aquaculture aqua culture cultured clam clams cheriton virginia chesapeake bay seed spat spreading spread seeding bed plot water wade males men people man wading work working industry seafood jobs farm farming raised little neck shallow delmarva eastern shore clamming littlenecks stack heap pile shellfish crustacean food hard bivalve mollusk fish cherrystones raw live freshness fresh cloudy sky wetland wetlands raising planting saltwater brackish aquafarming aquatic populations controlled conditions catch dredge sort sorting color colour us usa north america united states person persons people vertical