Black scabbardfish (Aphanopus carbo Lowe, 1839) in the southern Northeast Atlantic: considerations on its fishery

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Análisis de la forma del otolito como una herramienta para la segregación de stocks de sable negro, Aphanopus carbo Lowe, 1839, en aguas portuguesas

The variability in otolith contour shape of black scabbardfish (Aphanopus carbo) from Portuguese waters was analysed for stock discrimination purposes. The contour shape of otoliths from specimens caught off mainland Portugal, Madeira and Azores archipelagos was digitised and extracted according to the closed-form Fourier analysis technique. Mainland and Madeira specimens were compared through the adjustment of a MANOVA model to the normalised elliptic Fourier descriptor (NEFDs) obtained for the otoliths of 200 females and 200 males sampled at each area. Significant differences were found between areas and between sexes; the interaction term was not statistically significant. The effect of the area also proved to be significant when samples from the three regions were considered. These results were further supported by the discriminant analysis of the individual NEFDs for which the correct classifications were 87.5-89% when they were considered by sex and total length for the mainland and Madeira, and 90.9-97.7%, when NEFDs from the three areas were compared by sex and fish length. Otolith contour shape was shown to be a possible tool for differentiating between black scabbardfish stocks in the NE Atlantic.Se analizó la variabilidad de forma del contorno de otolitos del sable negro (Aphanopus carbo) procedentes de aguas Portuguesas como posible herramienta por la gestión de stocks. La imagen del contorno de otolitos de ejemplares capturados frente a la costa portuguesa, Archipiélago de Madeira y Archipiélago de Azores fue digitalizada y extraída conforme la técnica de análisis de Fourier para contornos cerrados. Como primer paso se compararon ejemplares de la costa portuguesa y de Madeira a través de un MANOVA sobre los descriptores elípticos de Fourier normalizados (NEFDs) estimados para los otolitos de 200 hembras y 200 machos de cada localidad. Se observaron diferencias significativas entre áreas y entre sexos, pero no hubo interacción entre los dos factores. El efecto del área también resultó ser significativo cuando se consideraron las muestras de las tres regiones. Estos resultados fueron corroborados por el análisis discriminante de los NEFDs para los cuales el porcentaje de clasificaciones correctas estuvo comprendido entre 87.5 y 89% cuando se compararon los NEFDs de la costa portuguesa y de Madeira por sexo, y considerando la talla del pez; y entre 90.9 y 97.7% cuando se consideraron las tres áreas por sexo y la talla total. Se demostró que la forma del contorno del otolito es una posible herramienta para diferenciar grupos de sable negro

Fecundity and sex steroid profile in boarfish Capros aper

The boarfish Capros aper is one of the most commonly discarded non-commercial species in the International Council for the Exploration of the Sea (ICES) Subdivision VIII in the Atlantic. An increasing interest in this fishery and an incomplete knowledge on the status of the stock justified the present investigation focused on the determination of fecundity type and its estimation, supported by sex steroid profiles for 17 beta-oestradiol (E2), 11-ketotestosterone and 17,20 beta-dihydroxypregn-4-en-3-one (17,20 beta-P). C. aper was found to have indeterminate fecundity with a mean relative batch fecundity during the spawning peak of 50 oocytes g(-1) eviscerated weight (W-E) and a mean relative annual fecundity of 4020 oocytes g(-1) W-E. E2 variations throughout the year indicated the existence of at least two important spawning events, one in winter (January-February) and the other in summer (June-August), with concentrations in females increasing from those with growing oocytes in the developing phase to those in the spawning capable phase. Higher E2 concentrations were also found from 2000 to 2400 hours and from 0800 to 1200 hours suggesting more intense vitellogenesis activity during the night and in the morning, in contrast to 17,20 beta-P concentrations, which were higher between 1200 and 2000 hours, suggesting a more intense spawning activity during this period.UID/MAR/04292/2019, UID/Multi/04326/2019, CEECIND/02705/2017, CEECIND/01528/2017, SFRH/BPD/108917/2015info:eu-repo/semantics/publishedVersio

Estrategias reproductivas en el sable negro (Aphanopus carbo Lowe, 1839) en el Atlántico nordeste

