A 492-ton sand and gravel carrier collided with a yacht at about 8:15 a.m. Wednesday in waters roughly two kilometres northeast of Hoto Island off Tsukumi, Oita Prefecture, the Oita Coast Guard said. The impact apparently sank the yacht. Rescuers found a 70-year-old man, identified as Oita City physician Makoto Yamamoto, floating unconscious about two hours after the crash. He was pronounced dead at hospital. Authorities have not confirmed how many people were aboard the yacht and continue to search the area with seven patrol vessels and an aircraft. The Coast Guard on Wednesday night arrested the carrier’s captain, 28-year-old Yuki Mochizuki, on suspicion of professional negligent homicide and endangering maritime traffic. Investigators allege the captain failed to stop or take other precautions despite poor visibility at the time of the collision. None of the five crew members on the carrier were injured. The vessel involved, the 64.71-metre Dai 38 Sadamaru, reported the accident immediately after it occurred. The Coast Guard is analysing radar and voyage-data records while interviewing crew members to determine the precise cause of the fatal crash.