Uitbreiding bestandsmonitoring IJsselmeer en Markermeer (BO-20-010-100, BO-20-010-064)

The stocks of pikeperch, perch, bream and roach in the lake IJssel and Marker are sampled annually with active fishing gear.

However, this gear is selective for small fish and therefore not suitable to monitor the characteristics of the population structure of these fish species. Larger fish are not caught properly. This means that the regular survey is not sufficient for the development and evaluation of fisheries policy with regard to the stocks of the species roach , bream, pike and perch.

Additional monitoring using gillnets with different mesh sizes is a good supplement to the regular monitoring when it comes to collecting information on the population development. This monitoring also provides information on the share of sized and undersized fish, which is needed for the implementation of the Water Framework Directive (WFD). The 2014 developed yardstick for pikeperch is based on data from the gillnet monitoring IJsselmeer and Markermeer 2014.

The additional information will also be used for the new catch and effort advices for pikeperch, perch, roach and bream.