Black scabbardfish is a deep-water species, common in the NE Atlantic at depths between 450 and 1300 m, currently exploited by some European countries. Between May 1998 and April 2000, specimens collected at three different locations in the NE Atlantic—NW of Scotland, Sesimbra (mainland Portugal) and Funchal (Madeira)—were analysed. The evolution of maturity of both sexes throughout the year was studied based on the macroscopic and microscopic analysis of the gonads. Specimens with the largest total length were found in Funchal, whereas the smallest size was recorded in the NW of Scotland. Neither spawners nor post-spawners were ever observed in NW of Scotland and Sesimbra. In Sesimbra, only a few individuals attained pre-spawning stage and most of the early developing females exhibited atresia in their ovaries. In Funchal, all the maturity stages were found; spawners occurred from September to December (females) and from August to December (males). Length of first maturity for females was estimated to be around 1000 mm. Two groups of spawners with different sizes were observed during the spawning period off Madeira.
In mainland Portugal, rays constitute an important by-catch of multi-gear shelf fisheries. However and despite their economical importance, landing information discriminated by species is scarce. The relative stability in Portuguese annual landings of rays and skates can be misinterpreted as no evidence for species declines. The present concern on the overexploitation of individual species arises from both theoretical considerations about biological and ecological traits and for historical reasons. This work constitutes an approach for a retrospective analysis of ray landings in mainland Portugal. Data from research surveys carried along the Portuguese coast was used to infer possible changes in species composition on Portuguese landings. Clusters were determined based on data collected during surveys from species composition for three timeperiods, 1989-1991, 1995-1997 and 2001-2003. The relative importance of the associate species within clusters was the input data to define discriminating rules posteriorly used to assign clusters to landings from each commercial vessel. The results show an increase of species relative importance and changes on species abundance: Raja brachyura and Raja clavata decreased, whilst Leucoraja naevus, increased. Furthermore, it was observed a decrease on the mean weight of the two first species and a relative stability in the last one. Such results reflect the importance of species life-history characteristics in particular, on the response to fishing impact.
suMMarY: For several decades, the black scabbardfish (Aphanopus carbo, lowe 1839) has been a valuable resource for fishing communities in Madeira and more recently for those in mainland Portugal. the evaluation of the species' exploitation status was conducted only in the late 20th century and separated for the two areas of the Portuguese exclusive economic Zone (eeZ). nowadays, species stock assessment studies are usually conducted in the framework of scientific working groups from regional fisheries organizations: ices analyses data from the fishery operating in continental waters, whereas cecaF deals with the data pertaining to the Madeiran fishery. this paper presents the first attempt to combine the information available from the two longline fisheries targeting black scabbardfish in Portuguese waters in one single analysis. a description of the two fleets' technical characteristics was conducted and a unique model was developed for the standardization of the fishing effort aimed at the species in the Portuguese eeZ. From this model, weekly landings-per-unit-effort time series were estimated by region for the period 2005-2007 and compared using a non-parametric statistical test. Percentages of discarded species, in number and weight, were calculated and reveal consistently low figures. these discards seem to depend on the number of hooks, soaking time and depth.Keywords: lPue, fishing regime, deep-water, longline, discards, glM, time-series. resuMen: Pesquería del sable negro (AphAnopus cArbo Lowe, 1839) frente a la costa continental portuguesa y la isla de Madeira. -durante varias décadas, el sable negro (Aphanopus carbo) ha sido un recurso valioso para las comunidades de pesca de Madeira y más recientemente para las comunidades de pesca de Portugal continental. la evaluación del estado de explotación de la especie se inició a finales del siglo XX y se realizó separadamente para dos áreas de la Zona económica exclusiva (Zee) portuguesa. hoy en día, los estudios de evaluación de stock de la especie son, por lo general, conducidos por grupos de trabajo científicos pertenecientes a organizaciones pesqueras regionales; ices analiza datos de las pesquerías de las aguas continentales mientras que cecaF trabaja con los datos pertenecientes a la pesquería de Madeira. este trabajo representa el primer intento de reunir, en un único análisis, la información disponible de las dos pesquerías de palangre que capturan el sable negro en aguas portuguesas. se realizó una descripción de las características técnicas de las dos flotas y se desarrolló un modelo único para la estandarización del esfuerzo de pesca dirigido a la especie en la Zee portuguesa. a partir de este modelo, se estimaron series temporales de desembarques semanales por unidad de esfuerzo para esta región durante el periodo 2005-2007, y se compararon utilizando una prueba estadística no paramétrica. se espera que los resultados, alcanzados gracias a la reciente cooperación entre las organizaciones regionales de Pesca, ayuden a entender el papel del llamado...
