Scottish Marine and Freshwater Science Vol 7 No 16

In this report, we review the use of indicators in the assessment and advisory process and management of data limited stocks, both fish and shellfish, worldwide. For the purposes of the review, we define an ‘indicator’ as quantifiable information that acts as a proxy for, or can be related to the state of the stock (spawning stock biomass, demographic properties or recruitment) and anthropogenic pressure (fishing mortality). Measured (or derived) regularly, indicators are able to show changes in the state of the population or system and can give information on stock status and fishing mortality and support a data-limited stock assessment. Used alone or more often in combination, indicators can provide the means to assess progress towards one or more management objectives. We describe the derivation and theoretical basis of a variety of indicators which can be calculated from commercial fishery data, fishery-independent survey data and biological data, and the ways in which indicators are used in fisheries management. We give details on methods for selecting, evaluating and combining indicators, for developing management strategies, determining reference points and for the testing of harvest control rules (HCRs). We then consider examples of shellfish stocks worldwide for which an indicator-based approach has been applied. Finally, we consider candidate indicators for Scottish shellfish stocks and fisheries and discuss their development in the context of existing and potential future data collection programmes.