Sounds crazy. Are you sure its nothing to do with safety regulations. Because if an accident should happen to a youngster, the club could be held responsible. On the other hand, the club could be seeing it like this, young anglers bring young none anglers to a water who spoil it for other anglers ie noise litter rowdy behavior etc. However if the matter is caused by non friends, outsiders etc then it is upto the clubs bailiffs to sort it, in this case the club could have looked at alternatives ie accomanied by an adult,fishing on not so prized waters only, or even a rule like any angler haveing litter in swim or being a pain in the butt to others etc should be barred from club. Dont think the club would have done it if a problem was not evident. So a minority might have spoilt it for you. best to join a club that caters for young peeps.