Browsing by Author "Russo, Tommaso"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- An approach to map and quantify the fishing effort of polyvalent passive gear fishing fleets using geospatial dataPublication . Sales Henriques, Nuno; Russo, Tommaso; Bentes, Luis; Monteiro, Pedro; Parisi, Antonio; Magno, Ramiro; Oliveira, Frederico; Erzini, Karim; Gonçalves, Jorge Manuel SantosThe use of tracking devices, such as vessel monitoring systems or automatic identification system, enabled us to expand our knowledge on the distribution and quantification of fishing activities. However, methods and models based on vessel tracking data are mostly devised to be applied to towed gears, whereas applications to multi-gear and passive fisheries have been underrepresented. Here, we propose a methodology to deal with geospatial data to map and quantify the fishing effort, as soak time, of passive fishing gears used by a multi-gear fishing fleet. This approach can be adapted to other passive multi-or single-gear fisheries, since it requires only three variables that can be extracted from a pre-classified dataset, to identify the beginning (gear deployment) and the end (hauling) of passive fishing events. As far as we are aware, this is the first time a methodology that allows quantifying the soak time of static passive fishing events, within a polyvalent fishery context, is presented. We argue that the information that can be extracted from such approaches could contribute to improved management of multi-gear and static-gear fisheries and the ecosystem-based approach.
- Identifying persistent hot spot areas of undersized fish and crustaceans in southern european waters: implication for fishery management under the discard ban regulationPublication . Milisenda, Giacomo; Garofalo, Germana; Fiorentino, Fabio; Colloca, Francesco; Maynou, Francesc; Ligas, Alessandro; Musumeci, Claudia; Bentes, Luis; Gonçalves, Jorge Manuel Santos; Erzini, Karim; Russo, Tommaso; D’Andrea, Lorenzo; Vitale, SergioThe 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
- Let’s measure it: an approach of high-resolution estimates of bottom fixed net fishing effort at national levelPublication . Sales Henriques, Nuno; Erzini, Karim; Gonçalves, Jorge Manuel Santos; Russo, TommasoFisheries are one of the most important food sources for human consumption whilst being amongst the most impacting and extractive activities happening within the marine environment, which makes it imperative to properly manage this activity. To improve fisheries management, the precise quantification of fishing effort is of the outmost importance. Yet, present methods for effort estimation, especially at broad scales, are hampered by difficulties in data access and usually rely on coarse effort metrics or on costly data collection for quantifying fishing effort with higher resolution. In the present work, we propose an approach of high-resolution fishing effort estimates of net fishing, as length of nets operated by a given fleet, at the national level. It relies on sampling of effort, derived from classified and easy to access vessel tracking data - AIS, and fishery dependent data - logbook and landings data. The proposed methodology combines trip-based effort estimates, derived from AIS data, as a foundation to extrapolate the total fishing effort, through the number of fishing trips linked to official landings and logbook data. It is estimated that in the years from 2014 to 2020 an average of 180 200 km of static nets (gillnets and trammel nets), which corresponds to approximately 4.5 and 210 times the lengths of the equator and the Portuguese Atlantic coastline respectively, are used in Portuguese mainland waters each year, by a fleet of slightly more than 100 vessels. The presented methodology allows to quantify and study the variation of the nominal fishing effort, at country level, with a higher resolution than what is usually used and at very low cost. We argue that such methodologies need to be developed and explored in order to have better and more comprehensive estimates of fishing effort which will contribute and improve the sustainable management of fisheries and the marine environment.
- On the accuracy of self-reported data for fishing effort estimates – a case study from a polyvalent coastal fisheryPublication . Russo, Tommaso; Sales Henriques, Nuno; Erzini, Karim; Gonçalves, Jorge Manuel SantosThe quantification and the analysis of fishing activity is one the most important features in fisheries sciences and ocean management, and fishery-dependent data has always been the main source of information used to that end. Within the different types of fishery-dependent data, self-reported logbook data provides vast amounts of different information about fishing activities. Despite their enormous importance, the quality and reliability of these data are surprisingly understudied. Yet, the accuracy and consistency of this type of data are sometimes difficult to quantify. With the purpose of studying how logbook data can be a reliable source for fishing effort quantification, here we estimate and compare, for the Portuguese mainland coastal polyvalent fleet, the fishing effort of each vessel from two types of fishery-dependent data: 1- logbook data and 2- official landing data. The results showed a difference of 22.7 % between the overall number of fishing trips from both data types. In particular, vessels had a significantly lower number of fishing trips logged on logbook data than the trips estimated from official landing data. Our findings support the concerns regarding the accuracy of logbook data, especially for estimating fishing effort. As far as effort inference is concerned, we suggest that the estimation of fishing effort from data logged and recorded from a third party, like official landing data, is a more reliable source of information than selfreported data.
- The MINOUWApp: a web-based tool in support of by-catch and discards managementPublication . D’Andrea, Lorenzo; Campos, Aida; Erzini, Karim; Fonseca, Paulo; Franceschini, Simone; Kavadas, Stefanos; Maina, Irida; Maynou, Francesc; Russo, TommasoCurrent fishing practices often do not allow adequate selection of species or sizes of fish, resulting in unwanted catches, subsequently discarded, with the consequent negative effects on both marine communities and fisheries profitability. The cross-analysis of density patches of potential unwanted catches and distribution of fishing effort can support the identification of spatial-temporal hot-spots in which the fishing pressure should be reduced to limit the amount of discards. The MinouwApp represents a technological and methodological framework to bring different, and structurally complex, sources of georeferenced data together into a simple visual interface aiming to interactively explore temporal ranges and areas of interest. The objective is to improve the understanding of fisheries dynamics, including discards, thus contributing to the implementation of discard management plans in a context of participative, ecosystem-based fisheries management strategies.