By: Olivia Sherman, News Writer
By looking at past salmon populations in the Skeena Watershed in northern BC, Michael Price, SFU postdoctoral fellow, can estimate what the future holds for salmon populations in BC.
Through his research, Price discovered that salmon populations in the Skeena River watershed have increased over the past century. Price and his team examined a “rich collection of fish scales” dating back to 1913. These preserved scales tell “the literal life stories of each fish,” including the estimated size of the fish and what it may have encountered in its life. What Price has found is that the juvenile sockeye salmon population has been “growing more and more now in response to increasing temperatures and reduced competition.
“There are two large influences” that determine the rate of survival in salmon, especially in freshwater lakes where they hatch, rear, and grow. These influences are “temperature and competition.” Lake sizes can vary in temperature, elevation, depth, and size, and all these variables provide different outcomes for the populations within. Colder temperatures have lower “productivity,” meaning they produce less food. In colder areas, juvenile salmon tend to take two to three years to leave these habitats. However, warmer temperatures in freshwater lakes and rivers increase the metabolism of young salmon, providing more food, and helping them grow larger so they become strong enough to venture to the ocean sooner.
The other factor is competition, which is “measured by the number of other little juvenile sockeyes that are rearing in that lake.” When there is not enough food or space available to tend to the salmon in these habitats, “growth tends to be lower.”
The main threat to salmon is largely due to negative human interaction with salmon populations and the surrounding habitats in which they reside. “They transcend freshwater and ocean environments, they rear in lakes and river systems [ . . . ] and in each of these locations there are a myriad of threats,” noted Price. Upcoming projects in BC, such as the liquified natural gas (LNG) pipeline and continuous logging projects, threaten the environment that is “endowed with a diversity of habitat.”
The future of salmon populations in BC varies depending on their location. The study concluded, “Such diverse responses of populations and their habitat to a changing climate form a dynamic portfolio that may endow salmon watersheds with resilience to future change.” However, the ongoing changing climate will ultimately create both “opportunities and constraints for salmon during freshwater rearing,” according to his research.
“At the end of the day, it’s really humans and our collective, everyday decisions that we make that aren’t in the best interest of salmon that continue to erode the abundance and diversity that salmon once held in British Columbia,” said Price.
