Billy Joel - The Downeaster "Alexa" Lyrics Meaning
More specifically, this song is about the decline of the fishing trade on Long Island, New York, where Billy Joel grew up.
A downeater is a type of boat, for anyone who didn't grasp that.
Fishing was always a big business on Long Island, but a host of problems have made it almost impossible for many fishermen there to make a living today.
First, much of the ocean around Long Island is heavily polluted, which means that many fish caught there cannot be sold legally. When Billy sings "they told me I can't sell no stripers," he means that, due to pollution, the government has banned the sale of striped bass caught off Long Island.
Second, the rise of suburbia has driven up the price of housing on Long Island. Working class people, increasingly, can't afford to own homes in the towns where their families have lived for generations. The captain in this song had to sell his house, to keep up payments on his boat.
The captain is proud of his job and vows to keep fishing as long as he can... but he sees that the fishing business may be doomed, in the long run.
Incidentally, Billy Joel's daughter's name is Alexa. Since many real-life fishermen name their boats after their wives or daughters, it makes sense that Billy's fictional fisherman would give his boat that name.