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An example of such a challenge exists in the mudflats that trace Maines winding coastline. Soft-shell clams Mya arenia Maines third most profitable fishery have been managed as an open-access resource for centuries. The industry which employs approximately 1600 licensed harvesters and grosses 15 million annually from landings alone utilizes some of the best practices for managing a common pool resource. This management approach is outlined in Elinor Ostroms Nobel prize-winning theoryGoverning the Commons.1 A key tenet of Ostroms framework that the industry follows is harvesters taking part in setting limitations based on their local knowl- edge of the resource. Yet despite local town-level management efforts Maines soft-shell clam fishery has recently taken a turn for the worse. Over the course of three years the town of Brunswick which has some of Maines most productive clam flats had to drop 26 of its 68 clamming licenses as harvestable populations dropped 38.2 Officials from the town reported that the decline is a direct result of the green crab invasion.3 While local acidification and pollution can stress soft-shell clam growth most see the European green crabs Carcina maenas as the biggest threat to the industry. The crabs as their name implies are native to Europe but were introduced to New England in the early 1800s from the ballast water of cargo ships. They have been crawling up and down the Eastern Seaboard ever since and were first documented on Maines coastline in the early 1900s. Green crabs are invasive and resilient creatures they are omnivores and eat almost anything can live in a variety of habitatswithstanding wide ranges of temperature and salin- ityand female crabs can spawn up to 185000 eggs at a time twice a year.4 They have even been reported to survive for ten days out of water in the heat of summer. The crabs are seem- ingly unstoppableand they are feasting on soft-shell clams. Soft-shell clams are very attractive morsels for the crabs as the brittle clam shells are easy to flake off and the clams have no way to defend themselves. In the laboratory green crabs have been seen to prey on adult clams while they seem to target juveniles in the wild. This is problematic because flats are now unable to naturally regenerate as the bigger clams are being harvested and small clams are being devoured by green crabs. In 2013 Chad Coffin a shellfish harvester from Freeport Maine told a local news station that because of the green crab problem Were only maybe two years away from really no commercial viability in the state on soft-shell clams which has been historically and traditionally one of the most important and economically valuable resources on the coast of Maine.5 So if these crabs have been around since the 1880swhy are we just starting to hear about them Because cold winter waters used to kill off most of the green crabs and kept their populations in check. But now the Gulf of Maine is heating up faster than 99 of the worlds oceans allowing the green crab population to grow rapidly. This is just one of the indirect effects of global climate change that is already radically impacting the resources we rely on. But these crabs are native to Europewhy dont we just ask Europeans how they handle the problem Green crabs are not as big of a problem in Europe because they have another native species a parasitic barnacle which is known to castrate green crabs. While the barnacles keep the green crab population in check no one is really looking to bring another potentially harmful species to the region.6 Wait. Humans eat crabs. Why arent people harvesting green crabs for food to control their populations Entrepreneurs have explored using green crabs as food flavoring fertilizer and even cat food but no real economi- cally feasible options have emerged. The amount of meat in each green crab is so small that the return on investment is not sufficient to create a viable market. Compared to other fisher- ies harvesters would lose money if they focused on harvesting green crabs. Communities have also tried to take matters into their own hands by trapping out green crabs in their local inlets but it is nearly impossible to catch the pests fast enough to keep up with their reproduction. 1 Ostrom E. 2002. GOVERNING THE COMMONS The evolution of institutions for collective action. Retrieved from httplawschool.unm.edunrjvolumes32206_ostrom_governing.pdf 2 Royte E. 2014 October. Clawing Their Way to the Top. OnEarth Magazine. Retrieved from http archive.onearth.orgarticles201410could-invasive-crabs-scuttle-maines-softshell-clam-fishery 3 Mistler S. 2014 January 22. Maine clam diggers worm harvesters square off over mud flats. Portland Press Herald. httpwww.pressherald.com20140122maine_worm_and_clam_dig- gers_argue_over_bill_to_close_off_mudflats_ 4 Beale B. 2013. Green Crabs Ecology and Their Effects on Soft-shell Clams. Powerpoint slides. Retrieved from httpseagrant.umaine.edugreen-crab-summit 5 Wight P. B. 2013 August 28. Voracious Invasive Crab Threatening Maines Shellfish Industry. Maine Public Broadcasting Network. Retrieved from httpwww.mpbn.netHometabid36ctlViewItem mid5347ItemId29698Default.aspx 6 Gallessich G. 2013. Researchers Find Invasive Species are Healthy Species-They Leave Their Parasites Behind. The UC Santa Barbara Current. Retrieved from httpwww.ia.ucsb.edupadis- play.aspxpkey761 Manomet President John Hagan measures a green crab. He is conducting an ongoing study on green crab population dynamics around the clam farm site. 4 Manomet Partnerships for Sustainability Summer 2015