Differential age-related phenology in lesser black-backed gull Larus fuscus wintering in the Malaga area

[EN]: We aimed to identify the existence of age-classes groups that shared similar seasonal patterns in migration movements for the lesser black-backed gull Larus fuscus. The gull age-classes groups were defined as sets of age-classes that were present in the harbour of Malaga (South of Spain) simultaneously during the wintering season. We distinguished ten groups of age-classes, which can be subsequently lumped into four big age-class groups: (i) immature stage-class, (ii) young breeders, (iii) age-classes from 6 to 11 years old, and (iv) age-classes older than 11 years old. Our present results supported the 'dominance and arrival time model'.[ES]: Se pretendía identificar la existencia de grupos de clases de edad con un patrón estacional similar en la gaviota sombría Larus fuscus. Los grupos se definieron como conjuntos de clases de edad que estuvieron presentes de forma simultánea siguiendo un mismo patrón temporal en el puerto de Málaga durante la temporada de invernada. Se distinguieron diez grupos de clases de edad, los cuales a su vez pueden agruparse en cuatro grandes grupos: (i) inmaduros, (ii) jóvenes reproductores, (iii) clases de edad de 6 a 11 años y (iv) clases de aves mayores de 11 años. Nuestros resultados apoyan la teoría de la ‘posición dominante y el modelo de la hora de llegada’.This study was partially funded by the project CGL2009-11316 (Ministerio de Ciencia e Innovación, Spain, and FEDER).A. Estrada has a postdoctoral contract jointly financed by the European Social Fund and by the Junta de Comunidades de Castilla-La Mancha (Spain), in the framework of the Operational Programme FSE 2007-2013.Peer Reviewe

Permeable frontiers in the open sea: The case of Swordfish in the Atlantic Ocean

There is a vivid debate about the border location between North and South Atlantic swordfish stocks. Climate oscillations, East Atlantic (EA) and North Atlantic Oscillation (NAO), have a major impact on the Northern Hemisphere climate and weather conditions. The initial hypothesis of present study was that if it is considering the southern frontier, each stock will be differentially affected by both climatic oscillations, which would imply the existence of a strong border. However, a similar effect on both sides of the border would result in a permeable barrier. The results suggest that the combined effects of EA and NAO affect both the North and the South Atlantic swordfish stocks in similar ways, and consequently, the location of the border may reside farther north than the current management boundary at 5°N.Postprint0,60

DIFFERENTIAL TEMPORAL AND SPATIAL DISTRIBUTION OF ADULT LOGGERHEAD SEA TURTLES FROM GULF OF CÁDIZ TO WESTERN MEDITERRANEAN SEA

The aim of this paper was to search for and model spatial and seasonal trends in occurrences (stranding or by-catches) of adult loggerhead turtles in the western Mediterranean area and Gulf of Cádiz (Atlantic) independently of their origin. Adult turtles were only bycaught on longlines from May to August. Adults were stranded in the eastern and western areas of the Strait of Gibraltar threshold throughout the year. In the Gulf of Cádiz (Atlantic), strandings were significantly concentrated in May and June, whereas in the Alboran Sea (Mediterranean), strandings mainly occurred in June and July. The probability of catching a mature loggerhead increases during June and July south of the Balearic Islands. The results suggest that adult loggerhead turtles move (migrate) from the Atlantic area (Gulf of Cádiz) to the Mediterranean (Alboran Sea) from May to June, and subsequently move to the Balearic Sea from June to July. These results are in line with those obtained by previous studies.Postprin

Assessing the response of exploited marine populations in a context of rapid climate change: the case of blackspot seabream from the Strait of Gibraltar

