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Aquaculture Environment Interactions

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AEI 11:249-261 (2019)  -  DOI:

Fish welfare based classification method of ocean current speeds at aquaculture sites

Kristbjörg Edda Jónsdóttir1,*, Malthe Hvas2, Jo Arve Alfredsen1, Martin Føre1,3, Morten Omholt Alver1,3, Hans Vanhauwaert Bjelland3, Frode Oppedal2

1Department of Engineering Cybernetics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
2Research Group of Animal Welfare, Institute of Marine Research, 5984 Matredal, Norway
3SINTEF Ocean, 7465 Trondheim, Norway
*Corresponding author:

ABSTRACT: A major trend in marine aquaculture is to move production to more exposed sites with occasionally rough ocean current events. However, it is unclear whether fish will thrive in these extreme environments, since thorough descriptions of ambient current conditions with regards to fish welfare is lacking. In the present study, ocean current data were collected using acoustic Doppler current profilers at 5 exposed sites along the Norwegian coast over minimum periods of 5 mo. To evaluate welfare risks, current data was compared to known limits of swimming capabilities, such as onset of behavioural changes and critical swimming speeds (Ucrit), of Atlantic salmon Salmo salar and lumpfish Cyclopterus lumpus. Specifically, at each site, current speeds were classified into 6 categories based on expected impact on swimming behaviours of Atlantic salmon, and duration of currents within each category were inspected using a homogeneous and non-homogeneous criterion for the water column. Current speeds were then compared with projected Ucrit at relevant temperatures and fish sizes of Atlantic salmon and lumpfish. Furthermore, a detailed characterization of extreme events at the most exposed site was performed. Of the 5 locations, only 1 exceeded the Ucrit of Atlantic salmon, while all sites featured currents above Ucrit of lumpfish for up to 33 h at a time. These results suggest that responsible Atlantic salmon farming is possible at sites considered exposed, while lumpfish should be restricted to more sheltered environments. The presented method can be applied for other aquaculture fish species if adequate data are available.

KEY WORDS: Atlantic salmon · Lumpfish · Ucrit · Exposed farming · Ocean current speed · Swimming behaviour · Sea cage environment

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Cite this article as: Jónsdóttir KE, Hvas M, Alfredsen JA, Føre M, Alver MO, Bjelland HV, Oppedal F (2019) Fish welfare based classification method of ocean current speeds at aquaculture sites. Aquacult Environ Interact 11:249-261.

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