A new chimaerid species closely related to Hydrolagus pallidus is described from 13 specimens captured on the Portuguese continental slope (north-east Atlantic) by commercial longliners at depths of c. 1600 m. The new species is large-bodied with a rose to light brown body colouration. Hydrolagus lusitanicus n.sp. presents a combination of external morphological characters that allow it to be clearly differentiated from its congeners, in particular, the ratios of pectoral fin length: pectoral fin width and pelvic fin length: pelvic fin width; in having a serrated posterior edge of the dorsal spine; a high number of ridges in the dental plates. Additionally in males, there are differences on the shape and number of hooks in the frontal tenacula, on the number of spines in the prepelvic tenacula and on the length of the pectoral fin margin.
The black scabbardfish is a deep-sea teleost species with high commercial interest in the NE Atlantic. While it is caught by large offshore trawlers in the North of Europe, in the south it is captured by artisanal longlines. On the Portuguese continental slope, in the south of ICES Division IXa, a longline fleet has been engaged in the capture of black scabbardfish for more than 20 years. This paper reviews and analyses the features of this fishery from a temporal perspective based on information from different data sources. The fishery is based on the port of Sesimbra, where a family type fishing community strives to keep catches profitable without altering the artisanal features that characterizes the fleet. Although the fleet has experienced some technical improvements through time, the fishing operations and strategy have changed very little. Fishing occurs at particular areas on the slope, where individual vessels have their own fishing grounds. Annual landings surpassed 4,000 tonnes in the early 1990's, but decreased to nearly 3,000 tonnes and have remained at this level since 2000. The length structure of the landings was stable from 2000 to 2005, with a modal (total length) class of 1,090 mm.Monthly landings per unit effort estimated by a generalized linear model did not present any marked trend for the period 2000-2004. The landings reported in mainland Portugal were compared with the ones from other regions of the ICES area and the different characteristics of the fisheries operating in the north and south of Europe were analysed.
SuMMarY: Black scabbardfish stock structure is still unknown in european waters where, due to the scarcity of biological information, the IceS considers that there is a single stock unit. this study is the final outcome of a scientific project that applies a holistic approach to research on the population structure of the black scabbardfish and aims to define the most appropriate strategy for the conservation of this resource in southern ne atlantic waters. the factors studied include life history parameters, otolith shape analysis, parasites, landings-and-effort data and contaminants. Sampling was conducted between 2005 and 2007 in three areas of the southern ne atlantic: mainland portugal, Madeira and the azores. the mainland and the azores have an established commercial fishery, whereas the azores has only an exploratory fishery. the majority of results indicated the existence of different stocks of black scabbardfish in the study area. of the 8 parameters, 6 were in agreement with separate stocks between the mainland and Madeira, 5 were in agreement with separate stocks between the mainland and the azores, and 4 were in agreement with separate stocks between Madeira and the azores.Keywords: Aphanopus carbo, black scabbardfish, stock identity, holistic approach, northeast atlantic.reSuMen: Estructura de stock de sable negro (AphAnopus cArbo Lowe, 1839) en el sur del Atlántico nordeste. -La estructura de la población de sable negro en las aguas europeas es todavía desconocida y, debido a la escasez de la información biológica disponible, IceS ha considerado una sola unidad de stock en la totalidad de dichas aguas. el proyecto que originó este estudio es un trabajo integrado para investigar la estructura poblacional de sable negro y pretende definir la estrategia más apropiada para la conservación de este recurso en aguas del sur del atlántico nordeste. para cumplir con el objetivo del proyecto se llevaron a cabo varios estudios: determinación de parámetros que definen el ciclo vital, análisis de forma del otolito, parásitos, datos de desembarques y esfuerzo pesquero, y contaminantes. el muestreo fue realizado entre 2005 y 2007 en tres áreas del sur del atlántico nordeste: portugal continental, aguas de Madeira y azores. Las dos primeras áreas tienen una pesquería comercial establecida, mientras que en azores existe una pesquería exploratoria. La mayoría de los resultados concluyeron la existencia de diferentes unidades poblacionales del sable negro en el área sur del atlántico nordeste. Seis de los ocho parámetros confirman la separación entre los individuos del continente y Madeira, mientras que 5 parámetros corroboran la separación entre el continente y azores. Solamente 4 técnicas corroboran la separación entre Madeira y azores.Palabras clave: Aphanopus carbo, sable negro, identidad de stock, aproximación holística, atlántico nordeste.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.