Use of acoustics to assess a small aggregation of orange roughy, Hoplostethus atlanticus (Collett), off the eastern coast of Tasmania
1993
Elliott, N.G. | Kloser, R.J. (Commonwealth Scientific and Industrial Research Organisation, Hobart (Australia). Div. of Fisheries)
A relatively small aggregation of orange roughy (Hoplostethus atlanticus) was located in April 1989 off the eastern coast of Tasmania. A Simrad EK400 (38 kHz) scientific echo-sounder was used to survey the aggregation over a period of eight days, during which time the aggregation was commercially fished. The aggregation was confined to an area of approximately 4 sq km, with the dimensions of the aggregation varying within and between days. High densities of orange roughy were located near the bottom on some days and more than 24 m off the bottom on others. Average fish densities during the survey and an estimate of the extremes of densities (fish per cu m) are presented. Estimates of the original biomass of this aggregation as obtained from acoustic data and commercial catch-and-effort data are compared, and the mean target strength of the population is estimated.
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