vessels, hobby farms, and stormwater runoff. Toxic wastes have also been 
implicated in declines and contamination of shellfish stocks. Paralytic 
shellfish poisoning (PSP) also remains as a significant water quality 
factor affecting shellfish in Puget Sound. In the discussion that 
follows, we will review the extent, impact and treatment of each of these 
problems in greater detail, but we'll focus on bacterial contamination. 
Shellfish-Distribution, Fisheries and Farming 
This paper began with a brief look at the past. The present 
production of bivalve molluscs includes the aquaculture of oysters, clams 
and mussels, and the capture fishery for clams. Several other 
shellfish, such as scallops, make up a minor part of the present 
harvests. In addition, there are many bivalve clams not taken in the 
commercial or recreational fisheries, such as the tiny but abundant 
Macoma balthica , which are eaten by valuable fish and bird species. 
Puget Sound bivalve shellfish are harvested from intertidal to shallow 
subtidal (i.e., less than 20 meters) depths throughout Puget Sound 
(Figure 1). 
The production and harvest of shellfish in Puget Sound is carried 
out on both public and private lands. While all subtidal lands and 
overlying waters are managed and controlled by state or federal agencies, 
much of the tidelands are under private ownership. This is a result of 
legislation passed in the late 1800's to encourage the development of an 
oyster industry. The development of new culture and harvest methods and 
improved management have opened up additional areas and resources in 
Puget Sound. For example, in the subtidal areas, geoduck clams ( Panope 
qenerosa ) weighing up to 20 pounds each, are now hand-harvested by divers 
and subtidal hardshell clams are obtained using mechanical hydraulic 
harvesting machines. Soft-shelled clams ( Mya arenaria ) are suffiently 
abundant in the intertidal areas of some embayments to warrant harvest. 
In addition, new advancements in artifically seeding oyster and clam beds 
have allowed an increase and stability in yields beyond what is possible 
with recruitment from natural setting. Both the capture fishery, or 
wildstock harvest of shellfish, and aquaculture or aquatic farming, have 
benefitted from these changes. 
The farm production of oysters in Puget Sound has not varied greatly 
since the 1950's, and now accounts for about 50% of the total state 
production. The total production of Pacific oysters in Puget Sound is 3 
million pounds of oyster meats, or about 6% of the total U.S oyster 
production. Most oysters are farmed on tidelands in the highly 
productive small bays and inlets of south Puget Sound. 
48 
