The 1982-83 El Niño Southern Oscillation (ENSO) event brought huge numbers of pelagic red crabs (Pleuroncodes planipes) northward to Monterey Bay. 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).