Appendix E. Report on emergency sampling to verify reports of a 

 mussel die-off in the Upper Mississippi River. 



In September 1982, fishery biologists attending the meeting 

 of the Fish Technical Section of the Upper Mississippi 

 Conservation Committee reported seeing an unusually large number 

 of mussel "meats" (the soft interior tissue of the mussels) 

 floating in the Mississippi River in July from Rock Island, 

 Illinois, to as far north as Lacrosse, Wisconsin (UMRCC 1983) . 



In spring 1983, commercial clammers who used diving gear 

 reported large numbers of freshly dead shells in formerly 

 productive beds. Mr. Arnold ("Bill") Fritz, commercial fishery 

 biologist for the Illinois Department of Conservation, asked us 

 to investigate and guantify the mortality in two beds in Pools 1* 

 and 15 near Rock Island. 



We sampled a total area of 8 m in Pool 14, 100 m from the 

 Illinois shore (river mile 494.7) and 4 m in Pool 15, 150 m 

 upstream of Arsenal Island at the entrance to Sylvan Slough, 

 approximately 50 m from the Illinois shore (river mile 486.0). 

 We used 0.5-m 2 steel sampling frames and the surface supply 

 diving gear we described previously. 



Recently dead mussels met the following criteria: 



1. periostracum (horny brown/black layer covering the 

 outside of the shell) retained, 



2. valves firmly joined at the hinge, 



3. interior nacre shiny, not chalky, 



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