Evaluación de la respuesta de las poblaciones marinas explotadas en un contexto de cambio climático rápido: el caso del besugo de la pinta en el estrecho de Gibraltar Existe una creciente preocupación por la disminución de la pesca y la posibilidad de que esta disminución se acelere debido al cambio climático. Los estudios sobre la pesca a pequeña escala podrían ayudar a mejorar nuestra comprensión de los efectos del clima en la ecología de las poblaciones explotadas. El estrecho de Gibraltar es una importante zona de pesca para la flota artesanal. En esta zona, el besugo de la pinta (Pagellus bogaraveo) es la especie más importante para la pesca artesanal en vista de su volumen de descarga. Los objetivos de este estudio consisten en estudiar los posibles efectos de dos oscilaciones atmosféricas: la oscilación del Atlántico Norte (NAO) y la oscilación del Ártico (AO), en la captura del besugo de la pinta en el estrecho de Gibraltar con objeto de determinar su relación con las condiciones oceanográficas, y mejorar nuestro conocimiento sobre los posibles efectos del cambio climático en la ecología de la pesca, para poder mejorar la gestión de la actividad pesquera. Utilizamos dos tipos de datos de diferentes fuentes: (i) los desembarques por unidad de esfuerzo registrados por un segundo grupo de trabajo entre Marruecos y España sobre el besugo de la pinta en la zona del estrecho de Gibraltar, para el período 1983–2011, y (ii) los desembarques registrados de besugo de la pinta obtenidos de las estadísticas anuales de pesca publicadas por la Junta de Andalucía. Nuestros resultados indican que el desembarque a largo plazo del besugo de la pinta en el estrecho de Gibraltar está íntimamente relacionado con las oscilaciones atmosféricas. Por lo tanto, los períodos prolongados de tendencias positivas en la NAO y la AO podrían favorecer altos rendimientos pesqueros. En contraste, las tendencias negativas de la NAO y la AO reducen drásticamente el rendimiento pesquero.There is a growing concern over the decline of fisheries and the possibility of the decline becoming worse due to climate change. Studies on small–scale fisheries could help to improve our understanding of the effect of climate on the ecology of exploited stocks. The Strait of Gibraltar is an important fishery ground for artisanal fleets. In this area, blackspot seabream (Pagellus bogaraveo) is the main species targeted by artisanal fisheries in view of its relevance in landed weight. The aims of this study were to explore the possible effects of two atmospheric oscillations, the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO), on the capture of blackspot seabream in the Strait of Gibraltar, to determine their association with oceanographic conditions, and to improve our knowledge about the possible effects of climate change on fisheries ecology so that fishery management can be improved. We used two types of data from different sources: (i) landings per unit of effort reported from a second working group between Morocco and Spain on Pagellus bogaraveo in the Gibraltar Strait area, for the period 1983–2011, and (ii) the recorded blackspot seabream landings obtained from the annual fisheries statistics published by the Junta de Andalucía (Andalusian Regional Government). Our results indicate that the long–term landing of blackspot seabream in the Strait of Gibraltar is closely associated with atmospheric oscillations. Thus, prolonged periods of positive trends in the NAO and AO could favour high fishery yields. In contrast, negative trends in NAO and AO could drastically reduce yield.Evaluación de la respuesta de las poblaciones marinas explotadas en un contexto de cambio climático rápido: el caso del besugo de la pinta en el estrecho de Gibraltar Existe una creciente preocupación por la disminución de la pesca y la posibilidad de que esta disminución se acelere debido al cambio climático. Los estudios sobre la pesca a pequeña escala podrían ayudar a mejorar nuestra comprensión de los efectos del clima en la ecología de las poblaciones explotadas. El estrecho de Gibraltar es una importante zona de pesca para la flota artesanal. En esta zona, el besugo de la pinta (Pagellus bogaraveo) es la especie más importante para la pesca artesanal en vista de su volumen de descarga. Los objetivos de este estudio consisten en estudiar los posibles efectos de dos oscilaciones atmosféricas: la oscilación del Atlántico Norte (NAO) y la oscilación del Ártico (AO), en la captura del besugo de la pinta en el estrecho de Gibraltar con objeto de determinar su relación con las condiciones oceanográficas, y mejorar nuestro conocimiento sobre los posibles efectos del cambio climático en la ecología de la pesca, para poder mejorar la gestión de la actividad pesquera. Utilizamos dos tipos de datos de diferentes fuentes: (i) los desembarques por unidad de esfuerzo registrados por un segundo grupo de trabajo entre Marruecos y España sobre el besugo de la pinta en la zona del estrecho de Gibraltar, para el período 1983–2011, y (ii) los desembarques registrados de besugo de la pinta obtenidos de las estadísticas anuales de pesca publicadas por la Junta de Andalucía. Nuestros resultados indican que el desembarque a largo plazo del besugo de la pinta en el estrecho de Gibraltar está íntimamente relacionado con las oscilaciones atmosféricas. Por lo tanto, los períodos prolongados de tendencias positivas en la NAO y la AO podrían favorecer altos rendimientos pesqueros. En contraste, las tendencias negativas de la NAO y la AO reducen drásticamente el rendimiento pesquero

