A study of the relationship between tag-signal characteristics and achievable performances in acoustic fish-tag studies

Abstract

Acoustic tags have been used in fish-behaviour studies in a variety of marine and freshwater environments. The intended objectives of these studies vary widely. In some cases, they require accurate three-dimensional tracking of the individual fish locations. In other cases, tags are used for estimating fish survival along a migration route. There are varieties of schemes that have been proposed and used for implementing tag systems. The purpose of this paper is to explain the relationship between the various characteristics of acoustic signals transmitted by the tags and the tag-system performance that can be achieved. In particular, the ranges at which the tags can be detected and uniquely identified, the positional accuracy, and the number of unique codes that can be assigned to individual fish are all functions of the signal type. This paper demonstrates that when the pulse-repetition period is used to encode the tag identification, the range performance for the tag is superior to that achieved using a scheme that has binaryencoded bits as part of the transmitter signal. The parametric results presented will assist investigators in their selection of the type of acoustic tags or tag parameters needed to achieve the objectives of acoustic fish-tag studies. © United States Government, NOAA/NMFS/AFSC 2009.