The Israeli military enforces a naval blockade on the Palestinian coastal enclave of Gaza, which is controlled by the militant group Hamas. Israel says the blockade is necessary to prevent weapons smuggling.

Ismail al-Shrafi, 62, a fisherman, said Sunday that he was unable to join his friends who were preparing their boats because the Israelis had confiscated his boat five months ago and taken it to the Israeli port of Ashdod. Mr. Shrafi said that his boat had been fired on and impounded within four nautical miles of Gaza’s coast and that his son, fishing with him, had been injured by the Israeli fire.

Lt. Col. Peter Lerner, a spokesman for the Israeli military, had no comment on the case involving Mr. Shrafi. Colonel Lerner denied that naval forces had fired at boats within the permitted fishing zone. But he said, “Anybody who breaches the limit is stopped or arrested, and those who don’t comply with the navy forces’ calls to turn back — then, yes, their boats can be impounded.”

Over the weekend, the Israeli Navy sank a suspected smuggling boat that was approaching Gaza from Egypt. Naval forces fired warning shots, and the boat’s crew threw “suspicious cargo overboard” and jumped into the sea before the vessel was sunk, the military said.

Under the Oslo peace accords, the fishing zone was supposed to extend to 20 nautical miles, but it has shrunk over the years as Israel has imposed greater restrictions, citing security concerns. In the years before 2006, fishermen could go out 10 to 12 nautical miles, but from 2006 until 2012 the zone was limited to three nautical miles.