Sentence:  But its soon apparent that there are more boats than fish—at least for the moment. We all drift quietly, keeping an eye out for other boats and other nets. <WSD>Corking</WSD> another guy's net is a screaming—bastard offense. 
Meaning of the word marked with <WSD> tags:  To position one's drift net just outside of another person's net, thereby intercepting and catching all the fish that would have gone into that person's net.