Carp spawning

hi again guy was wondering if anyone could help me out? Ive been told by more than 1 person on several lakes that the carp do not spawn for 1 reason or the other i have tryed to find out more on the net but it offers no real answer.
1, Do all carp spawn?
2, Does shocking the water cause carp to go infertile?
3, Would carp spawn even in colder waters?
4, any other reasons for lack of spawning?

Any information would be gladly received ty all

Carp reproduction process catch carp during spawning period

ANNEX X - Breeding of Common Carp

http://www.environment-agency.gov.uk/static/documents/Business/manage__eng_171950.pdf

Spawning is dependant on water temperatures. Survival of the fertilized eggs also depends on water temperature. It's entirely possible for carp to never spawn in some waters. It's also entirely possible for carp to successfully spawn in a water but no young fish ever reach any level of maturity due to cold and/or predation. It's relatively unusual to find self sustaining carp populations in the UK. In my part of the world I know of very few waters where carp have bred successfully. Even when they have, it's very unusual for those fish to survive beyond the fry stage without a helping hand. Those waters that have shown signs of successful breeding are invariably relatively shallow waters. If they also have relatively low stock levels and plenty of natural food, so much the better.

thank you very much dude that has answered all of my question and was much appreciated , tight lines