Applicability of the current stock assessment models to the priority azorean fishery resources

This 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.This study is part of the PESCAz project (ref. MAR-01.03.02-FEAMP-0039) financed by the European Maritime and Fisheries Fund (EMFF) through the Regional Government of the Azores under the MAR2020 operational program.info:eu-repo/semantics/publishedVersio

Trends in the fishery and catch patterns of kitefin shark, Dalatias licha (Bonaterre, 1788), from off Azores, through a GIS spatial analysis.

During the last two decades the Azorean fishing community has profited from the kitefin shark fishery which in the year 2000 generated an estimated revenue of approximately €12,500. This resource has been targeted mainly by small fishing vessels operating in the Azores archipelago since the late 1970s. The vulnerability of this species to exploitation has raised the concern about the impact of the fishery on the resource. The monthly landings of three artisanal fishing vessels were monitored and possible changes to kitefin shark abundance and catch pattern, for the period between 1986 and 1998, were geographically analysed. A vector-based GIS (Geographic Information System) was constructed to evaluate the changes in the number of individuals captured and squalene oil barrels obtained through a spatio-temporal perspective. In order to investigate which were the most profitable fishing areas. An optimum fishing pathway was generated for one of the vessels in 1997 based on a raster GIS. The results indicated a decrease of kitefin shark catches in several areas around Azores archipelago and over the time period analysed. The analysis of the data in a GIS environment yield a dynamic and integrated view of the species catches off Azores in a temporal and spatial perspective

Staining techniques for ageing tope shark, Galeorhinus galeus (Linnaeus, 1758), from the Azores : a comparison based on precision analysis.

A vertebrae sample of tope shark, Galeorhinus galeus (Linnaeus, 1758), stratified by sizeclasses,was used to test between different staining techniques of enhancing vertebral growth ring visibility. Four techniques were tested: alizarin red, silver nitrate and cobalt nitrate staining, and the “deep-coned vertebrae” technique. The latter was discarded due to its unsuitability for tope shark vertebrae. The cobalt nitrate original protocol was modified. Upon staining, each vertebra was subject to three replicated independent readings, by a single reader. Within-reader consistency and bias of growth ring counts determination were evaluated using four different precision indices: percent of agreement (PA), average percent error (APE), coefficient of variation (V) and index of precision (D). Results indicated that the vertebrae stained with the cobalt nitrate technique showed both better optic enhancement of growth rings and higher degree of count consistency, comparatively to the alizarin red and silver stained vertebrae. Conclusively, the cobalt nitrate was the most efficient staining technique upon tope shark vertebrae, among the methods tested herein

Stock assessment prioritization in the Azores : procedures, current challenges and recommendations

To 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.info:eu-repo/semantics/publishedVersio

Nueva contribución a las características reproductivas del Helicolenus Dactylopterus Dactylopterus en el Atlántico noreste (Archipíelago de Azores)

This work describes and identifies the macroscopic and corresponding microscopic changes of the gonads of an important commercial fish species, Helicolenus dactylopterus dactylopterus, from Azores Archipelago. The new contribution relates the macroscopic scale with the histological stages. The annual changes in the gonad, together with the analysis of the monthly gonadosomatic indices, and complementary observations with scanning electron microscopy, allow us to conclude that the females are internally inseminated between July and November and spawn between January and March. There is a separation between female and male reproductive cycles. The overall sex-ratio observed was 1:1, but seasonal and length related differences were observed. This suggests differences and changes in availability, probably related to the annual reproductive cycle and changes in feeding behaviourEste trabajo describe e identifica las etapas de madurez macroscópicas y correspondientes etapas microscópicas de las gónadas de una especie comercial importante, Helicolenus dactylopterus dactylopterus, de la pesquería del archipiélago de las Azores. La nueva contribución relaciona la escala macroscópica con las etapas histológicas. Los cambios anuales de las gónadas, junto con el análisis de los índices gonadosomáticos y con las complementarias observaciones con microscopía electrónica (SEM), permiten concluir que las hembras son inseminadas internamente entre julio y noviembre y desovan entre enero y marzo. Hay una separación entre los ciclos reproductivos de las hembras y los machos. En general la proporción sexual es 1:1; pero desviaciones de esta proporción fueron registradas estacionalmente y para para ciertas clases de talla. Estas desviaciones sugieren diferencias y cambios en la disponibilidad, relacionadas probablemente con los cambios reproductivos anuales y con el comportamiento alimentario.  

