the vent will be defrayed by the replacement cost 

 of the laths, resulting in a cost savings. 



Therefore, those fishermen interested in captur- 

 ing only lobsters and, perhaps, minimizing their 

 crab catches, would be encouraged to use rectan- 

 gular vents, while fishermen interested in both 

 lobsters and crabs or solely the latter should 

 employ circular vents. 



ACKNOWLEDGMENTS 



I thank David A. Libby for his assistance in field 

 collections, data compilation, and figure prepara- 

 tion; and Charles Begin, a commercial fisherman, 

 who often at an inconvenience to himself, fur- 

 nished me with invaluable catch information. 



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