New Standard News reports that Environmentalists Attack Massachusetts Wetlands Bank.  Specifically:

At issue are state-run wetlands mitigation banks, a concept that gives
"mitigation credits" that permit the destruction of otherwise protected
lands in exchange for present or future promises to restore, enhance,
preserve or otherwise improve wetlands elsewhere. Critics argue that
mitigation credits provide financial and regulatory cover for
development projects that harm vital ecosystems and. [sic]

From an economic stand point allowing flexibility in allocation of resources is a good thing.  However, it is difficult for humans to create, nevermind restore, etc. a wetland.  The webs of life are too complex for our modern mind attuned to putting things in little orderly compartments. 

As such, the wetlands we destroy won’t be as good as those  we create.  All in all, "migration credits" sounds like a horrible idea.