What’s behind recent rise in whale deaths around San Francisco Bay?

Hard evidence and a recent scientific study point to collisions with ships as top culprit. New technology offers possible solutions

Beach enthusiasts and those living around the San Francisco Bay Area have witnessed a spike in whale deaths in recent weeks.

Since May, no fewer than four such deaths have been documented by local media sources, making images of whale carcasses washing ashore along beaches and in bay estuaries —typically a rare occurrence — a more frequent sight recently.

The scene of whale carcass washed ashore is becoming a more common sight in recent weeks in and around the San Francisco Bay. This blue whale, a rare and endangered species, washed ashore at Point Reyes on June 18. This was the fourth such whale death documented in the area since May. Photo posted by local citizen scientist on West Marin Feed, a Facebook group.

Innovative model-based study

In an innovate recent study, scientists used naval encounter models to estimate how many collisions between ships and whales might occur each year. The study covered the coastal waters along California, Oregon and Washington.

When a ship strikes a whale at sea, it typically goes unnoticed. If the whale dies, it usually sinks. Other factors make measuring death rates from such collisions challenging, such as bad weather or when collisions happen at night. But scientists are using new models to help understand just how frequent collisions with whales can be, especially in areas where both large ships and significant populations of whales overlap.

The recent collaborative study traced three major species of whales within heavily trafficked shipping routes along the U.S. west coast, including blue, humpback and fin whales.

The study is authored by R. Cotton Rockwood, a data scientist and senior marine ecologist and Jaime Jahncke, a marine biologist — both of Blue Point, a conservation group based in Petaluma, California — and John Calambokidis, a research biologist and co-founder of Cascadia Research located in Olympia, Washington.

Whales Love the California Coast

A recent study considered where major whales species hang out along the coasts of California, Oregon and Washington. Big populations and greater density of three species of whales are shown above, including (from left to right) Blue, Humpback and Fin whales.

Ship Traffic Overlaps Where Whales Congregate, Live and Feed

Whales versus Ships — The study shows ship traffic heaviest along three major shipping corridors: northern Washington (port of Seattle-Tacoma) (shown in E), the San Francisco Bay Area (F), and the Long Beach to Santa Barbara Channel corridor (G)

The takeaways from this study highlight the hotspots for whale collisions and likely deaths. No surprise to many Bay Area locals, ships transiting areas like The Farallons, as well other areas designated as marine sanctuaries, are the zones with the highest probability of collisions with whales.

What Might Be Done

Ships can slow down, especially within dense shipping channels, like around The Farallons, or any areas known to have high concentrations of whales. There might also be innovative ways for ships to steer clear of whales. They might use new technology like drones that fly ahead and scout for whale activity. Promising new and inexpensive technology like floating passive, non-invasive sensors could help ships detect whales and avoid collisions before they happen.

Blue Whale death at Point Reyes — June 18, 2018 — This latest whale death gives scientists a rare opportunity to study a blue whale. In the past 43 years, only 10 such blue whales, an endangered species, have ever been examined by scientists at The Marine Mammal Center, a local observatory located in Marin County, California. Photo by The Marine Mammal Center

Sources

Endangered blue whale found on Point Reyes beach likely killed by ship strike

New study: West Coast ships kill more than 80 endangered whales annually

High mortality of blue, humpback and fin whales from modeling of vessel collisions on the U.S. West…

As a burgeoning science writer, I cover stories happening in and around where I live. My beat is my backyard. My approach is to cultivate environmental awareness, empower citizen science, and inspire mindful ecological activism. I seek not only to write about scientific topics but to help people take actions toward positive and meaningful change, and to highlight better choices for sustainable living in the age of the Anthroprocene. My work combines my lifelong meditation practice with writing to raise awareness and highlight solutions in an era of rising human impact upon all life on this planet.