Analysis of the effect of atmospheric oscillations on physical condition of pre–reproductive bluefin tuna from the Strait of Gibraltar

Análisis del efecto de las oscilaciones atmosféricas en la condición física del atún rojo del estrecho de Gibraltar antes de su reproducción El objetivo de este estudio fue explorar los posibles efectos de las oscilaciones atmosféricas, la oscilación del Atlántico Norte (NAO) y la oscilación del Ártico (AO), en la condición física del atún rojo (Thunnus thynnus). Para ello, estimamos un índice de condición física para cada clase de talla y año a partir de 3.501 pares de datos de talla–peso de atunes capturados en la pesca de cebo vivo antes de la temporada de desove (enero, febrero y marzo). Con el fin de obtener un valor único del índice de condición física (K–mean) por año calculamos el promedio de todas las clases de talla. Además, calculamos el índice de condición física de Le Cren (KLC). Observamos correlaciones positivas significativas entre las oscilaciones atmosféricas y los dos índices decondición física. En el caso del K–mean, la AO explicó un 75% de la variabilidad observada. En relación con el KLC, la NAO explicó aproximadamente un 73% de la variabilidad observada, mientras que la AO explicó un 70% de la variabilidad observada. El aumento de la prevalencia de fuertes vientos de componente oeste podría intervenir en la mejora de la condición física del atún rojo asociada con una fase positiva de las oscilaciones atmosféricas. Llegamos a la conclusión de que el aumento de la prevalencia de fuertes vientos de componente oeste, ya sea por una AO o una NAO positiva, favorece el viaje de los atunes que llegan desde el Atlántico hasta el Mediterráneo porque, por un lado, reduce los costes energéticos de la migración y, por otro, aumenta la cantidad de nutrientes en superficie al mezclar las capas de agua profundas y superficiales en zonas locales como el estrecho de Gibraltar.The aim of this study was to explore the possible effects of atmospheric oscillations: North Atlantic Oscillation (NAO) and Arctic Oscillation (AO), on the physical condition of bluefin tuna (Thunnus thynnus). We estimated a fitness ratio from 3,501 pairs of length–weight data based on bluefin tuna caught in bait–boat fisheries before the spawning season (January, February and March), for each length class and year. In order to obtain a single fitness ratio (K–mean) per year we determined the average for all length classes. We also evaluated Le Cren’s condition index (KLC). We observed significant positive correlations between the atmospheric oscillations and both physical condition indexes. In the case of K–mean, the AO explained 75% of the observed variability. Regarding KLC, the NAO explained approximately 73% of the observed variability, while the AO explained 70% of the observed variability. The increase in physical conditions of bluefin tuna in association with positive atmospheric oscillations could be mediated by the increase in the prevalence of strong trade winds. We concluded that the increase in the prevalence of strong westerly winds, mediated by a positive AO or NAO, favours the trip from the Atlantic to the Mediterranean by reducing energy costs due to migration and by increasing the supply of nutrients at the surface by the mixing of deep water and surface water in local areas such as the Strait of Gibraltar.Análisis del efecto de las oscilaciones atmosféricas en la condición física del atún rojo del estrecho de Gibraltar antes de su reproducción El objetivo de este estudio fue explorar los posibles efectos de las oscilaciones atmosféricas, la oscilación del Atlántico Norte (NAO) y la oscilación del Ártico (AO), en la condición física del atún rojo (Thunnus thynnus). Para ello, estimamos un índice de condición física para cada clase de talla y año a partir de 3.501 pares de datos de talla–peso de atunes capturados en la pesca de cebo vivo antes de la temporada de desove (enero, febrero y marzo). Con el fin de obtener un valor único del índice de condición física (K–mean) por año calculamos el promedio de todas las clases de talla. Además, calculamos el índice de condición física de Le Cren (KLC). Observamos correlaciones positivas significativas entre las oscilaciones atmosféricas y los dos índices decondición física. En el caso del K–mean, la AO explicó un 75% de la variabilidad observada. En relación con el KLC, la NAO explicó aproximadamente un 73% de la variabilidad observada, mientras que la AO explicó un 70% de la variabilidad observada. El aumento de la prevalencia de fuertes vientos de componente oeste podría intervenir en la mejora de la condición física del atún rojo asociada con una fase positiva de las oscilaciones atmosféricas. Llegamos a la conclusión de que el aumento de la prevalencia de fuertes vientos de componente oeste, ya sea por una AO o una NAO positiva, favorece el viaje de los atunes que llegan desde el Atlántico hasta el Mediterráneo porque, por un lado, reduce los costes energéticos de la migración y, por otro, aumenta la cantidad de nutrientes en superficie al mezclar las capas de agua profundas y superficiales en zonas locales como el estrecho de Gibraltar

