Home range dynamics of the American lobster, Homarus americanus

A fixed array ultrasonic telemetry system was used to track the fine scale movements of American lobsters, Homarus americanus, within a large enclosure (mesocosm, 3125 m2). Positions of lobsters were obtained continuously, at 5 min intervals, for an average of 4.1 days. A kernel method was used to estimate the daily home ranges (95% utilization distribution, UD), core areas of activity (50% UD) and distance traveled by each lobster. The mean home range size for all lobsters was 760.1 ± 132.0 m2 (n = 32), and the average core area was 74.0 ± 10.9 m2. Home range size was closely correlated with the daily distance traveled by lobsters (523.2 ± 78.1 m day−1; r 2 = 0.62, p = 0.0001). Within the size range of lobsters used in this study (62–93 mm carapace length), there was no correlation between the lobster sizes and the areas of their home ranges. Lobsters changed core areas and home ranges often, occupying 1.4 ± 0.1 different core areas each day. However, despite changing their core areas, the size of their home ranges remained fairly consistent from one day to the next. These data illustrate both the residential and the nomadic nature of lobster movements and demonstrate the utility of fixed array ultrasonic telemetry for quantifying the fine-scale movements of lobsters

Daily patterns of locomotion expressed by American lobsters (Homarus americanus) in their natural habitat

The local movements and activity patterns of American lobsters, Homarus americanus, were monitored inside a 50 m by 50 m underwater enclosure (mesocosm) using ultrasonic telemetry. Forty-four lobsters of both sexes, ranging in size from 62 to 93 mm in carapace length, were continuously tracked for 2-10 days in 2002 and 2003. As a population, the movement rate of lobsters depended on time of day, as defined by dawn, day, dusk or night. Lobster movement rates were significantly higher during night and dawn than day and dusk hours. Movement rates did not differ by lobster sex, size or between years of the study. The effect of time of day differed between lobsters, and there was considerable variability in the time of day when individual lobsters were most active. Thirty lobsters moved significantly more during the night, five moved significantly more during the day, and nine did not move significantly more during the day or night. Therefore, while there was a general tendency for lobsters in this study to be more active at night, certain factors in their natural habitat modulated this nocturnal bias, which led to a tremendous amount of variability in their daily patterns of behavior

Daily patterns of locomotion expressed by American lobsters (Homarus americanus) in their natural habitat

The local movements and activity patterns of American lobsters, Homarus americanus, were monitored inside a 50 m by 50 m underwater enclosure (mesocosm) using ultrasonic telemetry. Forty-four lobsters of both sexes, ranging in size from 62 to 93 mm in carapace length, were continuously tracked for 2-10 days in 2002 and 2003. As a population, the movement rate of lobsters depended on time of day, as defined by dawn, day, dusk or night. Lobster movement rates were significantly higher during night and dawn than day and dusk hours. Movement rates did not differ by lobster sex, size or between years of the study. The effect of time of day differed between lobsters, and there was considerable variability in the time of day when individual lobsters were most active. Thirty lobsters moved significantly more during the night, five moved significantly more during the day, and nine did not move significantly more during the day or night. Therefore, while there was a general tendency for lobsters in this study to be more active at night, certain factors in their natural habitat modulated this nocturnal bias, which led to a tremendous amount of variability in their daily patterns of behavior