Gonads of the NE Atlantic black scabbardfish were examined to give an insight into the reproductive biology of this species. It was concluded that black scabbardfish had determinate fecundity because: (i) a distinct hiatus in oocyte size was observed between pre-vitellogenic and vitellogenic oocytes; (ii) vitellogenic oocytes increased in size during the spawning season; (iii) the number of vitellogenic oocytes did not increase during the spawning season; and (iv) the intensity of atresia was low in pre-spawning and spawning ovaries. Fecundity estimates ranged from 73 to 373 oocytes g-1 female. Comparison of developing ovaries from mainland Portugal and Madeira revealed that those from Madeira were more advanced in development, with more cortical alveoli stage oocytes and a higher gonadosomatic index. Starting in July, the reproductive development of all females from mainland Portugal was interrupted by a generalised atresia of developing oocytes. Completion of gametogenesis and spawning only occurred for fish from Madeira but some fish from this area also failed to complete oocyte development due to mass follicular atresia of vitellogenic oocytes. The percentage of Madeiran fish that failed to spawn due to follicular atresia ranged from 21.2% in 2006 to 37.4% in 2005.Las gónadas del sable negro del Atlántico nordeste fueron examinadas para conocer la biología reproductiva de esta especie. Los resultados sobre el tipo de fecundidad mostraron que la especie tenía una fecundidad determinada en base a los siguientes hechos: (i) hiato entre ovocitos previtelogénicos y vitelogénicos; (ii) aumento de tamaño de los ovocitos vitelogénicos durante el período de puesta; (iii) ausencia de incremento en el número permanente de ovocitos vitelogénicos avanzados durante el período de puesta y (iv) una pequeña atresia en los ovarios antes de la ovulación y durante ella. Las estimaciones de fecundidad se establecieron entre 73 y 373 ovocitos g-1 hembra. La comparación de los ovarios de hembras en desarrollo de aguas frente a Portugal continental y las de Madeira mostró una diferencia significativa en el tamaño medio de los ovocitos entre las dos áreas, y que las hembras de Madeira presentaron una mayor cantidad de ovocitos con alvéolos corticales y un índice gonadosomático mayor. A partir de julio y en hembras recolectadas frente a Portugal de continente, todos los individuos comenzaron a sufrir una atresia generalizada en sus ovocitos, mientras que en las aguas de Madeira, el ciclo reproductivo continúa hasta ovulación. Sin embargo, en algunas hembras de Madeira la gametogénesis también se paraliza y todos los ovocitos vitelogénicos son absorbidos vía atresia folicular. El porcentaje de hembras no reproductivas varió del 21.23% en 2006 al 37.4% en 2005

Otolith shape analysis as a tool for stock discrimination of the black scabbardfish, Aphanopus carbo Lowe, 1839 (Pisces: Trichiuridae), in Portuguese waters

suMMarY: the variability in otolith contour shape of black scabbardfish (Aphanopus carbo) from Portuguese waters was analysed for stock discrimination purposes. the contour shape of otoliths from specimens caught off mainland Portugal, Madeira and azores archipelagos was digitised and extracted according to the closed-form Fourier analysis technique. Mainland and Madeira specimens were compared through the adjustment of a ManoVa model to the normalised elliptic Fourier descriptor (neFds) obtained for the otoliths of 200 females and 200 males sampled at each area. significant differences were found between areas and between sexes; the interaction term was not statistically significant. the effect of the area also proved to be significant when samples from the three regions were considered. these results were further supported by the discriminant analysis of the individual neFds for which the correct classifications were 87.5-89% when they were considered by sex and total length for the mainland and Madeira, and 90.9-97.7%, when neFds from the three areas were compared by sex and fish length. otolith contour shape was shown to be a possible tool for differentiating between black scabbardfish stocks in the ne atlantic. Keywords: black scabbardfish, otolith, contour, shape, Fourier descriptors. resuMen: Análisis de la forma del otolito como una herramienta para la segregación de stocks de sable negro, AphAnopus cArbo Lowe, 1839, en aguas portuguesas. -se analizó la variabilidad de forma del contorno de otolitos del sable negro (Aphanopus carbo) procedentes de aguas Portuguesas como posible herramienta por la gestión de stocks. La imagen del contorno de otolitos de ejemplares capturados frente a la costa portuguesa, archipiélago de Madeira y archipiélago de azores fue digitalizada y extraída conforme la técnica de análisis de Fourier para contornos cerrados. Como primer paso se compararon ejemplares de la costa portuguesa y de Madeira a través de un ManoVa sobre los descriptores elípticos de Fourier normalizados (neFds) estimados para los otolitos de 200 hembras y 200 machos de cada localidad. se observaron diferencias significativas entre áreas y entre sexos, pero no hubo interacción entre los dos factores. el efecto del área también resultó ser significativo cuando se consideraron las muestras de las tres regiones. estos resultados fueron corroborados por el análisis discriminante de los neFds para los cuales el porcentaje de clasificaciones correctas estuvo comprendido entre 87.5 y 89% cuando se compararon los neFds de la costa portuguesa y de Madeira por sexo, y considerando la talla del pez; y entre 90.9 y 97.7% cuando se consideraron las tres áreas por sexo y la talla total. se demostró que la forma del contorno del otolito es una posible herramienta para diferenciar grupos de sable negro. Palabras clave: sable negro, otolito, contorno, forma, descriptores de Fourier. 2009, 47-53, Barcelona (spain) Issn: 0214-8358 Scientia Marina 73s2 decembe

