Photo credit: Sherif Sadek (Egypt)
Review: Abdel Rahman El Gamal (Founder of the website)
The inserted picture of a brown shrimp specimen was taken in a fish farm in Egypt.
Introduction: Brown shrimp (Farfantepenaeus aztecus) is a species of marine penaeid shrimps which has an important commercial species in the USA. The species has several common names such as northern brown shrimp; golden shrimp, red shrimp or red tail shrimp.
Distribution: The brown shrimp are found along the USA Atlantic coast from Massachusetts to Texas, and along the Atlantic coast of Mexico from Tamaulipas to Campeche and now been confirmed to occur in the Mediterranean, probably introduced in ship’s ballast water.
Habitat: The species occurs at its highest densities at depths between 27 – 54 m and rarely observed at depths exceeding 165 m. The primary habitats for brown shrimp are muddy bottom areas, often with sand, clay or broken shells.
Brown shrimp and environmental conditions
Temperature: The species experiences physiological stress at temperatures as low as 10°C, and at temperatures above 32°C with preferred temperature of about 20°C. In laboratory studies, P. aztecus was observed to burrow as temperatures fell below the 12 – 17°C range, and re-emerge from sediments when temperatures rose above 18 – 21.5°C.
Salinity: Research revealed that the growth rate of the species maintained almost the same rate
when salinity ranged between 5 – 40 ppt. There are published reports indicating the collection of brown shrimp in waters where salinity was as low as 0.2 ppt. whereas the high end of the salinity scale came as high as 69 ppt. at which brown shrimp are able to continue osmoregulation.
Dissolved oxygen: Brown shrimp can detect and avoid low Dissolved oxygen conditions as levels approach 1.5 – 2 ppm.
Description: The brown shrimp exhibits sexual dimorphism in regard to growth females growing larger than males. Individual specimens may attain a total length of up to 20 cm for male and 24 cm for female. In general, males attain only 3/5 of female weight, and 5/6 of female length. The antennae of the species are significantly longer than body length. Its carapace has a medial carina on the anterior surface that is bordered on either side by a broad, somewhat rounded groove. The prominent rostrum is slightly upturned with 5-10 sharp teeth on the upper edge. The Chromatophores give the animal a brown to olive-green appearance. The species is an active swimmer and burrower. Also, it is more active at night in open waters than it is during the daylight hours.
The first 3 pairs of walking legs are chelate. Uropods are rounded and generally colored reddish-brown in the distal portions. The telson bears a sharp tip and a deep medial groove anteriorally. Females are distinguished by the presence of a closed thelycum located on the ventral sternum of the thorax, while males are identified by the presence of the pentasma.
Feeding habits: Brown shrimp is an opportunistic omnivore that feeds –depending on their age- on some algal species (i.e., filamentous green algae, benthic diatoms, plant detritus, etc.) as well as small invertebrates such as copepods and mollusks, annelid worms, amphipods, zooplankton larvae, and nematodes.
Reproduction: P. aztecus becomes reproductive after reaching a size of 140 mm. This species is known to have an extended spawning season that is likely to vary in different geographic areas of its range. Brown shrimp spawn offshore at depths that generally exceed 18 m.
Eggs of brown shrimp are demersal and spherical, measuring approximately 0.26 – 0.28 mm in diameter. Hatching occurs after about 24 hours. Larvae develop offshore through 5 naupliar, 3 protozoeal, and 3 mysis stages before metamorphosing into postlarvae that undergoes several postlarval stages over about 11 days at 32C prior to metamorphosis to the juvenile stage.
Capture fisheries: Brown shrimp is an important fishery species of commercial value in its native range whether in North Carolina or along the north and east coast of the Gulf of Mexico. According to FAO statistics, the world catch of the species amounted 63,651 tons in 2015 whereas 50,472 tons of which was produced in USA in that year. Besides their importance to commercial fisheries as food shrimp, they are used as a live or frozen bait product used by fishermen.
Aquaculture: Farming of F. aztecus launched on experimental bases in the seventies, in earthen ponds located in Texas whereas information on growth, production, survival, feed conversion, and condition of shrimp in commercial ponds were obtained. The shrimp used for these experiments were collected from the wild. Research continued targeting to evaluate the species performance whether in monoculture or in polyculture systems under different management protocols. In fact, there is a growing interest to use brown shrimp at its appropriate size as live bait shrimp produced in culture ponds rather than harvested from the wild.
Brown shrimp in the Mediterranean: Brown shrimp was first collected in the Antalya Bay, Turkey in 2009. Since then, the species quickly spread along the coasts of southern Turkey, the Aegean Sea, the East Ionian Sea, the South Adriatic, and Tyrrhenian Sea. The inserted picture is for brown shrimp collected from the Egyptian waters of the Mediterranean whereas exploring the potential of the farming the species has started on an experimental level.