A large, natural infection of sea lice on juvenile Pacific salmon in the Gulf Islands area of British Columbia, Canada

Beamish, Richard; Wade, Joy; Pennell, William; Gordon, E.; Jones, Simon R. M.; Neville, Chrys‐Ellen M.; Lange, Klaus; Sweeting, R. M.

doi:10.1016/j.aquaculture.2009.09.001

Cited by 25 publications

(28 citation statements)

References 16 publications

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“…salmonis were found on the juvenile pink salmon as well as the other juvenile Pacific salmon species examined with no significant difference in levels of prevalence observed among the species. The sea lice prevalence levels on juvenile pink salmon in our study were considerably lower than those reported from other regions of BC: some of which have Atlantic salmon farms present (Jones and Hargreaves 2007), but others which come from regions with no salmon farming activity such as the southern BC area reported in Beamish et al (2009). Intensity was also low with most infected fish hosting just a single louse.…”

Section: Discussioncontrasting

confidence: 46%

“…Caligus clemensi is very mobile and it has been generally accepted that with its wide host range, which consists of both salmon and non-salmon species (Johnson et al 2004, Beamish et al 2005, salmon farms are unlikely to be the primary source (Krkošek et al 2007a). Beamish et al (2009) suggested that a possible source of C. clemensi could be Pacific herring (Clupea harengus pallasi) in their study of sea lice on wild juvenile salmon on the south coast of BC. The logistic regression analysis indicated that size (length) of juvenile pink salmon was significantly associated with C. clemensi infections with larger fish more likely to be infected.…”

Section: Discussionmentioning

confidence: 99%

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Sea lice on wild juvenile Pacific salmon and farmed Atlantic salmon in the northernmost salmon farming region of British Columbia

Saksida

Greba

Morrison³

et al. 2011

Aquaculture

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The Kitasoo/Xai'xais First Nation established a program to monitor sea lice levels on seaward migrating wild juvenile salmon in their traditional territory which contains the most northerly salmon farming region of British Columbia. A total of 12 locations were routinely sampled during the period between 2005 and 2008 to gain a better understanding of the levels and patterns of sea lice infestation on wild salmonids in the region. Over 5000 juvenile salmon were collected and examined for sea lice. Around 78% were identified as pink salmon, 18% were chum salmon and the remainder classified as 'other' salmon (coho and sockeye salmon). Two species of sea lice were observed: Lepeophtheirus salmonis and Caligus clemensi. Over 91% of all the juvenile salmon examined had no sea lice and there was no significant difference in L. salmonis prevalence levels among salmon species. However, chum salmon had significantly lower C. clemensi prevalence levels than either pink or 'other' salmon. There were significant annual and regional differences in L. salmonis prevalence on juvenile pink salmon; the lowest prevalence in all sampling zones occurring in 2008, while channels containing salmon farms consistently had higher levels than those without salmon farms. Mean prevalence of L. salmonis in the channels with salmon farms ranged from 2% to 9% which is lower than levels published for the same region in different years or for other areas without salmon farms. C. clemensi prevalence on wild pink salmon was associated with sampling zone and the size of pink salmon; larger juvenile fish were more likely to be infected than smaller fish. During the period of wild juvenile salmon migration, the mean abundance of motile stages of L. salmonis on farmed salmon ranged from 0.13 to 0.79 lice per fish but there were no significant differences among years. In comparison, 2 C. clemensi abundance levels on farms were significantly higher in 2005. Factors contributing to variations in these observations are discussed.

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Section: Discussioncontrasting

confidence: 46%

Section: Discussionmentioning

confidence: 99%

Sea lice on wild juvenile Pacific salmon and farmed Atlantic salmon in the northernmost salmon farming region of British Columbia

Saksida

Greba

Morrison³

et al. 2011

Aquaculture

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“…Infection risk for juvenile sockeye is exacerbated by the generalist nature of the C. clemensi; Pacific herring (Clupea pallasii) can also be infected by C. clemensi at high abundances and are likely a second sea louse reservoir to sockeye (Beamish et al 2009;Morton et al 2008). However, it is not known how or whether parasite exposure fits into the long-term decline of sockeye productivity.…”

Section: Introductionmentioning

confidence: 96%

Sea lice, sockeye salmon, and foraging competition: lousy fish are lousy competitors

Godwin

Dill

Reynolds

2015

Can. J. Fish. Aquat. Sci.

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Pathogens threaten wildlife globally, but these impacts are not restricted to direct mortality from disease. For fish, which experience periods of extremely high mortality during their early life history, infections may primarily influence population dynamics and conservation through indirect effects on ecological processes such as competition and predation. We conducted a competitive foraging experiment using outmigrating juvenile Fraser River sockeye salmon (Oncorhynchus nerka) to determine whether fish with high abundances of parasitic sea lice (Caligus clemensi and Lepeophtheirus salmonis) have reduced competitive abilities when foraging. Highly infected sockeye were 20% less successful at consuming food, on average, than lightly infected fish. Competitive ability also increased with fish body size. Our results provide the first evidence that parasite exposure may have negative indirect effects on the fitness of juvenile sockeye salmon and suggest that indirect effects of pathogens may be of key importance for the conservation of marine fish.Résumé : Les pathogènes sont une menace pour les espèces sauvages à l'échelle planétaire, mais leurs impacts ne se limitent pas à la mortalité directe découlant de maladies. Pour les poissons, caractérisés par une période de mortalité extrêmement élevée au début de leur cycle de vie, les infections pourraient influencer principalement la dynamique des populations et la conservation par le biais d'effets indirects sur des processus écologiques comme la concurrence et la prédation. Nous avons mené une expérience d'approvisionnement concurrentielle en utilisant des saumons rouges (Oncorhynchus nerka) juvéniles du fleuve Fraser dans leur migration vers la mer, afin de déterminer si les poissons présentant une forte abondance de poux du poisson (Caligus clemensi et Lepeophtheirus salmonis) parasitiques présentaient également une capacité concurrentielle réduite durant l'approvisionnement. Les saumons rouges très infectés avaient un taux de succès de consommation de nourriture 20 % plus faible, en moyenne, que les poissons légèrement infectés. La capacité concurrentielle augmentait également avec la taille du corps du poisson. Nos résultats sont les premiers à indiquer que l'exposition aux parasites pourrait avoir des effets négatifs indirects sur l'aptitude des saumons rouges juvéniles et donnent à penser que les effets indirects des pathogènes pourraient être d'importance capitale pour la conservation des poissons de mer. [Traduit par la Rédaction]

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“…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). Unlike L. salmonis, C. clemensi is sometimes common on juvenile pink salmon away from fish farms (13).…”

mentioning

confidence: 99%

“…One other sea louse species, Caligus clemensi, occurs on pink salmon, but it is more common on other fish hosts (13). Unlike L. salmonis, C. clemensi is sometimes common on juvenile pink salmon away from fish farms (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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A large, natural infection of sea lice on juvenile Pacific salmon in the Gulf Islands area of British Columbia, Canada

Cited by 25 publications

References 16 publications

Sea lice on wild juvenile Pacific salmon and farmed Atlantic salmon in the northernmost salmon farming region of British Columbia

Sea lice on wild juvenile Pacific salmon and farmed Atlantic salmon in the northernmost salmon farming region of British Columbia

Sea lice, sockeye salmon, and foraging competition: lousy fish are lousy competitors

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

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