Pelagic Red Crabs Enter Monterey Bay (2015-18, 1982-83, 1969, & 1959)

Thousands of pelagic red crabs (Pleuroncodes planipes) cover Coral Street Beach in Pacific Grove, CA on October 7, 2015 — Thousands of pelagic red crabs (*Pleuroncodes planipe*s) cover Coral Street Beach in Pacific Grove, CA on October 7, 2015

FACTS

In 1859 pelagic red crabs were first discovered after a large stranding in Monterey Bay.
Warm currents generated during ENSO events carried pelagic red crabs to Monterey Bay in 1959, 1969, 1982-1983, and 2015-2017.
Pelagic red crabs normally live off the coast of Baja California, Mexico.
Pelagic red crabs are an attractive food to species that include migratory fishes, tuna, giant squid, turtles, pinnipeds, seabirds, and whales.
A 2021 publication indicates the crabs are carried northward during anomalous currents. See article from UCSC here, and the paper itself here.

Most recent sightings:

November 15, 2018 at Lover’s Point, Pacific Grove, CA. See Monterey Herald article and embedded video.

March 8, 2017 at Lover’s Point, Pacific Grove, CA. Monterey Herald Article (3/9/17)

Esther Vanderhorst tries to avoid stepping on pelagic red crabs that are still alive while crossing a large pile of them after kayaking with her husband, Phil, at Lovers Point Beach in Pacific Grove on Thursday. Pelagic red crabs washed ashore on 3/8/17. Photo by David Royal – Monterey Herald

————–

January 6, 2017 at Fisherman’s Shoreline Park, Monterey, CA

Pelagic red crabs washed ashore at Fisherman’s Shoreline Park (near the wharf) on January 6, 2017. (Photo: Chad King, NOAA/MBNMS)

The 2015-16 and 1982-83 El Niño Southern Oscillation (ENSO) events brought huge numbers of pelagic red crabs (Pleuroncodes planipes) northward to Monterey Bay (watch video). The presence of Pleuroncodes, which look like bright-red baby lobsters, is indicative of the intrusion of southern sub-tropical waters into central California, since these crustaceans normally live in the warm waters off the coast of Baja California. During an ENSO event, warmer southern water moves poleward, often bringing marine species not normally found in the cold temperate waters off the coast of California. Several warm temperate and sub-tropical species, including Pleuroncodes, are observed beyond their normal geographic range during ENSO events, and sometimes as far north as Oregon and Washington.

Pleuroncodes stranding events are rare occurrences in Monterey Bay and usually coincide with ENSO events. The species was first discovered in 1859 during a mass-stranding event in Monterey. Further stranding events in Monterey occurred later in 1959 and again in 1969. Dr. Steve Webster, senior marine biologist at the Monterey Bay Aquarium, noted that when present, seagulls were feeding on so many crabs that they could not get airborne. Pleuroncodes are also a source of food for fishes, rays, and pinnipeds (seals and sea lions).

More images of pelagic red crabs from the SIMoN Photo Library