Browsing by Subject "pelagic fleet"

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    Open Access
    Overall results for the effect of the presence of an observer on catches made by the pelagic fleet
    (2005) Somhlaba, S; Brandão, Anabela; Butterworth, Doug S
    The analysis of the observer data for the pelagic fishery is taken further for the complete data base from 1999 to 2004. Previously the analysis had been based on steel vessels (Somhlaba et al., 2005); those findings showed that there were statistically significant positive effects on catches given the presence of an observer on the steel vessels. The results below include the analysis of the combined data for all three categories of vessels: bait, ordinary and steel vessels. Sardine and anchovy data were analysed in detail using one model but with two different error structures: one lognormal (henceforth termed LogCPUE) and the other Poisson (henceforth termed catch).
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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.