Experimental investigation of Canadian East and West Coast fish farm hydrodynamic wake properties and its implications for Integrated Multi-Trophic Aquaculture

Abstract

The objective of this research was to determine the hydrodynamic properties of salmon cage arrays. Drag and wake properties of aquaculture cage arrays have been studied to further understand the movement of released nutrients from cages as a means to improve Integrated Multi-Trophic Aquaculture (IMTA) performance. Experiments have taken place with 1:15 scale model arrays (2x3) of both circular cages typically used on the East Coast of Canada, and square cages typically used on the West Coast of Canada. The models were deployed for experimentation at the large recirculating flume tank, located at the Fisheries and Marine Institute of Memorial University in St. Johns, Newfoundland. Drag measurements were completed for individual cages within the array with respect to current velocity. Results show the highest drag for the first row of cages, with drag reducing significantly through rows two and three. A wake velocity study behind individual cages within the array and in the wake of the entire array was completed to observe velocity deficits, wake topology, wake recovery and turbulence in the flow field. Results show high velocity deficits directly behind cages within the array, causing flow to be accelerated around and below the cages. The presence of a shear layer in the wake of the cages is observed to cause high levels of turbulence downstream. Finally, dye release was used as a tool to visualize the large scale topology of the flow field and help confirm measured results.