What to Know about Lobster Season. Lobsters are harvested year-round in Maine and New Hampshire, however the majority are caught between late June and late December when the lobsters are the most active. Lobsters are also harvested during the winter and early spring months, but in smaller quantities. Regardless of the time of year, lobster fishing is easily the most active in the Gulf of Maine, which includes the Bay of Fundy and has the highest tidal variations on the planet, as well as cold, nutrient-rich water.