The almeja chocolata is the clam of Baja California Sur: a thick, glossy brown venus clam that divers pull from sandy bottoms in La Paz, Loreto and Bahía Magdalena. In Loreto it’s cooked under burning brush and called the almeja loretana.
A heavy, triangular-oval clam with a thick, porcelain-like shell covered by a smooth, glossy, greyish-brown skin (periostracum); underneath, the shell is light brown to cream. Young clams show zigzag or radiating lines, and adults often keep them near the hinge. Inside, each valve has three strong cardinal teeth and a deep, tongue-shaped pallial sinus reaching about halfway into the shell.
The chocolate clam ranges from Guerrero Negro lagoon in Baja California Sur to Máncora, Peru. It lives buried in fine sand, silty or muddy bottoms and shell-gravel, usually 1 to 15 m deep near shore, though it has been found down to 160 m. It forms large beds of its own or shares them with white clams (Dosinia ponderosa), pen shells and other bivalves, and filters phytoplankton, bacteria and detritus from the water.
Sexes are separate and spawning goes on through much of the year, with one or two peaks. Young clams grow 3 to 5 mm a month, slowing to about 0.6 mm a month once large; in Loreto they first mature at about 63 mm. Clams up to 7 years old have been aged in Bahía de La Paz and Bahía Concepción, and up to 10 in Sonora. Their predators include murex snails (caracol chino), swimming crabs, octopus, porcupinefish and reef fish such as the pargo coconaco and the mojarra mueluda.
For almejas tatemadas, Loreto cooks lay a bed of gravel on the sand, set the clams in it face down, pile dry brush on top and set it alight; the clams are then opened and eaten in flour tortillas. Mexico’s cultural heritage inventory traces the dish to pre-Hispanic times.
Source ↗Loreto’s management plan counts about 20 fishers, nicknamed patitos, who gather chocolate clams with only fins, mask and snorkel and a small floating mesh bag, and sell to local restaurants on demand. Licensed boats use hookah compressors instead.
Source ↗Chocolate clams lay down growth bands on the outside of the shell. Counting them under strong light, researchers in Yavaros, Sonora, found clams up to 10 years old, with an average of 6; the largest measured 104 mm.
Source ↗In Loreto spawning normally stays low, under 15% of females from April onward. During the 2015–16 El Niño, more than 40% were spawning from February to July 2015, and over 90% from January to May 2016.
Source ↗By 2017 the chocolate clams of the Bahía Magdalena–Almejas lagoon system had fallen to about 10% of their estimated 2015 abundance, and Mexico closed the commercial fishery there for two years.
Source ↗Over 2001–02, chocolate clams in Bahía de La Paz held paralytic shellfish toxins in six months of the year, from the dinoflagellate Gymnodinium catenatum, but the peak was 5.46 µg per 100 g, far below the 80 µg safety limit.
Source ↗Baja California Sur lands most of Mexico’s clams, and the chocolate clam is one of its key bivalve fisheries. From 1999 to 2006, Bahía de La Paz (36%), Laguna Ojo de Liebre (35%) and Bahía Magdalena (25%) supplied 96% of the state’s catch, with smaller fisheries at San Ignacio, Loreto and Santa Rosalía. Licensed divers work 2 to 10 m deep with hookah, probing the sand with a small fork, and some clams are picked by hand at low tide. Around Los Cabos there are museum and naturalist records, including a 1972 specimen from Cabo San Lucas, but no commercial beds; the clams on Cabo menus come from the bays farther north.
Recreational digging is not allowed: Mexico’s sport fishing rules ban taking any mollusk except squid, and that includes spearfishing and free diving. If you buy or order clams, red tide matters. When marine toxins pass Mexico’s limits, health authorities (COFEPRIS and the state COEPRIS) close bivalve harvest and sale in the affected zone, as with saxitoxin in Mulegé’s esteros. Cooking, freezing, pickling or smoking does not destroy shellfish toxins, so respect the closures and buy only from legal vendors.
Chocolate clams are eaten raw, opened with salt, chile, lime and crackers, as well as in escabeche, with garlic and as Loreto’s almejas tatemadas. There’s no fixed closed season in the Loreto plan; harvest runs under permits, quotas set at 20% of clams above legal size, and a 64 mm minimum. Bivalves from any zone under a sanitary closure (veda sanitaria) must not be eaten or sold.
| Sport fishing (NOM-017-PESC-1994, 2013 update) | Taking mollusks is prohibited, except squid; that includes clams |
|---|---|
| Commercial fishery | Permits with quotas set by INAPESCA per zone and bed (20% of clams above legal size) |
| Minimum size | 64 mm shell length on the Gulf coast of BCS (Carta Nacional Pesquera) |
| Gear | Hookah diving; hand extraction only |
| Sanitary closures | COFEPRIS/COEPRIS ban harvest and sale of bivalves where marine toxins exceed official limits |
| Mexico (NOM-059) | Not listed |
| IUCN Red List | Not evaluated |
Chocolate clam beds often mix with white clams (Dosinia ponderosa) and other venus clams; the chocolate clam stands out for its heavy shell and smooth, glossy greyish-brown skin, with zigzag or radiating lines when young.
No. Mexico’s sport fishing rules ban taking mollusks other than squid, so clams can’t be harvested recreationally, by hand or by diving. Order them from restaurants or buy from legal vendors.
From Loreto, where the chocolate clam is known as the almeja loretana. The clams are set in gravel and cooked under burning brush, a method Mexico’s heritage inventory traces to pre-Hispanic times.
Only from areas that are not under a sanitary closure. Health authorities close harvest and sale when toxins exceed official limits, and cooking or freezing does not destroy shellfish toxins.
Top illustration: Top Anglers. Photos: iNaturalist contributors, credited on each photo.
Pangas and small boats that work the beaches, points and rocky reefs. From $453 with license included.