Permeable frontiers in the open sea: The case of Swordfish in the Atlantic Ocean : Probando las barreras en mar abierto: El caso del pez espada en el océano Atlántico

There is a vivid debate about the border location between North and South Atlantic swordfish stocks. Climate oscillations, East Atlantic (EA) and North Atlantic Oscillation (NAO), have a major impact on the Northern Hemisphere climate and weather conditions. The initial hypothesis of present study is that if it is considering the southern frontier, each stock will be differentially affected by both climatic oscillations, which would imply the existence of a strong border. However, a similar effect on both sides of the border would result in a permeable barrier. The results suggest that the combined effects of EA and NAO affect both the North and the South Atlantic swordfish stocks in similar ways, and consequently, the location of the border may reside farther north than the current management boundary at 5ºN

Assessing the responses of exploited marine populations in a context of rapid climate change: the case of blackspot seabream from Strait of Gibraltar.

Assessing the response of exploited marine populations in a context of rapid climate change: the case of blackspot seabream from the Strait of Gibraltar.— There is a growing concern over the decline of fisheries and the possibility of the decline becoming worse due to climate change. Studies on small–scale fisheries could help to improve our understanding of the effect of climate on the ecology of exploited stocks. The Strait of Gibraltar is an important fishery ground for artisanal fleets. In this area, b lackspot seabream ( Pagellus bogaraveo ) is the main species targeted by artisanal fisheries in view of its relevance in landed weight. The aims of this study were to explore the possible effects of two atmospheric oscillations, the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO), on the capture of blackspot seabream in the Strait of Gibraltar, to determine their association with oceanographic conditions, and to improve our knowledge about the possible effects of climate change on fisheries ecology so that fishery management can be improved. We used two types of data from different sources: (i) landings per unit of effort reported from a second working group between Morocco and Spain on Pagellus bogaraveo in the Gibraltar Strait area, for the period 1983–2011 , and (ii) the recorded blackspot seabream landings obtained from the annual fisheries statistics published by the Junta de Andalucía (Andalusian Regional Government). Our results indicate that the long–term landing of blackspot seabream in the Strait of Gibraltar is closely associated with atmospheric oscillations. Thus, prolonged periods of positive trends in the NAO and AO could favour high fishery yields. In contrast, negative trends in NAO and AO could drastically reduce yield.Postprint0,000

