Whether you’re trolling for salmon or dropping a line for halibut, the bait of choice is herring. After a much-publicized split between Widespread Panic and lead guitarist George McConnell in August, the band replaced McConnell with versatile gunslinger Jimmy Herring. If Panic’s performance at the Agganis Arena is any indication, the fans are swallowing what the band is dangling – hook, line, and sinker.

Inserting Herring into the mix upgraded a razor-sharp filleting blade to a Swiss Army knife. Waltzing in mid-tour, Herring dispelled any fears that he, the band, or its fans would suffer through the horrors of on-the-job training. His assimilation was nearly perfect, much as it was during his tours of duty with legends like the Allman Brothers, The Dead, and Phil Lesh and Friends. Resisting the temptation to “Be Like Mike,” Herring tore through Panic classics and newer tunes with torrid yet melodic leads, which recalled the tenacity of the late Mike Houser, but never succumbed to slavish imitation.

Panic’s comfort level with their new guitarist was apparent from the onset. Opening with “Tall Boy,” the band took flight immediately. Herring and guest guitarist John Keane toyed with the anthem’s bent-note signature lick and laid down the economic but crackling solo break with authority.

Fan favorite “Space Wrangler” began as usual with John Bells lilting, country-influenced strumming before evolving into full-tilt boogie. This version was bolstered by the edgy percussion of Todd Nance and Sunny Ortiz, who erupted often, especially during the turnarounds. During “Wrangler’s” extensive solo, Dave Schools thundered away and appeared ready to race across the stage and embrace Herring in a bear hug.

Mid-set, Panic offered a slinky “Surprise Valley” and executed the call-and-response segment between the instrumentalists energetically if not flawlessly. The Band’s rocker “Chest Fever” appeared in Panic’s set list for the first time, and Bell confidently howled the lyrics as if he had delivered them a hundred times before. Many have referred to The Band’s repertoire as Americana rock, and Panic made it clear that they are on the same page with their own gritty interpretation. “Pigeons,” the band’s epic about the trials of window washing, closed the set. It might not have been the most adventurous “Pigeons” ever played, but it packed a wallop, with the crowd responding deliriously to Bell’s boisterous commands to “Wake up!”

The buzz generated by the first set didn’t let up as the band opened Set Two with “Chilly Water,” a savage exercise reminiscent of classic rockers from the seventies. Sandwiched within was “Jack,” a ballad that Bell sang with tenderness despite its bizarre deck-of-cards metaphor. Herring and Schools brought the second half of “Water” to a clamorous conclusion with searing leads and a rumbling bottom.

Funk figures as a prominent ingredient in Panic’s gumbo, and “Rebirtha” and “You Should Be Glad” displayed the band’s affection for and knowledge of Sly Stone and James Brown. In between, Bell serenaded the crowd with a heartfelt “Pilgrims,” which JoJo Herman brought home with piquant, downward-spiraling piano mastery.

The second set concluded with the one-two punch of Herman’s driving, cautionary hurricane tale, “Greta,” which segued into the percussion-laden “Fishwater,” another funk workout that pays tribute to the unconquerable spirit of New Orleans. Nance and Ortiz again proved that they are workhorses on skins, bells, and whistles, and that a contrived and anticipated drum solo isn’t necessary to drive home their obvious capabilities.

Panic has never enjoyed the popularity in the Northeast that they do in the Southeast and West, where they often sell out venues in minutes. The Agganis was less than half full, but from the conviction of the band’s performance and the fans’ reaction, one might have thought Panic was performing to a rabid, festival crowd. If a band can deliver under such adverse conditions and mesh with a new guitarist mid-tour, their future as a touring staple appears to be very bright indeed.