Table 2.
Definitions and formulae for each predictor variable measured through the accelerometer data
| Variable | Formula | Definition |
|---|---|---|
| Static acceleration | Filtered 0.06, 0.6 | 1 s means for static acceleration representing body posture in each axis |
| Dynamic acceleration | Raw (g) – Static (g) | 1 s means for dynamic acceleration representing body movement in each axis |
| Vector of Dynamic Body Acceleration | √Dynamic (X axis)2 + Dynamic (Y axis)2 + Dynamic (Z axis)2 | Square root of the sum of squares of absolute dynamic body acceleration in each axis |
| Cycle | Cycle for the dominant frequency obtained through the continuous wavelet transformation generated spectrogram. Represents the inverse of tail-beat frequencies. | |
| Amplitude | Amplitude for the dominant frequency obtained through the continuous wavelet transformation generated spectrogram. | |
| Pitch | atan(X axis/(sqrt(Z axis*Z axis) + (Y axis)*(Y axis))) *180/pi | Body inclination of the fish [64] during ascending (+) or descending (−) |
| Roll | atan2(Z axis, Y axis)*180/Pi | Spinning movements of an individual around the main axis of the fish [53]. Absolute values for roll were used to alleviate influence of roll direction. |
| Standard deviation | Standard deviation of static and dynamic acceleration, VeDBA, pitch and roll in each axis. | |
| Skewness | A measure of the symmetry of the variable | |
| Kurtosis | A measure of the tail shape of the variable | |
| Minimum | Minimum value of static and dynamic acceleration, VeDBA, pitch and roll in each 1 s increment | |
| Maximum | Maximum value of static and dynamic acceleration, VeDBA, pitch and roll in each 1 s increment |