Pelagic red crab in Los Cabos

How to recognize it

Not a true crab but a squat lobster: bright red, with a short tail folded under the body, a fan for swimming and a long first pair of legs armed with pincers. Rows of hair-like bristles line the walking legs. Stranded adults in Magdalena Bay measure about 1.2 to 2.8 cm in carapace length. In BCS it’s called langostilla.

Biology

The pelagic red crab lives in the eastern Pacific, and its heartland is the Pacific side of the Baja California peninsula; it also occurs in the Gulf of California. INAPESCA research cruises in 2019 found the densest catches south of Ensenada, in the Gulf of Ulloa and off the Magdalena Bay lagoon system, mostly shallower than 100 m. Stock estimates for Baja’s Pacific coast run from about 275,000 t in summer–fall to 460,000 t in winter–spring. It handles water from about 9 to 28 °C and low oxygen, but is densest at 13–16 °C.

Larvae, juveniles and young adults drift and swim in the open water for about a year; at 17–20 mm carapace length they start living on the bottom and rising toward the surface mostly at night, and at 32–34 mm they are fully benthic. They breed from December to April, peaking in February, and females can brood twice a season. They graze directly on phytoplankton, which makes them a short link between the sea’s primary production and tunas, seabirds, sea lions and whales.

Seeing them from the boat

The big concentrations are on Baja’s Pacific side, between Bahía Sebastián Vizcaíno, the Gulf of Ulloa and Magdalena Bay; U.S. research trawls caught red crabs from Vizcaíno all the way to Cabo San Lucas, but off Los Cabos itself encounters are irregular and there is no clear season. In Magdalena Bay in the early 1970s, Mexican shrimp crews reported crabs so abundant they sometimes couldn’t trawl, and hundreds of birds sat on the water picking them off the surface.

For anglers the crab matters as food: 567 yellowfin tuna stomachs used to estimate red crab consumption off Baja held almost 31 quarts of them, and they are the most common single prey of yellowtail in the Baja–California population. Under Mexico’s sport fishing rules, crustaceans may not be taken, so the crab is something to watch for, not to collect. When red crabs show up off California, it usually means warm water from Mexico has pushed north.

Rules & conservation

Don't confuse it with

The squat lobster Munida quadrispina is a similar size and can overlap in range, but has much longer pincer arms (chelipeds) and lives on the bottom; the pelagic red crab is the one seen swimming at the surface.

Questions

By Max VargasTop Anglers, Cabo San Lucas · international judge at big game fishing world championships · reviewed October 2026

Sources

• Aurioles-Gamboa et al. 1994, annual mass strandings in Bahía Magdalena (Fishery Bulletin)
• Kato 1974, development of the pelagic red crab fishery (Marine Fisheries Review)
• Vallarta-Zárate et al. 2023, red crab distribution off Baja California (Rev. Mex. Biodiversidad)
• Cimino et al. 2021, poleward advection and red crab range expansions (Limnology & Oceanography)
• Nichols et al. 2000, transpacific migration of a loggerhead (Bulletin of Marine Science)
• Ben-Aderet et al. 2020, yellowtail jack life history and diet (Fishery Bulletin)
• Simon-Lledó et al. 2023, mass falls of crustacean carcasses (Ecology)
• SeaLifeBase: Grimothea planipes
• NOM-017-PESC-1994, 2013 amendment (DOF)

Top illustration: Top Anglers. Photos: iNaturalist contributors, credited on each photo.