D3 Monitoring & assessment

Specifications and standardised methods for monitoring and assessment

The Joint Research Centre of the European Commission (JRC) with the contribution of experts from Member States, Regional Seas Conventions and ICES, and following consultation of the Working Group on Good Environmental Status, have published the:
Evaluate the stock status against the three GES criteria mentioned in EC Decision
i. Criterion 3.1 - Level of pressure of the fishing activity
Criterion 3.1 relates to fishing pressure and states that "achieving or maintaining good environmental status requires that fishing mortality rates (F) are equal to or lower than those that produce MSY (FMSY)".
  • For most of the so-called data-rich stocks, for which quantitative estimates of exploitation rates relative to FMSY (or a proxy) are available; the assessment of Descriptor 3 should be carried out using the primary indicator for the level of pressure of the fishing activity (3.1.1). A stock can be classified as fulfilling Criterion 3.1 (i.e. "green status") if fished at or below the FMSY reference.

  • Data-limited stocks (Categories 2-5), generally lack assessment of fishing mortality and estimates of FMSY reference points. Nevertheless, where qualitative assessments have been conducted, these results should be used. For DLS stocks the catch/biomass ratio (secondary indicator 3.1.2), should be used for the assessment of stock status (in terms of exploitation rate) under Criterion 3.1. For those stocks for which time-series of survey data or standardized commercial cpue are considered a reliable index of stock biomass, the secondary indicator can be used. While this is only indicative of trends, further exploration would be required to determine how appropriate reference levels should be set. For the time being, it is possible to provide an indication of partial fulfilment of Criterion
ii. Criterion 3.2 - Reproductive capacity of the stock
Criterion 3.2 relates to the reproductive capacity of the stock and the EC Decision (EU, 2010) states that "any observed SSB value equal to or greater than the SSB that produces MSY (SSBMSY) is considered to meet this criterion".
  • For most data-rich stocks, assessed with analytical methods, information on the lower bound of SSB fluctuations around BMSY, e.g. MSY biomass trigger (Btrigger) for ICES stocks, is available to be used as a reference level for Criterion 3.2. ICES considers a stock fulfils the criterion ("green status") if SSB is above the MSY Btrigger. Bpa has, for the time being, been adopted for many of the stocks assessed by ICES as MSY Btrigger, even though Bpa and MSY Btrigger correspond to different concepts. The MSY Btrigger marks the lowest boundary associated with SSBMSY, and in practice this is set as the border of safe biological limits (Bpa).

  • For data-limited stocks (Categories 2-6), quantitative data on SSB in relation to reference points are not available. For some of the stocks in these categories, ICES does however use trends in data and/or expert judgement to provide a qualitative estimation of biomass against reference points. This should be used where available. It is possible to provide an indication of partial fulfilment of the Criterion 3.2 by assessing stocks using short-term trends with respect to long-term historical development.
ii. Criterion 3.3 - Population age and size distribution
Relies on the concept of a healthy size/age structure of the stocks, and it is not essential to assess the exploitation status of resources in terms of pressure (F) and status (SSB). However, it provides the ability to track biological improvements in stock development, although possibly with a time delay, as MSY-based management is achieved, and has also utility where stock status and exploitation rate information are unavailable.

There isn't yet an agreement about a valid indicator across stocks and functional groups and no reference levels agreed. Therefore, no assessment with respect to Criterion 3.3 has been considered.