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Bottlenose dolphins are known to have high dispersal capabilities that could lead to genetic connectivity. However, local resident populations are found worldwide as happens in southern Galicia (NW Spain). The aim of this research is to explore whether population substructure and habitat segregation do exist within the Galician bottlenose dolphin community. In the present study, samples from 43 bottlenose dolphins stranded or by-caught in Galicia between 1994 and 2008 were genotyped at 10 microsatellite loci and sequenced at the highly variable mitochondrial control region. In addition, variability of stable isotope ratios (δ13C and δ15N) was assessed for 43 dolphins (5 calves, 38 juveniles and adults) stranded or by-caught in Galicia between 1998 and 2007. Genetic results highlighted the existence of two populations in the area and dolphins from southern Galicia were assigned to a single genetic group. Seven dolphins were classified as possible migrants between putative populations as their genetic makeup did not correspond with their geographical stranding location. Values of δ13C and δ15N were significantly different between the two populations, suggesting resource specialization and partitioning. Dolphins from southern Galicia (inhabiting coastal inlets) showed more variation in their diet, higher trophic levels and greater δ13C compared to animals from northern Galicia (present in more open waters). The existence of fine scale population substructure should be considered in the future designation of Special Areas of Conservation (SACs) for the species as required by the European Habitats Directive.

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A specimen of the neon flying squid Ommastrephes bartramii (LeSueur, 1821) was caught using a surface longline in the Eastern Tropical Pacific Ocean in October 2007. The animal was frozen whole on board and landed in Vigo, where it was defrosted and examined. The squid represents the largest specimen of this species yet recorded, with a mantle length of 102 cm (30+ kg), compared to the recorded maximum of 80 cm (25 kg). The specimen was a mature female, with an ovary weight of around 500 g. There appeared to be spermatangia stored in the buccal membrane. Its stomach contents included beaks of ommastrephid cephalopods and bones of a mackerel-like (scombrid) fish. Age of the animal is also studied.

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Los resultados obtenidos del marcado y posterior recaptura de los ejemplares son una herramienta muy valiosa para contribuir a mejorar el conocimiento de la biología y ecología de una especie, examinando ciertos aspectos como son: el crecimiento, los movimientos o migraciones, la mortalidad o supervivencia, la abundancia y distribución de la especie, el hábitat y diferenciación de poblaciones o stocks. Actualmente la técnica de marcado se aplica a muchas especies, tanto terrestres como marinas, pertenecientes a diversos grupos zoológicos: peces, crustáceos, reptiles, moluscos y mamíferos. Este libro repasa algunos ejemplos de marcado de especies marinas de interés comercial. No todas las especies pueden ser marcadas, porque es necesario cumplir una serie de requisitos para poder llevar a cabo con éxito un experimento de marcado. En uno de los apartados de esta guía, se describen los distintos aspectos a tener en cuenta para obtener buenos resultados. Se describen los principales proyectos de marcado actualmente en ejecución o en marcha llevados a cabo por el Instituto Español de Oceanografía (IEO). En primer lugar, se describe brevemente la especie, su distribución, crecimiento, reproducción, alimentación, etc. A continuación, se presenta la información del marcado, es decir, campañas realizadas, número de ejemplares marcados y algunos de los resultados obtenidos hasta la fecha a partir de las recapturas disponibles. En algunas especies, los programas de marcado se llevan realizando desde hace más de 20 años, como es el caso del atún rojo, por lo que la información disponible es bastante amplia. En otros casos por el contrario como la merluza, los proyectos son relativamente recientes, no obstante los resultados son bastante interesantes y prometedores., Nowadays many different marine animals are being tagged. This book summarizes recent tagging programs carried out by the Spanish Institute of Oceanography (IEO). Although the objectives of these various studies mainly depend on the species and each project in particular, the general aim is to better understand the biology and ecology of these animals the structure and dynamics of their populations and their capacity to respond to human activities. This book provides an overview of different aspects of this technique such as a brief history of tagging, the types of tags currently used, including both conventional and electronic tags, where and how to put them on the marine animals, some recommendations regarding how to perform a tagging survey and where to go or what to do if anyone recovers a tagged fish or marine animal. The book then summarizes the main species tagged by the IEO, making a short description of their biology followed by some of the results obtained from tagging studies undertaken until now. Other applications are to know the spatial distribution (spawning or feeding areas), estimate growth parameters, mortality and survival rates, longevity, the size of the population or identifying stocks. Nowadays the advances in electronics have also open new fields such us the possibility of tracking an animal and knowing its habitat preferences and behaviour. Besides some of these tags have the capacity of recording this information during long periods and sending the data from long distances even without the need to recover the animal. Tagging activities constitute a very useful tool to improve the knowledge of many species and contribute to their management and conservation. For that reason this methodology is included in many IEO projects in which other activities like the monitoring of the fishery (landings, fishing effort, fleet characteristics, fishing areas, biological sampling, etc.) are carried out. Some projects are related with coastal pelagic fisheries including anchovy, sardine and mackerel or oceanic pelagic fisheries like tuna and billfish species and pelagic sharks. Others are focused on benthic and demersal species such as hake, black spot seabream, anglerfish, flatfish, etc. Nevertheless not all species can be tagged, as they have to survive being caught and handled before being release. For this reason, tagging techniques may not easily be applied to some species.

