Salmon Upstream Lab: Swim Bioenergetics & Waterfall Leap (2D)

This 2D companion replaces the 3D scene's decorative swimming with a real river-hydraulics and fish-bioenergetics model: flow speed rises in narrower zones exactly as continuity demands, the fish's own swim cost follows the sustained-vs-burst distinction real ichthyologists use, an anaerobic energy reserve genuinely depletes and recovers, and clearing the waterfall is gated by the actual projectile formula v² = 2gh applied to the fish's current, energy-dependent burst capability — so raising the waterfall or throttling the fish's burst speed measurably changes whether the leap succeeds.