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Rojo-Bartolome I.,University of the Basque Country | De Cerio O.D.,University of the Basque Country | Diez G.,Marine Research Division | Cancio I.,University of the Basque Country
PLoS ONE | Year: 2016

The estimation of maturity and sex of fish stocks in European waters is a requirement of the EU Data Collection Framework as part of the policy to improve fisheries management. On the other hand, research on fish biology is increasingly focused in molecular approaches, researchers needing correct identification of fish sex and reproductive stage without necessarily having in house the histological know-how necessary for the task. Taking advantage of the differential gene transcription occurring during fish sex differentiation and gametogenesis, the utility of 5S ribosomal RNA (5S rRNA) and General transcription factor IIIA (gtf3a) in the molecular identification of sex and gametogenic stage was tested in different economically- relevant fish species from the Bay of Biscay. Gonads of 9 fish species (, Atlantic, Atlantic-chub and horse mackerel, blue whiting, bogue, European anchovy, hake and pilchard and megrim), collected from local commercial fishing vessels were histologically sexed and 5S and 18S rRNA concentrations were quantified by capillary electrophoresis to calculate a 5S/18S rRNA index. Degenerate primers permitted cloning and sequencing of gtf3a fragments in 7 of the studied species. 5S rRNA and gtf3a transcript levels, together with 5S/18S rRNA index, distinguished clearly ovaries from testis in all of the studied species. The values were always higher in females than in males. 5S/18S rRNA index values in females were always highest when fish were captured in early phases of ovary development whilst, in later vitellogenic stages, the values decreased significantly. In megrim and European anchovy, where gonads in different oogenesis stages were obtained, the 5S/18S rRNA index identified clearly gametogenic stage. This approach, to the sexing and the quantitative non-subjective identification of the maturity stage of female fish, could have multiple applications in the study of fish stock dynamics, fish reproduction and fecundity and fish biology in general. © 2016 Rojo-Bartolomé et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Prellezo R.,Marine Research Division | Curtin R.,Bord Iascaigh Mhara
Ocean and Coastal Management | Year: 2015

This paper confronts, by meta-synthesis of the literature, the definition of ecosystem-based management provided in the reform of the European Common Fisheries Policy (CFP) with the specific measures and the institutional framework foreseen in it.By analysing the reform of the CFP by means of the ecosystem-based management framework, we conclude that there is a lack of instruments to deal with the social sustainability objective while economic and ecological sustainability could be simultaneously achieved with the specific measures considered in the reform.Individually analysed, the specific measures could further benefit ecosystem-based management implementation, although not all the observed or analysed consequences of the implementation of these measures move in this direction. In that sense we conclude that the success of the ecosystem based management of EU fisheries depends much more on the specific implementation of the measures and on the accompanying incentives, which in the end, implies that the institutional and political settings will determine its success. © 2015 Elsevier Ltd.


Diez G.,Marine Research Division | Soto M.,University of the Basque Country | Blanco J.M.,University of the Basque Country
Journal of Fish Biology | Year: 2015

This study characterized the morphology, density and orientation of the dermal denticles along the body of a shortfin mako shark Isurus oxyrinchus and identified the hydrodynamic parameters of its body through a computational fluid-dynamics model. The study showed a great variability in the morphology, size, shape, orientation and density of dermal denticles along the body of I. oxyrinchus. There was a significant higher density in dorsal and ventral areas of the body and their highest angular deviations were found in the lower part of the mouth and in the areas between the pre-caudal pit and the second dorsal and pelvic fins. A detailed three-dimensional geometry from a scanned body of a shark was carried out to evaluate the hydrodynamic properties such as drag coefficient, lift coefficient and superficial (skin) friction coefficient of the skin together with flow velocity field, according to different roughness coefficients simulating the effect of the dermal denticles. This preliminary approach contributed to detailed information of the denticle interactions. As the height of the denticles was increased, flow velocity and the effect of lift decreased whereas drag increased. The highest peaks of skin friction coefficient were observed around the pectoral fins. © 2015 The Fisheries Society of the British Isles.


Urtizberea A.,University of Bergen | Urtizberea A.,Marine Research Division | Dupont N.,University of Bergen | Dupont N.,Norwegian Institute of Marine Research | And 2 more authors.
Ecological Modelling | Year: 2013

In marine ecosystem models, the underwater light intensity is commonly characterized by the shading of phytoplankton in addition to a background light attenuation coefficient. Colour dissolved organic matter (CDOM) is an important component of the background light attenuation, and we investigate how variation in CDOM attenuation affects euphotic zone properties in a general marine ecosystem model. Our results suggest that euphotic zone properties are highly sensitive to CDOM variations occurring in nature. While the nutrient input to the euphotic zone scales the magnitude of the primary production, the vertical structure of nutrients and phytoplankton is largely determined by the variation in CDOM attenuation in our simulations. This suggests that knowledge of CDOM variation is useful to constrain uncertainties in predictions of water column structure in marine ecosystem modelling, but also in analyses utilizing the oceanic nutricline depth as proxy for primary production. Finally, according to our sensitivity analysis, many coastal areas experiencing high loads of terrestrial CDOM are expected to show eutrophication symptoms induced by altered optics. © 2013 Elsevier B.V..


Alonso-Saez L.,Spanish Institute of Oceanography | Alonso-Saez L.,Marine Research Division | Diaz-Perez L.,Spanish Institute of Oceanography | Moran X.A.,Spanish Institute of Oceanography | Moran X.A.,King Abdullah University of Science and Technology
Environmental microbiology | Year: 2015

Rare microbial taxa are increasingly recognized to play key ecological roles, but knowledge of their spatio-temporal dynamics is lacking. In a time-series study in coastal waters, we detected 83 bacterial lineages with significant seasonality, including environmentally relevant taxa where little ecological information was available. For example, Verrucomicrobia had recurrent maxima in summer, while the Flavobacteria NS4, NS5 and NS2b clades had contrasting seasonal niches. Among the seasonal taxa, only 4 were abundant and persistent, 20 cycled between rare and abundant and, remarkably, most of them (59) were always rare (contributing < 1% of total reads). We thus demonstrate that seasonal patterns in marine bacterioplankton are largely driven by lineages that never sustain abundant populations. A fewer number of rare taxa (20) also produced episodic 'blooms', and these events were highly synchronized, mostly occurring on a single month. The recurrent seasonal growth and loss of rare bacteria opens new perspectives on the temporal dynamics of the rare biosphere, hitherto mainly characterized by dormancy and episodes of 'boom and bust', as envisioned by the seed-bank hypothesis. The predictable patterns of seasonal reoccurrence are relevant for understanding the ecology of rare bacteria, which may include key players for the functioning of marine ecosystems. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

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