Fraser River sockeye salmon: data synthesis and cumulative impacts

Data needs, uncertainty and availability: The availability of data required for Holt et al andPestal/Cass was summarized in a table, which indicated more gaps for the former approach. Bothapproaches make noteworthy attempts to account for uncertainty.Benchmark setting: Holt takes into account uncertainty in the data in setting benchmarks. Theadvantages include that the benchmark is more reflective of that CU and takes into accountuncertainty. But you need a lot more data to develop these benchmarks vs. Pestal/Cass, whichtakes a more qualitative approach to develop benchmarks. Both have clear consistent rules toavoid comparing apples and oranges, so both are defensible. The Holt et al approach didn’t reachconsensus on metrics to use for distribution and also presented several possible benchmarks forfishing mortality.Feasibility: Holt is very technical, so it requires a lot of effort to roll out in order to determinestatus, raising the question of whether it is reasonable to expect DFO to implement a method thatis so rigorous and data intensive across all CUs, given limited resources, data and funding. Grantet al applied a modified version, using only abundance and trends in abundance, and weren’t ableto determine status for 15 CUs. Pestal/Cass applied their method to all CUs and were unable toassess 11 CUs, as they had a broader array of indicators and could thus better deal with the onesthat are data-poor.Considerations moving forward include ease of dissemination and transparency, as there needs tobe trust that CU status has credence. Other issues include data gaps, resources for monitoring andanalysis and indicator roll-up (weighting).Pestal and Cass plotted out an assessment that combined status and uncertainty for each CU.Status for the 36 CUs was also mapped geographically.Habitat status:Population status is a function of survival, which is a function of habitat condition. Habitatcondition in turn relies on a number of freshwater factors. One thing that has not been fullydeveloped is how to assess habitat and incorporate the results in an assessment of stock status.Landscape-level indicators were used to assess the quality and quantity of migratory, spawningand rearing habitats. These indicators are based on mapped habitat features extracted or derivedfrom provincial GIS data sets and DFO lake productivity estimates.Migratory habitat: Factors examined included CU migration route/distance, thermal profile ofadult migration routes and historical spring air temperatures at nursery lakes.Spawning habitat: Factors included the extent of sockeye spawning reaches for each CU,whether it was lake outlet (buffered) or tributary/inlet, and the ratio of each spawning categoryrelative to total spawning extent in the CU.Rearing habitat: Factors included combined surface area of nursey lakes for each CU andaverage juvenile productivity in smolts per hectare.The results for each type of habitat for each CU were presented in a dashboard summary thatshows how results for the CU line up with all other Fraser sockeye CUs. Three indicators weretaken from each of the three categories (migration distance, ratio of lake buffered spawning andlake area). Instead of trying to roll them up into one composite index, the approach was to try toshow where a CU lay with respect to all three dimensions. Migration distance was stronglycorrelated with air temperature with both upstream and downstream migrations, so was34