OAKLAND - Hundreds of peace activists prevented the unloading of an Israeli ship at the Port of Oakland Sunday by forming a picket line that was considered a threat to longshoremen who could otherwise have worked.

Aleta Ballinger-Dickerson, 9, of Davis is one of the picketers demonstrating in Oakland against the Israeli Gaza blockade. (Photo: John Sebastian Russo / The Chronicle) Organizers said their goal was to delay the ship's unloading for 24 hours in protest of the Israeli military's May 31 open seas raid on a humanitarian aid flotilla that had been bringing goods to Gaza. The raid resulted in the deaths of nine Turkish citizens.

Several hundred people gathered around 5:30 a.m. at berths 57, 58 and 59, which is operated by SSA Terminals. An Israeli Zim Lines ship was expected to arrive in the morning, but though it didn't arrive until the afternoon, the crowd stayed, preventing workers from unloading a ship from China, according to SSA officials.

"Free, free Palestine! Don't cross the picket line!" the crowd's leaders and pickets shouted, blocking the berths' entrances and preventing about 100 longshoremen from walking past.

The longshoremen's union largely cooperated with the picket line. No workers tried to cross it and Clarence Thomas, an executive board member of the International Longshore and Warehouse Union Local 10 said, "We don't want our members getting into fist fights or anything. We don't want police escorting us to work. That's unsafe."

Organizers had informed Oakland police of their plans for the picket, and OPD reported no arrests.

Richard Mead, president of Local 10 said Sunday evening that SSA decided against ordering night shift workers to unload the Israeli ship so employees didn't show up and didn't have to cross any picket lines.

"We can't make them order a crew," said Mead. "It is what is."

The shutdown was a success for protesters who wanted to halt the business of the ship for 24 hours, said organizer Richard Becker.

"We consider this to be a huge victory and a historic moment," he said. "This is the first time this has happened, that an Israeli ship was blocked from unloading in a U.S. port."

Even after protesters heard that the shutdown was successful, around 200 people continued to picket until 7 p.m., about an hour and a half after the ship docked.

The flotilla raid, protesters said, was only the latest injustice to come from Israel's actions toward what it considers hostile neighbors: marchers demanded Israel end its blockade of Gaza and its occupation of the West Bank in Palestine.

"My grandmother's Jewish. I'm not anti-Semitic," said Larkspur resident Frank McClain, who had joined the picket line.

"But what Israel's doing is murdering people. They staged a raid in international waters. If Somalis had done that, they'd be called pirates and we'd have punished and stopped them immediately. Israel does
it and our president calls it 'an unfortunate incident.' Israel is the third rail of politics and no one will touch it because all their funding will get cut off."

With no recourse available from elected officials, McClain said, U.S. citizens concerned with Israel's actions are left with no way to change the situation besides hitting Israeli businesses where it hurts: their bottom line.

Organizers Forrest Schmidt called the event part of "a worldwide campaign to change Israel's behavior by way of boycotts, sanctions and divestment."

The demonstration was ostensibly held in the name of peace, but organizers said they hoped to avoid costing workers a day's pay by convincing an arbiter called to the scene that the line was "a threat to the health and safety" of any longshoreman who tried to cross the picket line.

Under the longshoremen's contract, that judgment could require SSA to pay the scheduled workers, vessel operations manager Randy Laugel said.

However, Laugel added, if the workers were not available for the employer to call on them to work, they might not be paid at all, and at best they can hope for a half-day's wages, a far cry from the full-day's overtime pay they'd have gotten for working a Sunday. Most scheduled longshoremen drove by the SSA berths, saw the picket line and drove away, he said.

"I just think it's sad that 100 or so workers who took the day away from Father's Day to work aren't going to make their money," Laugel said.

Michael Eisenscher, a national coordinator for U.S. Labor Against the War and an organizer of the picket, declined to expressly call the event a threat to workers, but the crowds cheered when the arbiter declared that it was.

"If you see a handful of people like this, and they're angry and making a lot of noise, you draw your own conclusion," Eisenscher said.

Israel has held Gaza under blockade since shortly after Hamas took power there in 2007.

While officials have sworn that Israel will not apologize for the raid, citing videos of one ship's passengers attacking the Israeli troops, in a statement issued Sunday Israel's prime minister outlined some steps the country plans to take to ease the blockade.

Staff writer Elizabeth Nardi contributed to this report