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Common Name:
Most common: White shrimp; northern white shrimp. Other associated names: gray shrimp, Daytona shrimp, lake shrimp, green shrimp, green-tailed shrimp, blue-tailed shrimp and others (Muncy 1984).

Its carapace has a medial carina (keel-like ridge) that is continuous with the rostrum at the anterior end of the animal, and extends posteriorly approximately 2/3 the length of the carapace. The rostrum is elongate and slender, somewhat distally upcurved, with 5 – 11 (usually 9) sharp teeth on the dorsal surface, and 2 teeth on the ventral edge. Unlike its congeners P. aztecus and P. duorarum, P. setiferus has no bordering groove along the carina. The integument is thin, and appears polished and translucent.

The abdomen is carinate on segments 4 – 6, with the carina of segment 6 having a narrow groove on either side. The telson has a deep medial groove along its length, and a sharp tip. The ventral margin of the pleura of the first segment is almost straight.

P. setiferus is sexually dimorphic, with females growing larger than males. Additionally, the female thelycum, which lies between pereopods 3- 5, is open and has raised ridges along the anterolateral surface. The male pentasma has a diagonal ridge across the dorsolateral lobe.

Synonymy:
Cancer setiferus Linnaeus, 1767

Other Taxonomic Groupings:
Subphylum: Crustacea
Subclass: Eumalacostraca
Suborder: Dendrobranchiata

II.  HABITAT AND DISTRIBUTION 

Regional Occurrence:
White shrimp are known from Fire Island, New York south to St. Lucie Inlet, Florida. The range then extends around the Florida Peninsula into the Gulf of Mexico from the Ochlocknee River in northwest Florida to Campeche, Mexico. Several centers of abundance have been identified for P. setiferus. Primary among them is coastal Louisiana around the Mississippi River Delta. Other abundance areas occur in northeast Florida, Georgia, and the region around the Bay of Campeche, Mexico (Williams 1984).

IRL Distribution:
White shrimp are distributed throughout the Indian River Lagoon and along the east central Florida coast where they are commonly utilized as bait and for food.

III.  LIFE HISTORY AND POPULATION BIOLOGY

Age, Size, Lifespan:
Large males measure approximately 182 mm in length. Large females grow slightly larger and eventually reach 200 mm. Williams (1984) reported that females beyond the juvenile stage are consistently larger than males.

In estuaries, juvenile white shrimp grow approximately 1.2 mm per day during late spring and summer months (Williams 1965). Growth is slow in spring, but quickens with the onset of summer. Growth rates decrease during the fall months, but shrimp that remain in estuaries to overwinter resume growing the following spring (Muncy 1984). Few white shrimp live as long as a year (Anderson 1966), however, mark-recapture studies have revealed that some white shrimp live from 27 months to as much as 4 years (Etzold and Christmas 1977; Klima et al. 1982).

Abundance:
Penaeus setiferus is a commercially valuable fishery species and can be highly abundant throughout its range. Major abundance centers are located from Georgia to Florida, Louisiana, and the Bay of Campeche, Mexico.

Locomotion:
Penaeus setiferus actively swims, burrows shallowly, and crawls.

Reproduction:
Mature males produce ripe sperm when they reach lengths of approximately 118 mm. Females mature at lengths of approximately 135 – 140 mm. Gonadal development in females can be judged by ovary color. Undeveloped ovaries are opaque and white in color. Developing ovaries appear yellow, a stage which may last 1 – 2 months. Ripe ovaries are an olive color, and may remain so until fully spent (generally in less than 1 month). Spent ovaries quickly develop to the yellow stage within a few days, and will ripen again within 2 – 3 months (King 1948; Brown and Patlan 1974).

Spawning behavior in P. setiferus is initiated by an increase in offshore bottom water temperatures during spring (Whitaker 1981). In the Carolinas, spawning occurs from May through September (Williams 1955), while further south in the Gulf of Mexico, spawning occurs from March through September. Williams (1965) and Joyce (1965) each reported only one spawning period for P. setiferus. However, Gunter (1950) suggested spring and fall spawning periods in Texas waters.

