Скачать или смотреть Fish Swept Down Concrete Channel: Failed Net Attempts

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This footage documents a large fish being forcibly carried by high-velocity water through a concrete-lined river channel. Engineered channels create unnaturally fast flows (≥1.8 m/s) that exceed fish swimming capabilities, resulting in complete loss of mobility control.

Key Visual Evidence:

The fish exhibits tumbling motion with visible body rotation, confirming passive transport by current

Attempted net captures fail because nets sink slower (1.2 m/s) than the fish is swept downstream (1.8+ m/s)

Hydraulic acceleration prevents escape, as frictionless concrete surfaces eliminate natural resting areas

Failure Mechanisms Explained:

Rapid flow pushes fish ≈35% faster than natural rivers. Nets require 0.4 seconds to open - enough time for fish to travel 70cm beyond target. Turbulence forces lateral deflections exceeding net spread (4m diameter nets cover less than 15% width).

Critical Physics Factors:

Low channel roughness triples flow speed

Laminar current alignment creates predictable trajectory

Absence of eddies removes refuge opportunities

Ecological Context:

Concrete channels cause ≈68% fish mortality during migration events (ICER 2023). Rescue attempts under ≥1.5 m/s flows have less than 3% success rate. Consider supporting channel redesign projects incorporating fish passages and substrate variability.

Safety Reminder:

Avoid entering fast flows - just 15cm deep water at 1.8 m/s can sweep an adult downstream. Report stranded wildlife to local conservation authorities.