Jacksmelt, Atherinopsis californiensis

The Jacksmelt, Atherinopsis californiensis, whose common Spanish name is pejerrey mocho, is a species in the New World Silverside or Atherinopsidae Family, known collectively as charales and pejerreyes in Mexico. Although this fish is a smelt by name, it is not considered a true smelt. Globally, there are only two species in the genus Atherinopsis, only one being found in Mexican waters, the species described herein found in the Pacific.

The Jacksmelt have elongated and somewhat compressed bodies. They are silvery overall being greenish-blue dorsally and silvery ventrally. They have a bright yellow patch on their cheeks and a silvery-gray stripe with a blue border on their sides. Their head is oblong and compressed with a pointed snout, small eyes, and a small terminal mouth that is extendible and equipped with two or three rows of conical teeth. Their anal fin is inserted midway between the origins of their first and second dorsal fins and has one spine and 21 to 26 rays. They have two well separated dorsal fins, the first before the anal fin with 5 to 9 spines and the second with one spine and 10 rays. Their pectoral fins are short just reaching the pelvic fin origin. Their pelvic fins are closer to the anal fin origin than to the pectoral fin origin. They have 30 to 40 rounded gill rakers and are covered with small smooth scales.

The Jacksmelt are a schooling pelagic species found in bays and shallow murky waters over sandy bottoms and around piers from the surf zone to depths up to 100 feet. They are the largest member of the Silverside Family and reach a maximum length of 49 cm (19 inches). They are active daytime feeders and consume algae and small crustaceans. Reproduction is oviparous with large masses of sticky eggs released by females several times per year; eggs attach themselves to shallow water seaweed via long filaments and are then fertilized by males. The larvae are planktonic. They have a lifespan of up to eleven years.

In Mexican waters the Jacksmelt have a limited distribution being found only along both coasts of Baja; they are absent from Guaymas to Guatemala along the west coast of the mainland.

The Jacksmelt is similar to, and can be confused with, the California Grunion, Leuresthes tenuis (first dorsal fin origin over anal fin origin) and the Topsmelt, Atherinops affinis (first dorsal fin origin behind anal fin origin).

The Jacksmelt are a favorite of California pier fishermen where they are normally caught on high tides with baited or unbaited Sabiki rigs. If one is hooked often several others will be hooked on the reel. They are also caught by surf fishermen. On light tackle, they are a reasonable foe for their size. They are consumed as a food fish and sold commercially in Asian markets. They have numerous small bones, however. Historically they were an important food source for Native Americans. They are an important food source for a wide variety of fish, marine mammals, and sea birds. From a conservation perspective they are believed to be common and widespread, thus classified as of Least Concern, however, their population status and trends are unknown.

Jacksmelt, Atherinopsis californiensis. Fish caught off the Oceanside Pier, Oceanside, California, May 2006. Length: 23.0 cm (9.1 inches).

Jacksmelt, Atherinopsis californiensis. Fish caught from coastal waters off Santa Cruz, California, May 2016. Length: 25.0 cm (9.8 inches). Catch, photo, and identification courtesy of Andrew Hansen, Santa Cruz, CA.