Spawning occurs as far as 9 km from the shore, in water depths of at least 9 m (Whitaker 1983b), with females discharging eggs directly to the water column without brooding them as is common in other crustaceans. During copulation, which occurs between hard-shelled individuals, the male attaches a spermatophore to the thelycum of a female. Spermatozoa are released simultaneously with eggs from the female, with fertilization occurring in the water column. Eggs are opaque with a blue-tinged chorion (Linder and Cook 1970) and measure approximately 0.19 – 0.20 mm in diameter. Eggs sink to the bottom of the water column as they are released, and hatch within 10 – 12 hours into planktonic nauplii larvae that measure approximately 0.3 mm in length. Between 500,000 to 1 million eggs are released per spawn.

Embryology:
The larval period in P. setiferus lasts 10 days or more. Perez-Farfante (1969) reported 5 naupliar stages, 3 protozoeal stages, 3 mysis stages, and 2 postlarval stages before the juvenile stage is reached. The non-feeding nauplius stage undergoes 5 molts over 24 – 36 hours to the protozoeal stage which measures approximately 1 mm in length. Feeding behavior is initiated with the first protozoeal stage. Protozoea grow to a length of approximately 2.5 mm before achieving the mysis stage. Following a third mysis stage, the postlarval stage is attained.

Postlarvae of P. setiferus are planktonic, gradually moving inshore to estuarine nursery grounds on tidal currents (Whitaker 1983a). Most enter estuaries as second stage postlarvae measuring approximately 7 mm in length. Upon reaching estuaries postlarvae become benthic (Williams 1965). In North and South Carolina, postlarval P. setiferus enter estuaries from June through September; in Georgia, postlarvae may enter estuaries as early as April and May. In northeastern Florida, postlarvae first begin to appear in early June.

Perez-Farfante (1969) considered postlarvae to be juveniles once they had acquired 4 – 10 upper rostral teeth, and 1 to 3 lower rostral teeth.

IV.  PHYSICAL TOLERANCES

Temperature:
Growth in Penaeus setiferus occurs at temperatures above 20 ° C (Etzold and Christmas 1977) with growth ceasing at temperatures below 16 ° C. Perez-Farfante (1969) reported that increasing temperatures increased molting rates. Zein-Eldin (1964) found that inadequate temperature and food supply could limit growth rates in P. setiferus more than salinity differences in the range between 2 – 35 ppt.

Survival of white shrimp at low temperatures is dependent on ambient temperatures, rate of cooling, and the duration of low temperatures (Joyce 1965). Critical thermal minimum for this species is 8 ° C or lower (Joyce 1965), with the mortality rate being total at a temperature of 3 ° C or lower, regardless of salinity (Muncy 1984). Adult P. setiferus may be somewhat more susceptible to cold temperatures than are juveniles (Whitaker 1983a).

Burrowing has been studied as a behavioral response to low temperatures (Aldrich et al. 1968). In laboratory studies, brown shrimp were observed to burrow as temperatures fell below the 12 – 17 ° C range, and re-emerged from sediments when temperatures rose above 18 – 21.5° C. White shrimp, however, showed no such response to lower temperatures, though they are known to burrow shallowly during quiescent periods. It was hypothesized from this result that burrowing would have more survival value to brown shrimp than other congeners since brown shrimp are known to recruit to estuarine habitats earlier in the year than other penaeids. White shrimp, for example, arrive at coastal bays with the onset of summer, and thus would not be exposed to the low temperatures that elicit the burrowing response in brown shrimp.

Salinity:
Juvenile white shrimp tend to move into the upper reaches of estuaries to seek out low salinity waters more so than either pink or brown shrimp (Williams 1958). In Louisiana, white shrimp have been sampled as far as 160 km upriver; while in northeast Florida, they have been collected as far upriver as 210 km (Perez-Farfante 1969).

