SAN FRANCISCO — Anne Pyke was tailgating at Candlestick Park near a large sign that read: “Today’s Theme — Mutual Respect.”

“Wouldn’t that be nice?” said Pyke, a Merced County resident. “But we’ve been coming to games for 30 years and we’re not going to let one weekend ruin it and keep us away.”

In fact, civility and respect did rule during the 49ers preseason game against the Houston Texans.

Although the score was ugly — the Niners lost 30 to 7 — there was no repeat of the ugly fan mayhem that a week earlier had marred the annual 49ers-Raiders showdown.

The combination of a beefed-up, visible police presence and new stadium rules designed to curb alcohol consumption contributed to a subdued atmosphere at the sparsely attended game.

The violence was limited to where it’s supposed to occur — on the field.

San Francisco police said it was a very quiet night. They made only three arrests, including just two drunk-in-public busts. Only 12 people were ejected from the stadium. And nobody ended up in the hospital.

“It’s a beautiful thing,” said Enrique Barreto, of Vallejo, as he watched two police officers ride slowly past on bicycles. “It’s always sad when a few knuckleheads ruin it for the rest of us, so we need them here.”

On Aug. 20, the combustible mix of the Bay Area’s two football tribes in the same stadium had produced a stunning eruption of unruly behavior.

Two people were shot outside the stadium and one other was badly beaten inside a restroom. Cameras captured numerous fistfights in the stands. The game produced twice the usual number of crime-related and medical calls for police and emergency response personnel.

But hours before Saturday’s game, 49er fans were promising this game would be much different.

“That’s because the Raiders aren’t here,” said Skip Green, who was tailgating with Pyke. “It’s not The Battle of the Bay.”

That game was a public-relations disaster not just for the 49ers and Raiders, but also for the image-conscious NFL. That’s why Jeffrey Miller, the league’s chief security officer, was present Saturday and also will be attending Sunday’s game in Oakland between the Raiders and New Orleans.

“A lot of those people weren’t true 49ers fans — and they weren’t true Raiders fans,” Miller said. “They were people who just chose to make this their own crime scene. It was unsettling. But I think the police have put in place an exemplary plan to make this a safe environment going forward.”

In addition to 49ers CEO Jed York’s recommendation to cancel the annual 49ers-Raiders preseason series, officials had vowed a zero-tolerance response. And that was evident Saturday at Candlestick.

While San Francisco police Chief Greg Suhr declined to reveal specific numbers, he said there was a 40 percent increase in officers deployed at the ‘Stick. Uniformed officers could be seen patrolling on foot, bikes, motorcycles and in vehicles. They also manned every stadium entrance alongside an increased number of security personnel hired by the 49ers.

“We’re just trying to set the tone,” said Suhr, who toured the tailgating area, handing out stickers to kids and posing with fans for pictures. “We want people to see us, but not act like an occupying army.”

The 49ers also didn’t open up the parking lot until four hours before the game and cleared out tailgaters at kickoff. DUI checkpoints were set up after the game. Those measures, which will be continued all season, are designed to limit the amount of drinking.

Longtime 49ers fans have told this newspaper that they’ve seen a change in the composition of Candlestick crowds. When Joe Montana and Steve Young were leading the team to Super Bowl victories, spectators were more upscale. That led to national mocking that the 49ers had “wine-and-cheese” fans.

But longtime fans say the new Niners crowd has become younger, more male, and more likely to be intoxicated. Because the team has struggled, season-ticket holders also are more likely to sell their seats on the secondary market — or just give them away in the preseason. That has reduced the “family” atmosphere in the stands.

“It contributes to the idea that you’re not going to be held accountable for your actions because nobody knows you in the stands,” said Christian End, a Xavier University professor who studies fan psychology. “You’re already in a crowd and it makes it that much harder for you to be identified.”

But 49ers spokesman Steve Westland said the team intends to revoke season tickets, when appropriate, to keep the peace.

If a fan kicked out of the game isn’t a season-ticket holder, he said, the team will track down who originally purchased the ticket.

“We want them to know that whoever had their ticket caused a problem,” Westland said. “We want them to be concerned about behavior in their seat.”

The small crowd Saturday was on its best behavior.

“Apples and oranges compared to last weekend,” said Suhr, a 49ers fan. “A football game is supposed to have a certain amount of testosterone. But who in their right mind brings a gun to a football game? That’s just stupid.”

Earlier, Suhr had noticed two men talking — one wearing a 49ers jersey and the other in Raiders’ garb.

“It’s good to see you guys getting along this week,” Suhr joked.

“Hey,” responded one fan, “can’t we all just get along?”

Contact Mark Emmons at 408-920-5745.