The fact is that there is still a week to go before the start of the coarse fishing season, but there will always be some over-keen enthusiasts who insist on starting a few days early in order to get an advantage over the fat ones with a misguided sense of their own safety.
Both the Queen Mother and Wraysbury Reservoirs are well known for harbouring immense and valuable perch and bream that have spent the winter swimming quite near the surface, gathering all sorts of information on local aircraft movements. As such they represent a very desirable catch, and "foreign" elements will go to great lengths to bring these in before the general public can get near them.
The MAF flights therefore focus on these particular reservoirs at this time of year, and are demonstrably successful in keeping enemies away. Whilst there have obviously been interceptions in the past that have been kept secret on the grounds of national security, it is common knowledge that no Russian Trawlers have been spotted on either stretch of water now for several years, showing the huge deterrent effect of these surveillance flights.