It lives in cold, clear, rocky areas of the mountain rivers, and feeds on microbes, algae, and small animals like snails.

[7] By May, most eggs will have hatched and the babies stay attached to their mother for a short duration before separating and becoming a free-willed organism P. fortis is nocturnal and remain idle behind cover for the majority of the day.

Chemicals from agriculture have also washed into streams, and groundwater has been pumped to the point of lowering the water table, further decreasing the numbers of P. fortis over the last three decades.

[10] Its decline mimics that of its closest relative, the Pacifastacus nigrescens crayfish, whose similar habitat loss and aggression from invasive species led to its eventual extinction.

Attempts at controlling or extirpating invasive species are very expensive and rarely succeed; reintroducing Pacifastacus fortis to California cost $4.5 million.

[14] This restoration project was completed in collaboration with the Pacific Gas and Electric Company (PG&E), the United States Fish and Wildlife Service, CDFW, and the consulting firm Spring Rivers Ecological Sciences LLC.

[14] Today, the formerly dry portion of Rock Creek flows with around 0.6 miles of cool, clear water: a suitable habitat for the Shasta crayfish.

[6][14] After completing the Rock Creek restoration, scuba divers gathered Shasta crayfish from the bottom of Crystal Lake for relocation.

[14] In the long term, the progress of these crayfish will be monitored closely by the CDFW with the hope that the population can sustainably grow without intervention.