Rough Silverside, Membras martinica
Rough Silverside, Membras martinica. Fish caught off from coastal waters of the Pawley’s Island Delta, South Carolina, July 2021. Length 6.1 cm (2.4 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
The Rough Silverside, Membras martinica, is a member of the New World Silverside or Atherinopsidae Family, and is known in Mexico as pejerrey rasposo. Globally, there are six species in the genus Membras, of which two are found in Mexican waters, one, this species, in the Atlantic Ocean, and one in the Pacific Ocean.
The Rough Silverside has a slender, elongated, compressed body that is six or seven times it length. Their upper body is a bright yellow to sea-green with their scales providing a speckled or cross-hatched with dark pigment appearance. They have a mid-lateral silver stripe, and their lower body is silvery. Their head has a long snout that is longer than the eye width, a strongly extendable upper jaw and a mouth that is equipped with well developed teeth set in bands. Their anal fin has 15 to 21 rays. Their first dorsal fin has 5 or 6 spines and originates just in front of the anal fin origin, their pectoral fins are inserted high on the body above the mid-eye level and reach past the pelvic fin origin, their pelvic fins are inserted nearer the anal fin origin than the top corner of the pectoral fin base, and their anus is nearer the origin of the anal fin than the pelvic fin base. The base of the pelvic fins have a large scale that is greater than one-third of the fins length. They have a well-developed systems of prominent pits and troughs. They are covered with rough-edged scales.
The Rough Silverside is a schooling species that is found a variety of shallow water different habitats that include coastal lagoons, exposed shoreline, beaches and coastal rivers, brackish waters and freshwater at depths up to 15 m (50 feet). They have the ability to tolerate a wide variety of salinities providing them with numerous types of habitats. They reach a maximum length of 15 cm (5.9 inches). Their diet primarily consists of zooplankton. Reproduction is oviparous. The larvae are planktonic. The Rough Silverside 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 Rough Silverside is found in Mexican waters along the northern coast of the Gulf of Mexico from the Texas boarder south to the Yucatán Peninsula and a number of river systems including the Rio Grande to Campeche. They have been introduced in the Amastad Reservoir and the Falcon Reservoir within the Rio Grande River system in Mexico.
The Rough Silverside is similar to the Golden Silverside Labidesthes vanhyningi (first dorsal fin orginates slightly in front of the anal fin origin) and the Inland Silverside, Menidia beryllina (first dorsal fin originates far before the anal fin origin; lacks a lateral line).
From a conservation perspective the Rough Silverside is currently considered to be of Least Concern with stable, widely distributed populations. They are very small in stature and are of limited interest to most, however due to their abundance and size they are considered to be a key component of the food webs being a predator of small crustaceans and prey for birds, other fishes and marine mammals. They are utilized by recreational anglers as a live bait on a limited basis.