Fraser River sockeye salmon: data synthesis and cumulative impacts

Workshop participants pointed out that Harrison sockeye are interesting – given that they lingerin the estuary for much longer; they should be getting the highest levels of contaminantexposure, but yet have done the best. Other issues raised included 2007 (did levels ofcontamination or water quality change?) and pulp mill effluents (before-after effects ofreductions in pollutants during the 1990’s).Freshwater FactorsMarc Porter, ESSA TechnologiesThe focus of this study is to evaluate the impacts of local human activities on Fraser Riversockeye spawning habitats, rearing / nursery lakes, and migratory corridors for smoltoutmigration / adult migration. The focal human activities (potential stressors) included forestry,hydroelectricity, urbanization, agriculture, mining and water use. GIS was used to assessinteractions between stressors and sockeye habitats across CUs. At the time of the meeting,initial quantitative / qualitative assessments were completed for only a few of the stressors.Run-of-river Independent Power Producers (IPPs) are located in the upper, fishless reaches ofstreams, which makes it very unlikely that they would have any serious direct impacts onsockeye rearing, spawning or migratory habitats. In addition, there are very few IPPs in theFraser Basin. Thus it seems highly unlikely that IPPs have had any significant role in recentsockeye declines. Log storage and associated handling activities can have potentially seriousimpacts to local habitats in the Fraser Estuary. However, as the magnitude or timing of logstorage activities in the Estuary appear generally unchanged over the past decade, there is noevidence that increasing log storage has played a significant role in recent sockeye declines. Nolarge hydro projects exist in the Fraser River itself and only a limited number of large projectsexist in large Fraser tributaries. Potential impacts on survival of migrating sockeye smolts andadults at these facilities are well known and have apparently been successfully mitigated to alarge extent. As it appears that mitigation targets have been sufficient to consistently minimizesockeye losses at the projects, there is no evidence that large hydro projects have played asignificant role in recent sockeye declines. Mining activities are widespread in the Fraser Basinand have the potential to cause local impacts to sockeye spawning and migratory corridors.However, mines in the Fraser are generally not located close to areas that support the majority ofsockeye spawning. While there may be significant localized effects on fish habitat, the impactsof mining on sockeye population densities are likely to be small and difficult to detect. A majordata gap is the general lack of time-series data for most stressors that could allow researchers torelate changing stressor intensity to changes in fish population or fish habitat status.Key issues raised by workshop participants were: 1) the importance of scaling the indicators to amore directly interpretable measure, relative to the stress on sockeye, 2) lack of high quality data