Browsing by Author "Leal, Wendell Medeiros"
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- Applicability of the current stock assessment models to the priority azorean fishery resourcesPublication . Leal, Wendell Medeiros; Pinho, Mário Rui; Santos, RégisThis work presents a guidance to conduct stock assessment based on ICES Maximum Sustainable Yield framework. A cross-analysis based on the models’ assumptions and inputs and data available for 22 Azorean priority stocks was performed to assess the applicability of each model to each stock. Information currently available for coastal and some demersal/deep-water stocks limits the use of most models validated by ICES. Only four demersal/deep-water stocks (Pagellus bogaraveo, Helicolenus dactylopterus, Phycis phycis, and Pontinus kuhlii) have data availability and quality enough to perform trend analysis, length-based and catch and survey-based methods. The next steps involve validating life-history parameters, evaluating model performances, and applying alternative tools for data-deficient stocks. Additional monitoring programs are of utmost importance, which must collect missing information and clarify stock delimitation to improve assessment quality. This study guides future stock assessment actions and highlights data gaps where future research should focus.
- Estimates of biomass and potential yield for the deep-water red crab, Chaceon affinis and the toothed rock crab, Cancer bellianus (Decapoda: Brachyura) off the Azores (Mid-North Atlantic)Publication . Pinho, Mário Rui; Santos, Régis; Melo, Octávio; Isidro, Eduardo; Novoa-Pabon, Ana Maria; Leal, Wendell Medeiros; Gonçalves, João M.Available information on the deep-water red crab, Chaceon affinis and the toothed rock crab, Cancer bellianus, resulting from exploratory research surveys and commercial fishing experiments carried out in the Azorean Exclusive Economic Zone (EEZ), were summarized to estimate the biomass and potential yield (Maximum Sustainable Yield – MSY) for both fishery resources. The fishery potential was estimated through empirical methods usually applied when available information is scarce in line with the precautionary approach principle. Results suggest modest MSY values (considered as precautionary Total Allowable Catch – TAC), around 2,205 t for the deep-water red crab (2,159 t year-1 at seamounts and 46 t year-1 at coastal areas), and 471 t for the toothed rock crab (281 t year-1 at offshore seamounts and 189 t year-1 at coastal areas). Considering the limited available data and high uncertainty associated with these estimations, it is suggested that only a reduced number of vessels should be allowed to fish in the aggregated areas, namely coastal and seamount areas. The exploitation of these resources should be started in a very limited way followed by an ad hoc observer programme, aiming to collect reliable data that will allow, if it is the case, to raise in the future the exploitation level in a gradual and sustainable way.
- Stock assessment prioritization in the Azores : procedures, current challenges and recommendationsPublication . Santos, Régis; Leal, Wendell Medeiros; Pinho, Mário RuiTo implement the Marine Strategy Framework Directive (MSFD) of the European Union (EU) in order to achieve the Sustainable Development Goals (SDGs) of the United Nations (UN) regarding the biological sustainability of marine fisheries, it is fundamental to apply a framework for prioritizing stocks. This process helps the regional managers to make the best use of data and resources for management. The present study describes and applies a standard framework for prioritization of stock assessment in the Azores. The current state of the selected stocks is identified and the main issues and gaps for assessment are presented and discussed. A total of 138 species were landed in the region during the period 2009-2019. Twenty-two (18 fishes, 2 molluscs and 2 crustaceans) were selected as priority stocks according to the Food and Agriculture Organization of the United Nations (FAO) and International Council for the Exploration of the Sea (ICES) criteria. Most of these showed a decreasing trend in their abundances. Only four stocks are currently assessed using data-limited approaches: Pagellus bogaraveo, Aphanopus carbo, Raja clavata, and Trachurus picturatus. No biological reference points are defined and stock and exploitation status relative to Maximum sustainable yield (MSY) are not assessed. The main issues identified were the lack of information regarding catches and population structure and validated analytical methods. Future studies should evaluate which methods for assessment may be suitable for each stock and identify what additional data are needed to improve the analyses.
- Synopsis of biological, ecological and fisheries-related information on priority marine species in the Azores regionPublication . Santos, Régis; Leal, Wendell Medeiros; Pinho, Mário RuiStudies on life history and stock structure of marine species have evolved in the Azores region during the last 40 years. This information is essential to feed fishery stock assessment models that fit available data to determine current stock status and provide advice on the optimum (sustainable) exploitation. However, most of these data are only available in a fragmented manner in several scientific papers, books, theses and reports. In some cases, these sources of information are difficult to access. The present document aims to gather and summarize biological, ecological and fisheries-related information for the main commercially exploited species in the Azores. The species treated here have previously been selected as priority stocks for assessment and monitoring at regional level by applying a standard framework aligned with the ICES and FAO recommendations. They are: the blackspot seabream Pagellus bogaraveo, veined squid Loligo forbesii, blue jack mackerel Trachurus picturatus, blackbelly rosefish Helicolenus dactylopterus, red porgy Pagrus pagrus, forkbeard Phycis phycis, European conger Conger conger, alfonsino Beryx decadactylus, splendid alfonsino B. splendens, parrotfish Sparisoma cretense, silver scabbardfish Lepidopus caudatus, red scorpionfish Scorpaena scrofa, Atlantic chub mackerel Scomber colias, blacktail comber Serranus atricauda, offshore rockfish Pontinus kuhlii, amberjacks nei Seriola spp., common mora Mora moro, common spiny lobster Palinurus elephas, black scabbardfish Aphanopus carbo, rough limpet Patella aspera, thornback ray Raja clavata, and Mediterranean slipper lobster Scyllarides latus. The document is presented as concisely and effectively as possible. An overview table of the current data available is presented by stock.