MUSSELS MARKED AND RECAPTURED 



During June 1984, we collected, marked, and replaced a total 

 of 735 live and 16 dead mussels in the two experimental and two 

 control plots (Table 3) . Data for all mussels marked in 1984 are 

 presented in Appendix C. 



In October 1984, we recaptured 3 of the 16 dead shells and 172 

 of 735 live shells we had marked in June (Table 3). Data for 

 recaptured mussels are presented in Appendix D. We also collected 

 and marked 740 live, previously unmarked shells, so that the total 

 number of live, marked mussels replaced in the study area in 19 84 

 was 1,475 (Appendix C) . Although the recapture percentage for 

 mussels which were alive when marked (23.8%) was higher than that 

 for shells which were dead when marked (18.4%), we feel the sample 

 of dead shells was too small to assert that once a marked mussel 

 dies it is less likely to be found than one which remains alive. 

 We are now marking more dead shells to determine correction factors 

 for mussel mortality. 



Recapture rates for live mussels were relatively high in the 

 piling plot (58.3%) and the downstream control (48.4%) (Figure 3). 

 High recovery rates were due, in part, to intact corrals 

 restricting movements of mussels and facilitating sampling by the 

 diver. Unrecovered mussels may have escaped from enclosures by 

 burrowing or climbing out where siltation had occurred, been moved 

 by currents, or, in the case of mussels placed outside corrals, 

 been missed by the diver. Recovery rates where barges were 



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