The Israeli Navy opened fire on Sunday at a Palestinian boat off that strayed from a permitted fishing area in the northern Gaza Strip towards Israel, killing one of the three men on board.
The Navy opened fire after the boat ignored verbal warnings and warning shots, the IDF said. The soldiers than reportedly boarded the vessel and attempted to treat one of the fishermen, who was seriously wounded from the gunfire, but he succumbed to his wounds.
Two others were taken into custody for questioning.
The Gaza fishermen's union, however, claimed the boat was targeted as it was making its way back to Gaza, and Nizar Ayyash, the secretary of the Gaza fishermen's syndicate, said in a statement that the men did not violate the maritime limit.
The union and his family named the dead man as 18-year-old Ismail Saleh Abu Reyala. Fishermen called an immediate two-day strike.
Israel maintains a naval blockade on the Gaza Strip, which is dominated by Hamas Islamists. It patrols the waters to stop arms from being smuggled into the enclave and to stop terrorists trying to attack or infiltrate its territory from the sea.
"Israeli forces targeted a Palestinian fishing boat which was on the way back to Gaza shore, which led to the death of one fisherman and wounding two others," the fishermen's union said.
An IDF spokeswoman said a Palestinian vessel with three suspects aboard was shot at after it had deviated from the designated fishing zone in the northern Gaza Strip.
"Naval forces called on the suspects to stop and when they did not comply, warning shots were fired into the air. Upon their continued advancement, shots were fired towards the vessel. Subsequently, one of the suspects was severely injured and he later succumbed to his wounds. The other two suspects were handed to security forces for interrogation," she said.
Fishing is one of the biggest industries in the Gaza Strip, a coastal enclave of almost 2 million inhabitants.
Over the past two years, Israel has detained dozens of Gaza fishermen who have strayed beyond the border, a senior naval commander said.
Boats are not allowed to stray beyond a fixed limit to the north towards Israeli waters, and Egypt keeps similar limitations to the south-west. Israel restricts fishing to a seasonally adjusted zone of between six and nine nautical miles.