Some people strolling past the brick building at the head of Merrill's Wharf in Portland's Old Port probably spot the twenty-foot-tall sign spelling out "Browne Trading" in old-fashioned gilt letters and wonder who exactly Mr. Browne is and what he trades. If they duck into the retail store that takes up half of the lower floor, they might then think that the sign is a bit of overkill, even though the selection of fresh fish and shellfish, wine, caviar, and other specialty food items packed into the high-ceilinged, wooden-floored space is both gorgeous and unusual.What they don't know is that up the stairs behind the fish counter and through the glass door lies a far-ranging seafood empire built by Rod Mitchell and his wife, Cynde, since 1990.

You can get a glimpse of that empire's breadth and reach by standing in the packing room and simply reading the mailing labels on the outgoing boxes. To New York, Las Vegas, Chicago, and Los Angeles are going meticulously packed crates of turbot, halibut, bluefin and yellowfin tuna, swordfish, Arctic char, barramundi, snapper, fresh sardines, Dover sole, divers scallops, Bang Island mussels, Peeky-Toe crab, and Maine lobster. All of this is bound for the kitchens of renowned chefs like Daniel Boulud, Eric Ripert, Thomas Keller, Charlie Trotter, and Jean-Georges Vongerichten, as well as to the restaurants of nearly every grand hotel from Portland, Maine, to Portland, Oregon. Along with the fresh fish, whole sides of smoked salmon, sable, and trout, as well as tins of caviar from around the world will make their way to the mail-order customers and retail stores of Williams-Sonoma, Balducci's, and Dean & DeLuca.

Who is Rod Mitchell? A guy who drives a beat-up pickup with 160,000 miles on it and commutes from Peaks Island in a boat whose bait wells have known a thousand mackerel. In person, with his sun-reddened face, intense blue eyes, windblown hair, and muscled forearms, he looks and speaks like a fisherman, his words leavened with more than a bit of braggadocio. He even moves like one, with that particular rolling gait of someone used to keeping his balance on a rocking boat. When he begins to talk about his youth, you can see from his enthusiasm that the sea put its mark on this one early on in life.

"My Grandfather Browne used to take me fishing as a boy in Cundys Harbor for mackerel and stripers," he says, sitting in the cluttered office looking out over Commercial Street. "He taught me how to fish for flounder, where you dig some clams, crack them open, and then put 'em on the hook and jig 'em." His early resume includes a marine biology degree and summers at the side of a striper guide out of Boothbay Harbor and as a launch tender at the Camden Yacht Club. There, he met the owner of a chain of wine stores, Bruce MacDiarmid, who took him one day to the derelict Highland Mill. "Bruce said, 'I just bought it, and I'd like you to help me rebuild it.' After that, he asked me if I wanted to run the wine store he was putting in." That store was the Winemporium, which Mitchell eventually bought.

Mitchell confesses to knowing, at that point, next to nothing about wine or the fine food trade. A crash course at MacDiarmid's hands followed, and Mitchell also found friends in local chefs like David Grant, then chef-owner of Aubergine, who pushed him to cook and to taste. "He taught me about pairing food and wine," Mitchell says, "and introduced me to his mentor, Jean-Louis Palladin, the chef at the Watergate Hotel in Washington. I had him taste Maine scallops, and he got very excited, telling me 'These are like what I can find in Bordeaux. Find me other things I want to cook with!' This was before diver's scallops were an industry — I had to go out to the divers myself to get what I wanted. Palladin also said, 'You don't have any caviar, you need caviar!' " Thus was planted the seed for what would, a few years and more than a few hard knocks later, become Browne Trading.

While today we take the Food Network for granted, in the early eighties its celebrity chefs were just beginning their climb to fame and fortune. Mitchell courted them, arriving at their restaurants with coolers of fish and caviar and taking them fishing in Maine. It was not all smooth sailing, particularly in the early years, after he'd sold the wine shop and started his first caviar venture in Camden. When he set out to sell the delicacy to other chefs in the Northeast, he was barely thirty and in for a brutal and expensive apprenticeship.

"I remember," Mitchell recalls with a rueful smile, "calling up the Park Plaza Hotel. Roland Czekelius, the chef, told me to bring a sample. I arrive, pull out a seven-ounce tin of my best caviar. [More than five hundred dollars worth, back then.] Roland turns to his sous-chef and says, 'Bring me my caviar spoon.' The guy comes back with a huge serving spoon, almost a ladle." Mitchell shook his head, recounting the tale. "He takes half the tin and puts it in his mouth, then finishes the whole thing! He looks at me. 'Your first lesson,' he says. 'Don't bring more than a two-ounce sample to any chef who loves caviar!' " The second lesson: all chefs love caviar.

The late eighties were particularly difficult and eventful. He'd sold his first caviar company, he was newly married, and his wife was expecting their first child. After considering other opportunities that would have meant leaving Maine, he realized not only that he wanted to stay, but that what made him want to stay was the sea and his connection to it. First he had to fight the restrictive non-compete clause he'd signed, and, with money short, he had to ask his wife to borrow three thousand dollars.

Cynde's response was, "If I lend you the money, I'm not only going to keep the books, I'm going to be CEO and CFO!"

