Comparación de la malla de rombo y cuadrada en la pesquería de arrastre de la merluza (Merluccius merluccius L. 1758) en el mar Adriático (Mediterráneo central)

A traditional codend (40 mm diamond mesh) and an experimental codend (40 mm square mesh) made of 2.6 mm diameter knotless PA netting were tested on a commercial trawl net on a sandy-muddy bottom (~70 m depth) of the Adriatic sea in order to assess the size selectivity of European hake (Merluccius merluccius) and the reduction of the discards in a demersal multi-species trawl fishery. The catch was sorted as target species and bycatch and the selectivity with respect to European hake was investigated using the covered codend method. The square-mesh codend allowed a reduction of about 37% of the fraction discarded at sea. The mean catch obtained with the experimental codend was lower than that obtained with the traditional codend (about 14 kg per haul) but the short-term economic losses were low (~12%). The square-mesh codend was also more selective than the traditional codend, giving the juveniles of European hake a good chance of escape: the mean selection length (L50) was 7.60 cm in DM and 12.98 cm in SM. Moreover, the mesh configuration did not affect the gear’s performance. Thus, the square-mesh codend could be an easy, inexpensive and useful solution for a more sustainable management of the resources in Adriatic multi-species fishery.Se han probado copos de malla tradicional (rombo de 40 mm) y una malla experimental (cuadrada de 40 mm), hechas en fibra de 2.6 mm de diámetro sin nudo en PA, en una red de arrastre comercial sobre fondos fangosos (~ 70 m de profundidad) en el Adriático, con el fin de conocer la talla de selectividad de la merluza (Merluccius merluccius) y la reducción de los descartes en una pesquería demersal mutiespecífica. La captura fue separada en especies objetivo y especies acompañantes. Para conocer la selectividad de la merluza se utilizó el método del sobrecopo. El copo de malla cuadrada obtuvo una reducción del 37% de la fracción descartada al mar. La captura media obtenida mediante el copo experimental fue menor que la obtenida con el copo tradicional (14 kg por lance aproximadamente), pero las pérdidas económicas a corto plazo fueron bajas (~ 12%). El copo de malla cuadrada fue también más selectivo que el copo tradicional, dando a los juveniles de merluza mayor probabilidad de escape; la talla de selección (L50) fue de 7.60 cm en malla de rombo y 12.98 cm en malla cuadrada. La configuración de la malla no afectó el funcionamiento del arte. De este modo, el copo de malla cuadrada podría representar una fácil, barata y práctica solución para conseguir una gestión más sostenible de los recursos en la pesquería multiespecífica del Adriático

Vertical Integration between Public and Private Parties A Legal Reconstruction of Local Public Utilities Mixed Corporation according to the Organizational Economic Theories.

L’assunto centrale della richiesta è che la partecipazione congiunta e la cooperazione tra parti pubbliche e private in una entità costituita in forma di società di capitali può essere intesa e ricostruita come una organizzazione ibrida all’interno del modello teorico dell’economia dei costi di transazione. La ricerca intende affermare che il partenariato pubblico privato istituzionalizzato è un’organizzazione ibrida all’interno della quale, le due parti (quella privata e quella pubblica) combinano impegni comuni ed obiettivi confliggenti. La ricerca rivela i tratti giuridici significativi, all’interno dell’ordinamento italiano, del partenariato pubblico-privato istituzionalizzato dove la partecipazione comune avviene all’interno della società di capitali. L’approcio al partenariato pubblico-privato istituzionalizzato secondo la teoria dei costi di transazione offre una nuova prospettiva circa la ricostruzione giuridica della cooperazione tra il soggetto pubblico e la parte privata. Le organizzazioni ibride costituite in forma di società di capitali forniscono soluzioni per la gestione dell’incertezza conseguenti all’incompletezza contrattuale attraverso l’inserimento della relazione di partenariato all’interno del sistema societario di amministrazione e controllo. In dipendenza del lungo periodo di funzionamento, il partenariato pubblico-privato istituzionalizzato deve essere in grado di adattarsi a cambiamenti nell’ambiente economico, giuridico e tecnologico e tali cambiamenti debbono essere considerati ed approvati nel contesto della relazione societaria tra il soggetto pubblico ed il socio privato. L’analisi, dedicata al sistema giuridico italiano, conferma che il diritto delle società di capitali ed il diritto amministrativo rilevano effettivamente e svolgono un ruolo cruciale nella costruzione appropriata della transazione tra le parti al fine di evitare squilibri di relazione tra il socio privato e la Parte Pubblica, la quale opera anche come Pubblica Autorità (il c.d. “problema di doppio allineamento”).Core assumption of the research is that the joint participation and cooperation of public and private parties in a corporatized entity could be regarded and reconstructed as a hybrid organization within the theoretical model of the Transaction Cost Economics (TCE). The research is inteded to affirm that the IPPP is a hybrid” where the two parties (the public and the private one) combine joint efforts and competing goals. The research reveals the most distinctive legal features, within the Italian Jurisdiction, of this form of “Institutionalized PublicPrivate Partnerships (IPPP)” where the joint participation takes place within a corporatized entity. The TCE Approach to Institutionalised Public-Private Partnerships (IPPP) offers a new perspective on the legal reconstruction of the cooperation between the public entity and the private party. The Corporatized Hybribs organizations provide solutions to manage uncertainty due to contract incompleteness by means of embedded relationships within the corporate governance framework. Due to the long-term functioning, the IPPP must be able to adjust to changes in the economic, legal or tecnological environment and those changes must be assessed and approved in the context of the corporate relationship between the public entity and the Private Partner. The analysis, focused on the Italian legal system, confirms that company law and administrative law do matter and play a key role in the appropriate design of the transaction in order to avoid unbalanced relationship between the Private Partner and the Public Party which acts as Public Authority too (the so called “double alignment problem”)

