When did world records start? In athletics, I would imagine that they started with the inaugural Olympic Games.
Referring back to my post about fishing, I have a book in front of me entitled "The Domesday Book of Mammoth Pike" in which the author, Fred Buller (long since deceased - this book dates from 1979) compiled a list of reports of very large pike caught through the ages and rates them according to size and credibility. The fish he rates as probably the World Record pike dates from 11th May 1862 and its credibility is based on a letter to the local paper (he reproduces the letter). The pike was allegedly 90lb 8oz in weight and was 5' 8" in length and caught in Lough Derg. No-one was talking about records of any kind, presumably because it have never occurred to anyone to record such things.
I have cycled alongside Lough Derg and it is a monstrous lake, with the Shannon flowing through it.