Efecto de las oscilaciones atmosféricas sobre las capturas de Grandes

Tunas and related species are considered Highly Migratory Pelagic animals (HMP) with a high fisheries interest and an important commercial value. Many authors have highlighted the effect of climatic oscillation such as NAO (North Atlantic Oscillation) and AO (Arctic Oscillation) on HMP. In this paper we analyzed the differential effect of these oscillations on three HMP: albacore (Thunnus alalunga), yellowfin tuna (Thunnus albacares) and swordfish (Xiphias gladius). Fisheries data for the Spanish fleet from North Atlantic area were obtained from International Commission for the Conservation of Atlantic Tunas (ICCAT). Data since 1950 for albacore, 1962 for yellowfin tuna and 1950 for swordfish, from different gears: troll (TROL), purse seine (PS), longline (LL) and bait boat (BB) were analyzed. We used the nonparametric test U Mann Whitney to test the relationships between species, gear and oscillation phases (positive or negative) of NAO and AO. Our results indicated that the landings of albacore caught with TROL increased with the positive phase of AO and AOw. The landing of swordfish caught with LL in the North Atlantic and Mediterranean Sea significantly increased with the positive phase of AO, AOw, and NAOw. Finally, the landing of yellowfin tuna caught with PS in the East Atlantic increased significantly with the positive phase of NAOw, and LL landing increased with the negative phase of NAOw. The inclusion of the climate effects on the standardization of abundance indexes used in the assessment of HMP could improve its results and catch projections.Postprin

Analysis of the effect of atmospheric oscillations on physical condition of pre–reproductive bluefin tuna from the Strait of Gibraltar

Analysis of the effect of atmospheric oscillations on physical condition of pre–reproductive bluefin tuna from the Strait of Gibraltar .— The aim of this study was to explore the possible effects of atmospheric oscillations: North Atlantic Oscillation (NAO) and Arctic Oscillation (AO), on the physical condition of bluefin tuna ( Thunnus thynnus ). We estimated a fitness ratio from 3,501 pairs of length–weight data based on bluefin tuna caught in bait–boat fisheries before the spawning season (January, February and March), for each length class and year. In order to obtain a single fitness ratio (K–mean) per year we determined the average for all length classes. We also evaluated Le Cren’s condition index (K LC ). We observed significant positive correlations between the atmospheric oscillations and both physical condition indexes. In the case of K–mean, the AO explained 75% of the observed variability. Regarding K LC , the NAO explained approximately 73% of the observed variability, while the AO explained 70% of the observed variability. The increase in physical conditions of bluefin tuna in association with positive atmospheric oscillations could be mediated by the increase in the prevalence of strong trade winds. We concluded that the increase in the prevalence of strong westerly winds, mediated by a positive AO or NAO, favours the trip from the Atlantic to the Mediterranean by reducing energy costs due to migration and by increasing the supply of nutrients at the surface by the mixing of deep water and surface water in local areas such as the Strait of Gibraltar.Postprin

Factors Associated with the Differential Distribution of Cetaceans Linked with Deep Habitats in the Western Mediterranean Sea

Deep-habitat cetaceans are generally difficult to study, leading to a limited knowledge of their population. This paper assesses the differential distribution patterns of three deep-habitat cetaceans (Sperm whale—Physeter macrocephalus, Risso’s dolphin—Grampus griseus & Cuvier’s beaked whale—Ziphius cavirostris). We used data of 842 opportunistic sightings of cetaceans in the western Mediterranean sea. We inferred environmental and spatio-temporal factors that affect their distribution. Binary logistic regression models were generated to compare the presence of deep-habitat cetaceans with the presence of other cetacean species in the dataset. Then, the favourability function was applied, allowing for comparison between all the models. Sperm whale and Risso’s dolphin presence was differentially favoured by the distance to towns in the eastern part of the western Mediterranean sea. The differential distribution of sperm whale was also influenced by the stability of SST, and that of the Risso’s dolphin by lower mean salinity and higher mean Chlorophyll A concentration. When modelling the three deep-habitat cetaceans (including Cuvier’s beaked whale), the variable distance to towns had a negative influence on the presence of any of them more than it did to other cetaceans, being more favourable far from towns, so this issue should be further investigated.Postprint2,92