News & Resources

Juvenile salmon field studies at Roberts Bank

September 3, 2020 7:52 pm

 

Since 2011, the Vancouver Fraser Port Authority has been conducting field studies at Roberts Bank and the surrounding areas. Due to the COVID-19 pandemic, we have adjusted many of our field study practices to ensure the safety and health of our employees, contractors and stakeholders, but the scope and importance of the work remains unchanged.

Juvenile salmon is one of the species for which we are currently gathering data through our fieldwork. We are conducting juvenile salmon studies with a focus on juvenile chum and ocean-type Chinook, as they are the most estuarine-dependent species and have the potential to interact with the project. We are sampling within the intertidal and subtidal areas north and south of the Roberts Bank causeway, as well as the intertidal marsh habitats seaward of Westham Island to collect baseline data on the density and distribution of juvenile chum and Chinook salmon.

As part of this fieldwork, our team of experts deploys seine nets from the shore of the causeway to catch juvenile salmon. We then record the body length and body weight of each fish captured. Tissue samples are also collected before the fish are released safely back into the water. We also collect information about habitat conditions such as water temperature, salinity, dissolved oxygen, water depth, and tidal state at the time of sampling.

We will collect this same information over many years. This will allow us to see if the density of juvenile salmon after the project is constructed is significantly different north and south of the causeway compared to other places in the estuary. This information will also inform appropriate actions we may need to take to manage things if there are changes. The monitoring reports will be made available publically each year for the duration of this study.

Interesting facts about Pacific salmon

As part of our ongoing research at Roberts Bank, we will also undertake field studies on great blue heron, Dungeness crab, barn owls, and diving birds.

  • Five different species of Pacific salmon live in Canada: Chinook, chum, coho, pink, and sockeye
  • Chinook and chum salmon are the two species to visit Roberts Bank most frequently
  • Chinook salmon are the largest of the Pacific salmon species
  • Ocean-type Chinook juveniles (or sub-yearlings) spend up to two months at Roberts Bank to rear while stream-type Chinook juveniles (or yearlings) leave the estuary rapidly, within hours or a few days
  • Juvenile salmon use intertidal marsh and eelgrass habitats to eat and grow before continuing on their ocean journey
  • Juvenile Chinook eat insects and crustaceans, and switch to fish such as herring and anchovies when they are adults
  • After living for years at sea, salmon travel long distances to return to the river in which they were born to spawn—some believe they use the earth’s magnetic field to help guide them, while others say they use their strong sense of smell

 

For more details on these studies, and to read up on past field studies notices, visit the field studies page. Click here to learn more about what we’re doing to protect salmon at Roberts Bank.

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