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Blue whales are the largest animals on the planet and yet curiously invisible to people, with sometimes deadly consequences.

Bigger and more numerous ships are plying the coastal waters off western North America, unloading goods at increasingly busy ports, notably Oakland and Long Beach, California. The problem? The ships’ routes overlap with blue whale foraging spots. Each year, an average of two blue whales are struck by ships in the California Current, though that is only documented cases and the reality is likely higher.

To help the situation, researchers from Oregon State University and the University of Maryland have been working with the fisheries department of the National Oceanic and Atmospheric Administration (NOAA) to build WhaleWatch, a new forecasting tool to alert ship captains to the presence of these endangered whales. It’s the first system to provide monthly maps of projected blue whale hotspots off the US west coast.

WhaleWatch combines location data from 104 blue whales tagged from 1994 to 2008 along with current and historical environmental data that effect blue whale migration, including sea surface temperature, chlorophyll levels, and wind speed, and runs the data through statistical models and machine learning algorithms. The output is predicative maps of where whales are likely to be.

“We aren’t having to rely on historical averages,” says Helen Bailey, the project’s coordinator and an ecologist at the University of Maryland’s Center for Environmental Science. Bailey says the whales have favorite locations that they return to regularly, but there are other spots that they return to only occasionally. The models used by WhaleWatch are able to take this into account.

The maps could help ship captains decide whether to use voluntary, short-term measures to reduce the potential for collision, such as slowing their speed or posting more lookouts.

“Nobody wants to hit a whale,” says Captain Kip Louttit, executive director of the Marine Exchange of Southern California, which tracks ship traffic into and out of Southern California ports. Louttit says even when it’s hard to see a whale, at night or in bad weather, captains can use the maps.

“It’s an all-weather, 24-hour a day solution,” Louttit says.

The mobile app Whale Alert served as inspiration for WhaleWatch says Elliott Hazen, a research ecologist at NOAA Fisheries’ Southwest Fisheries Science Center. Whale Alert uses hydroacoustic listening in shipping lanes and user sightings to populate maps. Another model was TurtleWatch, a NOAA-produced map with up-to-date information about areas where loggerhead sea turtles are likely to congregate in the Pacific Ocean north of the Hawaiian Islands.

Unlike Whale Alert, WhaleWatch uses predictive modeling to create its maps.

Though the funding for the project is now over, the researchers hope to keep working on WhaleWatch. Bruce Mate, the Marine Mammal Institute director at Oregon State University who supplied the blue whale tagging data for WhaleWatch, says the past three years have been particularly hard on blue whales, due to low volumes of prey with two warm water years followed by an El Niño. Eighty percent of the whales Mate’s team saw on a tagging mission in Southern California in 2016 were emaciated. This makes updating WhaleWatch with current data essential for keeping the maps accurate.

“The information we’ve collected these last three years since the data collected for the WhaleWatch launch is going to be very significant to suggest what climate change might look like for blue whales,” Mate says.

The models might also already be showing the impact of climate change. The maps showed whales to be likely in the North Pacific, although there was not a lot of satellite data from whales there.

“The model may be more accurately predicting suitable habitat,” Hailey says.

WhaleWatch’s maps are available on NOAA’s website and webinars are planned to highlight the maps for captains and any interested parties, including fishermen who want to keep whales from their nets. But WhaleWatch is not likely to be particularly useful to whale watching enthusiasts, since the maps often show zones far offshore. Whale watching tour companies also won’t see much use for the site, since they are often going out daily and will already have a good understanding of the whales’ movements.

“They can tell with even finer data than we can sometimes about where the whales are,” Hazen says. In fact, Hazen says he would like to find a way to incorporate whale watchers’ observations into a future version of WhaleWatch.