Underwater Sockeye Compass
Naknek & Brooks River, Alaska, USA · Arctic & Subarctic · ocean_reef
About this place
Investigate Oncorhynchus nerka geomagnetic navigation, olfactory amino-acid imprinting, and gill osmoregulatory remodeling.
For kids: Dive underwater to discover how ocean salmon sniff their exact baby home stream from thousands of miles away!
Underwater Sockeye Compass · 360° Habitat Camp
What to look for
- Clean spawning-redd gravel — Oxygenated hyporheic redd. Locate rounded gravel substrate ventilated by cold hyporheic flow
- Current-shadow resting pocket — Kármán street energy conservation. Centre the slackwater eddy where migrating fish utilize Kármán vortices
- Refractive Snell's window above — Air-water critical angle cone. Scan the bright overhead refraction window watched by holding salmon
Source: Putman et al. (2013), Current Biology & Scholz et al. (1976), Science — Geomagnetic coastal homing & thyroid-driven olfactory imprinting in salmon.
Ask together: What special smell from your own home or kitchen could you recognize with your eyes closed?
Field quiz
Kids' question: How does a salmon find the exact creek where it hatched after swimming across the huge ocean?
- It remembers Earth's magnetic map and the unique smell of its home stream
- It follows painted signs on rocks
- Sea turtles swim ahead to show the way
Answer
It remembers Earth's magnetic map and the unique smell of its home stream
Adults' question: Which dual sensory toolkit guides sockeye salmon from open-ocean gyres into their specific natal tributary?
- Geomagnetic inclination map at sea followed by imprinted stream amino-acid olfaction
- High-frequency biosonar clicks echoed off continental shelves
- Celestial star-pattern memorization above surface waves
- Following thermal Gulf Stream plumes
Answer
Geomagnetic inclination map at sea followed by imprinted stream amino-acid olfaction
360° photo: Khondoker Zobaed, CC BY 4.0
See it live: Live check: Underwater Salmon & Snorkeling Bears
- By day
- Schooling crimson sockeye, rainbow trout, & snorkeling brown bear muzzles! Notice crimson spawning coloration (astaxanthin carotenoids mobilized from muscle into skin) and hooked male kypes.
- By night
- Dark river current & nocturnal upstream salmon pulses The mechanosensory lateral line detects hydrodynamic pressure gradients so salmon hold station in pitch-dark currents.
Other language: Русский