This project aimed to understand interactions between spawning salmon and their ecosystems and
translate this information into policy advice for conservation. We linked data from Fisheries and
Oceans Canada (DFO) on salmon population sizes to new data collected through detailed physical and
biological assessments of 40 sockeye spawning streams across two regions of the Fraser Basin.
Our first objective was to test quantitative links between proposed physical habitat characteristics and
salmon abundance, which is a key goal of Canada’s Wild Salmon Policy. We found that a few key
habitat features, all of which provide cover to spawning sockeye, predict differences among streams in
salmon abundance. Then we analyzed these stream habitat indicators within a cost-benefit framework
that quantitatively assessed both the indicator performance and the cost of measuring it. We identified
the habitat indicators that would maximize either the total information gained given various budget
scenarios or the efficiency (information gained per dollar spent) of a monitoring program.
Our second objective was to test quantitative links between salmon abundance and ecosystem
productivity – another key goal of the Wild Salmon Policy. First, we examined how salmon abundance
related to the uptake of nutrients from salmon carcasses by stream algae, aquatic insects, and fish,
using stable isotope techniques. As predicted, the amount of salmon-derived nitrogen in all three
groups of species was strongly related to the abundance of salmon in each stream. Interestingly, we
found that this increased uptake of nutrients did not always translate into greater abundance of these
three species groups. This means that stream algae, insects, and fish species differ in their value as
indicators of the influence of salmon on freshwater ecosystems.
Our third objective was to use these results to inform future management decisions aimed at improving
the sustainability of wild salmon populations. We developed collaborations related to implementation of
Wild Salmon Policy Strategies 2 and 3 as our work can aid both the development of effective and
efficient habitat monitoring programs and the incorporation of ecosystem values into management.