Danny Wren, 63, was last seen wearing a red shirt with no lifejacket.
Around 11:15 p.m., Sector Houston-Galveston watchstanders were alerted about a missing boater near Middle Deer Island who had lost control of his 16-foot skiff while trying to get to his brother, who was wade fishing at the time.
Wren's brother saw him clinging to the side of the skiff, but because all of their communication devices were on the adrift vessel, the brother couldn't contact authorities until a good Samaritan vessel arrived.
Anyone with information is asked to contact the Sector Houston-Galveston command center at 281-464-4854.