SOUTH PORTLAND, Maine — The Casco Bay Bluefin Bonanza is in full swing this week at Port Harbor Marine in South Portland.

When a massive bluefin tuna sold in 2019 for a record-breaking $3.1 million at Tokyo's then brand-new Toyosu fish market, it brought renewed attention to how extraordinarily valuable bluefin is.

The head of a 276-kilogram bluefin tuna that was auctioned for 207 million Japanese yen (about $1.3 million) is carried by a sushi chef at an Onodera sushi restaurant after the first tuna auction ...