METHODS 



LOCATING MUSSEL BEDS 



Initially we used a brail (also called a crowfoot bar) to 

 locate mussel beds in the fleeting area at Naples. The brail was 

 1.6 m long and had 30 4-pronged hooks or crowfeet attached to it. 

 We fished the brail from a 6-m boat as the boat floated downstream 

 with the current. 



On 6 July 1983, we had great difficulty using the brail to 

 identify mussel beds in the fleeting area. The hooks continually 

 snagged on steel cables used for fleeting, submerged trees and 

 brush, and even a discarded automobile. One day of brailing 

 yielded only 12 mussels. On 12 July 1983, surface-supplied diving 

 was used to reexamine plots within the fleeting area where a few 

 mussels had been taken with the brail. An area on the west bank 

 near river mile 65 had the greatest density of the plots 

 investigated and was chosen for quantitative sampling by diving. 



DIVING 



For diving we used an 8-m pontoon boat equipped with an air 

 compressor, primary and secondary storage banks, and a control 

 console for air-pressure regulation and two-way communication to a 

 diver using a US Divers' Superlite 17 diving helmet. In shallow 



