Fish stock assessment by a statistical analysis of echo sounder signals

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dc.contributor.advisorDenbigh, P Nen_ZA
dc.contributor.authorWeintroub, Jonathanen_ZA
dc.date.accessioned2016-05-09T08:56:02Z
dc.date.available2016-05-09T08:56:02Z
dc.date.issued1986en_ZA
dc.description.abstractA means of assessing the quantity of exploitable fish in the sea is a requirement for effective management of the resource. Sonar is widely used in this regard, as it provides a rapid means of assessment. Two acoustic assessment techniques currently used are the echo counting and echo integration· methods. The echo counting method requires that only single fish echoes are present in the backscatter from the shoal, while the echo integration technique requires an a-priori knowledge of the average target strength of the fish in the shoal. A novel method of assessment has been proposed. It relies on the relationship between the statistics of the backscatter from a volume distribution of scatterers and the number of scatterers contributing to the backscatter at any one time. The attraction of the method when applied to the estimation of number density of fish, is that estimates can be produced in the presence of overlapping echoes, and that knowledge of the target strength of the fish is unnecessary. The application of this method to acoustic fish stock assessment is investigated in this work. Current methods of assessment are reviewed and the theory of the statistical method is given. A computer simulation of the scattering problem gives a useful insight into the effects of sample size and density on the accuracy of the method. The method has been applied to the assessment of fish at sea, where it was run in tandem with an echo integrator. The results obtained with the two techniques are compared. Reasons for discrepancies are proposed and problems in the application of the method are identified.en_ZA
dc.identifier.apacitationWeintroub, J. (1986). <i>Fish stock assessment by a statistical analysis of echo sounder signals</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Electrical Engineering. Retrieved from http://hdl.handle.net/11427/19509en_ZA
dc.identifier.chicagocitationWeintroub, Jonathan. <i>"Fish stock assessment by a statistical analysis of echo sounder signals."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Electrical Engineering, 1986. http://hdl.handle.net/11427/19509en_ZA
dc.identifier.citationWeintroub, J. 1986. Fish stock assessment by a statistical analysis of echo sounder signals. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Weintroub, Jonathan AB - A means of assessing the quantity of exploitable fish in the sea is a requirement for effective management of the resource. Sonar is widely used in this regard, as it provides a rapid means of assessment. Two acoustic assessment techniques currently used are the echo counting and echo integration· methods. The echo counting method requires that only single fish echoes are present in the backscatter from the shoal, while the echo integration technique requires an a-priori knowledge of the average target strength of the fish in the shoal. A novel method of assessment has been proposed. It relies on the relationship between the statistics of the backscatter from a volume distribution of scatterers and the number of scatterers contributing to the backscatter at any one time. The attraction of the method when applied to the estimation of number density of fish, is that estimates can be produced in the presence of overlapping echoes, and that knowledge of the target strength of the fish is unnecessary. The application of this method to acoustic fish stock assessment is investigated in this work. Current methods of assessment are reviewed and the theory of the statistical method is given. A computer simulation of the scattering problem gives a useful insight into the effects of sample size and density on the accuracy of the method. The method has been applied to the assessment of fish at sea, where it was run in tandem with an echo integrator. The results obtained with the two techniques are compared. Reasons for discrepancies are proposed and problems in the application of the method are identified. DA - 1986 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1986 T1 - Fish stock assessment by a statistical analysis of echo sounder signals TI - Fish stock assessment by a statistical analysis of echo sounder signals UR - http://hdl.handle.net/11427/19509 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/19509
dc.identifier.vancouvercitationWeintroub J. Fish stock assessment by a statistical analysis of echo sounder signals. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Electrical Engineering, 1986 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/19509en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Electrical Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherUnderwater Acousticsen_ZA
dc.titleFish stock assessment by a statistical analysis of echo sounder signalsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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