For many of Dorchester Avenue's publicans, it's been a rocky decade. Due to a strong economy in Ireland, an increasingly restrictive immigration policy, and the falling value of the American dollar, many of the Irish that once bar-hopped establishments like Tara Pub, Ned Kelly's and Nash's have opted for greener pastures in the old country.

Rising beer and food prices have squeezed bar-owners from the other end, forcing many to face the small businessman's classic decision when times are tough. Cut costs, sell the business or invest in big changes.

Changeover scenarios are playing out all up and down the Avenue. Tara Pub closed and the space became a beauty parlor. Mickey's Place in Fields Corner fell to the wrecking ball, now the site of a new Viet-AID devlopment. Ned Kelly's sold and was refashioned into Dbar. Emerald Isle has closed pending a sprinkler installation, and may not re-open, and now Nash's Pub will shed its Irish décor and take on a new identity as a sports and sushi bar called Van's.

The new identity on the Ave in the past few decades, outside of the bars, has been overwhelmingly Vietnamese. Grocery stores, travel agencies, and restaurants have sprung up like wildfire. But so far, say bartenders, most Vietnamese haven't been drinking much.

"The Vietnamese community here hasn't really been introduced to the Asian bar yet," said new co-owner Karen Diep from behind the bar at Nash's last week. "We're excited, and the neighborhood loves the idea. And there's not too many things they are supportive of."

Diep's parents own the Vietnamese restaurant across the street.

Peter Nash, who sold Nash's to Diep and her husband Mateo Van, sat at the bar under a poster for the Kerry Gaelic Football Club he used to sponsor and talked to Diep about her renovation plans. He said he sold the place so he could focus on other business, and relax a bit, but slower business played a part.

"We'd get the older crowd after work and the young kids at night. I'd have 200 people in here on a Sunday night," Nash said. "Most of them have gone back to Ireland. And there's nobody coming out from Ireland."

Diep will need neighborhood approval for her plans, which include a sushi bar, several small tables and a second floor addition to welcome more diners. The interior, currently full of dark wood and Irish street signs, will be transformed into something brighter and more modern with multiple big screen TVs and a large bank of windows on either side of the building. It doesn't seem that there will be any trace of Nash's pub when the project is completed.

Another spot, the Emerald Isle in Fields Corner, is also on the cusp of change. Members of the Mawn family, which owns the bar, could not be reached for comment, but according to Dan Pokaski of the city's licensing department they were told last week that they had 90 days to either install a sprinkler-system and open the doors, transfer their liquor license, or see it cancelled.

Still, the Irish pub is hardly an endangered species in Dot. A plethora of shamrocks and Guinness taps attest to that. A number of places that are still owned by Irish-Americans are thriving, and some are sprucing up their image.

Thom English the third just put a new look on his dad's old bar on the Ave, and owners of the Harp and Bard and even Peggy O'Neill's indicated they may be doing some work soon. Each of those pubs have been in the same families for decades.

And of course, it would be remiss not to mention the Blarney Stone, which is Irish in name still, and has become something of a premier attraction on the Ave in the Fields Corner area.

The true Irish brogue too can still be heard just about anytime at the Banshee, the Centre Bar or particularly the Twelve Ben's over on Adams Street, even if there is a little less competition for the bartender's attention.

"You go to Canton, at the Irish Cultural Center, you used to get 2,500 or 3,000 for game of football five or six years ago," said Dermot Korragan of Belcoo, sipping Magners Cider amongst a quiet mid-day crowd at The Centre Bar last week. "Now you're lucky to get seven or 800 down there."

Ireland experienced exceptional economic growth starting in 2002, according to The Economist magazine, including the fastest rising residential property prices among the most developed countries in the years leading up to 2006. This spurred construction to a degree that may have overshot demand, and recently the Irish housing market, like the American, has been experiencing a "correction." Already, Irish émigrés, many of whom are in the construction field, are talking about the possibility of new waves of Irish immigrants coming back to Boston, depending on how the two economies play out over time.

"I talked to Ireland yesterday," said Mike Galvin, owner of the Harp and Bard. "Jobs are very scarce in Ireland now. Galway people are driving up to Dublin just to make a paycheck. I'd say there are going to be a lot of Irish here for the summer, either for work or for pleasure."

Galvin's Harp and Bard, the Dbar and others have also managed to appeal to another new crowd in Dorchester: young professionals moving back into the city.

"I've noticed a huge change over the last 10 years," Galvin said. "There's a lot more professional people than blue collar. Now there's 32 different kinds of martinis, purple martinis, chocolate martinis, we make all kinds."

The real key, though, to a long-living, healthy pub seems to be a big family, a good set of heirs, or at least one good son or daughter to hand the bar over to.

Tracy and Caron O'Neill paid their father a discounted price for his 1310 Lounge about 20 years ago, and renamed the place after their mother, Peggy O'Neill. A modest place, the business has been in the family for 43 years, and Tracy O'Neill, for one, seems to retain a real affinity for a true blue-collar bar.

"I've basically known most of these people most of my life," she said, pointing at her clientele from the end of the bar. "Dennis' parents used to come in here when my dad owned the place."

Asked if the next generation is waiting in the wings to take the place over, Tracy O'Neill said she wasn't sure exactly.

"Could be, you never know. I have a bunch of nieces and nephews."