Biomass survey (IMAGE) University of Washington Caption Joe Williams, front, and Darrell Williams with the Swinomish Indian Tribal Community’s Fisheries Department dig clams on a beach in Skagit Bay as part of a survey that is conducted to estimate clam biomass. Credit Northwest Indian Fisheries Commission Usage Restrictions No restrictions. License Public Domain Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.