About This Project

Many research and conservation efforts are dedicated to managing species like salmon, and these often try to mitigate the impact of humans. But what about other predators? We are taking a look at one potential candidate: the salmon shark. Using sightings reports, tissue samples, and tagging, we will learn what they eat, how often, and where. Our goal is to determine how much these sharks affect salmon numbers in the Pacific Northwest.

Cover Image: Shelton Dupreez

Ask the Scientists

What is the context of this research?

No matter where you live, it’s likely that you have heard of, seen, or even tasted salmon. They are important fish in many ways – economically, culturally, and ecologically. As a result, much research focuses on making sure we can fish them sustainably. However, natural ecosystems are complicated and hard to predict. For some salmon populations, conservation strategies work well, while other populations don’t respond as expected. This may be because while we can control our own actions (by limiting our fishing, for example), there are other factors affecting salmon populations that we need to consider. Key among these is predation. Our goal is to examine a potential salmon predator: the salmon shark.

What is the significance of this project?

For decades there have been reports of salmon sharks feeding on salmon and other commercially valuable prey throughout the Pacific Northwest (PNW). Salmon sharks may be a particularly impactful predator because they have an unusually high metabolism, and therefore need to consume large amounts of prey. In Alaska, these sharks may take 12-25% of the annual run of Pacific salmon. But, there is little information on salmon sharks in the PNW. We still don't know how many there are, how often they feed on salmon versus other prey, and what drives their movement patterns. All of this is necessary data to determine the ecological impact of salmon sharks, but is missing from salmon management plans. This information could lead to more accurate fishing regulations, such as quotas.

What are the goals of the project?

Starting in March 2022, we aim to determine the feeding behavior and ecosystem impact of salmon sharks in the Pacific Northwest. To do so, we have two different objectives. First, we will use stomach dissections and other samples (muscle, liver, and blood) to determine what salmon sharks are eating, and how much. We are relying on fishermen and fishery observers to help us collect these from deceased individuals that have washed ashore or are captured onboard. We will also use cameras attached to the dorsal fin of live sharks to capture predation events on film. Second, we will use tagging data, in addition to existing datasets, to model how frequently salmon shark movement and habitat overlap with those of salmon.