Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation

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dc.contributor.authorCoetzee, J C
dc.contributor.authorMerkle, D
dc.contributor.authorde Moor, C L
dc.contributor.authorTwatwa, N M
dc.contributor.authorBarange, M
dc.contributor.authorButterworth, Doug S
dc.date.accessioned2018-05-08T13:20:49Z
dc.date.available2018-05-08T13:20:49Z
dc.date.issued2008
dc.date.updated2016-01-22T08:00:11Z
dc.description.abstractThe biomass of small pelagic fish species off the coast of South Africa has been monitored since 1984 using hydro-acoustic survey techniques. These time-series of spawner biomass and recruitment estimates form the basis for management of both the South African sardine Sardinops sagax and anchovy Engraulis encrasicolus resources and are central to the setting of annual total allowable catch levels. However, these survey estimates have, for the most part, been treated as relative indices as there are several biases inherent in acoustic survey methodology that remain difficult to quantify. Advances in acoustic technology together with an improved understanding of the major sources of survey errors have enabled estimation of and correction for biases such as receiver saturation, acoustic signal attenuation and target strength. Incorporation of these corrections over the entire time-series has resulted in an improved accuracy of acoustic survey estimates and substantial changes to the biomass estimates of both species, without jeopardising the requirement that the time-series remains comparable throughout its duration. Furthermore, the resultant decrease in the level of uncertainty associated with these abundance estimates has rendered improved utilisation of these resources possible.
dc.identifierhttp://dx.doi.org/10.2989/AJMS.2008.30.2.1.551
dc.identifier.apacitationCoetzee, J. C., Merkle, D., de Moor, C. L., Twatwa, N. M., Barange, M., & Butterworth, D. S. (2008). Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation. <i>African Journal of Marine Science</i>, http://hdl.handle.net/11427/28010en_ZA
dc.identifier.chicagocitationCoetzee, J C, D Merkle, C L de Moor, N M Twatwa, M Barange, and D S Butterworth "Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation." <i>African Journal of Marine Science</i> (2008) http://hdl.handle.net/11427/28010en_ZA
dc.identifier.citationCoetzee, J. C., Merkle, D., de Moor, C. L., Twatwa, N. M., Barange, M., & Butterworth, D. S. (2008). Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation. African Journal of Marine Science, 30(2), 205-217.
dc.identifier.ris TY - AU - Coetzee, J C AU - Merkle, D AU - de Moor, C L AU - Twatwa, N M AU - Barange, M AU - Butterworth, D S AB - The biomass of small pelagic fish species off the coast of South Africa has been monitored since 1984 using hydro-acoustic survey techniques. These time-series of spawner biomass and recruitment estimates form the basis for management of both the South African sardine Sardinops sagax and anchovy Engraulis encrasicolus resources and are central to the setting of annual total allowable catch levels. However, these survey estimates have, for the most part, been treated as relative indices as there are several biases inherent in acoustic survey methodology that remain difficult to quantify. Advances in acoustic technology together with an improved understanding of the major sources of survey errors have enabled estimation of and correction for biases such as receiver saturation, acoustic signal attenuation and target strength. Incorporation of these corrections over the entire time-series has resulted in an improved accuracy of acoustic survey estimates and substantial changes to the biomass estimates of both species, without jeopardising the requirement that the time-series remains comparable throughout its duration. Furthermore, the resultant decrease in the level of uncertainty associated with these abundance estimates has rendered improved utilisation of these resources possible. DA - 2008 DB - OpenUCT DP - University of Cape Town J1 - African Journal of Marine Science LK - https://open.uct.ac.za PB - University of Cape Town PY - 2008 T1 - Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation TI - Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation UR - http://hdl.handle.net/11427/28010 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/28010
dc.identifier.vancouvercitationCoetzee JC, Merkle D, de Moor CL, Twatwa NM, Barange M, Butterworth DS. Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation. African Journal of Marine Science. 2008; http://hdl.handle.net/11427/28010.en_ZA
dc.language.isoeng
dc.publisher.departmentMarine Resource Assessment and Management Groupen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.sourceAfrican Journal of Marine Science
dc.source.urihttp://www.tandfonline.com/doi/abs/10.2989/AJMS.2008.30.2.1.551
dc.subject.otheranchovy
dc.subject.otherattenuation
dc.subject.otherhydro-acoustic surveys
dc.subject.otherreceiver saturation
dc.subject.othersardine
dc.subject.otherSouth Africa
dc.subject.othertarget strength
dc.titleRefined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation
dc.typeJournal Article
uct.type.filetypeText
uct.type.filetypeImage
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