Habitat restoration: Fraser River Connectivity Project
The need to increase connectivity in the Fraser River Estuary
The Lower Fraser and estuary is a highly modified environment with more than 70% of tidal marsh habitats that juvenile salmon rely on lost or locked away behind manmade structures. On the Fraser delta, this includes the jetties, causeways and training walls that were built to control the arms of the river for ship navigation.
The estuary is now very fragmented by these structures that alter the flow of water, sediment and nutrients. They also restrict the passage of juvenile salmon that want to move onto the shallow tidal salt marshes and eelgrass to feed and grow. For juvenile Chinook, chum and pink salmon, which enter the estuary as fry, this lack of access to marsh habitats may be particularly harmful, and they may not have had time to prepare their bodies for the transition to salt water.
Five year restoration project
In 2016, Raincoast began a five-year restoration project to create openings in several of these man-made barriers that prevent the natural migration of juvenile salmon. The project includes baseline research on juvenile salmon, such as their presence and distribution in different habitats, their size and growth over the season(s) and how long they reside in the estuary. It also includes establishing baseline information on estuarine conditions and salmon movements prior to creating the openings, so that we can evaluate the success of the breaches once they are created.
The Steveston North Jetty
The Steveston Jetty is an 8 km long rock jetty constructed in the early 1900’s, which controls the position of the main arm of the Fraser River as it enters the estuary for the benefit of shipping. This jetty is a significant barrier to the natural movement of the juvenile salmon entering the estuary, preventing them from moving into brackish marsh habitats on Sturgeon Bank and instead forcing them into the deeper and salty water of the Salish Sea.
In 2019, we created three breaches in the Steveston Jetty, creating access to Sturgeon bank to juvenile salmon. We removed 7,870 tonnes of material and placed 3,278 tonnes of rock. As part of our project, we have monitored juvenile salmon at our breach locations over the last three years as they have been developed, and ever since the first breaches were made, we have seen high levels of juvenile salmon passing through the breaches. In particular, we have seen high numbers of juvenile Chinook salmon, the main target of our restoration efforts as they have been shown to rely on estuary habitats for a crucial growth period before continuing their migration to sea.
The North Arm Jetty
The North Arm jetty was constructed in 1916 to aid in navigation, creating a 6.9-kilometre-long barrier and altering connectivity between the North Arm of the Fraser River and its estuary. This barrier interrupts the natural movement of juvenile salmon and other fish species, forcing them directly from freshwater river areas into the deeper waters of the Strait of Georgia, bypassing the brackish marsh and sandflat habitats upon which they rely to make the transition from freshwater to saline ocean water.
Raincoast is constructing three 30-metre wide breaches in the North Arm Jetty in the Fraser River Estuary to restore natural migration pathways for juvenile salmon and other fish species and natural movement of freshwater and fine sediments.
Construction of the first breach began in January 2022. Construction of further breaches is expected to follow in 2022 and 2023.
