Even as this city has evolved into a showplace for locavore restaurants and edgy designers, its working waterfront has remained a point of pride. Across Commercial Street from the gaslight-and-cobblestone retail district, the rough-hewn wharves and piers of Portland Harbor still house bait shops, ship chandleries and other marine businesses. But with the fishing industry in constant decline, a push is on to relax zoning rules in the central waterfront district and allow other businesses on the wharves. A group of wharf owners asked for the change, saying they could no longer afford to care for the aging structures with the rents they get from fishermen and their like. The owners point to bleak statistics: Landings at Portland's seafood auction, for example, dropped to 6.3 million pounds last year from 17 million in 2006. 'We're only trying to find ways to keep these properties generating revenue,' said Charlie Poole, whose family has owned Union Wharf since the 1800s. 'We can't afford to have a lot of space sitting idle as we wait for fishing to come back.' With stringent regulations limiting fleets to ever-smaller regions and catches, the glory days of Maine's fishing industry may never return. The proposal by Poole and other wharf owners, which the Portland City Council may vote on next month, has still stirred an outcry. While other cities -- Boston and Miami, to name two -- long ago surrendered much of their waterfront to developers, allowing hotels, condominiums and office towers to dominate their coastlines, Portland has resisted. Regrets over a condominium project, built on the waterfront in the 1980s, led to the tight zoning that exists today. Under the proposal, up to half of the ground-floor space in buildings along the wharves could be devoted to nonmarine use. Hotels and condominiums would be banned, as they are now, but offices, shops and restaurants could open if the city deemed them compatible with maritime tenants. Portland agreed a few years ago to allow nonmarine businesses on the upper floors of wharf buildings, and there are now some 50 of them in the central waterfront zone. In the biggest such experiment, Pierce Atwood, the state's largest law firm, will move next year to a 19th-century warehouse on the Portland Fish Pier. The plan has been criticized, partly because the warehouse owner is getting a $2.8 million tax break to help pay for renovations before the move. Poole has rented space to an engineering firm, a real estate brokerage and other white-collar tenants since the upper-floor zoning rules were loosened in 2006. They have co-existed well with his marine tenants, he said. The fishermen who still use the wharves were quiet through much of the debate over the past year, but some have organized against the changes recently. They are against a proposal to modestly increase the amount of berthing space set aside for pleasure boats in the waterfront zone. 