Reburial potential and survivability of the striped venus clam (Chamelea gallina) in hydraulic dredge fisheries

The striped venus clam (Chamelea gallina) is the main edible bivalve living in Italian waters. According to Regulation (EU) 2020/2237, undersized specimens (total length of the shell, < 22 mm) must be returned to the sea. C. gallina specimens of different size classes that had undergone hydraulic dredging and mechanized sorting were analysed for reburial ability in a laboratory tank and for survivability in the laboratory (135 clams, 21 days) and at sea (320 clams, 15 days). In the tank experiments, the reburial times ( T50 and T90) and the upper (+) and lower (−) confidence intervals (CIs) of the whole sample were about 4 h (CI+ 4.4, CI− 3.6) and 8 h (CI+ 8.2, CI− 7.7), respectively, and were significantly shorter for the medium-sized clams (22–24.9 mm) than for the smallest (< 21.9 mm) and the largest (> 25 mm) specimens. For the field survivability experiments, clams under and above the minimum conservation reference size were placed in separate metal cages. Survival rates were 94.8% and 96.2% respectively in the laboratory and at sea, without significant differences between the two experiments or among size classes. These findings conclusively demonstrate that C. gallina specimens returned to the sea have a very high survival probability and that they can contribute to mitigate the overexploitation of natural populations

Dredge selectivity in a Mediterranean striped venus clam (Chamelea gallina) fishery

The striped venus clam Chamelea gallina is the target of a large fleet of hydraulic dredgers, which represent an important fishing sector in terms of income and landings in the Mediterranean Sea. Although there is information on the catch rates, impact and discards related to this fishery, the size selection process carried out by the dredge during trawl under commercial conditions is practically unknown. The present study aimed to fill this gap, assessing the selectivity of the gear at different haul durations. We demonstrated that 25% of the clams entering the dredge were not size selected by it. Clams with a length (i.e. maximum distance between anterior and posterior margins) of 18.9 mm had 50% retention probability and tow duration did not affect the size selection process in the dredge. The dredge catch efficiency was 79% in numbers of clams and 89% in weight. 58% of the clams caught were below the minimum conservation reference size of 25 mm. The study demonstrates that to land only the legal sizes of clams, the additional size selection process carried out on board the fishing vessels by the sorting sieves is necessary.publishedVersio

Effect of Extension Piece Design on Catch Patterns in a Mediterranean Bottom Trawl Fishery

The catch composition of bottom trawls is commonly refined and improved through changes in codend design. Measures like reducing the number of meshes in codend circumference or turning diamond netting by 90 degrees are well known to improve the size selectivity of fish species with rounded cross-sectional shape. Based on this we speculated whether the same measures, if applied in other parts of a bottom trawl, would provide similar benefits as in the codend. Therefore, experiments were carried out by deploying these changes to the trawl extension piece in a Mediterranean bottom trawl fishery. However, for European hake and monkfish, results showed no indication of improved selectivity or catch pattern compared to the standard extension piece in the trawl. Contrary, for red mullet, one of the most important species in this fishery, reducing the number of meshes in the circumference of the extension piece jeopardized the size selection obtained in the trawl with a standard extension piece. The lesson learnt from this study was that the design changes that work for the codend do not necessarily work for other parts of the trawl. In fact, they can even have negative effects.publishedVersio

Transferable Fishing Concessions (TFC): A pilot study on the applicability in the Mediterranean Sea

Fisheries management systems based on Transferable Fishing Concessions (TFC) and similar rights-based systems have been developed during the last decades in some European countries. However, at present there is not a clear view on the possible effects caused by the application of this management systems in the Mediterranean Sea. The current study, involving nine Geographical Sub-Areas (GSAs) of the Mediterranean Sea, focuses on the appropriateness, transferability and modes of applicability of a TFC system in the Mediterranean area. Three different scenarios of quota allocation have been analyzed by taking into account biological, ecological, environmental, economic and social aspects: quota in terms of resource quantity, quota as a portion of the total fishing time, quota as a portion of the total fishing capacity. Results show that the transferability of a TFC-based system to the Mediterranean context appears to be low due to the characteristics of the Mediterranean fisheries (multispecificity of resources, fishing grounds shared among different countries, multigear, importance of small-scale fisheries) and to the general lack of sound and reliable individual historical data. The study also highlights rights-based systems such as Territorial Use Rights in Fisheries (TURF) might only be applied for the exploitation of sedentary resources, such as clams. A management system based on TFC could be theoretically reasonable for anchovy fishing, where a few species are caught, even if all countries and stakeholders should be involved in the decision making process

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