Abstract

A fishing net localization algorithm based on underwater acoustic sensor networks is proposed. Fishing vessels are utilized as mobile references for underwater localization. After collecting acoustic signals; the algorithm determines the underwater location of fishing nets; and different estimation methods are developed based on the number of ships detecting the signal. It then tracks the location in real-time to better determine whether the net is lost or discarded so that it can be collected in a timely manner. The algorithm is tested on various system parameters such as an acoustic signal range; the number of ships; and current velocity to verify its robustness.

Introduction

Pollution of the marine environment by marine debris has been considered a serious problem. In particular; lost or discarded fishing gears cause fish to get caught in the invisible net and die; which in turn harms the marine ecosystem. In this regard; it is essential to track and predict the net location so that people can timely collect it. This study; therefore; proposes the underwater location tracking system of fishing nets using acoustic signals between fishing nets and fishing boats. This system consists of GPS at the location buoy floating at the sea surface and acoustic sensors installed along the underwater net. Using GPS signals is indeed one of the most direct and easy ways in the ocean. However; in the case when the rope is broken or a fishing net is abandoned; it is hard to find the underwater location of the net. In these scenarios; the acoustic signals can be employed to track and predict the net locations. Thus; we develop an algorithm to estimate underwater net location only using acoustic signals. The signal provides the distance and azimuth angle between two locations. All fishing boats can track nets belonging to themselves and other fishermen. The collected signals are transmitted to the land control center so that all nets can be monitored.

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