The vessel activated an EPIRB (Emergency Position Indicating Radio Beacon) alert on 10.30 pm Saturday.
Dunmore East RNLI and Kilmore RNLI lifeboats responded and arrived on scene a short time later.
One fisherman was subsequently recovered by the US Coast Guard helicopter Rescue 117 but was pronounced deceased later.
The search for the other missing fisherman continued throughout the night.
Fethard RNLI joined the search next morning. As the search progressed through the day an Irish Naval vessel and over 20 local trawlers joined the search.
It was a long night for all involved in the search, our volunteers endured difficult conditions during the night and all day today. Our hearts go out to the families of the two fishermen at this sad time,
...Tony Kelly, Dunmore East RNLI Deputy Launching Authority said.
The search is ongoing for the missing fisherman.