General Fisheries Commission for the Mediterranean - GFCM

Experts come together to review the status of the stocks of small pelagic and demersal species in the Mediterranean


More than 80 experts from 15 countries worked together over two weeks to obtain the most up-to-date picture of the status of the stocks in the Mediterranean. In an effort to cope with the restrictions imposed by the current COVID-19 situation, the GFCM Working Groups on Stock Assessment (WGSAs) met for the first time online to review the stock assessments of demersal and small pelagic species in all Mediterranean subregions, covering a total of 24 geographical subareas (GSAs).

The main objective of the annual meetings of the WGSAs is to determine the status of the main commercial stocks in the Mediterranean Sea and to draft scientific advice. These are complemented by benchmark sessions (see box below).

To this end, the WGSAs:

  1. compile basic information provided by countries and experts on the main stocks and fisheries (life history information; catch time series, length frequency distributions, , and age structure of commercial and surveys data, among others.)
  2. run assessment models,
  3. agree upon scientific advice for each stock and include, when possible, the estimation of biological reference points and short-term simulations on the impact of a range of fishing mortality.

This scientific advice represents the technical basis for discussions on potential management measures within the relevant GFCM Subregional Committees (for the western, central and eastern Mediterranean and the Adriatic Sea). The compiled scientific evidence and expert views will be presented to the GFCM Scientific Advisory Committee on Fisheries (June 2021), and, upon their validation, will become the technical basis for the formulation of decisions (recommendations and resolutions) on the management and conservation of fisheries at the GFCM annual session in November.


During the meeting, 20 stocks of small pelagic species were analysed, four of them (anchovy and sardine in GSAs 06 and 07) in greater detail as they passed through the GFCM benchmarking process. Overall, three stocks were considered sustainably exploited (anchovy in GSA 20, anchovy and sardine in GSA 09), 11 overexploited or in overexploitation, two remained uncertain and one was deemed ecologically unbalanced. In addition, 54 stocks of demersal species, including fish, crustaceans and cephalopods, were analysed. Four stocks (red mullet in GSAs 15, 22 and 24 and Norway lobster in GSA 09) were considered sustainably exploited while 50 indicated some level of overexploitation. A number of new assessments were also presented, which enabled to produce preliminary advice (for Atlantic mackerel in GSA 27 and common dolphinfish in the western and central Mediterranean), qualitative advice (for deep-water rose shrimp in GSAs 03 and 04 and black-bellied angler in GSA 17) as well as quantitative advice (for purple dye murex and great Mediterranean scallop in GSA 17 and horned octopus in GSA 18).

The WGSAs proposed to include red mullet and blue and red shrimp in the western Mediterranean in the GFCM list of priority species and suggested performing benchmark assessments over the next intersession for red mullet in the Adriatic Sea (GSAs 17 and 18), deep-water rose shrimp in the Adriatic Sea (GSAs 17 and 18) as well as in the central (GSAs 19, 20) and eastern Mediterranean (GSAs 22, 23) and for mantis shrimp in GSA 17 as well as for anchovy and sardine in GSA 16.

The WGSAs acknowledged the gradual progress from simple deterministic assessment models towards statistical catch-at-age (SCAA) methods in order to make a better use of available data and to quantify uncertainty around model estimates. The groups also noted that significant efforts were being made to address data-limited stocks, with several methods being progressively used, notably in the eastern Mediterranean. The need to objectively assess the performance of the different models and to better specify the life-history characteristics of many stocks was also underlined.

Finally, the WGSAs commended the improvements introduced by the GFCM Secretariat to better coordinate among the different participating institutions and to promote transparency as well as quality control of outcomes produced. This was made possible thanks to the development of new tools to summarise validated stock assessments so that they could be included in relational databases. In particular, a new data system called “GFCM Stock Assessment Results” or “STAR” is being designed and developed by the GFCM Secretariat this year. During the WGSAs meetings, a new STAR template was presented and used to organize and submit the results of each assessment. More information about STAR can be found at


BOX : Benchmarking process and provision of advice on the status of fishery resources

The steadily increasing number of stock assessments performed every year and the urgent need to achieve commonly agreed-upon sustainability goals for Mediterranean and Black Sea stocks call for further assurance of assessment quality while optimizing the time dedicated to each.

In order to address both issues, the forty-second session of the GFCM endorsed a process for benchmarking stock assessments.

A benchmark assessment is defined as a complete analysis and review of all the information and methods currently used to provide advice on the status of a given stock, taking into consideration old and new data sources as well as new or improved assessment models and assumptions. In particular, the benchmark process includes: identifying all issues associated with past and current assessments, including data, assumptions and methodologies; identifying and providing additional data to address these issues; revising and agreeing upon data, assumptions and assessment methods; performing the assessment; estimating reference points; and formulating advice on the status of the stocks.

Benchmark sessions are attended by stock/fishery and stock assessment methodology experts, from relevant areas or GFCM subregions and from outside the GFCM area of application, and include external reviewers. In this way they provide a framework to ensure the quality of the advice produced. Following the benchmark session, all historical data, assumptions and models are fixed for the successive three to four years, while assessments carried out over this time period only provide updates incorporating data from the most recent year(s). Thisrelieves the relevant working groups from the need to perform further analysis.

The schedule of benchmark assessments is agreed upon each year by the Scientific Advisory Committee on Fisheries (SAC) and the Working Group on the Black Sea (WGBS). Benchmarks are carried out separately from the plenary WGSAs and the Subregional Group on Stock Assessment in the Black Sea. This potentially allows for a shorter interval between advice on stock status and management advice, ensuring that, if possible, they are based on the most recent data year.

The increase in coverage and the introduction of benchmarks have revealed a number of shortcomings in the framework for the provision of advice that was endorsed in 2014 and underlined the need to adopt a process enabling to produce advice under different conditions of data availability. In order to tackle this, the forty-third session of the GFCM agreed to launch a process to revise and update this framework in order to include indications on specific advice for the following stocks:

i)             stocks with both quantitative assessments and management strategy evaluations, in which case alternative management measures should be evaluated;

ii)            stocks with quantitative assessments, in which case short-term forecasts should be used; and

iii) stocks with no quantitative assessment, in which case precautionary advice should be provided.