scubaseason

Grey Reef Shark

Carcharhinus amblyrhynchos

Sighting evidence at Nosy Mitsio, Nosy Be

Grey Reef Shark

Photo: Luis P. B. · CC BY-NC

Grey reef sharks patrol the outer walls and current channels of Nosy Mitsio in numbers that indicate a healthy, lightly fished ecosystem. They communicate threat through a distinctive hunched posture combined with exaggerated lateral swimming — a warning display rarely seen in heavily dived locations where sharks have become habituated. Their role as mesopredators structures the entire reef community below them, and their abundance here is a proxy indicator of overall ecosystem health.

Evidence at this site

No confirmed records on file at this site

Grey Reef Shark is listed as a curated species here based on historical reports.

How is this calculated?

Sighting evidence is compiled from iNaturalist observation records within a set proximity radius, filtered for quality-grade observations. “Last confirmed” is the date of the most recent research-grade record. Record count covers a rolling 24-month window. Confidence reflects record count, recency, and consistency of seasonal signal.

Also seen at other sites