From the ocean to the table, Jim Stavis knows where his fish have been. They are tagged by type, lot, and the boat that dragged them from the sea.

``This is the last of the protein sources where you still deal with the hunters,'' says Stavis, co-owner of North Coast Seafoods, one of the region's largest fish processing and distribution companies. More than 10 million pounds of fish a year move through North Coast's facility on Fargo Street in South Boston.

What Stavis doesn't say is that his company, and the 112 others in Boston that process and distribute fish, are essentially all that remains of the city's once-thriving fishing industry. With the depletion of New England's fish stocks, distribution and, to a lesser extent, processing have supplanted the picture-postcard vocation for which Boston was once renowned.

And new economic pressures - especially the push to develop South Boston's waterfront - have made it a challenge to protect even these remnants.

``These guys basically have established themselves as one of the world's centers for seafood distribution, based on the region's historic role as a fish center,'' says Richard Henderson, planning director for the Massachusetts Port Authority, which owns nearly a third of the land in South Boston's Seaport District, where many of the companies are located. Fishing-related business within Boston accounts for about $600 million of the state's $2.6 billion fishing revenue.

Like his competitors, Stavis is as likely to purchase fish from Singapore or South America as at auction in Gloucester, New Bedford, or Boston. Fish is flown into Logan Airport, processed at North Coast, and trucked or flown to restaurants here and across the country and to supermarkets in the Northeast.

You could say Stavis has saltwater in his veins: His father founded North Coast, his grandfather sold clams. For more than 30 years, the company has been on Fargo Street. Stavis has turned the business high-tech, with an assembly line that weighs, fillets, skins, trims, and packages both fresh and frozen seafood for restaurants and supermarkets.

Now, as the city makes way for a 60-acre, $700 million convention center in South Boston, Stavis is preparing to move his operations to the city-owned Marine Industrial Park in South Boston - which, if city planners have their way, will one day be known as South Boston's fish district.

More than $35 million in public and private investment is being pumped into the park in an effort to make it into a haven for fish-related activities. It's a move designed to counter the economic squeeze planners knew would accompany any development along South Boston's strategically located waterfront. One challenge is how to preserve the Fish Pier, home to about a quarter of South Boston's fish processors and brokers.

But for some fishing folks, the talk of preservation presents a bit of a dilemma. Many of the companies headquartered at the Fish Pier - a cramped, 84-year-old building without air conditioning - would prefer to relocate to larger, more modern spaces.

And other realities - including expected federal Food and Drug Administration regulations imposing stricter handling standards for fish - may run counter to the notion of maintaining the pier as a kind of working museum.

Some have proposed the creation of a nearby fish auction, rescheduled from early morning to a more family-friendly time, so that visitors could pause by the harbor and watch as weathered hands bid for fish, clams, and lobster.

Moreover, plans for hotel and perhaps even residential development present other difficulties. Would hotel guests, luxury condominium owners, and office tenants have much patience for early morning truck traffic, diesel exhaust, and fish detritus?

Many compromises will have to be forged - between commerce and industrial activity, fish handling and shopping. Even those who are gung-ho about transforming the waterfront into a center of commerce and pedestrian bustle aren't sure how things will shake out.

``You can't have luxury housing on the next parcel if you are doing fish processing 24 hours per day,'' says Patrick Moscaritolo, president of the Greater Boston Convention & Visitors Bureau. But ``because we are talking about 1,000 acres, we have the potential to blend the uses so they don't conflict.''

But critics warn that even though planners envision a buffer zone between industrial areas and the residential-commercial neighborhood, balancing those will be a challenge. In the end, says Moscaritolo, ``Not everybody is going to get what they want.''

-- Jennifer Babson