Snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare
Sea lice are a critical health issue in most salmonid farming regions. New cage-based technologies can prevent infestations from occurring, such as the ‘snorkel’, which introduces an impermeable barrier that separates salmon lice Lepeophtheirus salmonis from Atlantic salmon Salmo salar in the surfac...
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ftdoajarticles:oai:doaj.org/article:f95be366641a40589c89bd3c3a36e285 2023-05-15T15:32:45+02:00 Snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare Oppedal, F Bui, S Stien, LH Overton, K Dempster, T 2019-09-01T00:00:00Z https://doi.org/10.3354/aei00321 https://doaj.org/article/f95be366641a40589c89bd3c3a36e285 EN eng Inter-Research https://www.int-res.com/abstracts/aei/v11/p445-457/ https://doaj.org/toc/1869-215X https://doaj.org/toc/1869-7534 1869-215X 1869-7534 doi:10.3354/aei00321 https://doaj.org/article/f95be366641a40589c89bd3c3a36e285 Aquaculture Environment Interactions, Vol 11, Pp 445-457 (2019) Aquaculture. Fisheries. Angling SH1-691 Ecology QH540-549.5 article 2019 ftdoajarticles https://doi.org/10.3354/aei00321 2022-12-31T00:58:24Z Sea lice are a critical health issue in most salmonid farming regions. New cage-based technologies can prevent infestations from occurring, such as the ‘snorkel’, which introduces an impermeable barrier that separates salmon lice Lepeophtheirus salmonis from Atlantic salmon Salmo salar in the surface waters where lice are most abundant. While snorkels provide protection from lice, their lice-reducing effect can vary under different environmental conditions. We conducted production-scale sea-cage experiments at 2 sites with contrasting salinity environments in Norway. At the coastal site, with a weak and unsystematic halocline, snorkels reduced lice infestations by 76%. However, at the fjord site, with brackish surface waters and a strong halocline, snorkels did not reduce lice relative to control cages, likely because both lice and salmon remained deeper in the water column below the brackish layer, and infection rate was similar. At the fjord site, as lice numbers between snorkel and control cages were similar, we tested for differences in the absence of the potentially confounding effect of different lice levels. Snorkel cages at the fjord site modified swimming speeds (1.14 times faster), surface breaching behaviours (2.8 times less), and total echo-sounder signal strength of fish (an index of swim bladder fullness; 30-40% less) relative to control cages. Production parameters remained similar, but snout condition was poorer in snorkel cages, suggesting more frequent contact with cage netting. Our results suggest that salinity is a significant environmental factor that alters the lice-reducing efficacy of depth-based technologies such as snorkels. Further, snorkels affect salmon behaviour, which must be considered in welfare assessments of their use. Article in Journal/Newspaper Atlantic salmon Salmo salar Directory of Open Access Journals: DOAJ Articles Norway Aquaculture Environment Interactions 11 445 457 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Aquaculture. Fisheries. Angling SH1-691 Ecology QH540-549.5 |
spellingShingle |
Aquaculture. Fisheries. Angling SH1-691 Ecology QH540-549.5 Oppedal, F Bui, S Stien, LH Overton, K Dempster, T Snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare |
topic_facet |
Aquaculture. Fisheries. Angling SH1-691 Ecology QH540-549.5 |
description |
Sea lice are a critical health issue in most salmonid farming regions. New cage-based technologies can prevent infestations from occurring, such as the ‘snorkel’, which introduces an impermeable barrier that separates salmon lice Lepeophtheirus salmonis from Atlantic salmon Salmo salar in the surface waters where lice are most abundant. While snorkels provide protection from lice, their lice-reducing effect can vary under different environmental conditions. We conducted production-scale sea-cage experiments at 2 sites with contrasting salinity environments in Norway. At the coastal site, with a weak and unsystematic halocline, snorkels reduced lice infestations by 76%. However, at the fjord site, with brackish surface waters and a strong halocline, snorkels did not reduce lice relative to control cages, likely because both lice and salmon remained deeper in the water column below the brackish layer, and infection rate was similar. At the fjord site, as lice numbers between snorkel and control cages were similar, we tested for differences in the absence of the potentially confounding effect of different lice levels. Snorkel cages at the fjord site modified swimming speeds (1.14 times faster), surface breaching behaviours (2.8 times less), and total echo-sounder signal strength of fish (an index of swim bladder fullness; 30-40% less) relative to control cages. Production parameters remained similar, but snout condition was poorer in snorkel cages, suggesting more frequent contact with cage netting. Our results suggest that salinity is a significant environmental factor that alters the lice-reducing efficacy of depth-based technologies such as snorkels. Further, snorkels affect salmon behaviour, which must be considered in welfare assessments of their use. |
format |
Article in Journal/Newspaper |
author |
Oppedal, F Bui, S Stien, LH Overton, K Dempster, T |
author_facet |
Oppedal, F Bui, S Stien, LH Overton, K Dempster, T |
author_sort |
Oppedal, F |
title |
Snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare |
title_short |
Snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare |
title_full |
Snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare |
title_fullStr |
Snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare |
title_full_unstemmed |
Snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare |
title_sort |
snorkel technology to reduce sea lice infestations: efficacy depends on salinity at the farm site, but snorkels have minimal effects on salmon production and welfare |
publisher |
Inter-Research |
publishDate |
2019 |
url |
https://doi.org/10.3354/aei00321 https://doaj.org/article/f95be366641a40589c89bd3c3a36e285 |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Atlantic salmon Salmo salar |
genre_facet |
Atlantic salmon Salmo salar |
op_source |
Aquaculture Environment Interactions, Vol 11, Pp 445-457 (2019) |
op_relation |
https://www.int-res.com/abstracts/aei/v11/p445-457/ https://doaj.org/toc/1869-215X https://doaj.org/toc/1869-7534 1869-215X 1869-7534 doi:10.3354/aei00321 https://doaj.org/article/f95be366641a40589c89bd3c3a36e285 |
op_doi |
https://doi.org/10.3354/aei00321 |
container_title |
Aquaculture Environment Interactions |
container_volume |
11 |
container_start_page |
445 |
op_container_end_page |
457 |
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1766363236956897280 |