New records and notes on little known shrimps (Crustacea, Decapoda) from Azorean waters.

Five species of shrimps (Crustacea, Decapoda) are recorded for the first time from the Azores: Funchalia villosa (Bouvier, 1905), Parapasiphae sucatifrons S.I. Smith, 1884 Heterocarpus ensifer A. Milne-Edwards, 1881, Heterocarpus laevigatus Bate, 1888 and Plesionika williamsi Forest, 1964. The variability of Plesionika gigliolii (Senna, 1903) and its relationship with P. sindoi (Rathbun, 1906) are discussed

Annotated list of fishes caught by the R/V ARQUIPÉLAGO off the Cape Verde archipelago.

A prospective survey was carried out in October - November of 2000, in the Cape Verde archipelago, by the R/V ARQUIPÉLAGO. The main objective was to determine the species composition and relative abundance of the demersal fish resources living in the waters of the Cape Verde archipelago. A list of fishes caught with bottom longline during the survey is presented in this document, along with information about the area, depth limits and the relative abundance of the species in the catches. Ninety-seven different species from 49 families were identified from 20 long-line sets. To our knowledge, the following 12 species were recorded for the first time from the waters of Cape Verde islands: Etmopterus princeps, Etmopterus pusillus, Gymnothorax maderensis, Myroconger compressus, Laemonema robustum, Beryx splendens, Scorpaena elongata, Serranus atricauda, Taractes rubescens, Taracthichthys longipinnis, Pagrus africanus and Cathidermis sufflamen. The species Laemonema robustum, were new to the CLOFETA area

Considerations on the biology of Plesionika narval (Fabricius, 1787) in the Northeastern Atlantic

Life history traits of Plesionika narval were studied in the Northeastern Atlantic, Madeira archipelago including growth, age, sexual maturity, recruitment pattern and mortality. A total of 28,262 specimens were sampled over a period of 8 years comprising two time series from 1991 to 1995 and 2004 to 2008. The relative growth pattern showed a negative allometric nature of growth for combined sexes, males, females, non ovigerous and ovigerous females. Estimated asymptotic carapace length (CL∞) and growth coefficient (K) showed higher values in females (CL∞=30.21 mm, K=0.450 year-1 ) comparatively to males (CL∞=28.61 mm, K=0.430 year-1 ), resulting in better overall growth performance in females. The maximum life span (tmax) was estimated at 6.81 years for combined sexes, 6.97 for males and 6.66 for females, however 99.95% of the individuals were younger than 3 years. Although a seasonal spawning season was evident from late summer to late autumn, reproduction may be prolonged throughout the year since ovigerous females are present in all months and achieving sexual maturity at 14.61 mm. The recruitment pattern was continuous throughout the year with a major peak occurring in spring. The total mortality (Z) and fishing mortality (F) were higher in females than in males while natural mortality (M) was similar between groups.info:eu-repo/semantics/publishedVersio

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)

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.Régis Santos was supported by the IMAR Institute of Marine Research, through a post-doc fellowship (ref. IMAR/DEMERSAIS/001-2018). Wendell Silva was funded by the IMAR Instituto do Mar, through a scholarship (ref. IMAR/UNI/MAR/04292/2013 MARE/001-2018). Ana Novoa-Pabon was funded by an FCT Ph.D. fellowship (ref. SFRH/BD/124720/2016).info:eu-repo/semantics/publishedVersio

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)

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.Régis Santos was supported by the IMAR Institute of Marine Research, through a post-doc fellowship (ref. IMAR/DEMERSAIS/001-2018). Wendell Silva was funded by the IMAR Instituto do Mar, through a scholarship (ref. IMAR/UNI/MAR/04292/2013 MARE/001-2018). Ana Novoa-Pabon was funded by an FCT Ph.D. fellowship (ref. SFRH/BD/124720/2016).info:eu-repo/semantics/publishedVersio