© 1996 by The Society for Integrative and Comparative Biology
The Development of Fast-Start Performance in Fishes: Escape Kinematics of the Chinook Salmon (Oncorhynchus tshawytscha)1
Department of Organismal Biology and Anatomy, University of Chicago 1027 E. 57th Street, Chicago, Illinois 60637 and Department of Zoology, Field Museum of Natural History Roosevelt Road at Lakeshore Drive, Chicago, Illinois 60605
C-starts are high acceleration swimming movements critical for predator avoidance by fishes. Since larval fishes are particularly vulnerable to predation, C-start behavior is likely to be especially important during early life history stages. This paper examines the developmental changes in C-start performance with kinematic data on immature chinook salmon (Oncorhynchus tshawytscha) (eleuthroembryo stage, sensu Balon, 1975). The scaling of C-start kinematics of immature fishes differs from that of adults. Adult C-start durations increase with increasing body length while C-start durations of immature fishes decrease (e.g., adult stage 1 duration [sec] = 0.0019.length [L] [cm] $ 0.026 [R2 = 0.77] [Webb, 1978]; eleuthroembryos stage 1 duration [sec] = –0.026L [cm] $ 0.100 [R2 = 0.81]). Distance traveled during stage 2 also differs between adult and immature fishes. Adult distance traveled scales directly with length (distance [cm] = 0.38L1.01 [cm], R2 = 0.96 [Webb, 1978]) while chinook eleuthroembryo distance traveled is positively allometric with length (distance [cm]= 0.37L131 [cm], R2 = 0.83). There are similarities in the development of C-starts and burst swimming. For example, mean velocity scales similarly between the two locomotor modes (For burst swimming: Umean [cm/sec] = 8.1 ± 1.1L [cm] $ 4.89 [R2 = 0.86] [Webb and Corolla, 1981]. For C-start stage 2: Umean [cm/sec] = 10.96L [cm] - 14.09 [R2 = 0.70]). This study demonstrates that C-start escape performance improves during early post-hatching development. Comparisons of immature chinook salmon fast-starts with data on larval burst swimming and on adult C-starts suggest that changes specific to developing fish affect the scaling of kinematic parameters.