The 1990 National Shellfish Register 



produces the neurotoxin saxitoxin. 

 Maine was the first state in the Nation 

 to monitor for paralytic shellfish 

 poisoning. As a result, some of the 

 State's productive shellfish-growing 

 waters have been closed for most 

 years since 1958. In the Pacific 

 region, the main toxic species causing 

 PSP is Protogonyalaux catenella. 

 Neurotoxic shellfish poisoning (NSP) 

 may result from a bloom of the 

 dinoflagellate Ptychodiscus brevis. 

 Restricted to the west coast of Florida 

 until the late 1980s, P. brevis recently 

 caused blooms in Texas and North 

 and South Carolina, and all four states 

 have developed monitoring and assay 

 programs at considerable cost. 

 Amnesic shellfish poisoning (ASP), 

 caused by acid released from the 

 diatom Nitzschia pungens has re- 

 cently been identified in mussels from 

 Canadian waters. The disease, which 

 has recently become a concern in the 

 North Atlantic region, causes both 

 gastrointestinal and neurological 

 disorders, and is assayed using high 

 performance liquid chromatography. 

 Diarrhetic shellfish poisoning (DSP), 

 caused by several species of 

 Dinophysis, has been identified in 

 Japan, Europe, and Canada. Be- 

 cause the symptoms of DSP are 

 easily confused with those of other 

 enteric diseases, U.S. cases may 

 have gone unreported. 



Through the use of NSSP marine 

 biotoxin guidelines which require 

 monitoring and tissue assay, coastal 

 states have generally succeeded in 

 eliminating toxic shellfish from com- 

 mercial distribution. However, recre- 

 ational harvesters are often unaware 



Table 3. Distribution of Classified 

 Estuarine Waters, 1985 

 and 1990 



of biotoxin risks, and may ignore 

 warnings if waters are not discolored. 

 Accordingly, the majority of PSP 

 cases in the United States result from 

 the recreational harvest of clams and 

 mussels (Nishitani, 1988). 



National Overview 



Information collected on the status of 

 3,172 individual shellfish-growing 

 areas in the U.S. is presented for five 



Table 4. Classified Offshore Acres 

 (x 1,000), 1990 



