Critically Endangered· population decreasing· assessed 2019

Scalloped hammerhead shark

Sphyrna lewini

Sighting evidence at Niihau, Kauai

Photo: Michaela Carrieres · CC BY-NC-SA

Scalloped hammerheads aggregate in cooler upwelled water off Niihau's western face, gathering in loose schools during the day before dispersing to hunt at night. Their wide-set eyes and hammer-shaped cephalofoil provide a nearly 360-degree visual field and amplify electroreception, making them highly efficient predators of fish and cephalopods. Critically endangered globally due to shark fin trade, their numbers at Niihau are one of the last reliable viewing populations within US waters and reflect the site's exceptional protection status.

Evidence at this site

0 records within 25 km

Confidence: low

No date on file

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.

Scalloped hammerhead shark

Evidence at this site

Also seen at other sites