Browsing by Subject "observer effect"

Now showing 1 - 2 of 2
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    Open Access
    An indirect investigation of the possible influence of port on the estimation of observer effects on catch rates in the pelagic fishery
    (University of Cape Town, 2006) Somhlaba, S; Brandão, Anabela; Plagányi, Éva E; Butterworth, Doug S
    Earlier GLM analyses of catch per hour data for sardine and anchovy to determine observer effects have suggested statistically significant increases in this catch rate with observers on the vessels over January-to June for the sardine fishery, and over May to October for the anchovy fishery (Somhlaba et al. 2006). This in turn has raised the possibility that this may reflect (and provide quantification of the extent of) slippage in the catching operations conducted without observers present.
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    Open Access
    Preliminary results of observer effect on pelagic fleet taking into account observer data from 1999 to 2011
    (University of Cape Town, 2014) Somhlaba, S; Brandão, Anabela; Butterworth, Doug S; van der Westhuizen, J
    A detailed update of the study of the data collected by scientific observers onboard the pelagic vessels is currently underway. The use of small pelagic commercial data base and an observer data base to investigate the effect of observers onboard commercial vessels has been an ongoing study since the mid-2000s (e.g. see Somhlaba et al, 2005, 2006, 2007). This paper updates those studies by including data from the more recent years 2008 to 2011.