Body length determines flow refuging for rainbow trout (Oncorhynchus mykiss) behind wing dams.
J Exp Biol
; 227(15)2024 Aug 01.
Article
in En
| MEDLINE
| ID: mdl-39022908
ABSTRACT
Complex hydrodynamics abound in natural streams, yet the selective pressures these impose upon different size classes of fish are not well understood. Attached vortices are produced by relatively large objects that block freestream flow, which fish routinely utilize for flow refuging. To test how flow refuging and the potential harvesting of energy (as seen in Kármán gaiting) vary across size classes in rainbow trout (Oncorhynchus mykiss; fingerling, 8â
cm; parr, 14â
cm; adult, 22â
cm; n=4 per size class), we used a water flume (4100â
l; freestream flow at 65â
cmâ
s-1) and created vortices using 45 deg wing dams of varying size (small, 15â
cm; medium, 31â
cm; large, 48â
cm). We monitored microhabitat selection and swimming kinematics of individual trout and measured the flow field in the wake of wing dams using time-resolved particle image velocimetry (PIV). Trout of each size class preferentially swam in vortices rather than the freestream, but the capacity to flow refuge varied according to the ratio of vortex width to fish length (WVLF). Consistent refuging behavior was exhibited when WVLF≥1.5. All size classes exhibited increased wavelength and Strouhal number and decreased tailbeat frequency within vortices compared with freestream, suggesting that swimming in vortices requires less power output. In 17% of the trials, fish preferentially swam in a manner that suggests energy harvesting from the shear layer. Our results can inform efforts toward riparian restoration and fishway design to improve salmonid conservation.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Swimming
/
Oncorhynchus mykiss
/
Body Size
Limits:
Animals
Language:
En
Journal:
J Exp Biol
Year:
2024
Document type:
Article
Affiliation country:
United States