Simultaneous observation of intermittent locomotion of multiple fish by fine-scale spatiotemporal three-dimensional positioning

Abstract

Recent advances in biotelemetry techniques, especially positioning methods, have revealed the detailed behaviour and movement of aquatic organisms. Behavioural intermittence in animal locomotion, such as the Lévy walk, is a popular topic in the field of movement ecology. Previous attempts to describe intermittent locomotion quantitatively have been constrained by the spatial and temporal resolution possible with conventional biotelemetry systems. This study developed a fine-scale spatiotemporal three-dimensional positioning method using a new biotelemetry system with a positional precision of <10 cm and positioning interval of <10 s. Using this proposed positioning method, the intermittent stop-and-go locomotion of Siebold’s wrasses (Pseudolabrus sieboldi) was observed during travel from an unsuitable to a suitable location following displacement. The fish displayed behavioural intermittence in relocating to a suitable location. Initially, their movement halted for reorientation, after which they moved intermittently yet in a straight line to the suitable location. To test the positioning ability of the proposed method, data sets were resampled at intervals of 5, 10, 30, 60, and 300 s. Longer sampling intervals failed to identify reorientations and underestimated the number of stops, distance travelled, and speed. Overall, the results highlighted the adequacy and ability of the proposed positioning method to observe the intermittent locomotion of fish, such as stop-and-go behaviour, in a natural environment.

Challenge of monitoring cohesive movement in homing fish using fine-scale 3D positioning

“…The horizontal and vertical components of the 3dimensional (3D) positions of the rockfish were obtained separately. Horizontal positions were calculated by hyperbolic positioning based on TDOA among 3 or more receivers (Takagi et al 2018). Vertical positions (swimming depths) were determined using a pressure sensor in the transmitters.…”

“…The Gold codes used in the transmitter signals were one of the pseudo-noise codes in a pair of M-sequences with low cross-correlation among codes (Gold 1967). The positional precision of the biotelemetry system used was < 0.1 m (Takagi et al 2018). For positioning, the algorithm outputs a position localised using 3 receivers judged to be the nearest to the position of a sound source (i.e.…”

“…1). We set shorter distance be tween the receivers (25.6 m on average; range: 15.1-30.5 m) than that of Takagi et al (2018) (~75 m) to enable signal detection by 3 or more receivers.…”

“…Guzzo et al 2018, Leclercq et al 2018, which is not possible with conventional biotelemetry systems. Previously, we also developed a fine-scale simultaneous positioning method for multiple individuals that locates several fish in 3 dimensions at intervals of <10 s with a precision of < 0.1 m (Takagi et al 2018). This positioning method allows us to monitor the entire route travelled by multiple fish during short-range homing.…”

A simple intuitive method for seeking intersections of hyperbolas for acoustic positioning biotelemetry

“…The exact positions of animals can be estimated using the time-difference-of-arrival (TDOA) method with a precision of approximately <10 m [8][9][10]. Several biotelemetry systems have recently achieved the localisation of animals with finer resolutions of approximately <1 m [11][12][13].…”