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.author Coetzee, J C
dc.contributor.author Merkle, D
dc.contributor.author De Moor, Carryn L
dc.contributor.author Twatwa, N M
dc.contributor.author Barange, M
dc.contributor.author Butterworth, Doug S
dc.date.accessioned 2016-03-14T07:08:05Z
dc.date.available 2016-03-14T07:08:05Z
dc.date.issued 2008
dc.identifier http://dx.doi.org/10.2989/AJMS.2008.30.2.1.551
dc.identifier.citation Coetzee, 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. en_ZA
dc.identifier.issn 1814-232X en_ZA
dc.identifier.uri http://hdl.handle.net/11427/17693
dc.identifier.uri http://www.tandfonline.com/doi/abs/10.2989/AJMS.2008.30.2.1.551
dc.description.abstract 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. en_ZA
dc.language eng en_ZA
dc.publisher National Inquiry Services Centre (NISC) en_ZA
dc.source African Journal of Marine Science en_ZA
dc.source.uri http://www.tandfonline.com/toc/tams20/current
dc.subject.other Anchovy
dc.subject.other Attenuation
dc.subject.other Hydro-Acoustic Surveys
dc.subject.other Receiver Saturation
dc.subject.other Sardine
dc.subject.other South Africa
dc.subject.other Target Strength
dc.title Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys:quantifying the effects of target strength, signal attenuation and receiver saturation en_ZA
dc.type Journal Article en_ZA
dc.date.updated 2016-03-14T07:01:48Z
uct.type.publication Research en_ZA
uct.type.resource Article en_ZA
uct.subject.keywords Anchovy en_ZA
uct.subject.keywords Attenuation en_ZA
uct.subject.keywords Hydro-Acoustic Surveys en_ZA
uct.subject.keywords Receiver Saturation en_ZA
uct.subject.keywords Sardine en_ZA
uct.subject.keywords South Africa en_ZA
uct.subject.keywords Target Strength en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Marine Resource Assessment and Management Group en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Coetzee, 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/11427/17693 en_ZA
dc.identifier.chicagocitation Coetzee, J C, D Merkle, Carryn L De Moor, N M Twatwa, M Barange, and Doug 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/11427/17693 en_ZA
dc.identifier.vancouvercitation Coetzee 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/11427/17693. en_ZA
dc.identifier.ris TY - Journal Article AU - Coetzee, J C AU - Merkle, D AU - De Moor, Carryn L AU - Twatwa, N M AU - Barange, M AU - Butterworth, Doug 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 SM - 1814-232X 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/11427/17693 ER - en_ZA


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