Fraser River sockeye salmon: data synthesis and cumulative impacts

Figure A3.5-3. Average chlorophyll concentration measured at two different locations in the Straight of Georgia.Each line represents a monthly mean for a given location. April – July means are shown for theNorthern location in black, and for the Central location in blue.Sea surface salinityWe found several extreme outliers in the Queen Charlotte Sound sea surface salinity data set(values exceeding 90) when the rest of the data set was around 30. We removed these valuesassuming they were a data entry mistake as such values are completely unrealistic (Parsons etal.1977).Predator and alternate prey dataThe technical report on predators (Christensen and Trites, 2011) provided a total of 21 data sets,including: 7 bird data sets, 3 pinniped data sets, 2 fish predator data sets, and 9 fish alternativeprey data sets. The three species of marine mammal (all pinnipeds) for which data wereprovided were used directly. However, it was less clear how to best incorporate the bird and fishdata. These data sets were selected by the authors of the predators technical report as being themost relevant available data, but recognising they were not collected specifically for thesepurposes and that other species may also be important (Christensen and Trites, 2011). In order toreduce the number of variables in the model and yet still incorporate these variables we tookeach data set individually and generated a new quantile based data set where the lowest 25 % of212