Clam recruitment and survival, Crab abundance in Willapa Bay 2024

In June-Sept 2024, seven stations spanning 20 km on intertidal flats of Willapa Bay, Washington (USA) were measured for recruitment of two clam species: Manila clams (Ruditapes philippinarum) and softshell clams (Mya arenaria). Recruitment was operationally defined as 250-500 micron size class and was measured from spat samplers four times during the summer, as well as seasonal recruitment of >500 micron clams that survived to mid-September. (Spat samplers = mesh bags of 15x10 cm, 1 mm mesh size, filled with round gravel) Predator exclosures were established at four tidal elevations at one site, and survival of 1-cm and 2-cm clams was measured over 6 weeks. Crab abundances were determined from traps mid-way through the experiment, including three native (Metacarcinus [Cancer] magister, Cancer productus, Hemigrapsus oregonensis) and one non-native crab species (Carcinus maenas).