Highly regional population structure of Spondyliosoma cantharus depicted by nuclear and mitochondrial DNA data

Resolution of population structure represents an effective way to define biological stocks and inform efficient fisheries management. In the present study, the phylogeography of the protogynous sparid Spondyliosoma cantharus, in the East Atlantic and Mediterranean Sea, was investigated with nuclear (S7) and mitochondrial (cytochrome b) DNA markers. Significant divergence of four regional genetic groups was observed: North Eastern Atlantic, Mediterranean Sea, Western African Transition (Cape Verde) and Gulf of Guinea (Angola). The two southern populations (Cape Verde and Angola) each comprised reciprocally monophyletic mtDNA lineages, revealed low levels of diversity in Cape Verde and high diversity for Angola despite being represented by only 14 individuals. A complete divergence between North Atlantic and Mediterranean populations was depicted by the mitochondrial marker, but a highly shared nuclear haplotype revealed an incomplete lineage sorting between these regions. Bayesian skyline plots and associated statistics revealed different dynamics among the four regions. Cape Verde showed no expansion and the expansion time estimated for Angola was much older than for the other regions. Mediterranean region seems to have experienced an early population growth but has remained with a stable population size for the last 30000 years while the North Atlantic population has been steadily growing. The lack of genetic structuring within these regions should not be taken as evidence of demographic panmixia in light of potential resolution thresholds and previous evidence of intra-regional phenotypic heterogeneity.info:eu-repo/semantics/publishedVersio

Pesquería del sable negro (Aphanopus carbo Lowe, 1839) frente a la costa continental portuguesa y la isla de Madeira

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.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. Apartir 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 “componente sur” del stock en la dinámica de población de la especie. Los porcentajes de especies descartadas, en número y en peso, fueron bajos, y parecían depender del número de anzuelos, tiempo de permanencia en el agua y profundidad

Variación ontogénica en la dieta y estrategia alimentaria de Raja undulata Lacepède, 1802 (Chondrichthyes: Rajidae) en la plataforma continental portuguesa

Under the scope of an ecosystem approach to fisheries, the understanding of trophic interactions is important for the assessment and consequently the proposal of suitable management measures. Raja undulata, like other rajids, is an important demersal predator in the Portuguese coastal community for which the biological and ecological information is still scarce. The ontogenetic dietary shift was investigated. Major length groups were defined through cluster analysis of the mean abundance of prey items. Prey diversity and feeding strategy were evaluated by length group. Multivariate analysis of variance was performed to test the influence of the factors sex, season and maturity on the diet of this species. It was concluded that R. undulata has a dietary ontogenetic shift within the definition of three major length groups (MLGs): 200-550 mm; 550-750 mm and 750-1000 mm. Diet varied from small and semi-pelagic to large and benthic prey. The feeding strategy of the species also changed from a generalised to a specialised diet. The decapod Polybius henslowi was the main prey item, especially for larger predators. Differences were found between sexes, maturity stages and seasons in each MLG.En el ámbito de la aproximación ecosistémica a las pesquerías, la comprensión de las interacciones tróficas es esencial para llevar a cabo una adecuada evaluación y gestión de los recursos. Raja undulata, al igual que otros rajiformes, es un importante depredador demersal que está presente en las costas portuguesas y sobre el que existe poca información biológica y ecológica. Se estudió la variación ontogenética en la dieta. Para determinar grupos de tallas se ha realizado un análisis de clusters empleando datos de abundancia media de presas. La diversidad de las presas y su estrategia alimentaria fueron evaluadas por grupos de tallas. Para comprobar la influencia de los factores sexo, estación del año y madurez en la dieta de esta especie se llevó a cabo un análisis multivariante de la varianza. Los resultados obtenidos indican que R. undulata presenta variaciones ontogenéticas en la dieta, habiéndose definido tres grupos de tallas (MLG): 200-550 mm; 550-750 mm and 750-1000 mm. La dieta varió desde organismos pequeños semipelágicos a presas bentónicas de mayor tamaño. Asimismo, se observó un cambio en la estrategia alimentaria de la especie, desde una dieta generalizada a otra más especializada. El decápodo Polybius henslowi constituyó, en concreto para los depredadores de mayor tamaño, la presa principal. Se detectaron diferencias por sexo, estado de madurez y estación del año en cada MLG