An invasion is happening in Padilla Bay in Washington state. European green crabs or the Carcinus maenas are settling into the banks along the Bay and could crowd out the native wildlife there. The green crabs are an invasive species found native in the north-east Atlantic Ocean and Baltic Sea but can now be found in Australia, South Africa, South America, and the coasts of North America.
The Global Invasive Species Database call the green crab one of the world’s worst alien invasive species. Padilla Bay, located between the San Juan Islands and the Washington state mainland, is a tidal bay and an easy target for the European green crabs.
Four crabs were found and removed, reported The News Tribune out of Tacoma, WA. Each one was located in a different spot along the seven miles of shoreline, bringing the concern of University of Washington research scientist, P. Sean McDonald. The crabs are likely coming from a larger population and will “continue making their way to Padilla Bay.” McDonald works in close collaboration with Washington Sea Grant and the state’s Department of Fish & Wildlife to monitor the European green crabs.
The two organizations plus the Padilla Bay National Estuarine Research Reserve worked together to search for the crabs. Reserve staff, trained volunteers, and others are also watching out for European green crabs since the species settled on Vancouver Island, a short distance away from Padilla Bay. In some areas, the invading crabs already impacted shellfish populations and uprooted vegetation important to the wildlife in the area. McDonald stated to The News Tribune that when the green crabs are concentrated in a zone, they eat “everything they can get their claws on” reducing the food available for other wildlife.
Depending on the number of European green crabs, will determine the impact on Padilla Bay’s ecosystem. The reserve, Washington Sea Grant and the Fish & Wildlife are discussing their next steps to stop the invasion. Padilla Bay is designated as a national reserve, with water quality and vegetation monitored closely. The organizations will coordinate with each other to monitor the European green crabs and how they affect the bay.
Trapping the crabs could mean reducing the population. “The fewer crabs there are, the less likely they are to find mates,” said McDonald. Captured crabs can potentially provide researchers with valuable information regarding the reproductive habits. The first green crab was discovered in the mudflats of Padilla Bay during low tide on September 19. It was reported to the Fish & Wildlife and Washington Sea Grant soon after. Emily Grason of Washington Sea Grant said that “ongoing vigilance is critical across all Puget Sound shorelines.”
Traps were set at 31 sites in Padilla Bay to estimate the population. Responders and volunteers looked over a two-mile radius near Westcott Bay, according to Ballard News Tribune. The crabs that were caught are all the same size, and researchers believe that they are the same age and could be the first green crabs in Padilla Bay. Green crab larvae could be carried over from the south side of Vancouver Island via currents. Or another possibility could be the accidental transportation by boats or shellfish shipments.
Invasive species, however, are not just localized to Padilla Bay. In August, Minnesota officials confirmed the presence of another invasive species in local lakes – the zebra mussels. “Early detection,” according to McDonald, “can help prevent damage to the state’s marine habitats.” The early detection followed by the community’s rapid response in Westcott and Padilla Bays is how to stop invasive species. For more CDA News, follow our tweets on Twitter and like us on Facebook.
By Cheryl Werber