Development, Growth, and Survival of <i>Lepeophtheirus Salmonis</i> (Copepoda: Caligidae) Under Laboratory Conditions

Johnson, Stewart C.; Albright, L. J.

doi:10.1017/s0025315400051687

Cited by 270 publications

(304 citation statements)

References 20 publications

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“…1), but the pattern within farms was different from the pattern when all area farm data were combined. Farm salmon enter the marine environment free of sea lice (24), but sea lice in the environment start to infest the fish within a few months of stocking (10). Within each farm, the monthly total number of adult female L. salmonis either remained stable-when freshwater runoff decreased the salinity (and louse replication) at many farms (10)-or increased, probably from (i) ongoing environmental exposure to new lice and (ii) maturation of young lice already on the fish; louse numbers decreased only when fish were treated or removed from the farm (Dataset S1).…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

“…1). Louse numbers steadily increased (i) in the fall, when adult wild salmon (infested with lice) (7,8) returned to the area to spawn, and (ii) in the winter, when increased salinity favored louse reproduction (24).…”

Section: Resultsmentioning

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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“…In BC waters, it takes three to four weeks for the egg to develop into an infective copepod, which has about a week to find a host otherwise it dies. A further four weeks of growth on a host is needed for a copepod to reach a reproductive adult [32]. The salmon louse can only complete its life history in SW with a salinity greater than 23 ppt, and the development of viable copepodids requires at least 30 ppt [32].…”

Section: The Parasite: Salmon Licementioning

confidence: 99%

“…A further four weeks of growth on a host is needed for a copepod to reach a reproductive adult [32]. The salmon louse can only complete its life history in SW with a salinity greater than 23 ppt, and the development of viable copepodids requires at least 30 ppt [32]. Therefore, juvenile pink salmon become hosts only after they enter SW. Salmon louse infections produce epidermal lesions, ionoregulatory disruptions and secondary infections in salmon [33].…”

Section: The Parasite: Salmon Licementioning

confidence: 99%

“…Shedding of salmon lice by juvenile salmon is well documented [44,62 -66] and is influenced by both biotic and abiotic factors, including parasite mortality, immune response by the host, water temperature and water salinity [32,44,63]. Thus, all controlled infection studies of Pacific and Atlantic salmon performed to date and designed to investigate the effect of fixed levels of infection have been confounded by the intensity of salmon louse infection decreasing with time.…”

Section: A Complicating Factor: Shedding Of Salmon Licementioning

confidence: 99%

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Physiological consequences of the salmon louse (Lepeophtheirus salmonis) on juvenile pink salmon (Oncorhynchus gorbuscha): implications for wild salmon ecology and management, and for salmon aquaculture

Brauner

Sackville

Gallagher

et al. 2012

Phil. Trans. R. Soc. B

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Pink salmon, Oncorhynchus gorbuscha, are the most abundant wild salmon species and are thought of as an indicator of ecosystem health. The salmon louse, Lepeophtheirus salmonis, is endemic to pink salmon habitat but these ectoparasites have been implicated in reducing local pink salmon populations in the Broughton Archipelago, British Columbia. This allegation arose largely because juvenile pink salmon migrate past commercial open net salmon farms, which are known to incubate the salmon louse. Juvenile pink salmon are thought to be especially sensitive to this ectoparasite because they enter the sea at such a small size (approx. 0.2 g). Here, we describe how 'no effect' thresholds for salmon louse sublethal impacts on juvenile pink salmon were determined using physiological principles. These data were accepted by environmental managers and are being used to minimize the impact of salmon aquaculture on wild pink salmon populations.

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