Technical background to fish stock indicators for state-of-environment reporting in New Zealand

Pressure-state-response environmental indicators are proposed for New Zealand fish stocks. This work was a technical background to the development of a core set of indicators sought by the Ministry for the Environment. It has led, through an extensive programme of consultation, to a set of confirmed indicators. The initial proposals and their basis are described together with their relationship to the confirmed indicators. The proposed indicators could readily be calculated as part of the stock assessments conducted annually by the Ministry of Fisheries and this is recommended. For many stocks, especially minor stocks, only proxies for the preferred indicators would be possible. The proxy indicators would not be useful in all cases, and target or threshold values for them could generally not be calculated. Shortcomings and difficulties in the proposed indicators are described. A state indicator that separates changes induced by fishing from those of a natural origin is described, but it could be obtained for only a few stocks.