Fine-scale movement, activity patterns and home-ranges of European lobster Homarus gammarus

Abstract

Understanding an animal's movement, distribution and activity pattern is vital for effective delivery of evidence-based management; however, such data are sparse for many economically important fishery targets, particularly the European lobster Homarus gammarus. This study aimed to elucidate high-resolution movement and activity patterns of a large cohort (n = 44; carapace length = 65-98 mm) of adult European lobsters, using a passive fine-scale acoustic telemetry VEMCO Positioning System (VPS) off Northumberland (UK). This is the first application of VPS on this species and the first offshore VPS study within the UK, providing novel positional data generated via triangulation based on time difference of arrival of acoustic signals. Individual home-ranges using kernel density and minimum convex polygons showed seasonal variation: 95% utilisation distribution ranged from 244 to 7722 m2 during spring (mean ± SE: 11 104 ± 397 m2), and declined to 237-784 m2 during autumn (mean ± SE: 455 ± 66 m2s.e.). The study also provides evidence of behavioural differences between sexes, with males using more space than females. Daily cumulative step-length and daily minimum convex polygons highlighted that while space-use decreased during the autumn, daily distance moved increased for the majority of lobsters observed, coupled with longer durations of diel activity during autumn. These results suggest that using home-range analyses alone to describe lobster movement may inadequately represent its full behaviour. This study demonstrates the potential for passive acoustic telemetry tracking of otherwise cryptic and difficult to study marine benthic animals.