Target strength measurements of Nile perch (Lates niloticus: Linnaeus, 1758) in Lake Victoria, East Africa

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dc.creatorRobert, Kayanda
dc.creatorInigo, Everson
dc.creatorTaabu, Munyaho
dc.creatorMgaya, Yunus D.
dc.date2016-03-02T06:49:29Z
dc.date2016-03-02T06:49:29Z
dc.date2012
dc.date.accessioned2021-05-03T13:36:41Z
dc.date.available2021-05-03T13:36:41Z
dc.descriptionResults of estimation of target strength (TS) of physoclistous Nile perch using in situ TS measurements and deformed cylinder model (DCM) at 70 and 120kHz are presented. The results of the two methods are compared with those from cage experiments conducted between 1999 and 2000. Cage experiments that assumed the 20 Log(L) relationship (TS = 20 Log(TL) - 66.55) provided a good fit only over the length range of 18-38 cm total length, but overestimated the length of large fish (>60cm TL). The DCM which lead towards a 30 Log(L) provides more accurate conversion over the full length range of single targets. An in situ study that made no assumptions about the shape, structure or orientation of the fish provided a close fit of acoustically estimated length frequency distributions to net hauls with the equations: It is suggested that using this approach can provide valid TS to length relationships for acoustic surveys on species for which little information exists and there is little opportunity for direct observation of behavioural aspects that are known to affect TS such as tilt angle and vertical migration.
dc.identifier0165-7836 CODEN FISRDJ
dc.identifierhttp://hdl.handle.net/123456789/523
dc.identifier.urihttp://hdl.handle.net/123456789/47748
dc.languageen
dc.subjectVertebrata
dc.subjectPisces
dc.subjectAfrica
dc.subjectEast African Lakes
dc.subjectFreshwater environment
dc.subjectFishery
dc.subjectIn situ
dc.subjectModels
dc.subjectEast Africa
dc.subjectLake Victoria
dc.subjectEcho sounding
dc.titleTarget strength measurements of Nile perch (Lates niloticus: Linnaeus, 1758) in Lake Victoria, East Africa
dc.typeOther

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