Fish are a problem. More accurately, fish that aren't there are a problem. So as the number of fish that weren't near Iceland increased, the nation redefined “near Iceland”. Unfortunately, Great Britain was trying to fish in areas not “near Iceland”, and, as more territory became “near Iceland”, there were fewer fish not “near Iceland”. Because of this, the Royal Navy came to blows with the Icelandic Coast Guard in 1958, 1972-1973, and 1975-1976. The two navies rammed each other, cut fishing nets, etc. Note that Iceland and Great Britain were both part of NATO.
The result was that British fishing was restricted “near Iceland”, because apparently Iceland won all three wars.