Manila Clam (Venerupis philippinarum) Die-off observed - possibly related to freezing temperatures.
Observation: While out sampling adult manila clams and collecting sediment samples as part of a larger project to understand settlement and recruitment of this important food. During the winter low tides, which exposes the tidal mudflats, have been happening at night. The weather has been very cold lately. Manila clams are typically only a few inches underneath the surface of the sediment - they can be easily exposed, and that layer of sediment in extremely cold weather does onto offer much protection from the elements. From the picture we can see that the clams are open indicating they are dead and there is no clam meat inside of them. There were thousands of empty shells - as far as the eye could see. It’s speculation that this is evidence of a freeze die off - but seems to be the most likely explanation.
LEO says: Lummi Natural Resources has been notified of this posted observation.
Lummi Natural Resources Department — The Lummi Indian Business Council NRD publication, Lummi Nation Atlas (March 2016), An overview of the history, natural and economic resources, and government of the Lummi Nation, see pages 41-42 for Manila Clam Distribution (Map 18).
Washington Department of Fish and Wildlife — "This important clam is not a native of North America, but was accidentally introduced to Washington State in oyster seed shipments from Japan. The animal quickly acclimated to our waters and is now found from British Columbia to northern California. They are similar in size and appearance to littlenecks; however, they are oblong in shape, being more long than high compared to littlenecks." Source: Wahsington Department of Fish and Wildlife, Fishing & Shellfishing