 There is evidence that the native blue crab in eastern North America , Callinectes sapidus , is able to control populations of C. maenas ; numbers of the two species are negatively correlated , and C. maenas is not found in the Chesapeake Bay , where Callinectes sapidus is most frequent . On the west coast of North America , C. maenas appears to be limited to upper estuarine habitats , in part because of predation by native rock crabs ( <unk> <unk> and Cancer productus ) and competition for shelter with a native shore crab , Hemigrapsus oregonensis . Host specificity testing has recently been conducted on Sacculina <unk> , a parasitic barnacle , as a potential biological control agent of C. maenas . In the laboratory , Sacculina settled on , infected , and killed native California crabs , including the Dungeness crab , Metacarcinus magister ( formerly Cancer magister ) , and the shore crabs Hemigrapsus <unk> , Hemigrapsus oregonensis and <unk> crassipes . Dungeness crabs were the most vulnerable of the tested native species to settlement and infection by the parasite . Although Sacculina did not mature in any of the native crabs , developing reproductive sacs were observed inside a few Metacarcinus magister and Hemigrapsus oregonensis . Any potential benefits of using Sacculina to control C. maenas on the west coast of North America would need to be weighed against these potential non @-@ target impacts . 
