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Callington, United Kingdom

Cook H.,Kingston University | Benson D.,University of Exeter | Couldrick L.,Westcountry Rivers Trust
Ecology and Society | Year: 2016

The adoption of bioregionalism by institutions that are instrumental in river basin management has significant potential to resolve complex water resource management problems. The Westcountry Rivers Trust (WRT) in England provides an example of how localized bioregional institutionalization of adaptive comanagement, consensus decision making, local participation, indigenous technical and social knowledge, and “win-win” outcomes can potentially lead to resilient partnership working. Our analysis of the WRT’s effectiveness in confronting nonpoint source water pollution, previously impervious to centralized agency responses, provides scope for lesson-drawing on institutional design, public engagement, and effective operation, although some evident issues remain. © 2016 by the author(s). Source


Horreo J.L.,University of Oviedo | Machado-Schiaffino G.,University of Oviedo | Ayllon F.,Autonomous University of Barcelona | Griffiths A.M.,Marine Biological Association of The United Kingdom | And 3 more authors.
Global Change Biology | Year: 2011

This study focuses on temporal changes in Atlantic salmon (Salmo salar) populations from the vulnerable periphery of the species range (northern Spain). Using microsatellite markers to assess population structuring and introgression of exogenous genes in four different temporal samples collected across 20 years, we have determined the relative weights of climate and stocking practices in shaping contemporary regional population genetic patterns. Climate, represented by the North Atlantic Oscillation Index, was identified as the main factor for determining the level of population genetic differentiation. Populations within the region have become homogenized through gene flow enhanced by straying of adult salmon from natal rivers and subsequent interchange of genes among rivers due to warmer temperatures. At the same time, and in line with documented changes in stock transfer strategies, evidence of genetic introgression from past stock transfers has decreased throughout the study period, becoming a secondary factor in erasing population structuring. The ability to disentangle the effects of climatic changes and anthropogenic factors (fisheries management practices) is essential for effective long-term conservation of this iconic species. We emphasize the importance of evaluating all factors which may be linked to stocking practices in vulnerable species, particularly those sensitive to climate change. © 2010 Blackwell Publishing Ltd. Source


Finnegan A.K.,University of Exeter | Griffiths A.M.,University of Exeter | King R.A.,University of Exeter | Machado-Schiaffino G.,University of Oviedo | And 4 more authors.
Heredity | Year: 2013

Glacial and postglacial processes are known to be important determinants of contemporary population structuring for many species. In Europe, refugia in the Italian, Balkan and Iberian peninsulas are believed to be the main sources of species colonising northern Europe after the glacial retreat; however, there is increasing evidence of small, cryptic refugia existing north of these for many cold-tolerant species. This study examined the glacial history of Atlantic salmon in western Europe using two independent classes of molecular markers, microsatellites (nuclear) and mitochondrial DNA variation. Alongside the well-documented refuge in the Iberian Peninsula, evidence for a cryptic refuge in northwest France is also presented. Critically, methods utilised to estimate divergence times between the refugia indicated that salmon in these two regions had diverged a long time before the last glacial maximum; coalescence analysis (as implemented in the program IMa2) estimated divergence times at around 60 000 years before present. Through the examination of haplotype frequencies, previously glaciated areas of northwest Europe, that is, Britain and Ireland, appear to have been colonised from salmon expanding out of both refugia, with the southwest of England being the primary contact zone and exhibiting the highest genetic diversity. © 2013 Macmillan Publishers Limited All rights reserved. Source


Selly S.L.C.,University of Exeter | Hickey J.,Westcountry Rivers Trust | Stevens J.R.,University of Exeter
Aquaculture | Year: 2014

Stock enhancement of Atlantic salmon (Salmo salar L.), a fish of considerable economic and social importance, is commonplace. Supportive-breeding is a well-recognised method of enhancement which, when compared with traditional hatchery practices, is thought to reduce the severity of selection pressures on broodstock fish. Critically, in supportive-breeding programmes, the eggs and sperm used in the breeding process are taken from wild adult fish originating from the same catchment that resulting juvenile fish are subsequently stocked into, thereby avoiding problems associated with a lack of local adaptation in the stocked fish. Previous studies have indicated that sex bias during the hatchery process may result in reduced genetic diversity of the offspring. Utilising 16 microsatellite loci and two expressed sequence tag (EST) loci, we examined progeny from two hatcheries located on the rivers Exe and Tamar in southwest England, assessing the genetic diversity and parental contribution at each. Two strains were assessed within each hatchery. Genetic diversity was found to be reduced in offspring compared with that of the parent fish. This is likely the result of utilising a small number of broodstock in combination with parental bias. In the four hatchery strains studied (Bar, LEx, Lyd and TXL), parental contribution ranged between 2.1 and 29.2%, 12.2-51.0%, 2.0-70.0% and 4.0-40.0%, respectively. If this practice is to be continued, efforts should be made to improve adherence to national rearing guidelines by increasing the number of broodstock fish utilised and ensuring a more balanced contribution of all adults during the crossing process. Ultimately, we suggest a need to review the suitability of current national Atlantic salmon hatchery guidelines, particularly with regard to their use and relevance in small European rearing systems. © 2014 Elsevier B.V. Source


Griffiths A.M.,University of Exeter | Griffiths A.M.,Marine Biological Association of The United Kingdom | Ellis J.S.,University of Exeter | Ellis J.S.,University of Plymouth | And 6 more authors.
Biological Conservation | Year: 2011

Since the 1970s, when major improvements to the water quality were made, the River Thames has been subject to a high-profile project aimed at restoring Atlantic salmon to the catchment. Whilst initially successful, with hundreds of salmon returning each year in the late 1980s, the number of adults returning to the river has declined steeply again in recent years, reaching a low in 2005 when no salmon were recorded. Using a baseline of genetic information gathered from 3830 salmon from throughout their southern European range, and incorporating samples from the hatchery fish used to stock the Thames, all 10 tagged hatchery fish captured in 2003 and all 16 returning untagged adult salmon captured between 2005 and 2008 were assigned to their most likely river of origin. The results suggest that untagged salmon currently ascending the river originate not from exogenous fish stocked into the Thames, but predominantly from other rivers in southern England. This highlights the potential for natural processes of recolonisation to operate in rivers where salmon have become locally extirpated. These findings also underscore several important considerations when undertaking species restoration projects: (i) previous causes of declines must be sufficiently ameliorated to allow new/translocated individuals to thrive, (ii) introduced individuals should originate from a stock that is closely related to the extirpated population, according to the principles of contemporary conservation biology, and (iii) dispersal and gene-flow from neighbouring populations may play a significant role in establishing new populations. © 2011 Elsevier Ltd. Source

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