Monitoring salmon in our latest breach in the North Arm Jetty

In December we completed construction on our second breach in the North Arm Jetty. This 30-meter wide breach will allow juvenile salmon access to Sturgeon Bank from the North Arm of the Fraser River, re-opening movement pathways that have been altered for over a century. 

This project was a major construction undertaking, requiring us to move a large amount of sand material and place a significant amount of rock to create a stable breach and jetty that will continue to function for many years to come. This comes after our first breach was successfully built back in February of 2022, which we have monitored for two years and observed high rates of juvenile salmon passage during the spring outmigration.

We have been monitoring fish passage at the sites, as well as changes to sediment patterns both in the river through sounding surveys and on the banks and in the breach through LiDAR surveys conducted annually at low tides. 

Based on our experience and modeling results, we anticipate this breach to function well as intended without any noticeable changes to navigation in the river as required by our permits. 

My Master’s research looking at sockeye salmon

While monitoring fish passage through the breach, the Lower Fraser research team and I have observed a diversity of species accessing habitat that was previously inaccessible, including sockeye salmon.

Over the last two summers, we have expanded Raincoast’s Wild Salmon research goals and efforts to address key questions on sockeye salmon in order to support population growth, being a fish of high conservation interest and value to people. As a Raincoast researcher and member of the UBC Pacific Salmon Ecology and Conservation laboratory, my Master’s research investigates how different groups of sockeye salmon use the Lower Fraser River and Estuary habitats while developing and migrating to the ocean as juvenile salmon. This is important to identify so that restoration work and projects, like the construction of the North Arm Jetty Breach, can be planned and enacted most effectively. 

Sockeye salmon are an iconic species of the Fraser River, though a large number of their populations are in some kind of danger. In the face of threats on the Fraser River, including marsh habitat loss and reduced connectivity between environments, these salmon migrate as juveniles through the lower Fraser River and Estuary habitats to the ocean where they spend their adulthood. The estuary, being the meeting place of fresh and saltwater, is a key zone for juvenile sockeye salmon, who can show variation in their life cycle depending on their place of origin. 

In fish less than a year old, called subyearlings, the estuary is a vital place of early development so that fish can survive and be competitive as ocean adults. Meanwhile, to fish who enter the estuary aged over a year, called yearlings, this region is valued as a migratory pathway to the next phase of life. These differences are referred to as life histories, and what is clear in both groups is that Lower River habitat matters to each one. This diversity within the sockeye species is important for conservationists to support because having variation within a species can increase their resilience to threats and change – something salmon are no stranger to. 

The North Arm Jetty Breach construction helps juvenile salmon, who show these different life-history strategies, utilize new habitat. This increases access to resources used for development and ocean-bound migration; a way forward to their future success. 

About the North Arm Jetty

The jetty was constructed back in the early 1900’s and this was paired with dredging of the river bottom, the material from which was sidecast onto the jetty and makes up much of the material that we are now moving. The material is not being taken off site, but simply moved to the area between the two breaches where it will become part of the jetty, and support the coastal sand dune ecosystem that existed there before. 

With this project completed, this is the end of our connectivity restoration work in the estuary for now, with three 50 meter wide breaches created in the Steveston jetty from 2019 to 2021 and two 30 meter wide breaches constructed in the North Arm jetty from 2022 to 2023. We will continue monitoring the breach sites for the next two years.

Moving forward, we are currently looking at opportunities to restore marsh habitats in the Lower Fraser River and Estuary to work towards a greenway of connected habitats for juvenile salmon during their downstream migration. 

Project partners

Thank you to our project partners, Ducks Unlimited Canada, Lower Fraser Fisheries Alliance, and Tsawwassen First Nation. Thank you to Musqueam Indian Band, Metro Vancouver, and the Vancouver Fraser Port Authority for their support.

You can help

Raincoast’s in-house scientists, collaborating graduate students, postdoctoral fellows, and professors make us unique among conservation groups. We work with First Nations, academic institutions, government, and other NGOs to build support and inform decisions that protect aquatic and terrestrial ecosystems, and the wildlife that depend on them. We conduct ethically applied, process-oriented, and hypothesis-driven research that has immediate and relevant utility for conservation deliberations and the collective body of scientific knowledge.

We investigate to understand coastal species and processes. We inform by bringing science to decision-makers and communities. We inspire action to protect wildlife and wildlife habitats.