Time filter

Source Type

Aberdeen, United Kingdom

O'Neill F.G.,Marine Scotland - Marine Laboratory | Ivanovic A.,University of Aberdeen
ICES Journal of Marine Science | Year: 2016

An improved understanding of the physical interaction of towed demersal fishing gears with the seabed has been developed in recent years, and there is a clearer view of the underpinning mechanical processes that lead to the modification and alteration of the benthic environment. The physical impact of these gears on soft sediments can be classified broadly as being either geotechnical or hydrodynamic in nature: penetration and piercing of the substrate, lateral displacement of sediment, and the influence of the pressure field transmitted through the sediment can be considered geotechnical, whereas the mobilization of sediment into the water column can be considered hydrodynamic. A number of experimental and numerical approaches have been used to gain better insights of these physical processes. These include small-scale modelling in towing tanks and sand channels; large-scale modelling in the field; measurements behind full-scale towed gears at sea; numerical/mathematical modelling of sediment mechanics; and numerical/mathematical modelling of hydrodynamics. Here, we will review this research, and that in associated fields, and show how it can form the basis of predictive models of the benthic impact of trawl gears. © 2015 Crown copyright 2015. Source

Collet B.,Marine Scotland - Marine Laboratory
Developmental and Comparative Immunology | Year: 2014

Viruses are the most serious pathogenic threat to the production of the main aquacultured salmonid species the rainbow trout Oncorhynchus mykiss and the Atlantic salmon Salmo salar. The viral diseases Infectious Pancreatic Necrosis (IPN), Pancreatic Disease (PD), Infectious Haemorrhagic Necrosis (IHN), Viral Haemorrhagic Septicaemia (VHS), and Infectious Salmon Anaemia (ISA) cause massive economic losses to the global salmonid aquaculture industry every year. To date, no solution exists to treat livestock affected by a viral disease and only a small number of efficient vaccines are available to prevent infection. As a consequence, understanding the host immune response against viruses in these fish species is critical to develop prophylactic and preventive control measures. The innate immune response represents an important part of the host defence mechanism preventing viral replication after infection. It is a fast acting response designed to inhibit virus propagation immediately within the host, allowing for the adaptive specific immunity to develop. It has cellular and humoral components which act in synergy. This review will cover inflammation responses, the cell types involved, apoptosis, antimicrobial peptides. Particular attention will be given to the type I interferon system as the major player in the innate antiviral defence mechanism of salmonids. Viral evasion strategies will also be discussed. © 2013 Elsevier Ltd. Source

Wright P.J.,Marine Scotland - Marine Laboratory
ICES Journal of Marine Science | Year: 2014

Age at maturity is one of the key variables determining the maximum rate of population growth and so may be a good indicator of stock recovery potential. Spawner age composition may also affect the probability of high recruitment and so could be relevant to stock recovery. This study examined the relation between early survival, age at maturity, and the demographic composition of spawners in many cod and haddock stocks. Reported measures of fecundity and maturity were used to estimate total egg production for comparison with numbers at age 1 and age at 50% maturity. The instantaneous rate of population growth (r) was estimated for cohorts from life history tables during periods when spawning biomass was depleted (e.g. pa) using reproductive and mortality data for stocks. Age-specific survival was found to be far more important than reproductive rate in determining population growth rate. Stocks that experienced low and more variable survival matured early and had a high relative fecundity. Hence, while early maturing stocks have the potential for high population growth following favourable recruitment events, they would not be expected to recover any faster than late maturing stocks because of the generally low early survival rate that they experience. Measures of spawner age diversity and mean age were found to be positively correlated with offspring survivorship in a few cod stocks. However, in general, it appears difficult to infer recovery potential from life history characteristics, which may be expected, given that regional variation in reproductive success will ultimately be expected to shape local reproductive schedules. © Crown copyright 2014. Source

Needle C.L.,Marine Scotland - Marine Laboratory
ICES Journal of Marine Science | Year: 2014

In recent years, scientists providing advice to fisheries managers have been granted access to an increasing range of spatio-temporal data from fishing vessels, using tools such as vessel monitoring systems and electronic observation platforms. This information should allow for the provision of more germane advice on the activity of vessels, and hence the likely impact of management measures which are becoming increasingly spatial in nature. However, the development of appropriate management simulation and assessment models has lagged behind the availability of these new data. This paper presents an accessible spatio-temporal simulation framework (Honeycomb) which features a weekly time-step, multiple stocks and vessels, and economic decision rules and applies this to a case study of a spatial evaluation of a simple closed-area fishery policy. We conclude that the development and utilization of such spatio-temporal simulation models is a key research task for fisheries in which both spatial fisheries data and spatial fisheries management are becoming paramount. © 2014 © Crown copyright 2014. Source

Jordan W.C.,Queens University of Belfast | Youngson A.F.,Marine Scotland - Marine Laboratory | Hay D.W.,Freshwater Fisheries Laboratory | Ferguson A.,Queens University of Belfast
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2015

Levels of temporal and spatial genetic heterogeneity within and among Atlantic salmon (Salmo salar) populations in Scotland were assessed through starch-gel electrophoretic analysis of variation at 30 protein-coding loci. Over three year-classes the level of temporal variation within populations was generally nonsignificant, although sig¬nificant heterogeneity among year-classes was found at some loci at some locations. Hierarchical analysis of gene diversity showed that 97.6% of the genetic diversity was found within single sites, with the remaining diversity distributed among sites. While there was no evidence of subpopulation differentiation among a number of samples of Atlantic salmon from the River Tweed system, significant genetic heterogeneity was observed among samples from different river systems within Scotland. Comparison of the levels of among-population heterogeneity in the Atlantic salmon with those found in the closely related brown trout (Salmo trutta) over a similar geographical area shows the Atlantic salmon to be relatively genetically homogeneous. Nous avons mesuré l'hétérogénéité génétique temporelle et spatiale entre populations et à lintérieur de popu¬lations de saumons de l'Atlantique (Salmo salar) d'Ecosse grâce à une analyse par électrophorèse sur gel d'amidon de la variation à 30 loci qui codent les protéines. Sur trois classes annuelles, la variation temporelle à lintérieur des populations n'était généralement pas significative, mais on a trouvé une hétérogénéité significative entre les classes annuelles pour certains loci sur des sites donnés. L'analyse hiérarchique de la diversité génétique a montré que 97,6% de cette diversité se retrouvait sur des sites pris individuellement, le reste étant distribué entre les sites. S'il n'y avait aucune indication de différenciation entre des sous-populations parmi un certain nombre d'échantillons de saumons de l'Atlantique du réseau de la Tweed, on a observé une hétérogénéité génétique significative entre des échantillons provenant de différents bassins hydrographiques d'Écosse. La comparaison de l hétérogénéité parmi les populations de saumons de l'Atlantique avec les résultats obtenus chez 1'espèce proche que constitue la truite brune (Salmo trutta) dans une zone géographique similaire montre que le saumon de l'Atlantique présente une relative hétérogénéité génétique. © 2015, National Research Council of Canada. All rights reserved. Source

Discover hidden collaborations