Surveys are carried out annually alongside the MIK herring larvae sampling during the first quarter of the International Bottom Trawl Survey (IBTS). Since 2012, sampling has been done using with 20 cm ringnets, called MIKeyM nets, which are attached to the MIK net and used during the IBTS for catching large herring larvae. Sampling is carried out to a maximum depth of 100 metres or 5 metres above the seafloor in shallower waters.
The survey database contains the haul information: position, time, duration, water volume, depth, temperature, and salinity. They are used to describe spawning habitat in terms of environmental parameters.