If you buy back a licence covering 250 traps, but keep using 200, that is a reduction of 50 traps. If you buy a licence for 250 traps, but you only want to use 200 of them, there are now 50 fewer traps. It is a way of reducing the fishing effort. But if a fisherman buys a licence and uses the same amount of traps, nothing changes in terms of fishing effort, but the boat will make more money because his catch will be greater.
On March 12th, 2009. See this statement in context.