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

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dc.creator Robert, Kayanda
dc.creator Inigo, Everson
dc.creator Taabu, Munyaho
dc.creator Mgaya, Yunus D.
dc.date 2016-03-02T06:49:29Z
dc.date 2016-03-02T06:49:29Z
dc.date 2012
dc.date.accessioned 2018-04-18T11:49:31Z
dc.date.available 2018-04-18T11:49:31Z
dc.identifier 0165-7836 CODEN FISRDJ
dc.identifier http://hdl.handle.net/123456789/523
dc.identifier.uri http://hdl.handle.net/123456789/10006
dc.description Results 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.language en
dc.subject Vertebrata
dc.subject Pisces
dc.subject Africa
dc.subject East African Lakes
dc.subject Freshwater environment
dc.subject Fishery
dc.subject In situ
dc.subject Models
dc.subject East Africa
dc.subject Lake Victoria
dc.subject Echo sounding
dc.title Target strength measurements of Nile perch (Lates niloticus: Linnaeus, 1758) in Lake Victoria, East Africa
dc.type Other


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