The effect of size on juvenile green sturgeon (Acipenser medirostris) behavior near water-diversion fish screens

Authors

Jamilynn B. Poletto, University of Nebraska - LincolnFollow
Dennis E. Cocherell, University of California, DavisFollow
Natalie Ho, University of California, Davis
Joseph J. Cech Jr., University of California, DavisFollow
A. Peter Klimley, University of California, DavisFollow
Nann A. Fangue, University of California, DavisFollow

Date of this Version

2018

Citation

Published in Environmental Biology of Fishes 101 (2018), pp 67–77.

doi 10.1007/s10641-017-0681-3

Comments

Copyright © 2017 Springer Science+Business Media B.V. Used by permission.

Abstract

Anthropogenic water management projects and facilities that alter the local and regional hydrology of riverine environments greatly influence the behavior, physiology, and survival of native fishes. To mitigate for losses of native fishes at these structures, many are outfitted with fish-exclusion screens to reduce entrainment. The effect of fish size and age on behavior near fish screens, however, is largely unknown. Therefore, we tested two size classes of juvenile green sturgeon (Acipenser medirostris; small, early juveniles: 9.2 ± 0.2 cm fork length [FL], 6.9 ± 0.3 g; intermediate juveniles: 18.8 ± 0.2 cm FL, 36.9 ± 0.8 g) near fish-exclusion screens in a laboratory swimming flume. Although size was a significant factor influencing the way in which fish contacted the screens (i.e., proportion of body contacts, p = 2.5×10⁻⁹), it did not significantly influence the number of times fish contacted screens or the amount of time fish spent near screens. We also compared the performance of these two size classes to that of older and larger sturgeon that were tested previously (29.6 ± 0.2 cm FL, 147.1 ± 3.1 g), and documented a clear difference in the behavior of the fish that resulted in disparities in how the large fish contacted screens relative to small- or intermediate-sized juveniles (p = 0.005, 5.4 × 10⁻⁴, respectively). Our results further our understanding of how ontogeny affects fish behavior near anthropogenic devices, and are informative for managers seeking to identify the most susceptible size and age class of juvenile green sturgeon to water-diversion structures to potentially develop size-specific conservation strategies.