The lowest recorded salinity from which white shrimp have been reported was in the northern Gulf of Mexico, where salinity measures 0.42 ppt. In Florida, juvenile white shrimp have been collected in the St. John’s River, Florida where salinity is generally less than 1.0 ppt. Muncy (1984) reported that white shrimp have been recovered from the Lake Monroe Power Station, a distance of 270 km from the mouth of the St. John’s River. High concentrations of calcium ion in the St. John’s River may explain the ability of white shrimp to thrive at such low salinity.

Spawning takes place in offshore waters when salinities are at least 27 ppt. However, laboratory experiments have shown that larvae can be successfully reared at a range of salinities between 18 – 34 ppt (Perez-Farfante 1969).

Parasitic Infestations and Diseases:
Parasites of white shrimp include microsporidians, helminths, nematodes, and cestodes. Disease in white shrimp is caused by exposure to viruses, fungi and bacteria such as Vibrio (Muncie 1984).

V.  COMMUNITY ECOLOGY

Trophic Mode:
White shrimp larvae feed on both zooplankton such as copepods, and phytoplankton such as unicellular green algae, and diatoms. Juvenile and adult white shrimp are benthic omnivores that feed on detritus, plants, microorganisms, macroinvertebrates (annelids, copepods, amphipods, snails, bryozoans, etc.) and small fish (Muncy 1984). Cannibalism is also common among adult white shrimp (Perez-Farfante 1969).

Competitors:
Penaeus setiferus is likely to compete with its congeners P. aztecus and P. duorarum for resources as well as for habitat. However, white shrimp are known to burrow more shallowly into muddy substrata, and have been shown to be somewhat more active during daylight hours than either brown or pink shrimp. Seasonal recruitment of the 3 common Penaeus species into estuarine nursery grounds is also somewhat staggered, thus reducing direct competition for resources.

Habitats:
Penaeus setiferus commonly inhabits estuaries and the inner littoral zone along coasts to depths of approximately 30 m. In the Gulf of Mexico, P. setiferus can be found in depths as great as 80 m; however, they are most abundant in brackish wetlands with connections to shallow, coastal areas.

Juvenile Penaeus setiferus prefer muddy substrata rich in loose peat and sandy mud (Williams 1958). Anderson (1966) reported that ideal nursery grounds for juvenile white shrimp are muddy bottom areas in waters with low to moderate salinity.

Activity Time:
Juvenile white shrimp are generally more active in daylight hours than juveniles of either pink or brown shrimp (Muncy 1984).

Associated Species:
White shrimp are often found in association with other shrimp species, specifically the brown shrimp P. aztecus. Habitat requirements between these 2 species are similar, and brown shrimp have been observed to force white shrimp from sandy, muddy substrata (Rulifson 1981). However, staggered recruitment periods between these species decreases direct competition for resources.

VI.  SPECIAL STATUS

Special Status:
Fisheries.

Benefit in IRL:
National Marine Fisheries Service data reported the statewide commercial catch for white shrimp in Florida between 1987 - 2001 to be 52.3 million pounds with a dollar value of $139.2 million. 

Figure 1.   Annual dollar value of the commercial catch of white shrimp to the 5-county area
     of the Indian River Lagoon. 

 Figure 2.  Total  white shrimp dollar value and percentage by county for the years
     1987 - 2001.

Table 1.  Total dollar value of the IRL harvest of white shrimp, Penaeus setiferus, between
     1987 -2001.

Table 2.   By-county percentage of the white shrimp harvest for the years 1987-2001.
 

Table 3.  By county cumulative dollar value and percentage of total for the IRL white shrimp
     harvest from 1987 - 2001.

VII.  BIBLIOGRAPHY

Aldrich, D.V., C.E. Wood, and K.N. Baxter. 1968. An ecological interpretation
     of low temperature responses in Penaeus aztecus and P. setiferus
     postlarvae. Bull. Mar. Sci. 18(1):61-71.

