In situ measurements of target strength with optical and model verification: A case study for blue grenadier, Macruronus novaezelandiae
In situ measurements of target strength (TS) of isolated fish surrounding dense schools need to be representative of the schooling fish to calculate their echo-integrated biomass. Using synchronous optical and acoustic measurements from a pelagic fishing net, the standard length (81 cm, n = 128), ti...
| Main Authors: | , , , |
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| Format: | Journal Article |
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Oxford University Press 2009
2011
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| Online Access: | http://hdl.handle.net/20.500.11937/52472 |
| _version_ | 1848758934841589760 |
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| author | Kloser, Rudy Ryan, T. Macaulay, G. Lewis, M. |
| author_facet | Kloser, Rudy Ryan, T. Macaulay, G. Lewis, M. |
| author_sort | Kloser, Rudy |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | In situ measurements of target strength (TS) of isolated fish surrounding dense schools need to be representative of the schooling fish to calculate their echo-integrated biomass. Using synchronous optical and acoustic measurements from a pelagic fishing net, the standard length (81 cm, n = 128), tilt-angle (-9°), and net-disturbed in situ TS (-34.4 dB) of Australian Macruronus novaezelandiae (blue grenadier) were confirmed at depth. In situ drift experiments of assumed undisturbed but dispersed blue grenadier recorded a mean TS of -31.8 dB (CI -33.1 to -30.9 dB) with attributed fish standard lengths of 83 cm (s.d. 7.5 cm) and weight 2.5 kg. Modelling the gasbladder showed that uncertainties in fish length, orientation, and gasbladder size could explain the differences observed. Blue grenadiers have negative buoyancy because the cavity size of their gasbladder is smaller than the volume of gas required for neutral buoyancy at depth. For the same species and length, New Zealand hoki weigh less and have smaller gasbladders than Australian blue grenadier, suggesting a conversion factor of 1.10 in length for comparative measurements. Net-attached acoustic and optical measurements indicate that model and drift in situ measurements are biased high by 2.9 and 1.0 dB, respectively. Net-attached acoustic and optical measurements are a cost-effective method of monitoring TS routinely at depth for changes in species length and weight. © 2011 International Council for the Exploration of the Sea. |
| first_indexed | 2025-11-14T09:51:53Z |
| format | Journal Article |
| id | curtin-20.500.11937-52472 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:51:53Z |
| publishDate | 2011 |
| publisher | Oxford University Press 2009 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-524722017-09-13T15:38:22Z In situ measurements of target strength with optical and model verification: A case study for blue grenadier, Macruronus novaezelandiae Kloser, Rudy Ryan, T. Macaulay, G. Lewis, M. In situ measurements of target strength (TS) of isolated fish surrounding dense schools need to be representative of the schooling fish to calculate their echo-integrated biomass. Using synchronous optical and acoustic measurements from a pelagic fishing net, the standard length (81 cm, n = 128), tilt-angle (-9°), and net-disturbed in situ TS (-34.4 dB) of Australian Macruronus novaezelandiae (blue grenadier) were confirmed at depth. In situ drift experiments of assumed undisturbed but dispersed blue grenadier recorded a mean TS of -31.8 dB (CI -33.1 to -30.9 dB) with attributed fish standard lengths of 83 cm (s.d. 7.5 cm) and weight 2.5 kg. Modelling the gasbladder showed that uncertainties in fish length, orientation, and gasbladder size could explain the differences observed. Blue grenadiers have negative buoyancy because the cavity size of their gasbladder is smaller than the volume of gas required for neutral buoyancy at depth. For the same species and length, New Zealand hoki weigh less and have smaller gasbladders than Australian blue grenadier, suggesting a conversion factor of 1.10 in length for comparative measurements. Net-attached acoustic and optical measurements indicate that model and drift in situ measurements are biased high by 2.9 and 1.0 dB, respectively. Net-attached acoustic and optical measurements are a cost-effective method of monitoring TS routinely at depth for changes in species length and weight. © 2011 International Council for the Exploration of the Sea. 2011 Journal Article http://hdl.handle.net/20.500.11937/52472 10.1093/icesjms/fsr127 Oxford University Press 2009 unknown |
| spellingShingle | Kloser, Rudy Ryan, T. Macaulay, G. Lewis, M. In situ measurements of target strength with optical and model verification: A case study for blue grenadier, Macruronus novaezelandiae |
| title | In situ measurements of target strength with optical and model verification: A case study for blue grenadier, Macruronus novaezelandiae |
| title_full | In situ measurements of target strength with optical and model verification: A case study for blue grenadier, Macruronus novaezelandiae |
| title_fullStr | In situ measurements of target strength with optical and model verification: A case study for blue grenadier, Macruronus novaezelandiae |
| title_full_unstemmed | In situ measurements of target strength with optical and model verification: A case study for blue grenadier, Macruronus novaezelandiae |
| title_short | In situ measurements of target strength with optical and model verification: A case study for blue grenadier, Macruronus novaezelandiae |
| title_sort | in situ measurements of target strength with optical and model verification: a case study for blue grenadier, macruronus novaezelandiae |
| url | http://hdl.handle.net/20.500.11937/52472 |