Vessel Traffic through Boundary Pass – a Saturna Island Perspective
This blog is written by guest blogger Sofia Osborne.
From the old fog alarm building on East Point, Saturna Island, I can see the buoy that marks the border between the United States and Canada. This is Boundary Pass where commercial ships come inbound to Vancouver and leave outbound towards destinations including Seattle, the Panama Canal, and Japan.
It’s challenging to capture just how large these ships are. Most Saturna Islanders who live on Cliffside, the road that faces Boundary Pass, like to sit out on their decks and watch the humongous ships move by. Many look the vessels up on AIS tracking to see what they’re carrying and where they’re headed.
But those who live on Cliffside are also in the best position to watch Orca whales, both salmon eating Southern Residents and marine mammal eating Transients, swimming and hunting along Saturna Island’s coast. When we think of vessels’ effects on Orcas we tend to focus on the whale watching boats that too often zip dangerously close to passing pods, but what about commercial shipping?
There are many initiatives being carried out to monitor underwater vessel noise along the west coast, including the use of hydrophones on Saturna Island. The hydrophones pick up acoustical information from passing whales, fish, and vessels of all sizes.
While we all know that the speed boats zooming by are deafeningly loud, the gigantic bulk carriers are only audible to us by their throbbing hum. We can feel them coming though, as the ground vibrates subtly before we even see a ship coming in the distance. Underwater, the substantial noise created by these large ships can prevent whales from communicating with each other and affect their ability to hunt.
The process that creates a lot of this underwater noise is called propeller cavitation, AKA “cold boiling.” Essentially the water is forced back by the ship’s propeller so fast that the pressure lowers. At a lower pressure water boils at a colder temperature thus creating the bubbles that we see. When the bubbles burst it not only damages propellers and reduces the efficiency of the ships themselves, but also creates a significant amount of underwater noise that affects marine mammals.
Sometimes while I watch the whales go by East Point I try to imagine myself in a similar situation to theirs. How do we balance our love of orcas with appropriate respect for their space and comfort? How do we juggle a need to protect nature with increasing globalization and demand for resources? As I watch Orcas swim by East Point, surrounded by whale watching boats and commercial ships I feel a mixture of awe and pity. I just know that this is not the answer.