Supplementary Material

Table S1. Parameter values used in the fish track detection function of Echoview.

Fig. S1. Example of target strength frequency response, TS(f), at 45 to 90 kHz obtained from Sarotherodon galilaeus #1. Vertical dashed lines represent the upper and lower limits of the frequencies used for data analyses. Color bar indicates the vertical swim velocities of the fish for each TS(f).

Fig. S2. Examples of the atypical target strength frequency responses, TS(f)s, of Sarotherodon galilaeus #1 with the irregular shapes, i.e., large variations of TS with f that were excluded from the data analyses. Color bar indicates the fish vertical swim velocity for each TS(f).

Fig. S3. Histograms of TS standard deviation calculated for each TS(f) curve and their empirical cumulative distribution function (see Table 1 in the main text for species abbreviations). For each studied fish, the 90th percentile was used as the threshold to exclude the TS(f)s with exceptionally large TS variations.

Fig. S4. Histogram of VSV variance over 5 sec measured from all studied fish. The 95th percentile of the VSV variance (vertical dashed line) was used as the threshold to remove the data with exceptionally large VSV variance.

Fig. S5. Target strength frequency response, TS(f), from various fishes (see Table 1 in the main text for species abbreviations). The data show large variations in TS at each f. Color bar indicates the fish vertical swim velocity for each TS(f).

Fig. S6. Relationships between TS at 70 kHz and fish positions in the cage: (a) fish depth, (b) major axis angle of the fish in the acoustic beam, and (c) minor axis angle. See Table 1 in the main text for species abbreviations. Large empty dots and vertical bars represent the means and 25th–75th percentile ranges of TS at each (a) 0.05 m depth bin and (b,c) 1° angle bin. The relationships between the TS and fish positions did not show distinct patterns.

Fig. S7. Relationships between ΔTS (Eq. 1 in the main text) and vertical swim velocity at different acoustic frequencies for Sg1. Large empty dots and vertical bars represent the means and 25th–75th percentile ranges of ΔTS at each 0.02 m s^-1 bin. The relationships show close similarities in patterns at various frequencies.

© EDP Sciences 2021