"That was sixteen years ago," Mitchell continues, "and she's still CEO and CFO. I'm just the president." One gets the impression on meeting Cynde, who is tall and lithe and gentle of voice and demeanor, that she is likely the safe harbor in Mitchell's churning sea of enthusiasms and ideas. Her office, a comfortable jumble of family pictures, kids' sports equipment, and unpretentious furniture amid the computers and neat piles of paperwork, seems to belong to someone adept at balancing the demands of home and business, even as the latter has morphed into a multimillion dollar enterprise over the years.

From its original two small rooms, Browne Trading has expanded to take over the entire building. While the upper floors are given over to offices, on the lower there is the retail store as well as a smoke room, a caviar-packing room, a fish-cutting room, and the order-assembly room. In the beginning, however, it wasn't more space Mitchell needed, but more customers, and so he turned to his friends, the chefs. Palladin sent him to Daniel Boulud, then chef of Le Cirque.

"I go down," Mitchell recounts, "my first time in New York City, I wait for an hour. Daniel finally comes in, tastes my scallops. 'Why would you bring me a scallop soaked in sugar?' he asks me. 'They're not sugared!' I tell him. 'They're naturally sweet, from the waters of Maine.' "

"Rod may be a star in Portland, Maine," Boulud says, "but he is actually just as well known and loved amongst chefs in New York and around the country. Purchasing seafood, and caviar in particular, is founded on a relationship of trust, and that's what we come to Rod for, day in and day out." Today, Boulud is his best customer, with Browne Trading producing Boulud's exclusive smoked fish and caviar offerings as well as selling his restaurants thousands of pounds of fresh fish each year.

"We started a revolution," Mitchell says passionately as he walks back to the fish cutting room, "by teaching people, chefs, what the most excellent, pristine, fresh seafood really is." The room, its air redolent with the clean smell of the sea rather than any odor we normally associate with a fish market, is all the way in the back, gray concrete floors dotted with small mountains of ice and clean-scrubbed tables and bright fluorescent lights overhead. Burly guys in rubber overalls and bundled up against the cold — they work, after all, in a refrigerator — are manhandling fifty, one hundred, and five hundred pound pieces of fish with huge gleaming hooks. In the bays against one wall lay headless and tailless carcasses, on the bottom the largest, like a 220-pound swordfish, various lengths of bright red bluefin tuna, and, on the higher shelves, the smaller cod and halibut and many others, each tagged with its origin, weight, and age.

"When you get a scallop," Mitchell says, "it should be moving; the flesh of the halibut should be translucent; a cod, the eyes should still be brown, like the skin." A swordfish loin two feet long and half that in diameter sits on one table, and Mitchell points out the bright red bloodlines that ran through the white flesh like the ink of a Rorschach blot. "The bloodline's gotta be red, red like when you prick your finger, not brown. And look at this." He points to the skin of the fish, which has a distinct, iridescent sheen. "I like to see them glisten like that, the color pigments, then you know it's fresh. Rub it, and it comes off on your finger. Sometimes [the sellers will] scrub them so you can't tell the age."

This insistence on quality makes all the difference to chefs like Rob Evans of Portland's Hugo's restaurant. "I can get a cod from Rod on Tuesday," Evans says, "and someone else on Friday. When I go to use that fish on Saturday, Mitchell's will still be fresher. I think he would have made a great chef in another life."

This is echoed by another chef, Eric Ripert. "I have known Rod for almost twenty years," he says, "and he is essential to what we do at Le Bernardin [in New York]. On top of it, he is a personal friend. What I like about Rod is not just his expertise but that he likes a challenge." Ripert laughs, continuing, "In the winter when the weather is really terrible, I'll ask him to get me something no one else has — and he goes and gets it! Not only does he get it, but the quality is amazing. We also buy his wild Iranian caviars and his Italian farm-raised, which I think is the best farm-raised caviar on the market."

Mitchell's caviar room is a place of spotless stainless steel tabletops, scales accurate to the thousandth of a gram, and tiled walls, from one of which cascades a river of exquisitely designed and printed labels, sparkling like jewels in the otherwise drab room. In the frigid air, two staff in royal blue T-shirts, their hair under ball caps, are packing an order of Italian farm-raised caviar for Zabar's deli counter. They fill each tray with exactly one kilogram (2.2 pounds) and then inject the sealed package with nitrogen gas so the precious eggs, each tray worth about $1,500 at retail, won't come into contact with any oxygen.

While Mitchell sells natural Iranian caviar, he had the prescience five years ago to explore ties with sturgeon farms in Italy, France, Germany, Bulgaria, and the United States. Today, because of an international ban on all trade in endangered beluga and sevruga sturgeon products, the only legal natural caviar is, like Mitchell's, from Iran. It costs, consequently, about $170 an ounce — about two tablespoons. This ban is so stringent that, when Mitchell's caviar arrives in Boston in lead-sealed crates, Customs will send samples off for DNA testing to confirm its species and origin. Between its Iranian sources and exclusive relationships with sturgeon farms and chefs, Browne Trading has become one of the more important caviar wholesalers in America.

Mitchell is always moving, always pushing Browne Trading to grow while keeping its reputation for having the best, the freshest, the most unusual. He seems to be at the top of his game, and not just among the chefs. "Browne Trading is the authority in its industry and backs it up with the highest quality of products," says Sandy Peterson, merchandising director at Williams-Sonoma, who goes on to cite the company's high level of customer service.

Before his death a few years ago, Jean-Louis Palladin, who had become a great friend of Mitchell's, used to tell him, "Whatever you do, be serious about it!"

Take just a few steps into Mitchell's world, listen to his customers, and there can be little doubt that he has taken his friend's words to heart.