Modelling the performance of fish tag monitoring stations on the Scotian Shelf

Abstract

The Ocean Tracking Network operates and maintains a continental shelf scale array of 256 bottom mounted fish-tag monitoring stations, spanning from the entrance of Halifax harbour to the Scotian Shelf break. These stations detect tagged keystone, commercially important, and endangered species as they migrate across this acoustic curtain, known as the Halifax line. The detection performance of each station is dependent on the local bathymetry, oceanography (sound speed profile variability), ambient noise level, and source depth distribution. At each station, local sound speed profiles from archived glider data were collected and sorted into representative groups. An Nx2D ray-trace model was used to calculate the transmission loss and relative strength of the noise field at fish tag frequencies (69 kHz) for each of the representative sound speed profiles at a number of stations across the array. The performance variability at each station and between stations is presented and compared to real detection data.