Ever since the night 10 years ago, when Oscar Aranda, a biology student out of college, witnessed the gruesome death of a sea turtle killed for its eggs and meat, he has patrolled Puerto Vallarta's beaches as an unofficial keeper of the sea turtle maternity ward.

He later founded a conservation group, La Sociedad Ecológica del Occidente,  dedicated to protecting turtles that nest along Mexico's northwest Pacific beaches.

From June through December — prime nesting season — Aranda and his unpaid volunteers watch over the shorelines where the turtles lay their eggs.

WATCH the video below, or read the story at CNN Heroes…