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

Abstract

Pressure–state–response environmental indicators are proposed for New Zealand fish stocks. This workwas 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.

An overview of recent global experience with recovery plans for depleted marine resources and suggested guidelines for recovery planning

“…It has been suggested (e.g. Gilbert et al, 2000), that indicators other than SRRs, derived more directly from fisheries data may be more robust and of more practical value in rebuilding strategies. For the majority of world fishery resources, this hopefully is the case, since data to construct SRRs are not generally available, and as noted, historical SRRs may be misleading if regime shifts have occurred.…”

Indicators to support an ecosystem approach to fisheries

“…These management actions may be formalized, pre‐determined and pre‐negotiated, as is often the case in single‐species management (e.g. if stock size = x , and fishing mortality = y then total allowable catch = z ) (Gilbert et al. 2000; Sainsbury et al.…”

Current usage of fisheries indicators and reference points, and their potential application to management of fisheries for marine invertebrates

“…Whether generated from models or from experience, Gilbert et al (2000) commented that "all the threshold RPs and conservative TRPs in the literature are likewise arbitrary". This is taken to mean that model-based RPs reflect expert judgement at two levels: (i) that the model is appropriate to the situation and species applied to and (ii) that the indicator value chosen as an RP has some relevance to events in the population, past, present, or future, as judged by experts.…”