EST and Mitochondrial DNA Sequences Support a Distinct Pacific Form of Salmon Louse, Lepeophtheirus salmonis

Yazawa, Ryosuke; Yasuike, Motoshige; Leong, Jong S.; Schalburg, Kristian R. von; Cooper, Glenn A.; Beetz-Sargent, Marianne; Robb, Adrienne; Davidson, William S.; Jones, Simon R. M.; Koop, Ben F.

doi:10.1007/s10126-008-9112-y

Cited by 54 publications

(59 citation statements)

References 47 publications

(63 reference statements)

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“…Comparing results from these 2 oceans is of interest, but must be done with caution. This is in part due to the large genetic differences between lice collected from these 2 oceans (Todd et al 2004, Tjensvoll et al 2006, Yazawa et al 2008, and in part due to the differences in the numbers, types and biology of hosts between the 2 oceans, both within and outside marine farms. Just as for studies conducted in the Atlantic, the 2 studies conducted within the Pacific display contrasting results.…”

Section: Discussionmentioning

confidence: 99%

“…A study based upon RAPD analysis (Dixon et al 2004) reported a highest pairwise F ST among samples from Scotland of 0.68, and the majority > 0.2. In a study of mtDNA in the Pacific (Boulding et al 2009), which might not be directly comparable due to the large genetic differences between lice in the Pacific and Atlantic (Todd et al 2004, Tjensvoll et al 2006, Yazawa et al 2008), a pairwise F ST of 0.19 was reported between L. salmonis samples taken on wild and farmed salmon co-existing in the Broughton archipelago. Studies revealing highly significant genetic variation among groups of lice collected within a small region have suggested that their observations may reflect combinations of restricted gene flow, and/or post-settlement selection mediated through local environmental factors.…”

Section: Discussionmentioning

confidence: 99%

“…Some of the samples were collected on fish as they were slaughtered, while other samples were taken in association with routine lice-counting on farms. As large genetic differences between L. salmonis in the Pacific and Atlantic have previously been well documented (Todd et al 2004, Tjensvoll et al 2006, Yazawa et al 2008, no outlier sample from the Pacific was included. For Canada, Ireland, Shetland and the Faroe islands, 2 samples country -1 were collected.…”

Section: Samplesmentioning

confidence: 99%

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Population genetic structure of the parasitic copepod Lepeophtheirus salmonis throughout the Atlantic

Glover

Stølen²,

Messmer³

et al. 2011

Mar. Ecol. Prog. Ser.

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The parasitic copepod Lepeophtheirus salmonis is responsible for huge economic losses in the salmonid aquaculture industry, and has been linked with declines of wild salmonid populations. In order to elucidate population genetic structure throughout the Atlantic Ocean, 2495 lice representing 27 samples collected from 22 locations were analysed for 14 microsatellite loci. Significant overall genetic variation was observed (14 loci: global F ST = 0.0057, p < 0.0001), although this decreased slightly when an outlier locus (LsalSTA3), detected as a candidate for positive selection, was removed (13 neutral loci: global F ST = 0.0022, p < 0.0001). A relationship between physical and genetic distance was observed (R 2 = 0.179, p = 0.0013), but only when data from LsalSTA3 was included. No overall genetic variation was observed among the 19 samples collected in Norway (Norwegian global F ST < 0.0001, p = 0.6). None of the within-country (Canada, Ireland, Shetland and Faroe Islands) pairwise F ST values were statistically significant when analysing the 13 neutral loci and following Bonferroni correction. Samples taken at 5 Norwegian farms did not exhibit significant genetic differences before and after medicated treatment. We conclude that L. salmonis displays weak but nevertheless statistically significant population genetic variation throughout the Atlantic. Analysis of temporal samples, potentially combined with larger numbers of markers giving greater genome coverage, will be required to fully elucidate the biological significance of the observed variation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Samplesmentioning

confidence: 99%

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Population genetic structure of the parasitic copepod Lepeophtheirus salmonis throughout the Atlantic

Glover

Stølen²,

Messmer³

et al. 2011

Mar. Ecol. Prog. Ser.

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“…In contrast, L. salmonis is rare on juvenile pink salmon in areas with no fish farms (9). L. salmonis occurs in the Atlantic and Pacific oceans, but the Pacific form is clinically less pathogenic than the Atlantic form (10), and the two forms have significant genetic differences (11,12). One other sea louse species, Caligus clemensi, occurs on pink salmon, but it is more common on other fish hosts (13).…”

mentioning

confidence: 99%

Relationship of farm salmon, sea lice, and wild salmon populations

Marty

Saksida

Quinn

2010

Proc. Natl. Acad. Sci. U.S.A.

