The overall number of listeners between 20 and 44 was down by 30,000.
In the past few months alone, there has been an overall loss of 15,000 listeners to Irish radio.
"What this shows is that we are losing a lot of younger radio listeners through emigration" one source said.
"This does not affect RTE Radio One as much, as its audience is mainly over-40s."
The latest JNLR (Joint National Listenership Research) figures show that Late Late Show presenter Ryan Tubridy (39) has seen his numbers fall to 160,000, from 175,000 in October, for his 2fm show.
This is a drop of 45pc on the 296,000 listeners he inherited from Gerry Ryan in August 2010.
Tubridy is one of a number of morning show hosts to suffer a drop in listeners since October.
Fellow 2fm presenter Hector O hEochagain (43) has lost 14,000, while Today FM's early birds Ian Dempsey (52) and Ray D'Arcy (48) dropped 14,000 and 6,000 respectively. But it means both D'Arcy and Dempsey are still outstripping Ryan Tubridy in the early-morning stakes, with the Ray D'Arcy show pulling in 243,000 listeners and the Ian Dempsey Breakfast show getting 175,000.
Meanwhile, Tom Dunne (52) saw his morning show attract 2,000 more listeners, to 53,000.
Despite their drop in numbers since October, D'Arcy and Dempsey have enjoyed an overall yearly increase of 9,000 and 4,000 each on their Today FM shows.
RTE One's John Murray was among the biggest winners in the listenership survey.
His weekday morning mix of entertainment, human interest and lifestyle issues attracted 5,000 more listeners in the latest poll.
He believes a desire for 'escapism' from grim economic and national news is one of the key reasons for the increase in listeners to his show.
"With so much discussion about our financial plight, there is definitely an appetite for something that is not hard news," he said.
"We try to give them entertainment and thought-provoking stories."
The figures show Today FM is the only national radio station to enjoy an increase in daily listenership over the past year.