OYSTER PRODUCTION 

 DELAWARE BAY 



IOO-- 



Ivuui 



1955 I960 1965 

 YEAR 



Figure 4. — Oyster production in New Jeresy waters of Delaware Bay, 1950-65. 



The organism that has caused these major 

 economic losses to the oyster industry of 

 lower Chesapeake Bay and Delaware Bay is a 

 haplosporidan protozoan parasite, recently 

 named Minchinia nelsoni by Haskin, Stauber, 

 and Mackin (1966). It was formerly known by 

 the nickname "MSX," and the disease it 

 causes is known as "delaware bay disease." 

 Its most common stage in the oyster, the 

 vegetative or plasmodial stage, is shown in 

 figure 5. The spore stage of the pathogen 

 (probably the stage in which the disease is 

 transferred) was recently identified by Couch, 



Farley, and Rosenfield (1966). Descriptions 

 of the disease in oyster populations have been 

 published by Mackin (1960), Andrews (1964, 

 1966), and Haskin, Canzonier, and Myhre 

 (1965). 



An interesting and possibly critical aspect of 

 the disease is that it has not been found where 

 salinity is consistently less than 15 parts per 

 thousand. This fact alone probably explains 

 why the decline in Chesapeake Bay oyster 

 production has not been as drastic as that in 

 Delaware Bay, where salinities in oyster 

 growing areas are higher. Virginia production 



