Another risky summer for West Coast humpbacks
1 September 2017 - 10:30pm
For the third year in a row, the coast of California has been treated to a “whale spectacular” of humpback whales coming very close to shore, even into San Francisco Bay, giving tourists and residents, both casual onlookers and avid whale watchers, an amazing look into the lives of these magnificent beings. The whales are here to eat, following the abundance of food – primarily anchovies – found in the cold, nutrient-rich waters of the south-flowing “California Current” that creates the incredible diversity of marine life off the west coast. But with this proximity also comes vulnerability, as reports of entangled humpback whales continue to increase, and people eager to get an even closer look put the whales, and themselves, in danger.
The California Coast has a long history of attracting whales and other diverse marine life to its shores while they forage on the buffet created by strong upwelling (when cold, nutrient-rich water from the deep ocean is brought to the surface) just off the coast. But in recent years, warming ocean waters and the notorious “Blob” of 2015 has caused fish to move closer to shore, and the coast has become a narrow cold-water refuge. Following their food, the whales also move into this narrow area close to the coast, already busy with human activities like shipping, recreational boating, and fishing.
This image shows the exceptionally warm waters seen in the Pacific Ocean in 2015, nicknamed "The Blob." Note the narrow band of colder water close to shore (image from the American Geophysical Union).
Entanglements on the rise
The past three years have been record-setting years for reports of entangled humpback whales off the west coast, and 2017 is on track to break those records yet again. In the last two weeks of July alone, three whales were reported and confirmed to be tangled in fishing gear. Humpbacks, gray whales, and blue whales have all been reported entangled off the California coast. Entanglements are one of the leading modern-day causes of death for whales large and small, and even if they are freed by expert, federally-designated disentanglement teams, the resulting injury or subsequent infection may still take the life of the whale.
On the California coast, humpbacks are entangled the most often, usually during the summer, when their feeding season overlaps with fishing seasons. Researchers estimate that for every one entangled whale that is seen and reported, there are probably ten more that are not seen. As a result, the 71 whales reported entangled in 2016 may mean there were closer to 700 whales entangled on the west coast. These incidents can range from loose wraps of rope that the whales eventually lose on their own to very extensive entanglements that can make it difficult for whales to swim, feed, nurse, or even result in anchoring a whale in place, leaving them to starve or drown.
This table, from the National Marine Fisheries Service 2016 West Coast Entanglement Summary, compares entanglements reported in 2015 with 2016 - reported humpback entanglements significantly increased (NMFS 2017).
Causing even more alarm, two of the humpback populations that come to the California coast in the summer are on the Endangered Species List, further impeding the recovery of these vulnerable populations. Although the State of California, the National Marine Fisheries Service (NMFS), and local fishermen and NGOs have developed a working group to address the growing number of entanglements, some feel they have not taken action quickly enough, and are pursuing legal action to protect endangered humpback populations and other marine life.
In this nearshore habitat, the whales are also at risk of run-ins with boats – a combination of busy shipping lanes and summertime recreational boats out to enjoy a day on the water. Some of those boaters, unaware of the guidelines protecting whales and other marine mammals from harassment, or perhaps ignoring them in the effort to grab that next viral video, go for the close approach, putting the whales, and themselves, in danger. The whales, often distracted and preoccupied with the important business of eating do not always get out of the way of oncoming vessels. Whales can be hit by the hull of a vessel or run over and struck by the propellers. Like entanglements, vessel strikes are also significantly underreported. New research on ship strikes off California indicates that mortality is probably far higher than what is currently estimated, and that risk of a ship strike is highest in shipping lanes off the busy ports of San Francisco and Long Beach (Rockwood et al. 2017).
This year, like last year, humpbacks are traveling all the way under the Golden Gate Bridge and into San Francisco Bay to feed. Photo ID efforts by researchers in the area indicate that some of these are the same whales, coming back to feed on the rich supply of food they know is here. These repeat visitors show that these whales are remembering that the San Francisco Bay is a good place to find food, and we could see numbers continue to increase next year if oceans conditions stay the same. However, coming so close to shore, and into the Bay, puts whales and boats into close proximity. There have been several incidents this summer, including a kiteboarder taken by surprise, a whale having to make a gymnastic dodge to avoid a sailboat, and a direct hit on a surfacing humpback.
These interactions with human activities could have a significant impact on the endangered humpback populations that spend their summers off the California coast. It is important that people understand that whales can be unpredictable, and respect the regulations for viewing whales that keep both whales and people safe from injury.
WDC is working to develop criteria for responsible and sustainable whale and dolphin watching. Our US programs for commercial whale and dolphin watching, Whale SENSE and Dolphin SMART, combines the extraordinary experience of watching whales in the wild with important data collection, community involvement, and public education. In addition, we work to educate recreational boaters about the guidelines for approaching marine life and how to be respectful around whales and dolphins, and have recently published a report on responsible whale watching worldwide.
- Rockwood et al. 2017. "High mortality of blue, humpback, and fin whales from modeling of vessel collisions on the U.S. West Coast suggests population impacts and insufficient protection." PLOSone.
- National Marine Fisheries Service, 2017. 2016 West Coast Entanglement Summary.