Anderson, W.W. 1966. The shrimp and the shrimp fishery of the southern United
     States. U.S. Fish and Wildl. Serv. Bur. Commer. Fish. Fish. Leafl. 589. 8 pp.

Brown, A., Jr. and D. Patlan. 1974. Color changes in the ovaries of penaeid
     shrimp as a determinant of their maturity. Mar. Fish. Rev., 36(7):23-26,
     colored figures 1-12.

Etzold, D.J. and J.Y. Christmas. 1977. A comprehensive summary of the shrimp
     fishery of the Gulf of Mexico United States: a regional management plan. Gulf
     Coast Res. Lab. Tech. Rept. Ser. No. 2, part 2. 20 pps.

Gunter, G. 1950. Seasonal population changes and distributions as related to
     salinity, of certain invertebrates if the Texas coast, including the commercial
     shrimp. Publications of the Inst. of Mar. Sci., Texas, 1(2):7-51.

Joyce, E.A. 1965. The commercial shrimps of the northeast coast of Florida. Fl.
     Board Conserv. Mar. Lab. Prof. Pap. Ser. 6. 224 pp.

King, J.E. 1948. A study of the reproductive organs of the common marine
     shrimp, Penaeus setiferus (Linnaeus). Biol. Bull. 94(3):244-262

Klima, E.F., K.N. Baxter, and F.J. Patella, Jr. 1982. A review of the offshore
     shrimp fishery and the 1981 Texas closure. Mar., Fish. Rev. 44:16-30.

Linder, M.J. and H.L. Cook. 1970. Synopsis of biological data on the white
     shrimp Penaeus setiferus (Linnaeus) 1767. FAO Fisheries Synopsis 101.
     FAO Fish. Rep. 4:1439-1469.

Muncy, R.J. 1984. Species profiles: life histories and environmental requirements
     of coastal fishes and invertebrates (south Atlantic): white shrimp. U.S. Fish and
     Wildl. Serv. FWS/OBS-82/11.27. U.S. Army Corps of Engineers, TR 
     EL-82-4. 19 pp.

Perez-Farfante, I. 1969. Western Atlantic shrimps of the genus Penaeus. U.S.
     Fish Wildl. Serv. Fish. Bull. 67(3):461-591.

Rulifson, R.A. 1981. Substrate preference of juvenile penaeid shrimp in estuarine
     habitats. Contrib. Mar. Sci. 24:35-52.

Whitaker, J.D. 1981. Biology of the species and habitat descriptions. In M.D.
     McKenzie, ed. Profile of the penaeid shrimp fishery in the south Atlantic.
     South Atlantic Manag. Council, Charleston, SC.

Whitaker, J.D. 1983a. Effects of severe winters on white shrimp stocks in the
    Atlantic Ocean off the southeastern United States. Presented at Natl. Shellfish
     Assoc. Hiltonhead, SC. June 1983. 6 pp.

Whitaker, J.D. 1983b. Roe shrimp tagging 1983. Proj. Rep. S.C. Wildl. Mar.
     Res. Dep., Charleston, SC. 4 pp.

Williams, A.B. 1955. A contribution to the life histories of commercial shrimps
     (Penaeidae) in North Carolina. Bulletin of Marine Science of the Gulf and
     Caribbean 5(2):116-146.

Williams, A.B. 1958. Substrates as a factor in shrimp distribution. Limnol. and
     Oceanogr. 3(3):283-290.

Williams, A.B. 1965. Marine decapod crustaceans of the Carolinas. Fish. Bull.,
     65(1):I-xi + 298 pages.

Williams, A.B. 1984. Shrimps, lobsters and crabs of the Atlantic coast of the
     eastern United States, Maine to Florida. Smithsonian Institution Press.
     Washington, D.C. 550 pp.

Zein-Eldin, Z.P. 1964. Growth and metabolism. U.S. Bur. Commer. Fish. Circ.
     183:65-67.

Report by:  K. Hill, Smithsonian Marine Station
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Page last updated: July 9,  2002