50 



Fishery Bulletin 101(1) 



; 20 



No rotation 

 3 year rotation 

 6 year rotation 

 9 year rotation 



160 



140 



120 



100 - 



Figure 5 



(A) Yield-per-recruit and (B) biomass-per- recruit for no rotation (solid line), 3-yr 

 (dotted line), 6-yr (dashed line) and 9-yr (dot-dashed line) pulse rotations of sea 

 scallops as a function of minimum selected shell height /i„,|„. Scallops are assumed 

 to be fully recruited to the fishery at shell height /i,,,,^ + 23 mm. 



results with no incidental fishing mortality (Table 2A). 

 Note that both yields and the value oi F^^.^y^ are reduced 

 if incidental fi.shing mortality exists and that the pen- 

 alty for overfishing without rotation is somewhat higher 

 (about 679f loss in yield-per-recruit for fishing at F=l 

 without rotation compared to 389f without incidental 

 mortality). However, at ^\,,\x• the loss of yield due to inci- 

 dental mortality is about the same for rotational fishing 

 as for steady fishing. 



Discussion 



Rotational fishing can generate increased yield- and bio- 

 mass-per-recruit for sea scallops compared to nonrota- 

 tional fishing. The expected increase in maximum vield- 

 per-recruit is modest (<109; ) for a fixed rotational pattern. 

 The over SO'/f gain in yield-per-recruit obtained from 

 cohorts that reached exploitable size near the time of the 

 closure is partially cancelled by the loss of yield-per-recruit 



