Teaching fish new tricks: Repeated exposure to a velocity barrier improves passage performance

  • 0School of Science, Environmental Research Institute, The University of Waikato, Hamilton, New Zealand.

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Summary

This summary is machine-generated.

Repeated exposure improved fish passage through high-speed water, suggesting learning enhances fish migration over barriers. Fish passage success increased significantly with daily practice over five days.

Area Of Science

  • Ecology
  • Animal Behavior
  • Fish Biology

Background

  • Instream structures like culverts and dams disrupt fish migration.
  • Fish passage success may depend on cognitive abilities and learning.
  • Understanding these factors is crucial for effective fish passage solutions.

Purpose Of The Study

  • To investigate the impact of repeated exposure on the passage performance of juvenile Galaxias maculatus.
  • To determine if learning and cognition enhance fish ability to overcome velocity barriers.

Main Methods

  • Juvenile Galaxias maculatus were exposed to a high-speed raceway (0.45-0.5 m s-1) daily for five consecutive days.
  • Passage performance, approach rates, and entry rates were recorded each day.
  • Time-to-event analysis was used to assess changes in passage speed.

Main Results

  • The proportion of fish successfully passing the barrier increased significantly from 40% on Day 1 to 63% on Day 5.
  • Fish passed the barrier significantly faster by Day 5 compared to Day 1.
  • Repeated exposure did not improve approach or entry rates; fish length affected approach rates only.

Conclusions

  • Cognition and spatial memory likely improve passage performance through velocity barriers.
  • Learning enhances fish ability to traverse challenging aquatic environments.
  • Attraction flows may also be critical for successful fish passage outcomes.