Palestinian fishermen say they cannot meet demand in Gaza due to Israel's naval blockade on the territory and limit of six nautical miles (11 km) in which they can take out their boats off shore.
Israel eased the blockade somewhat in 2010 after an Israeli commando raid on a ship in an activist flotilla bent on reaching Gaza left nine Turks dead and raised an international uproar, but Palestinians say the gestures were not enough.
On Monday, Gaza's Coalition Intifada group said about 200 youths boarded fishing boats heading out of Gaza City toward the fishing zone boundary, before returning to shore. Organizers said some boats crossed the six-mile maritime limit.
"We have sent a message of solidarity with the fishermen and a message to the world that they must act to end the Gaza blockade," said Shorouq Mahmoud, the group's spokeswoman.
An Israeli military spokeswoman said none of the boats breached the fishing zone limit. Israeli forces have regularly shot at Gaza boats seen as trying to breach the blockade.
Israel tightened its land blockade on Gaza after the Islamist Hamas seized control of the enclave in 2007.
Want to enjoy 'Zen' reading - with no ads and just the article? Subscribe todaySubscribe now