Sand Grunt, Pomadasys branickii
The Sand Grunt, Pomadasys branickii, whose common Spanish name is roncacho arenero and whose local name is roncador, is a species in the Grunt or Haemulidae Family, known collectively as burros in Mexico. Globally, there are thirty-six species in the genus Pomadasys, five of which are found in Mexican waters, one in the Atlantic and four in the Pacific.
The Sand Grunts have relatively slender bodies with a depth that is 32 to 34% of standard length. They have an overall silvery appearance with brown tinges, a large head, large eyes with yellow irises, and thick lips. They have a strong straight lateral line and a prominent yellow-brown gill cover. They have 13 dorsal spines (a key to identification) and long pectoral fins. This species is particularly well-protected with a long stout second anal spine, the length of which is two times the diameter of their eyes and four times the size and length of their first anal spine, and an enormous first pelvic spine that is approximately two-thirds the length of their second pelvic ray.
The Sand Grunts are inshore bottom dwellers found over sandy substrate and at depths up to 300 feet, as established by a fish that we caught. They will also enter muddy bays and estuaries. They reach a maximum 30 cm (12 inches) in length and under 1 kg (2.2 pounds) in weight. They are a relatively unknown species and very little is known about their behavior patterns.
In Mexican waters the Sand Grunt has a very limited distribution being found from Magdalena Bay southward along the southwest coast of Baja, from Loreto southward along the southeast coast of Baja (these southerly limit being established by fish that I caught), and along the coast of the mainland south of Mazatlán to Guatemala.
The Sand Grunt can be confused with the Panamic Grunt, Pomadasys panamensis (dark blotch at top of gill cover; slender second anal spine), the Longspine Grunt, Pomadasys macracanthus (12 dorsal spines; dark spot on top of gill cover and pectoral fin base), and the Yellowstripe Grunt, Haemulopsis axillaris (black blotch on top border of the gill cover; dark lines on flank; third anal spine longer than second).
The Sand Grunts are small and of limited interest to most. They are viewed as marginal table fare by locals.
Sand Grunt, Pomadasys branickii. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, January 2008. Length: 30 cm (12 inches). Identification courtesy of Dr. Ross Robertson, Smithsonian Tropical Research Institute, Panama.
Sand Grunt, Pomadasys branickii. Fish caught from coastal waters off Point Palmilla, Baja California Sur, March 2009. Length: 25 cm (10 inches). Fish identification reconfirmed by H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, CA.
Sand Grunt, Pomadasys branickii. Fish caught from coastal waters with Magdalena Bay, Baja California Sur, July 2016. Length: 26 cm (10 inches).