Foraging behaviour and activity of a marine benthivorous fish estimated using tri-axial accelerometer biologgers

Abstract

Fine-scale behaviour such as foraging is difficult to quantify in free-swimming wild fish yet has important basic and applied implications. Here, we used tri-axial accelerometer biologgers to determine accelerometric predictors of bonefish Albula vulpes behaviours (resting, swimming, bursting, coasting, and foraging) in a wetland mesocosm in Eleuthera, The Bahamas. We also used a swim flume to estimate the relationship between acceleration and swimming speed for bonefish (n = 9). In the wetland study, 5 bonefish were tagged externally with accelero - meter loggers and monitored for a 5 d period during which visual behavioural observations were conducted for 4 h. Classification tree models were used to identify accelerometric criteria for bonefish behaviours, and a classification algorithm was applied to estimate behavioural frequen- cies for bonefish in the wetland for the 5 d period. Bonefish spent the majority of time resting (57%), followed by swimming (26%) and coasting (17%), and foraged an average of 11 times h �1 . Bonefish exhibited primarily slow swimming speeds (average 0.18 m s �1 ) while in the wetland, with occasional burst swimming events (14 h �1 ) to maximum swimming speeds ranging from 4.3 to 6.4 m s �1 across individuals. Swimming and foraging behaviours varied among individuals and over the diel cycle. Bonefish generally swam most at dawn and foraged most at night. Tempera- ture and tide were also significant predictors of swimming behaviour, and fish were generally most active at lower temperatures (~24°C) and during ebbing tidal periods despite the fact that the wetland was disconnected from the ocean. The ability to estimate fine-scale behaviours such as foraging and activity levels has important implications for understanding energy dynamics, which is fundamental to the fitness of wild fish.