The Lower Fraser River 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 man-made 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 as they may not have had time to prepare their bodies for the transition to salt water.
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.
In 2019, we created three breaches in the Steveston jetty, providing juvenile salmon with access to Sturgeon bank. We removed 7,870 tonnes of material and placed 3,278 tonnes of rock. We are also constructing two 30-metre wide breaches in the North Arm jetty. The first breach was constructed in 2022 and the second breach started construction in the fall of 2023.
We have been monitoring juvenile salmon passage at our breach locations as they have been developed, which includes sampling a number of fish to determine which tributary they came from in the Fraser watershed. 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.
Gerle B. Fraser Estuary habitat restoration and sampling results. [web map]. Sidney (BC): Raincoast Conservation Foundation. 2023. https://www.raincoast.org/2023/11/fish-passage-habitat-restoration-lower-fraser-river-estuary/
About the map
This map displays the locations of current and planned breaches in the North Arm jetty and Steveston jetty, along with the home tributaries of sampled juvenile salmon that are using these breaches to rear in the Fraser River Estuary. The orange points seen along the tributaries are scaled to represent the number of sampled fish that came from each tributary. The values on this map only include fish that have been sampled at the jetty breach locations, and are not the total number of fish that have been documented using the breaches.
Using the map
The layers/legend widget provides a list of layers included on this map as well as the option to turn each layer on and off. The other widgets found on this map allow you to zoom in and out, zoom to your current location, expand the map to full screen, search for an address or place, and change the basemap.
When clicked on, jetty breach locations will display the year the breach was created, the number of fish that have been sampled at that breach, and photos before and after the breach was created. Points along each river will display the name of the tributary and the number of fish from that tributary that have been sampled at each jetty breach location.
References and sources
GeoBC Branch. Freshwater Atlas Stream Network. 2006. Distributed by B.C. Data Catalogue [cited 2023 Oct] from www.catalogue.data.gov.bc.ca/dataset/freshwater-atlas-stream-network. Contains information licensed under the Open Government Licence – Canada.
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