Fraser River sockeye salmon: data synthesis and cumulative impacts

Model: C3a1980-2004A model set was tested with the available data for brood years 1980-2004, which included thesame variables as described above, albeit for a shorter time period, but with the addition of SSTfor QCS. The individual models run within the model set are specified in Table A4.3-16.Table A4.3-16. Model specifications for the 1980-2004 (brood years) model set. This table shows the variablesincluded in each of the 10 models tested (i.e. M1 to M10) within this model set. Table 4.4-1 explains whichspecific data sets were used for each of these variables. “Rank of model” reflects the AIC c score showinglevel of support (#1 ranked model had the highest level of support and lowest AIC c score).Region Variable M1 M2 M3 M4 M5 M6 M7 M8 M9 M10QCS Temperature X X X X XQCS Salinity X X X X XQCS Discharge X X XQCS Wind X XSoG Temperature X X X XSoG Salinity X X X XSoG Discharge X XRank of model 6 3 10 1 2 8 4 9 5 7The three models with the lowest AICc scores were M4 (QCS SST, SSS and discharge), M5(QCS SST and SSS), and M2 (QCS SST, SSS, discharge, and wind) (Table A4.3-17). Togetherthey indicate that the QCS models have greater explanatory value than SoG models for FraserRiver sockeye salmon productivity during 1980-2004. This conclusion is supported further bythe fact that the models with the next two lowest AICc scores are M7 (QCS SSS) and M9 (QCSSST). This finding is an important new result because it is alters the conclusion of Peterman etal. (2010) based on new data and analyses that were not available at the PSC workshop.The results also highlight the importance of not being able to include for QCS SST in theprevious model set, because within this model set all of the models that include QCS SST have amuch higher level of support than any of the models that include SoG SST.Within both of the model sets discussed above (i.e. 1969-2004 and 1980-2004), and across allmodels for both QCS and SoG, SST demonstrated an negative or inverse relationship with theproductivity of Fraser River sockeye salmon (Table A4.3-18). This is an unsurprising result inthat it simply agrees with a well-established literature on the subject. SSS also had a consistentrelationship across all models within both of the model sets discussed above; however, thedirection of the relationship is in the opposite direction for the two regions, positive for QCS, andnegative for SoG. We cannot offer a definitive explanation for why this might be the case or255