Recent mortality event of Pacific razor clams, Siliqua Patula, alongthe Pacific coast of Washington state associated with record infectionintensity of the gills by nuclear inclusion X (NIX)

摘要

After the summer 2002 razor clam stock assessment, a record number of adult razor clams were determined to be available for harvest on the five management beaches located along the Washington State coast. However, due to high levels of the marine toxin domoic acid, no harvest occurred on any management beach with the exception of a limited tribal harvest on the northern beaches before the toxin arrived. Coincidently, a sample of 50 clams was collected in early October for analysis of infection intensity of nuclear inclusion X (NIX). NIX is a primitive, large bacterium obligately infecting the nucleus of gill epithelial cells of the razor clam. NIX is a member of the gamma subclass of the eubacterial class Proteobacteria. NIX was the suspected cause of a razor clam mortality event in 1983 that resulted in the loss of more than 90% of the adult clams found on some management beaches as well as high percentage losses in 1985 and 1989 associated with high NIX infection intensities. The high NIX infection intensities are followed by ruptured gill epithelia that may be synchronized by an environmental temperature drop. In October 2002, we found an average NIX infection intensity of 48.3, the highest ever recorded since records were first made in 1983. The summer 2003 razor clam stock assessment found a 49.7% loss of adult clams coastwide. NIX is again the likely suspect.