Sex on the beach: a beloved California fish wriggles ashore to spawn

Grunion run has fascinated scientists and locals for decades, but their future is threatened by the climate crisis

On certain nights on a quiet California beach, thousands of small, silvery fish gather in the moonlight to perform a unique mating ritual.

Known as the grunion run", the spectacle is one of the lesser known natural wonders of the US west coast. Grunion are a rare fish species that come ashore to spawn, and during the months of April to August they cover beaches from Baja California to Santa Barbara like a glittering carpet, wriggling in the sand to lay and fertilize eggs just after the highest tide of a full or new moon.