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Results of the Spanish spring acoustic survey PELACUS0407, carried out from the 27th March to the 23rd April 2007, indicated a stock biomass of 96,390 tons of sardine (1482 million fish) in northwest and northern Spanish waters. The main bulk of the resource was found in Galician waters (ICES sub-areas IXa-N, VIIIc-W) and consisted of age 3 fish (fish born in 2004). Age 3 fish also predominated in ICES sub-area VIIIcE-w but not in the eastern part of the surveyed area, where older fish were more abundant (ICES sub-area VIIIcE-e). The abundance and biomass obtained from PELACUS0407 are similar to the values estimated from the last 2 surveys (with a slight increase in the biomass but not in the number of fish). These figures seem to indicate that the last strong sardine recruitment (2004) probably halted the downward trend in stock size apparent since 2001 in Spanish waters. However, there is also evidence that the 2004 recruitment in the surveyed area was not as strong as the previous recruitment peak in 2000, since both biomass and abundance values are at their lowest since 2001. In addition, the area occupied by the sardine stock in Spanish waters appears also to have diminished continuously since 2001, which could make the resource even more vulnerable to fishing and/or predation. PELACUS0407 also obtained data on the distribution of sardine eggs and their number in the surveyed area: eggs were found in larger quantities and over a wider area than previously recorded by CUFES in the PELACUS series (2000-2007)

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Trends in ecosystem variables of the Eastern North Atlantic shelf near the Iberian Peninsula were analysed in relation to regional climate and oceanographic variability. In addition, detailed changes in oceanographic properties (surface temperature, upwelling and poleward current activity) and biological components (plankton and pelagic consumers) in the period 1989-2005 were compared with the main trends and multidecadal periods observed in time series dating back to 1950. In contrast to previous studies, the North Atlantic Oscillation did not appear as the main influence in the climate of the North Iberian region, while East-West and subtropical gradients were the dominant modes. Climatic oscillations at decadal scales were paralleled by similar oscillations in oceanographic and biological variables, but the latter appeared weakly related to climate. Time- lags of up to 5 years in the biological response may partly explain these relationships. The main planktivorous fish species (sardine and anchovy) alternate in periods of 10-15 years of relative dominance, in synchrony with equivalent species around the world. In contrast, plankton cycles appear greatly modified after 1990 in coincidence with shifts in climatic and oceanographic variables. Subregional variability indicated divergent trends in biological variables, particularly the zooplankton increase off A Coruña and the decrease in the Bay of Biscay since 1990. Such divergences are related to direct and indirect effects of global changes in this transitional upwelling region.

The natural abundance of stable nitrogen isotopes (δ15N) in sardine (Sardina pilchardus) and plankton was determined from samples collected between 1998 and 2003 in the northwestern shelf of the Iberian Peninsula with the purpose of studying the variability in the trophic position of sardine. Sardines were grouped in three size-length classes (small: < 16 cm; medium: 16-20 cm; large: > 20 cm). Plankton samples were size-fractionated between ca. 0.7 and 2000 μm of individual length. The plankton at the base of the pelagic food web in the western shelf region (Galicia) was more enriched in δ15N than plankton in the northern and eastern region (Mar Cantábrico), likely because of upwelling. Variability in δ15N in sardine was related both to changes in feeding strategies during growth and to the mobility of size classes between adjacent shelf regions. Large sardines showed regional differences in δ15N similar to those of small plankton, suggesting that old specimens remained for long periods in the same region. In contrast, small and medium-sized sardines have similar δ15N values in all regions. We hypothesize that interannual differences in δ15N of sardine are caused mainly by variations in the mobility of large size classes, as the isotopic signature of the small sardines was relatively less variable and suggests low variability in the plankton food web. In turn, such variations would be related to changes in the size of the sardine population in the north Iberian shelf.

The Spanish acoustic-trawl times PELACUS 0315 was carried out on board R/V Miguel Oliver from 14th March to 14th April, covering the north Spanish waters (Atlantic and Bay of Biscay) from the coast to the 1000 m isobath on a systematic grid with tracks 8 nmi apart and equally spaced. Acoustic , fishing stations, fish egg counting, microplastic, and apical predators observations were done during daytime whilst the oceanographic characterisation was done during night time. A total of 3979 nautical miles were steamed, 1190 corresponding to the survey track. Besides, 66 fishing stations were performed. PELACUS 0315 was characterised by a relative high strength of NE winds which led to change the survey sampling schedule. The area is typically covered continuously from the Spanish/Portuguese border to the French/Spanish one, but due to the wind the NW corner was steamed from the north-eastern part to the south-western one and also in the Cantabrian Sea, the inner part (i.e. Euskadi) was covered westward. Besides, this weather condition, together with the change in the strategy, would have been affected the mackerel fish distribution and abundance estimates: this was the first time in the time series that adult mackerel occurred in high quantities in IXaN while VIIIc-West was almost empty. Nevertheless, as compared with the biomass assessed in 2014 when the weather conditions were better and the therefore the stability would have increased the mackerel availability either for a change in the behaviour (i.e. spatial pattern distribution) or for an increase in the food availability, the estimated biomass in 2015 was lower. On the other hand, the increase in horse mackerel observed in 2014 was corroborated this year. In the case of anchovy, although during 2014 an important amount of new juveniles (young of the year) were detected during the JUVENA survey undertook in September in the Cantabrian waters, the anchovy distribution found at PELACUS was scarce in this area. During PELACUS 0315 blue whiting has been observed performing nictimeral migration towards the surface. This is the first time this movement has been recorded and described.