SALMON NUTRIENTS AND ECOSYSTEMS

The salmon are returning to spawn in the streams of the Great Bear Rainforest, and we are thrilled to be back in Heiltsuk Territory. As part of our long-term study of salmon nutrients and the ecosystems they nourish we have been counting the salmon that return to 26 streams every fall for 14 years. Our field team of SFU and Heiltsuk researchers walk each stream and count the live and the dead Pink and Chum salmon, recording where in the watershed they are located and whether they have senesced naturally after spawning or whether they were killed by predators such as bears and wolves. These counts provide information on the density of fish in each stream, how the populations are changing over time, and how nutrients from their carcasses are transferred to fertilize the productive riparian forests nearby.

The weather dictates our work schedule, as the fall storms come in the high winds can keep our small boat in the harbour. When heavy rain fill the streams with rushing water, this is fine for the salmon, but hazardous for us, and it’s difficult for us to see the fish! In between the storms we are busy, leaving on the boat early in the morning every day that we can and visiting as many streams as we can, racing to get as much data as possible during the short season.

This year there are quite a few Pink salmon returning to the streams, but fewer Chum salmon than usual. Pink salmon have a 2-year life cycle, which leads to different populations of Pink salmon in even and odd years. In this area the odd year population is much more numerous, and we are seeing a larger number of returning Pink salmon that we would expect to see in 2021. The larger Chum salmon have a less strict life cycle, usually spending between 3 and 7 years in the ocean before returning, which makes their population numbers harder to predict. The smaller number of Chum that we are seeing in the streams this fall may be a sign that their populations are declining, but we will need more data from others in the local area and comparison to the long-term dataset to be sure.

In 2020 Covid-19 protocols kept our SFU researchers from visiting our field sites, though our data collection continued through the hard work of our team-mates from Bella Bella. This year we are grateful to be able to work with our friends and colleagues once again in beautiful Heiltsuk Territory.