Fraser estuary research completed for 2018

76 field days, 35,000 fish,and over 6,400 juvenile salmon.

Raincoast scientists aboard their boat on the Fraser River getting the seine nets ready to do their summer research.

After a long five months we have now wrapped up our 2018 field season in the Fraser estuary, our best year yet! This year our team spent 76 days in the field and we captured more than 35,000 fish, including over 6,400 juvenile salmon. While it has been a long and hot season with a lot of early mornings and work weekends, I think everyone on the team is sad to see it come to an end.

The estuary is an incredibly beautiful setting that we never take for granted, where the herons, bald eagles, seals and seal lions are a more common sight than people, and the sunrise is always a little magical.

This year we had a new focus on our restoration goals, so we expanded our sampling areas to sites that we expect to restore. As part of our Fraser Connectivity Project, Raincoast is working with Fisheries and Oceans Canada over five years (2017-2022) to create new pathways for juvenile salmon through man made barriers that have restricted the connection between the river and its estuary for decades. While these barriers have stabilized the location of the mouth of the river and facilitated industrialization of the lower river and estuary, they have altered the natural movement of freshwater and sediments, and obstructed the nearshore migration pathways that juvenile salmon rely on to access important estuary habitats.

The restoration initiative is also allowing us to expand our field crew with some fantastic young biologists (Samantha Scott, Dylan Cunningham, Jack Hall, Kyle Armstrong and Riley Finn) and successfully use new methods to sample in different areas. This will better enable us to measure the impacts of our projects while also continuing to expand our knowledge regarding specific habitat preferences.

Baseline Monitoring

Along with studying the ecology of juvenile salmon in the estuary, sampling at the new restoration sites will allow us to monitor the effectiveness of our restoration activities. Baseline monitoring should always be carried out before commencing restoration projects, yet often it is not conducted due to limited funding. Our project has a rare opportunity to conduct intensive baseline monitoring prior to restoration and then follow up monitoring to assess the success of our activities. This will help us to adaptively manage our restoration activities and provide new information that can guide other restoration practitioners in their restoration plans.

Along with baseline monitoring, our research also provides us with the opportunity to learn an incredible amount about how juvenile salmon use the estuary. Due to the impressive diversity of juvenile salmon species and populations migrating through and rearing in the Fraser estuary, we conduct our sampling bi-weekly from early March until early August.

A warm spring

Our 2018 season started with a big pulse of juvenile chum that were quickly joined by pink and Chinook in April when juvenile salmon numbers peaked. We had an incredibly warm start to the spring which increased the run-off to the river earlier than normal, raising river levels and reducing salinities in the estuary to nearly zero. This shifts the fish communities in the estuary to more freshwater river species like peamouth chub and largescale suckers. All the while, juvenile salmon continued their migration seaward.

Throughout the rest of our season, we continued to catch juvenile Chinook in marsh habitats of the estuary. Chinook are our main focus for this research and a target beneficiary of our restoration activities. They are found in the estuary for the longest period – from late March through early August. To round out the group, we captured a pulse of juvenile sockeye salmon fry in June and July. The majority of sockeye remain in freshwater lakes for their first year, but a few populations take a different strategy to life and migrate to the estuary only a few months after their emergence from eggs.

Over the past three years we have learned much about juvenile salmon use of the Fraser estuary, yet many questions remain. Thankfully we will be able to continue our research for at least the next three years as part of our Fraser Connectivity Project. Future research goals include narrowing in on smaller scale habitat use within marsh areas, tracking juvenile salmon migration routes in the estuary, and examining the physiological condition of juvenile salmon and its relationship with how they use the estuary.

We are very excited to move forward with plans to restore some of the natural migration pathways for juvenile salmon and the flow of freshwater and fine sediments between the arms of the Fraser River and the estuary.

Full steam ahead!

David Scott, Raincoast Lower Fraser Salmon Program Coordinator A squinting David Scott explains about the Fraser River

David Scott is interested in resource and environmental management, ecology and conservation of aquatic ecosystems. He’s working in the Fraser river and doing a PhD at the University of British Columbia. You can find David in the wild, looking for salmon.

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