Elkhorn Slough Elasmobranch Project
Species List: Thornback Ray

Thornback rays are supposedly rare in the Elkhorn Slough, however the PSRF has identified a series of sites that periodically hold large numbers of them. Almost all thornback rays captured in the slough are adult females.

This species is one of the senior extent species of vertebrate on the planet, having remained almost unchanged in hundreds of millions of years; a true living fossil. Literally nothing is known about Thornback ray reproductive, migratory, or food habits in the Elkhorn Slough. Tag and release studies are an excellent tool for studying these obscure and ancient creatures.

• Talent (1985) found thornback rays to be rare in Elkhorn Slough. Only one individual was caught during Talent's study, and this was a mature male. Only two individuals were caught in 17 Elkhorn Slough shark derbies.
• PSRF has recorded 247 thornback rays in Elkhorn Slough in the last two seasons of sampling alone.
• Nothing is known about thornback ray reproductive, migratory, or food habits in the Elkhorn Slough.