This article was co-authored by Raincoast Conservation Foundation biologist Misty MacDuffee.
Southern resident killer whales (southern residents) feature prominently these days as their struggle for survival in the Salish Sea has become symbolic of the unsustainable nature of our economy, and often, our lifestyles. The mounting ecological cost of unrestrained economic growth presents a stark choice about our future and that of the whales -- will future generations of children grow up with a healthy population of southern residents or will we only save memories of what once was?
Raincoast Conservation Foundation recently submitted 500 pages of scientific evidence for the federal review of Kinder Morgan's proposed Trans Mountain pipeline and oil tanker expansion project. Central to our evidence is a new analysis on the status and probable fate of southern residents. Considering the declining quality of habitat in the Salish Sea -- a region facing increasing industrialization with proposals for oil, coal, and gas ports, and more container terminals -- our findings are offered with a sense of urgency.
Already critically endangered, southern resident killer whales are struggling to find enough salmon to eat in a noisy and polluted ocean. Sound is as important to killer whales as vision is to humans. Their most important seasonal feeding grounds are international shipping lanes; places where the opportunity to communicate (out to a range of 8 kilometres) is consistently compromised by noise from ships and boats. Nearly all opportunity for whales to speak with each other while hunting for food is lost during periods of busy traffic. Their primary food, chinook (a.k.a. spring) salmon, is managed for commercial and recreational fishing, not hungry whales. The abundance of chinook strongly influences birth, growth, and death rates ofsouthern resident killer whales. Lastly, the southern residents' popularity means a flotilla of whale watching boats follows them every day from spring to fall.
To assess this problem in a measurable way, Raincoast teamed with leading scientists studying killer whales, acoustic disturbance, and endangered wildlife to conduct an analysis of the southern residents' population viability. "Population viability analysis (PVA) can examine risks to wildlife populations over time and evaluate the likely effectiveness of recovery options," explains Raincoast senior scientist Dr. Paul Paquet. "We assessed the viability of the whales in light of cumulative disturbances and threats, including noise from existing and planned vessel traffic, ship strikes, oil spills, and Chinook salmon food supply."
The southern resident population has experienced almost no growth during the past four decades, and has declined in the last two decades to around 80 whales. Our study identified reduced consumption of chinook salmon has the largest effect on depressing the southern residents' population size, possibly leading to extinction. Reduced food consumption can occur through several ways: inhibiting the ability of whales to locate and catch fish as a result of physical and acoustic disturbance from boats and ships, exploitation by fisheries throughout the U.S. and Canada, and further declines in salmon abundance from factors like oil spills and climate change.
Another important factor in killer whale survival is the risk from exposure to oil spills. Our PVA found that a catastrophic oil spill has the potential to reduce the population to such a small number of whales (less than 30) that recovery would be unlikely. A comparable circumstance befell a population of transient killer whales in Alaska following the Exxon Valdez oil spill.
Given existing conditions, the southern residents cannot withstand the additional pressures that would result from proposed increases in the Salish Sea's shipping traffic, recover from their endangered status, and survive in perpetuity.
However, our PVA also had encouraging news as we determined what might happen if the Salish Sea were quieter, less polluted, and had more chinook salmon. We found that killer whale numbers could slowly build (up to 1.9 per cent with 20 per cent more salmon consumption) and the population could survive at larger and viable numbers into the future.
Increases in Chinook salmon abundance will benefit, and could save, the southern residents. More than one million chinook are typically caught every year in U.S. and Canadian commercial and recreational fisheries. Allowing more of these fish to reach maturity and their spawning grounds is key to rebuilding chinook abundance.
Associated with catching and consuming more food is reducing the disruption of feeding activity in the presence of boats and ships. Vessels are present an estimated 78 per cent of the time that the southern residents forage and feed. The presence of vessels cause whales to spend 25 per cent less time catching and eating salmon, translating to a 16 per cent reduction in food intake.
If we want to save more than memories of southern resident killer whales, we have to act now. This might include restricting the numbers and routes of vessels that travel through their critical habitat; addressing fisheries that adversely affect the age, size and abundance of chinook salmon; and cleaning up polluted waters while preventing additional contamination from new pollutants. Federal dollars identified to recover endangered whales also need to flow to stakeholders economically affected by such recovery measures. Finally, we need to stop Kinder Morgan's pipeline and oil tanker project, and other similar projects, that degrade the marine waters of the Salish Sea.
A version of this article recently ran in the Vancouver Sun.
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