Urquhart, K., Pert, C. C., Fryer, R. J., Cook, P., Weir, S., Kilburn, R., McCarthy, U., Simons, J., McBeath, S. J., Matejusova, I., and Bricknell, I. R. 2010. A survey of pathogens and metazoan parasites on wild sea trout (Salmo trutta) in Scottish waters. – ICES Journal of Marine Science, 67: 444–453. In all, 300 wild sea trout were sampled from three east coast and two west coast sites around Scotland over a 3-year period to establish the prevalence and the abundance of bacteria, viruses, and ecto- and endoparasites. No bacterial pathogens were isolated from any fish. One fish tested positive for viral pathogens (infectious pancreatic necrosis virus). The viral agent syncytium, resulting from aquareovirus infection, was found in four fish from the east coast. The parasitic fauna consisted of three classes of ectoparasite, Monogenea, Isopoda, and Copepoda, and four classes of endoparasite, Cestoda, Digenea, Nematoda, and Acanthocephala. Sea trout from the east coast sites were larger than those from the west coast. The abundance of Lepeophtheirus salmonis, Hysterothylacium aduncum, and Anisakis sp. was significantly greater at the east coast sites. The only parasite found in significantly greater numbers at a west coast site was Pomphorhynchus laevis.

Keywords: common dab, pancreas disease, salmonid alphavirus.Pancreas disease (PD) and sleeping disease (SD) are important, largely chronic conditions of farmed Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), respectively, and are caused by salmonid alphavirus (SAV) (Togaviridae) (McLoughlin & Graham 2007). Six SAV subtypes have been distinguished to date utilizing the partial E2 and nsP3-gene sequence data with subtypes I, IV, V and VI present in Scotland and Ireland, subtype II dominant in the UK and continental Europe and subtype III restricted to Norway (Fringuelli et al. 2008). The first evidence of a wild reservoir for SAV was reported by Snow et al. (2010) where SAV V was detected in several species of flatfish (Pleuronectidae), and later on, Bruno et al. (2014) and McCleary et al. (2014) confirmed the presence of SAV I, II and V in common dab and plaice. Also for first time the virus was successfully cultured on a salmonidderived cell line (Bruno et al. 2014). The present article aims to survey SAV in common dab from waters off the north-west coast of Ireland and report on apparent prevalence in wild fish.In total, 120 common dab were collected in Irish waters approximately 70 nautical miles from the north-west coast in February 2012 (Fig. 1).Gross changes consistent with epidermal hyperplasia/papilloma, lymphocystis and acute/healing skin ulcers and hyperpigmentation on the ocular side from individual dab were noted. Total RNA was extracted from 5 mg of heart tissue (QIAsymphony RNA Kit; Qiagen), genomic DNA was removed (DNA-free TM DNA Removal Kit; Life Technologies), and cDNA was synthesized (Snow et al. 2010). A nsP1 RT-qPCR assay (Hodneland & Endresen 2006) and 12s RNA endogenous control assay (McCleary et al. 2014) were run on the LightCycler â 480 detection system (Roche) using Quanta Custom Toughmix (Quanta Biosciences). A sample was recorded as SAV positive when crossing point (Cp) values were generated in all three replicates. Partial E2 gene was amplified using a nested PCR and sequenced according to Bruno et al. (2014). Virus culturing was attempted using heart and kidney tissue shown positive by nsP1 RT-qPCR. The prevalence and 95% confidence intervals (CI) were estimated from a generalized linear model assuming a binomial error distribution and comprising the intercept only as the explanatory variable (Nelder & Wedderburn 1972).Four dab tested SAV positive by nsP1 RT-qPCR assay in all triplicates (Table 1). This corresponds to an apparent prevalence of SAV type I of 3.3% (95% CI 1.3%-8.5%). No cytopathic effect was observed in the tissue culture, and supernatant tested negative for SAV by RT-qPCR. Sequencing was attempted from all positive samples, and a partial E2 sequence (KP091737) was obtained for one sample (2013/0118/048). This sequence showed 100% identity to the dab SAV type I detected in the Dublin Bay (Ireland) (f10_4, 5 and 6) and Celtic Sea (f12_181) and interestingly was also identical to SAV 4640 isolate from the Scottish farmed Atlantic salmon (SCO 07-887...

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