Movement patterns of a commercially important, free-ranging marine invertebrate in the vicinity of a bait source

• Published in: Animal Biotelemetry
• Main Authors: Kirsty J. Lees, Aileen C. Mill, Daniel J. Skerritt, Peter A. Robertson, Clare Fitzsimmons
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2018
• Subjects: European lobster; H. gammarus; Fisheries; Acoustic telemetry; Pot-fishing; Bait attraction; Ecology; QH540-549.5; Animal biochemistry; QP501-801; Homarus gammarus
• Online Access: https://doi.org/10.1186/s40317-018-0152-4; https://doaj.org/article/463124a5550c4ac2873e04170caff509

Abstract Background Catch per unit effort is a cost-effective index of abundance and fishing effort, and an integral part of many fisheries stock assessments. Trap fisheries data are often generated using non-standardised methodology and the information to improve the accuracy of estimates is not always available due to current ecological knowledge gaps. Despite its economic importance, the European lobster Homarus gammarus has been relatively understudied compared to the closely related H. americanus. Previous studies investigating behaviour of Homarus spp. in relation to bait sources have been undertaken in aquariums or mesocosms rather than on free-ranging lobsters in the field. This study uses fine-scale acoustic telemetry data, and a null model approach to investigate free-ranging H. gammarus behaviour and movement in relation to baited commercial traps. Results The distribution of lobsters $${\textit{n}} = 11$$ n=11 was largely similar in the presence and absence of traps. The time spent within 20 m of a trap ranged from 3 min to 16 h 55 min ($${\textit{n}} = 27$$ n=27 ), and the distance at which lobsters began approaching a trap varied considerably (5.40 m to 125 m, $${\textit{n}} = 22$$ n=22 ); the mean distances were larger than calculated by previous studies. A fifth of trap approaches resulted in movement against the current indicating a potential olfactory response to a bait plume. A pre-existing non-random association with a trap location may increase the time spent near the trap and reduce the minimum distance between the lobster and the trap. Conclusions This is the first study to assess the movement patterns of free-ranging H. gammarus in relation to a bait source. The larger approach distances in this study were likely due to the unrestricted ranging behaviour of the tagged lobsters. Aquarium and mesocosm studies provide greater experimental control, but may restrict movement and underestimate the area of bait influence. The use of null models to infer movement patterns of free-ranging lobsters ...