Khader Bakr, a 19-year-old fisherman, was thrilled to hear that he could now fish up to six nautical miles from the coast, up from the three-mile limit Israel had had in place since 2009. The change was part of the cease-fire deal that halted last month’s fighting in Gaza between Israel and Hamas.

But testing the waters late last month, Mr. Bakr apparently sailed out too far. An Israeli gunboat patrolling against arms smuggling ordered him to stop and strip to his underwear. As the Israelis sank his boat, he jumped into the sea and was hauled aboard the Israeli vessel for questioning.

“I spent four hours trembling, he said, before the Israelis ordered another Palestinian fishing boat to ferry Mr. Bakr back to shore.

Run-ins with Israeli patrols are still the bane of Gaza fishermen. But in most respects, the new arrangement has been a boon.

The fishermen have raced to take advantage of broader fishing grounds, farther from the shore where sewage is pumped into the water untreated.

Catches have improved in quantity, quality and freshness, and thus price. The fish are bigger and include desirable species like grouper, red mullet and Mediterranean sea bass that were no longer present closer to land.

But the fishermen risk rapidly overfishing. “In the first few days, I caught fish worth $1,580 to $1,850, said Yasser Abu al-Sadeq. “Today, I made around $1,050. But the situation is still better, he said. “Before the cease-fire, I would barely catch $790.

“It’s like when you come to a house that’s been abandoned for years and start cleaning it, he said. “When you start cleaning, you get out a lot of trash, but when you clean daily, you get out only a little.

He and his crew go out for 24 hours at a time, he said, cooking the small crabs and squid they catch in the nets.

He described an early trip out past the six-mile limit, when an Israeli gunboat circled his boat, shaking it in the wake, and ordered him back toward shore.

He remembers a golden time, before the second Palestinian intifada in 2000, when he could go out as far as 12 nautical miles, where he could find sardines and what he called guitarfish, a small ray. “There, it’s a reserve protected by God, he said.

The fishermen say they estimate their distance, since most of them lack precise navigational systems, but there is usually one indicator.

“When we were allowed within 3 miles, the gunboats would attack us at 2.5 miles, said Monzer Abu Amira, as he repaired his green nylon nets. “Today, they hit us when we are at 5.5 miles.

The Israelis generally use loudspeakers and water cannons, but sometimes they shoot live ammunition at fishing gear, the motor or the boat itself. Gazans in principle can apply for compensation if boats are damaged or destroyed, but in practice few do.

A senior Israeli official said that there had never been an official announcement that the fishing limit had been extended to six miles from three, but he confirmed that six was the new reality. Israel is continuing to negotiate indirectly with Hamas, the Islamist movement that rules Gaza, with Egypt as an intermediary, to turn the cease-fire agreement into something more permanent, the official said.

“We have an interest in prolonging the longevity of the quiet, the official said. “We understand that relaxation of some of the restrictions is conducive to that goal. Quiet is in our interest. So we have an interest in showing flexibility where we can, and to show the Egyptians that we’re serious.

There were problems immediately after the cease-fire, the Israeli official said, because “some in Gaza were interested in testing the limits and pushing the envelope, and because the expansion of the fishing zone meant deploying more Israeli resources to cover more sea.

“But if people don’t exceed the six-mile limit, it’s O.K., he said.

The Israelis are not interested in the smuggling of “Kalashnikovs and bullets, he added, but in preventing Iran from resupplying longer-range missiles and preventing Hamas from smuggling in foreign experts to aid them in missile development and technology. “The important thing for us is to prevent Hamas from rearming, he said.

2012 The New York Times Company