Last month, Puget Sound Institute senior writer Christopher Dunagan’s series on invasive species in Puget Sound highlighted some of the state’s worries about the arrival of the European green crab. The article noted that “the threat could be just around the corner.” It could not have been more timely.

Several weeks after the article was published, volunteer crab spotters led by Washington Sea Grant made the region’s first green crab sighting. The crab was found on San Juan Island and it led to a rapid response coordinated by the state to find out if others had spread further. This week, another crab has been spotted in Padilla Bay.

Emily Grason of Sea Grant said in a news release that there is little evidence so far of a larger population of the invasive crabs on San Juan Island, “but finding an additional crab at a site more than 30 miles away suggests that ongoing vigilance is critical across all Puget Sound shorelines.”

Green crabs are listed as one of 12 aquatic animals of greatest concern by the Washington Invasive Species Council. They cause an estimated $22 million each year in damage to fisheries on the East Coast and have started to disrupt fisheries in California as well.

Scientists suspect that green crabs may be spreading because of warming temperatures, but little is known for sure. Green crab larvae can also survive in the ballast water of ships entering Puget Sound, a major—and at times unregulated—pathway for a variety of invasive species. You can catch up on green crabs and other emerging threats from invasive species in our August series in Salish Sea Currents.