ICES Journal of Marine ScienceICES Journal of Marine Science 2 / 312 / 31 Echosounder impacts on PS fishing Fishing on a vessel's floating objects (FOBs) equipped with echosounder buoys can impact fishing in a number of ways: Reduce search time Increase catch Change catch composition Change fishing strategy 3 / 31 Echosounder impacts on PS fishing Fishing on a vessel's floating objects (FOBs) equi. [...] Datadistribution Type Time period Model equation A1 Total catch Gamma GAM 2010-2017 te(lon,lat,by=season)+vessel+s(year,by=category) A2 Total catch Gamma GAM 2012-2017 te(lon,lat,by=season)+vessel+s(year)+category L1 Total catch Gamma GLM 2012-2017 cwp55+vessel+season+year+category A3 Total catch Gamma GAM 2012-2017 te(lon,lat,by=category:season)+vessel+s(year) B1 Proportion ofSKJ Beta Beta regr. [...] F) 22.00 0.0000 *** 21.7 0.0000 *** Category O-E -2.26 0.2241 0.2 0.9253 Category O+E 1.98 0.0001 *** 2.5 0.0000 *** Model A2: total catch ~ te(lon,lat,by=season)+vessel+s(year)+category Model L1: total catch ~ cwp55+vessel+season+year+category → Both GAM & GLM: 2.0-2.5 tonnes per set increase → GAM more sophisticated, "better" standardization 25 / 31 Proportion SKJ Beta Model B1 Estimate Pr(>z) I. [...] SKJ ~ cwp55 + vessel + season + category*year + year2 + year3 + year4 → Positive interaction between time and proportion SKJ 26 / 31 Model N1: Set category ~ te(lon,lat,by=season) + vessel + s(year) + size class → Consistent with, but somewhat less dramatic than, analyses of raw data Set size composition 27 / 31 Model A3: te(lon,lat,by=category:season) Green-Yellow: More O+E catch Black contours:. [...] 2020) 2020) Temporal shift towards more SKJ?Temporal shift towards more SKJ? Weak spatial patterns?Weak spatial patterns? 29 / 3129 / 31 Stock assessmentStock assessment Reduction in PS abundance index since onset of echosounder useReduction in PS abundance index since onset of echosounder use 2012 for French Fleet2012 for French Fleet ?? for Spanish Fleet?? for Spanish Fleet Reduction size a func.
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- 31
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- Victoria, Seychelles
