Seasonal movements of American lobsters in southern Gulf of Maine coastal waters: patterns, environmental triggers, and implications for larval release

American lobsters Homarus americanus are known to move offshore during the fall-to-winter transition and inshore, into shallower, warmer water in the spring and summer. To determine whether all types of lobsters in New Hampshire coastal waters exhibit this movement pattern, we fitted 45 lobsters (ovigerous and non-ovigerous females, and males) with ultrasonic transmitters and tracked their movements over 3 successive seasons from 2006 to 2009. The major goals of this study were to determine (1) if ovigerous females express different seasonal movement patterns than males or non-ovigerous females; (2) what environmental cues might trigger offshore movements in the fall; and (3) the location of ovigerous females when their eggs hatch in the spring-summer. Most lobsters (82%) moved >0.5 km, whereas the rest remained close to their original release location. Of the lobsters that moved, 51% moved <5 km, 19% moved 5-10 km, and 30% moved >10 km. There were no significant differences in the seasonal movements of ovigerous females compared with non-ovigerous females, but females as a group moved significantly farther than males. The ovigerous lobsters that moved offshore tended to remain there until the time when their eggs most likely hatched. In conclusion, the seasonal movements of ovigerous lobsters in coastal waters significantly influence the location and timing of larval hatch and, ultimately, settlement.