Wave-generated currents threaten aquaculture sites

This study investigates the impact of wave-generated currents on fish farms, focusing on a novel exposed aqua-
culture site in the bay of Sandsvág, Faroe Islands. While shoals can attenuate wave height, our research reveals
that breaking waves generate localized currents, which can intensify into powerful jets during severe storms. A
strong correlation between wave height and current speed was established, demonstrating that these jets arise
under specific conditions and can contribute to significant fish mortality. We analyze how currents interact with
the cage structure, particularly reducing cage volume as the sinker tube is displaced sideways and lifted within
the water column. Frequency analysis of cage deformation reveals dominant oscillatory behaviors linked to infra-
gravity waves and current pulsations. The results indicate that slack generated during wave troughs allows these
currents to reduce cage volume further, increasing fish density and the risk of collisions with the netting. These
findings underscore the challenges of aquaculture in exposed locations and highlight the need for improved site
selection strategies and cage designs. Furthermore, predictive modeling is essential for assessing the formation of
jet currents, their impact on cage integrity, and the challenges of capturing extreme wave-current events through
short-term measurements.