Bairdiella, Bairdiella icistia
The Bairdiella, Bairdiella icistia, whose common Spanish name is ronco roncacho, is a member of the Croaker or Sciaenidae Family, known collectively as berrugatas or corvinas in Mexico. Globally, there are only five species in the genus Bairdiella, two of which are found in Mexican waters, both in the Pacific.
The Bairdiellas have elongated, oblong, and compressed bodies. They are silvery with yellowish fins and a dark spot at the base of their pectoral fins. Their upper lip and the tip of their lower jaw are dusky. Their head is narrow with a short blunt snout. They have a large slightly oblique mouth that opens in the front, reaches the middle of the eyes, and is equipped with conical teeth in narrow rows. They have no barbels. Their anal fin has two spines and 7 or 8 rays with the second anal spine being long and similar in length to the first anal ray. Their caudal fin is straight to slightly convex. Their first dorsal fin has 10 to 12 spines and their second dorsal fin has one or two spines and 24 to 28 rays. Their pectoral fin is short and extends to the second dorsal fin. Their gill covers have 8 or 9 spines including two to 4 spines at an angle. They have 23 to 27 gill rakers. Their lateral line extends to the center of the caudal fin. They are covered with rough scales.
The Bairdiellas are found in inshore waters including estuaries at depths up to 60 feet. They reach a maximum length of 30 cm (12 inches). They feed on crustacean larvae, shrimp, and small fish. They are preyed upon by a variety of larger fish and various sea mammals. In general, they are a poorly studied species and little is known about their behavioral patterns.
In Mexican waters the Bairdiellas are found in all waters of the Pacific with the exception that that are absent from Punta Abreojos northward along the central and northwest coasts of Baja.,
The Bairdiella is somewhat similar to, and can be confused with, the Armed Croaker, Bairdiella armata (21 to 23 dorsal rays; rounded caudal fin).
The Bairdiellas are small fish that are abundant in some locations but are considered of limited value due to their small size. From a conservation perspective, they are considered of Least Concern, with a wide distribution and being abundant within their range with stable populations, however, population trends are poorly monitored. They were introduced to the Salton Sea in Southern California in 1950; although they thrived for several years they were eventually extirpated due to the erosion of water quality caused by increased levels of salt and related pollution. They were also introduced to New Mexico waters but suffered the same fate.
Bairdiella, Bairdiella icistia, juvenile. Fish caught with a cast net off the pier in Puerto Adolfo Lopez Mateos, Baja California Sur, October 2016. Length: 2.5 cm (1.0 inches).
Bairdiella, Bairdiella icistia. Fish caught within Magdalena Bay, Baja California Sur, July 2016. Length: 22.0 cm (8.7 inches).