134

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Increased farm salmon production has heightened concerns about the association between disease on farm and wild fish. The controversy is particularly evident in the Broughton Archipelago of Western Canada, where a high prevalence of sea lice (ectoparasitic copepods) was first reported on juvenile wild pink salmon (Oncorhynchus gorbuscha) in 2001. Exposure to sea lice from farmed Atlantic salmon (Salmo salar) was thought to be the cause of the 97% population decline before these fish returned to spawn in 2002, although no diagnostic investigation was done to rule out other causes of mortality. To address the concern that sea lice from fish farms would cause population extinction of wild salmon, we analyzed 10-20 y of fish farm data and 60 y of pink salmon data. We show that the number of pink salmon returning to spawn in the fall predicts the number of female sea lice on farm fish the next spring, which, in turn, accounts for 98% of the annual variability in the prevalence of sea lice on outmigrating wild juvenile salmon. However, productivity of wild salmon is not negatively associated with either farm lice numbers or farm fish production, and all published field and laboratory data support the conclusion that something other than sea lice caused the population decline in 2002. We conclude that separating farm salmon from wild salmon-proposed through coordinated fallowing or closed containment-will not increase wild salmon productivity and that medical analysis can improve our understanding of complex issues related to aquaculture sustainability.B ecause salmon aquaculture production has rapidly increased over the past three decades, the potential for environmental impacts of salmon farms has generated heightened scientific and public interest (1, 2). One concern about salmon farms is that they are the source of ectoparasitic sea lice infestations that might reduce the marine survival of wild salmon (3, 4). In the Broughton Archipelago region of Western Canada (Fig. S1), farming of Atlantic salmon (Salmo salar) began in the late 1980s, and annual farm salmon production increased steadily to 17 Gg by 1999 (Fig. S2). Pink salmon (Oncorhynchus gorbuscha) is the most abundant wild salmon species in the Broughton Archipelago; they enter the marine environment at a very small size (0.2 g), and they return to natal streams to spawn 2 y after their parents (5). Because age at maturity never varies, they have distinct evenand odd-year populations ( Fig. S2 and SI Text). Record high numbers of pink salmon returned to spawn in rivers of the Broughton Archipelago in 2000 and 2001 (Dataset S1), but these returns were followed by population decline of 97% in 2002 and 88% in 2003 (Figs. S2 and S3 and SI Text). When juvenile pink salmon in the Broughton Archipelago were first examined for sea lice in June 2001, more than 90% were infested-leading to the hypothesis that sea lice from fish farms were the cause of population collapse in 2002 (4).Adult pink salmon are a natural host for the sea louse species Lepeophtheirus salmoni...

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“…Variability of pink salmon returns has been attributed to changes in climate (Downton & Miller 1998, Morita et al 2006, genetic variability (Geiger et al 1997), coded wire tagging or fin clipping (Wertheimer et al 2002), exposure to weathered crude oil during early development (Bue et al 1996, and differences in food availability and size of alevins (Cooney & Brodeur 1998). Recent papers have correlated infestations of parasitic copepods (sea lice) with pink salmon population decline (Krkosek et al 2006(Krkosek et al , 2007; however, Pacific strains of parasitic copepods (Yazawa et al 2008) cause minimal or no mortality with environmentally relevant infestations under controlled laboratory conditions (Jones et al 2007, Webster et al 2007.…”

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confidence: 99%

Ruptured yolk sacs and visceral fungi in emergent pink salmon alevins: histopathology and relation to marine survival

Marty¹,

Heintz²

2010

Dis. Aquat. Org.

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EST and Mitochondrial DNA Sequences Support a Distinct Pacific Form of Salmon Louse, Lepeophtheirus salmonis

Abstract: Nuclear deoxyribonucleic acid sequences from approximately 15

Cited by 54 publications

References 47 publications

Population genetic structure of the parasitic copepod Lepeophtheirus salmonis throughout the Atlantic

Population genetic structure of the parasitic copepod Lepeophtheirus salmonis throughout the Atlantic

Relationship of farm salmon, sea lice, and wild salmon populations

Ruptured yolk sacs and visceral fungi in emergent pink salmon alevins: histopathology and relation to marine survival

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