The Working Group on the Biology and Life History of Crabs (WGCRAB) is focused on the main exploited crab and lobster species in North-West Europe and North-East America to deliver stocks status and new knowledge on ecology and biology.
In this report, the working group presents the data and results which were available to develop the main methods to produce robust stock diagnostics. The report details where the data are missing and what work needs to be put in place to achieve this. Depending on the country, the administrative rules, resources available to follow the fisheries in place and the data available are different. This has led to different ways to analyse data and produce diagnostics on stocks status. Development of indices with long time-series have been used to follow stocks in some countries. Other countries produce stock diagnostics every three years from specific models us-ing the data recorded during the three year period. The data available by country are variable and it is not standardized in a way to develop the same methodology approaches at a large stock scale. Many fleets targeting crabs are made of small vessels (less 10 meters) where data on activ-ities are scattered without data collection taking place in different national programs. For most countries, the management rules in place provide a way to control ongoing trap fisheries The control of effort and the access of the fisheries are key to manage the main stocks in particular those with quotas.
There have been several studies on biology and ecology of crabs and lobsters but it is considered that more work needs to be performed on growth or migration, for example to establish the im-pact of climate change. Few studies have been focused on diseases but some biomass fluctuations should be studied looking at this aspect. Further work will be oriented to have diagnostics at stock scale when stocks are shared by fleets involving different countries.