Statistical Processing of Different Sounds of Vocalizing Fish and Mammals to Estimate Their Population Size With Two Acoustic Sensors

Abstract

Fish and mammals have an enormous impact on marine ecosystems. A proper estimation of their population size is necessary, not only for their ecological values but also for commercial purposes. Most conventional techniques for estimating fish population are visual sampling techniques, the environmental DNA (eDNA) technique, minnow traps, the removal method of population estimation, and echo integration techniques, all of which are sometimes complex and costly, require human interaction, and can be harmful for marine species. In order to overcome these limitations, in this paper, a passive acoustic fishery monitoring technique is proposed as an alternative. The method is based on a statistical signal processing technique called “cross-correlation” and different types of sounds—namely, chirps, grunts, growls, clicks, and so forth—produced by fish and mammals. Our goal was not only to propose an efficient technique for fish population estimation but also to measure its performance for different fish sounds by using numerical simulations. From the analyses of simulated results, we found that the chirp sound-generating species produced better results than the other two types of sound-generating species—the grunt- and growl-generating species.

Impact of unequal distances among acoustic sensors on cross-correlation based fisheries stock assessment technique

“…We have generated fish sounds considering different real-time parameters, i.e., frequency, time duration, bandwidth, etc. 9 . Similarly, fish signals can be represented as swift frequency wave 9 .…”

“…9 . Similarly, fish signals can be represented as swift frequency wave 9 . The toolbox of MATLAB provides functions to generate swept-frequency waveforms such as the chirp function.…”

“…A straightforward, cross-correlation based population estimation technique was proposed in Refs. 8 , 9 , was a passive acoustic monitoring technique, can solve some major drawbacks of conventional fish population estimation techniques. Researchers investigated different practical impacts which were associated with this technique.…”

“…In this section, the methodology of cross-correlation based population estimation technique 9 , 10 , 15 is deliberated. We have considered three acoustic sensors array in this study.…”

“…In this paper, we have considered three acoustic sensors, where the sensors maintain unequal distances. Three acoustic sensors can be organized by two types of topologies, i.e., acoustic sensors in line (ASL) scheme and acoustic sensors in a triangle (AST) scheme 9 . We have worked with both schemes to investigate the impact of unequal distances among the acoustic sensors.…”