Approval of Trans Mountain expansion puts Fraser River salmon and Salish Sea estuaries at risk

The science casts doubt on government and industry assurances that risk and consequences to salmon from the Trans Mountain expansion are minimal.

Salmon circle on the rocky bottom of the Fraser River.

Photo by April Bencze / Raincoast Conservation Foundation.

The Fraser River in British Columbia remains one of the world’s most productive salmon rivers. Equally significant is the Fraser River’s estuary, which serves as vital habitat for fish, bird, and mammal species that are linked across thousands of kilometers of the Northeast Pacific Ocean. All Fraser River populations of salmon (Chinook, sockeye, coho, pink, and chum) must transit the estuary twice in their lifetimes: once as they migrate to the ocean as juveniles and again as adults when they return to their natal streams to spawn. Species like Chinook and chum also spend extended time rearing in the estuary as they prepare for their ocean migrations.

Twice, as an expert intervener in successive National Energy Board hearings, Raincoast Conservation Foundation examined information put forth by Trans Mountain in their assessment of the effects to salmon from an oil spill in the Fraser River and found serious deficiencies with several aspects of their assessment. These deficiencies render Trans Mountain’s conclusion that the pipeline can be built with little risk and harm to Fraser River salmon unsubstantiated.

The Strait of Georgia (part of the Fraser River estuary) is considered the most important rearing area for juvenile salmon on Canada’s Pacific coast. In addition to the Fraser River, 190 large and small estuaries critical for salmon rearing, staging, and migration lie within the Salish Sea; five of these rank in the top 10 estuaries in British Columbia for their ecological value. These estuaries are vulnerable to diluted bitumen (dilbit) spills from either a Trans Mountain pipeline or associated oil tankers.

Prior to their migration to sea, juvenile salmon must spend time in estuaries transitioning to the marine environment. During this time, fish experience physiological stress and are highly sensitive to additional stress. Further, it may be impossible for them to avoid spilled oil while they are undergoing this process in the estuary.

Ocean-type Chinook, chum, and some coho salmon have the greatest reliance on estuaries and would be particularly vulnerable to a pipeline or tanker spill affecting the Fraser River estuary and other estuaries throughout the Salish Sea.

With nine species of salmon and trout spawning in the tributaries of the Lower Fraser River and using the main channels and sloughs to rear, a spill of dilbit into the river or its tributaries would be catastrophic, rendering many of these areas unsuitable for the growth and survival of salmon embryos and fry.

A salmon resting in the waters of the lower Fraser River.

Photo by April Bencze / Raincoast Conservatino Foundation.

Juvenile and adult salmon can be exposed to spilled oil via oil droplets in the water column, toxic components of oil that have dissolved in water, and through consumption of contaminated prey. However, embryonic fish (developing inside the egg), are most at risk because critical development is occurring at a rapid rate, and the embryos themselves are immobile and unable to escape exposure.

After eggs are fertilized, oil exposure has been shown to substantially increase mortality rates of embryos. For salmon embryos that do survive, exposure to oil can cause impaired heart function, physical deformities, reduced growth, and compromise their ability to produce offspring. This could mean effects across entire populations of salmon that are already facing multiple challenges to their survival.

Fertilized salmon eggs can be present in spawning gravels from late summer of one year to spring of the following year, providing a long window of potential exposure to toxic oil components. In addition, a spill can affect not only those embryos present at the time of the spill, but the embryos of future generations. Oil trapped in the river bed does not wash out quickly, and the slow release of sunken and stranded oil can result in concentrations of toxic compounds in the water that are high enough to cause embryotoxicity for months to years.

This is a critical consideration in the case of the proposed pipeline expansion. Spilled dilbit is likely to strand on shorelines and sink to bottom sediments, where it can create a long-term source of contamination not just to salmon embryos, but to other aquatic life, including the invertebrate species that are a key food source for salmon.

Raincoast has shown that Fraser River salmon are vulnerable to an oil spill based on their species life history. Whether as embryos, juveniles or adults, salmon spawn, rear, and migrate throughout the Lower Fraser River every month of the year. As such, there is no safe time for an oil spill.

The geography of the lower Fraser River makes effective oil recovery extremely difficult, if not impossible, resulting in the likelihood of long-term releases of the toxic components of oil. Twenty populations of Fraser River Chinook, sockeye, coho, and steelhead are already at low (or critically low) abundance. These populations are even more vulnerable to extinction as a consequence of random events like oil spills. All of these facts cast doubt on government and industry assurances that risk and consequences to salmon from the Trans Mountain expansion are minimal.


A version of this article was first published at the Georgia Straight.

Executive Summary: Wild Salmon, Pipelines, and the Trans Mountain Expansion

Investigate. Inform. Inspire.

Publications | Scientific Papers | Reports & Books

Find us & follow