Olfaction Contributes to Pelagic Navigation in a Coastal Shark

Area of Science:

• Marine Biology
• Animal Behavior
• Sensory Ecology

Background:

• Pelagic navigation in marine animals, especially cartilaginous fishes, remains poorly understood.
• The ability of animals to navigate vast, visually uniform ocean environments is a significant scientific challenge.

Purpose of the Study:

• To investigate the role of olfaction in the pelagic navigation of leopard sharks (Triakis semifasciata).
• To experimentally determine if scent cues guide sharks toward shore.

Main Methods:

• Leopard sharks were captured, transported offshore, and acoustically tracked.
• One group of sharks had their nares occluded (anosmic), while a control group did not.
• Swimming paths and proximity to shore were analyzed, accounting for ocean currents.

Main Results:

• Control sharks exhibited directed, straighter paths toward shore, ending significantly closer than anosmic sharks.
• Anosmic sharks displayed more tortuous, random-walk-like swimming paths.
• These differences persisted after adjusting for current drift.

Conclusions:

• This study provides the first experimental evidence that olfaction is crucial for pelagic navigation in sharks.
• Chemical gradients in the ocean may function similarly to airborne cues for avian navigation.
• Findings suggest potential for a unified understanding of navigation across aquatic and aerial environments.