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Fishery Bulletin 98(2) 



dredge lined with chicken wire were 0.16 (SE=0.02) 

 for model 1, and 0.16 (SE=0.03) for model 2. For the 

 nylon liner, estimates are 0.16 (SE=0.02) for model 

 1, and 0.13 (SE=0.02) for model 2. 



An estimate of absolute abundance 



A stratified random sample of 1412 stations was taken 

 in the Chesapeake Bay during the winter of 1994-1995 

 (Rothschild and Sharov'-). At each station, the stan- 

 dard Virginia crab dredge was towed for 1 minute 

 at 3 knots. The sampling intensity was equal in all 

 three geographic strata. The estimated baywide mean 



Table 3 



Estimates of dredge efficiency ( q ) from depletion experi- 

 ments carried out during the winter 1994-1995, with coef- 

 ficients of determination (r^')and degrees of freedom (df)for 

 the regressions. The jackknife estimates of average q for 

 the entire survey area were 0.18 (SE=0.02) for model 1 and 

 0.14 (SE=-0.03) for model 2. CBL = Chesapeake Bay Labo- 

 ratory; MDNR = Maryland Department of Natural Resour- 

 ces; and VIMS = Virginia Institute of Marine Studies. 



Chicken wire liner used. 

 Nylon mesh liner used. 



number of crabs (CW >15 mm) caught per 1000 m^ 

 swept was y = 8.53 (^=0.07). For age group l-i- (CW 

 >60 mm) the estimate was y = 3.75 (/j=0.08). With the 

 catchability coefficient q= 0.16 and standard error 

 0.01 (from model 1), the absolute abundance estimate 



