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| 30. April 2011 |
Studie der Raincoast Conservation Foundation belegt, dass
die Zuchtlachsfarmen für den stark erhöhten Seelausbefall
der jungen Rotlachse verantwortlich sind |
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Eine Studie der Raincoast Conservation Foundation, die gemeinsam mit anderen Umweltschutzorganisationen, der University of Victoria und der Simon Fraser University erstellt wurde, untersucht die potentielle Rolle der Zuchtlachsfarmen im Gebiet der Discovery Islands mit ihren 18 Fischfarmen bei der Übertragung von Seeläusen auf die jungen Rotlachse (Oncorhynchus nerka), die auf ihrer ersten Wanderung ins offene Meer an diesen Lachsfarmen vorbeischwimmen. Gerade die Wanderroute der jungen Rotlachse aus dem Fraser River führt an diesen Zuchtlachsfarmen vorbei, wobei die jungen Wildlachse der Parasitendusche aus den Zuchtlachsfarmen ausgesetzt sind und vor allem von zwei Arten von Seeläusen befallen werden (Caligus clemensi und Lepeophtheirus salmonis). „This is the first study to demonstrate a potential role of salmon farms in sea lice transmission to juvenile sockeye salmon during their critical early marine migration. Moreover, it demonstrates a major migration corridor past farms for sockeye that originated in the Fraser River, a complex of populations that are the subject of conservation concern“, stellen die Autoren dieser Studie fest (Price, Michael H. H.; Proboszcz, Stan L.; Routledge, Rick D.; Gottesfeld, Allen S.; Orr, Craig; Reynolds, John D. (2011). Sea Louse Infection of Juvenile Sockeye Salmon in Relation to Marine Salmon Farms on Canada’s West Coast). Der gesamte Artikel mit seinen Ergebnissen und einer Karte des Untersuchungsergebnisses steht online zur Verfügung unter:
PLoS ONE 6(2): e16851. doi:10.1371/journal.pone.0016851 |
| Unter dem Punkt „Methodology/Principal Findings“ fassen die Autoren ihre Hauptergebnisse zusammen: |
| „We used genetic analyses to determine the origin of sockeye from Canada’s two most important salmon rivers, the Fraser and Skeena; Fraser sockeye migrate through a region with salmon farms, and Skeena sockeye do not. We compared lice levels between Fraser and Skeena juvenile sockeye, and within the salmon farm region we compared lice levels on wild fish either before or after migration past farms. We matched the latter data on wild juveniles with sea lice data concurrently gathered on farms. Fraser River sockeye migrating through a region with salmon farms hosted an order of magnitude more sea lice than Skeena River populations, where there are no farms. Lice abundances on juvenile sockeye in the salmon farm region were substantially higher downstream of farms than upstream of farms for the two common species of lice: Caligus clemensi and Lepeophtheirus salmonis, and changes in their proportions between two years matched changes on the fish farms. Mixed-effects models show that position relative to salmon farms best explained
C. clemensi abundance on sockeye, while migration year combined with position relative to salmon farms and temperature was one of two top models to explain L. salmonis abundance.“ |
| Bei der Diskussion ihrer Forschungsergebnisse kommen die Wissenschaftler zu folgendem Schluss: |
| „Our evidence suggests that salmon farms are elevating parasite levels on Fraser River sockeye during their critical early marine migration; to establish the link more definitively between farms and wild fish would require collaborative work with the salmon farm industry as has begun in Europe and the Broughton Archipelago. Ultimately, risks to wild salmon posed by salmon farms can be more easily mitigated than the far-reaching effects on ocean productivity of climate change and ocean acidification. Options already recommended include removal of farm salmon from migration routes of juvenile sockeye from the Fraser, and transitioning of salmon farms to closed containment facilities. At minimum, the Discovery Islands’ migration corridor requires a co-ordinated aquaculture management plan to minimize the exposure of wild juvenile sockeye to sea lice.“ |
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