|Native littleneck and butter clams. Photo credit: C. Greiner|
Intertidal clams make up a significant portion of the biomass on pebble/sand beaches in Washington’s inland waters and serve as the basis for important commercial and subsistence fisheries. Four native species (butter clams, cockles, native littlenecks, and horse clams) and two non-native species (Manila clams and varnish clams) make up the majority of fisheries-targeted intertidal clam species. Clams are significant consumers of phytoplankton, valuable food sources for predators such as fishes, birds, and crab, and cultural keystone species integral to the health and wellbeing of Indigenous communities.
Following similar methods each year, Swinomish Fisheries biologists conduct bi-annual surveys on beaches within the Tribe’s usual and accustomed fishing grounds. Surveys typically consist of samples taken along transects running from uplands to the waterline. Results from these surveys are used to determine biomass for management purposes, but we also can use these results to investigate long-term changes in the clam populations. Research completed by Swinomish biologists has shown that local butter clam and native littleneck clam populations fluctuate synchronously regardless of location, indicating that large-scale processes likely influence these populations. Swinomish biologists are also investigating the role that various environmental factors (e.g., beach elevation, substrate, or fetch) play in the distribution of intertidal clams on certain beaches.
Swinomish Fisheries holds bait clam fisheries on beaches that have poor water quality, where clams cannot be harvested for consumption but can be harvested for use as bait in crab fisheries. Our department also opens beaches with good water quality for subsistence or ceremonial harvest. Fisheries staff monitor biomass harvest from these fisheries to ensure we stay within harvest limits and maintain sustainable populations.
To learn more, peer-reviewed publications and technical reports related to our intertidal clam work can be found on the Swinomish Publications web page.