In situ target strength estimates of visually verified orange roughy
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The first estimates of orange roughy (Hoplostethus atlanticus) target strength at 38 and 120 kHz with visual verification were obtained from a self-contained echosounder and video camera system affixed to a demersal trawl towed through dense aggregations of spawning orange roughy. Mean target strength estimates were obtained from 24 tracks of orange roughy containing 83 echoes. The mean target strength at 38 kHz was -52.0 dB with a 95% confidence interval of -53.3 to -50.9 dB for fish with a mean length of 33.9 cm. At 120 kHz the mean target strength was -47.9 dB (confidence interval of -48.8 to -46.4 dB). This work makes two significant advances: in situ TS measurements have been made that can be confidently attributed to orange roughy, and using a trawl to herd orange roughy past the system resolved the previously intractable problem of fish avoidance. © 2012 International Council for the Exploration of the Sea.
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Improved estimates of orange roughy biomass using an acoustic-optical system in commercial trawlnetsRyan, T.; Kloser, Rudy (2016)© 2016 International Council for the Exploration of the Sea. All rights reserved.Echo integration is a well-established method for estimating fish biomass, but is challenging for a low target strength (TS), deep-living ...
Kloser, Rudy; MacAulay, G.; Ryan, T.; Lewis, M. (2013)It is often assumed that in situ target strength (TS) measurements from dispersed fish are representative of the surveyed schooling fish. For in situ TS measurements of orange roughy in deep water, it has been difficult ...
Indicators of recovery for orange roughy (Hoplostethus atlanticus) in eastern Australian waters fished from 1987Kloser, Rudy; Sutton, C.; Krusic-Golub, K.; Ryan, T. (2015)© 2015 .Compared to an 18 year New Zealand study (. Clark et al., 2000) we found multiple signs of recovery for orange roughy in Australian waters. Orange roughy were listed as conservation dependent in Australian waters ...