The upcoming sixth season of “Jersey Shore” will be its last. (Ian Spanier Photography/AP)

All good things must end, even “Jersey Shore,” which will fold up shop at the end of its upcoming sixth season, MTV announced Thursday. The show that saved MTV will premiere its sixth and final season Oct. 4.

Unveiled to an unsuspecting public in December 2009, “Jersey Shore” is another of those tragic TV industry stories. The Situation, Snooki and the rest of the gang still had so many neighborhoods to terrorize, and so much binge-drinking, hooking up and emotionally fraught fighting to accomplish.

But some of the stars had become distracted with starring in their own spinoffs. MTV decided to pull the plug before the show’s ratings got any lower and costs got any higher.

The show’s headliners are reportedly making more than $2 million each for the sixth season, which works out to about the same paycheck per episode as the adults on ABC’ s “Modern Family” will get for that show’s upcoming season. The rest of the “Jersey Shore” cast make about what the “Modern Family” kids are slated to make this coming season.

But “Jersey Shore” ratings have slipped noticeably since the heady days at the start of its fourth season when it hit 8.8 million viewers — an MTV record. The network tried to broaden the show, sending the gang to terrorize Florence, Italy, for that fourth season. But the cast clearly hated playing fish out of water, the locals weren’t impressed and viewers began tuning out.

The show’s return to Jersey for Season 5 didn’t help revive the ratings. By that season’s penultimate episode, ratings were back down to first-season levels. “Jersey Shore” continues to be cable’s No. 1-ranked series among 12- to 34-year-olds, but here, too, the ratings have taken a big hit.

Besides, the show’s happy hedonistic days are behind it, what with Mike “The Situation” Sorrentino now living with a sober coach and giving interviews to MTV’s Sway about the “rainy days” he’s had since struggling in rehab with his addiction to “prescription drugs.” And Snooki is now a mom. Where’s the fun in all that?

Thursday’s announcement marks The End of an Era, MTV said modestly.

The news was unveiled Thursday to give fans time to grieve and clear their schedules for a mess of “Jersey Shore” send-off programming, starting almost immediately after the holiday weekend.

On Sept. 6, MTV will celebrate “Jersey Shore” all day long, until it takes a break to telecast the 2012 Video Music Awards. Beginning at 11 a.m., MTV will run a “Jersey Shore” marathon featuring past episodes that should have, but did not, win awards, for Best Bromance and the like. That will be followed by the retrospective show “Gym, Tanning, Look Back” at 6 p.m., in which cast members reminisce like middle-aged folk at their high school reunion.

At 7, the gang will gather — at the VMAs’ pre-show red carpet — for the first live interviews since MTV announced the show was kaput. The network threatened that other things also were in store, including an after-show each week during Season 6, a “scintillating reunion special,” etc.

Although the show will be gone after this coming season, it will live on in spinoffs. “Snooki & JWoww,” which wraps its first season Sept. 13, has already been renewed for a second season. But don’t hold your breath on “The Pauly D Project,” which had a lousy opening.

RNC plunge since 2008

Minus the mystique of Sarah Palin, the Republican National Convention lost about 17 million total viewers Wednesday.

About 20 million people tuned in to the 10 p.m. hour on the second night of the Republican Party confab to hear GOP VP nominee Paul Ryan address the crowd in Tampa.

Four years ago, a whopping 37 million tuned in when then-GOP VP nominee Palin addressed the nation for the first time.

Leading the exodus: CNN viewers.

Four years ago, CNN logged 6.1 million viewers when Palin spoke. This year, 1.3 million tuned in to hear Ryan speak — a 78 percent plunge.

MSNBC’s story isn’t much prettier. On Night 2, the network was down 56 percent from 2008, securing an average of 1.4 million viewers — vs. 3.3 mil in ’08 in the time slot.

Faring far better was Fox News Channel, which clocked 9 million viewers the hour Palin spoke in 2008. FNC averaged 7.7 million viewers Wednesday at 10 — a drop of about 15 percent.

FNC was the runaway ratings leader Wednesday, in prime time and in this key 10 p.m. hour when Ryan spoke. FNC widened its lead over its competitors compared with the first night of the convention.

The broadcast networks were also missing Palin, though maybe not as much as CNN.

ABC, for instance, lost 52 percent of its audience Wednesday night compared with RNC Night 2 in ’08 — averaging 2.9 million viewers vs. the 5.9 million who were curious to see Palin.

ABC did pull in more viewers Wednesday than CBS, which logged 2.6 million. Four years ago, CBS snagged 4.6 million viewers.

NBC finished first among broadcasters, though it trailed FNC by about 3.6 million viewers, which, coincidentally is about how much NBC trailed its own performance on Night 2 of the RNC in ’08.

Once again, the broadcasters covered the confab in that hour only (each network’s coverage ran a few minutes past 11).

The cable-news networks, however, devoted their prime time to convention coverage. FNC averaged 5.9 million viewers, beating the combined audience of MSNBC (1.3 million) and CNN (1.1 million). (Ratings for some networks that covered the convention, including PBS, were not available at press time.)

For previous columns by Lisa de Moraes, go to