in the North Mediterranean Sea, a First Step Towards the Implementation of Spatial Planning for Trawl Fisheries

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.Versión del editor4,411

Scientific, Technical and Economic Committee for Fisheries 73rd plenary report (STECF-PLEN-23-02)

Commission Decision of 25 February 2016 setting up a Scientific, Technical and Economic Committee for Fisheries, C(2016) 1084, OJ C 74, 26.2.2016, p. 4–10. The Commission may consult the group on any matter relating to marine and fisheries biology, fishing gear technology, fisheries economics, fisheries governance, ecosystem effects of fisheries, aquaculture or similar disciplines. The Scientific, Technical and Economic Committee for Fisheries held its 73 rd plenary from 10 to 14 July 2023.Peer reviewe