Relationships between swimming speed and tailbeat frequency during vertical migrations.

<p>A 202-cm male prickly shark (A), a 461-cm female sixgill shark (B), a 450-cm female sixgill shark (C; no swimming speed data), a 416-cm female sixgill shark (D), a 333-cm male sixgill shark (E; with a counter-weight) and a 440-cm male sixgill shark (F; with a counter-weight). Plots indicate ascent (×) and descent (◯), and colours indicate amplitude of acceleration signal. Lines are estimated by generalized linear models with lowest Akaike information criteria. The models indicate swimming speed increased with increasing tailbeat frequency, and swimming speeds at given tailbeat frequencies were slower during descent (solid lines) than during ascent (broken lines) in all individuals. Boxplots in the graphs show amplitude of acceleration signal during ascent and descent. The bottom and top of the box are the first and third quartiles, and the band inside the box is the median. The end of the whiskers indicate the lowest datum still within 1.5 of the interquartile range of the lower quartile, and the highest datum still within 1.5 of the interquartile range of the upper quartile. The circles indicate outliers. All individuals had significantly higher amplitude during descent than ascent.