SHELL DAMAGE IN RECAPTURED MUSSELS 



The same trends are apparent for new damage to marked 

 mussels which occurred between the times mussels were collected 

 and marked in spring and recaptured in fall. With all species 

 combined, the highest damage rates were from the fleeted plots 

 (20.4% in the grounded plot and 19.0% in the pilings) (Figure 

 6). Again the lowest damage rate (8.3%) was in the downstream 

 control. Only five marked shells were recaptured from the 

 upstream control plot. Results for Amblema plicata were 

 similar (Figure 7) . 



MORTALITY 



With all species combined, the highest mortality rate 

 (13.8%) was in the pilings (Figure 8). Rates in the grounded and 

 downstream control plots were 6.1% and 5.0% respectively. 



Again, low numbers of recaptured individuals made it 

 difficult to draw conclusions from the mortality rates for 

 individual species. Data from 116 recaptured Amblema plicata 

 (only four marked Amblema plicata were recaptured from the 

 upstream control) showed higher mortality rates in the fleeted 

 plots than in the downstream control with the highest rate 

 (13.5%) from the piling plot (Figure 9). While the bottom was 

 more disturbed in the grounded plot, the piling plot tended to 



32 



