Marine scientists looking for new ways to reduce the number of whales struck and killed off California’s coast by massive commercial ships have turned to a familiar tool: mobile devices. An app called “Whale Spotter” uses crowd-sourcing to gather data, allowing sailors, fishermen and marine scientists who spot whales to plot their location on an interactive map. The maps created could then be used by National Oceanic and Atmospheric Administration and U.S. Coast Guard officials to recommend different vessel routes. The app is the latest development in a collaboration between shipping companies, government officials and scientists to reduce whale strikes. Testing begins this weekend to see how effective it will be. “Everybody agrees that we need to try to keep whales and ships separated physically to the greatest extent possible,” said John Berge, vice president of the Pacific Merchant Shipping Association. “Right now, we know where the ships are, but we don’t know where the whales are.” Berge said the shipping industry supported development of the application as another tool in a new arsenal being created to reduce the strikes. In June, large vessels traveling to ports on the California coast began using new traffic lanes developed to move ships away from whales. In the busy ports of the San Francisco Bay Area, more than 7,300 large ships head through the Golden Gate each year. Just outside the bay, whales often swim along the continental shelf, where their food supply is plentiful. Several dead whales, including an endangered fin whale, suspected to have been killed by ship strikes have washed ashore this year in the Bay Area. The idea behind the app is to create a network of whale spotters off California’s coast so the marine mammals can be tracked, in real time, as they migrate. The weeklong tests of the app beginning Saturday will occur in the Cordell Bank and Gulf of the Farallones National Marine Sanctuaries. Marine scientists working on the Farallon Islands off San Francisco’s coast already have been inputting whale sightings from their unique perch, from where the westernmost shipping lanes can be seen. A big hurdle for the app is that cellphone coverage at sea is spotty at best, so data may be delayed to a point where it’s not immediately helpful.