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

Ke Jónsdóttir,Ja Alfredsen,M Hvas,M Føre,Mo Alver,F Oppedal,Hv Bjelland

doi:10.3354/aei00310

Abstract

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

Highlights

With the continuing expansion of the marine aquaculture industry and a decrease in available sites in nearshore areas due to spatial conflicts and competing claims, there is a growing interest in moving new production sites to more exposed coastal and offshore locations (e.g. Holmer 2010, Bjelland et al 2015, Gentry et al 2017)
The group structure of Atlantic salmon Salmo salar in commercial farms and experimental setups is observed to change from circular schooling to ‘standing’ on the current, i.e. remaining stationary while swimming against the current as the current speed increases (Johansson et al 2014, Hvas et al 2017b)
Observations from Ste and Aafj were predominantly within the ‘weak’ and ‘very weak’ classes, with nearly 99% of all current speeds measured at Ste and 93% at Aafj in 1 of these 2 classes

Summary

Introduction

With the continuing expansion of the marine aquaculture industry and a decrease in available sites in nearshore areas due to spatial conflicts and competing claims, there is a growing interest in moving new production sites to more exposed coastal and offshore locations (e.g. Holmer 2010, Bjelland et al 2015, Gentry et al 2017). Aquacult Environ Interact 11: 249–261, 2019 and frequency of strong current events affect behaviour, growth, stress and risks of mortality (Johansson et al 2014, Solstorm et al 2015, Remen et al 2016, Hvas & Oppedal 2017). The response of farmed fish to ocean currents may be expressed as behavioural changes. At low current velocities, swimming speeds are voluntary and independent of the ambient environment, while stronger currents may force the fish to swim at speeds dictated by the environment (Johansson et al 2014, Hvas et al 2017b). Preventing fish from swimming at their preferred cruising speed for prolonged periods is a legitimate welfare concern (Hvas et al 2017b), and the excess energy expenditure required for faster swimming will to some extent, affect production performance (Solstorm et al 2015)

Objectives

Results

Discussion

Conclusion