SUMMARY 



1. This is an interim report on a continuing study of effects of 

 barge fleeting on mussels in the Illinois River at Naples, 

 Illinois. Results will be used to evaluate requests for fleeting 

 permits where proposed fleeting sites and mussel beds overlap. 



2. In June 1984, we collected, marked, and replaced 735 live and 16 

 dead mussels in two experimental (fleeted) and two control 

 (unfleeted) plots. In one fleeted plot barges were tied to 

 pilings, and in the other barges were tied to deadmen and grounded 

 along shore. Mussels were placed in 25 aluminum corrals up to 

 normal densities, and additional mussels placed around the corrals. 



3. In October 1984, we recaptured 3 of 16 dead shells and 175 of 

 735 live mussels. We also collected and marked 740 live, 

 previously unmarked mussels bringing the total number of live, 

 marked mussels in the study area at the end of 1984 to 1475. 



4 . Corrals in the area where barges were grounded were destroyed 

 and remaining pieces had obviously been struck by large 

 propellers. There were several 1-2-m deep pits in the substrate 

 which may have been created by prop wash. Corrals by the pilings 

 were bowed and pushed into the substrate but otherwise intact. 

 Corrals at the upstream control site had been struck by small 



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