Sea lice infestation levels decrease with deeper ‘snorkel’ barriers in Atlantic salmon sea-cages

AbstractBACKGROUNDSalmon lice (Lepeophtheirus salmonis) are the most important parasites of farmed salmon. Infective larvae position themselves in the upper part of the water column to increase encounter probabilities with potential hosts. Previous studies have shown that a ‘snorkel’ sea‐cage techno...

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Bibliographic Details
Main Authors: F Oppedal, F Samsing, Tim Dempster, DW Wright, S Bui, LH Stien
Format: Article in Journal/Newspaper
Language:unknown
Published: 2017
Subjects:
Agricultural
veterinary and food sciences
Crop and pasture production
Fisheries sciences
Zoology
Environmental sciences
Environmental management
Animals
Biological Assay
Environment
Fisheries
Lice Infestations
Salmo salar
fish behaviour
Lepeophtheirus salmonis
parasite management
production parameters
sustainable farming
Atlantic salmon
Online Access:http://hdl.handle.net/10779/DRO/DU:24602463.v2
https://figshare.com/articles/journal_contribution/Sea_lice_infestation_levels_decrease_with_deeper_snorkel_barriers_in_Atlantic_salmon_sea-cages/24602463
Description
Summary:AbstractBACKGROUNDSalmon lice (Lepeophtheirus salmonis) are the most important parasites of farmed salmon. Infective larvae position themselves in the upper part of the water column to increase encounter probabilities with potential hosts. Previous studies have shown that a ‘snorkel’ sea‐cage technology protects salmon from infection in surface waters. We tested whether deep snorkels would more effectively reduce lice infestation than shallow snorkels and still uphold adequate conditions for the fish. Five sea‐cages (12 m × 12 m) each holding approximately 3000 Atlantic salmon (Salmo salar) (53 ± 10 g) were fitted with snorkels that gave protection from infection for 0, 4, 8, 12 or 16 m. We tested whether reductions in the settlement of new salmon lice copepodids were consistent among four separate infection periods.RESULTSLice infestation decreased exponentially with depth in all time periods. Infection levels in shallow snorkels (0 and 4 m) were consistently 4–10 times higher than those in deep snorkels (12 and 16 m). Key welfare and production performance indices were similar across all snorkel depths.CONCLUSIONDeeper snorkels dramatically and consistently reduced infection levels of salmon lice compared with shallow snorkels, without consequences for fish welfare and production performance. Therefore, reducing salmon sea lice encounters using a depth‐based barrier is a powerful management tool for salmon farming. © 2017 Society of Chemical Industry

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