Maine’s seafood harvest topped a half-billion dollars for the first time, as fishermen had the second-largest haul by weight since 1950, according to preliminary 2012 statistics released by the state’s Department of Marine Resources. For the year, fishermen harvested 318 million pounds of fish, shellfish, and other marine species valued at $527.7 million. The value of the harvest shatters the previous one-year best of $456.8 million in 2010, according to the department’s statistics. The 318 million-pound haul is the largest on record since 1950, when the catch topped 356 million pounds. Some fishermen fared particularly well in 2012, most notably fishermen who catch baby eels, known as elvers, whose prices have exceeded $2,000 a pound, but lobster harvesters saw the lowest prices since 1994.