ST. PAUL — The Trident Seafoods plant tucked inside this island’s small port is the largest snow crab processor in the nation. On a cold clear day in January, three Trident workers, within the hold of the Seattle-based Pinnacle, grabbed bunches of the shellfish, and placed them in an enormous brailer basket for their brief trip across a dock. The crab were fed into a hopper to be butchered, cooked, brined and frozen. Few of the 360 people who live on St. Paul, largest of the four Pribilof Islands, have opted to work in the plant. Instead jobs are filled with recruits from elsewhere. But the plant still remains a financial underpinning of this Aleut community. Trident pays taxes that help bankroll the expansive services of a city government, which rents apartments, leases construction equipment and even provides plumbers and electricians to make repairs.