New Zealand marine fishing activities create many types of environmental externalities. Legislation requires that the externalities be internalised and fisheries management agencies must choose from a wide range of instruments which are best suited to the task. Selection of best instruments can be aided by following a hierarchical decision process, which first screens the universe of instruments to produce a likely set, then tests that list against implementation criteria to establish the feasible set. Instruments in the feasible set can be evaluated against a range of environmental, Treaty of Waitangi, economic, socio-cultural and management criteria. This approach to selection can be formalised in decision support software to provide a useful tool for fisheries management agencies.