Every year, uncountable numbers of mussel larvae swim through the coastal waters. If these larvae settle on the seabed, mussel seed banks are created.
However, many of these banks are located in relatively unstable areas. At these locations, the young mussels are eaten by starfish and crabs, are washed away or are suffocated in silt. As a result, these banks can disappear within several months. Some of these banks are located in areas that are relatively stable, for example because they are more protected or fewer starfish are present. Based on the experience of mussel growers, fishery officials and researchers who are involved in monitoring fish stocks, in 2005 a stability map was created with 5 classes, ranging from unstable to stable.
As part of the PRODUS study, the factors were identified that have the greatest effect on the stability of the mussel banks. A focused study was conducted into the role of starfish, and a habitat map was prepared on which the relationships between abiotic conditions – such as flow velocities, salinity and protection – and the survival of mussel banks was used to create a spatial image showing where mussel banks have the best chance of developing. This data, together with other knowledge collected about the development of mussel banks after 2005, will be used to update the stability map. The improved stability map is crucial for mussel seed fishing because in the autumn it takes place specifically on the mussel seed banks at unstable locations.