Twobeak Searobin, Prionotus birostratus
Twobeak Searobin, Prionotus birostratus. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, July 2012. Length: 15.5 cm (6.1 inches).
The Twobeak Searobin, Prionotus birostratus, is a member of the Searobin or Triglidae Family, and are known in Mexico as vaca dospicos. Globally, there are twenty-three species in the genus Prionotus, of which fifteen are found in Mexican waters, ten in the Atlantic and five in the Pacific Ocean.
The Twobeak Searobin has a rectangular block-like body that is gray brown in color with white undersides. Their large square bony head features large eyes and is covered with many ridges and spines. Their anal fin is transparent; their caudal and fin has 3 dark bars; their first dorsal fin is dusky and the 3 spines have black tips; their second dorsal fin has a dusky margin; and, their pectoral fins are black with white blotches. They have flattened heads with 2 strongly projecting snout plates. There is a bony ridge under the eye and 2 spines at the rear of their eyes and 5 or 6 well-developed gill rakers. Their anal fin has 1 spine and 10 rays; their first dorsal fin has 10 spines; their second dorsal fin has 10 to 12 rays; their pectoral fins have 13 or 14 rays, are long and reach past the anal fin, and have short free rays with the second and third being enlarged. They have 5 or 6 gill rakers on the lower arch. Their body is covered with very rough scales.
The Twobeak Searobin is found over and within sandy and muddy bottoms at depths between 18 m (60 feet) and 60 m (200 feet). They are more active and feed at night; during the day they are found submerged in sand. They reach a maximum of 18.0 cm (7.1 inches) in length. The Twobeak Searobin is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Twobeak Searobin is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found from Magdalena Bay, Baja California Sur, southward along the southwest coast of Baja, in the southern half of the Sea of Cortez, and along the coast of the mainland south to Guatemala.
The Twobeak Searobin can be confused with six other Searobins found in Mexican waters of the Pacific Ocean, however, its extended snout plates, aerodynamic body profile, and unique spotting pattern on the tail make it easy to identify.
From a conservation perspective the Twobeak Searobin is currently considered to be of Least Concern with stable, wide ranging populations. Due to their bony structure and rarity, they are of limited interest to most. They are a frequent by-catch of deepwater shrimp trawlers around the tip of Baja.