Pink shrimp, continued 



Galveston, often associated with coarse substrate 

 (Sheridan pers. comm.) (Table 5.07). For the pur- 

 poses of Table 5.07, all larval and postlarval stages of 

 pink shrimp are considered together as "larvae" (L). 



Life Mode 



Eggs and adults are demersal; larvae are planktonic to 

 the postlarval stage (Costello and Allen 1 970). Postlar- 

 val and juvenile stages are demersal in estuaries and 

 coastal bays (Perez-Farfante 1 969, Costello and Allen 

 1970, Williams 1984). Juvenile pink shrimp burrow 

 during the day and are active nocturnally. The noctur- 

 nal activity is most obvious during new and full moons 

 (Hughes 1967, Williams 1984). In the Florida Bay 

 region juvenile pink shrimp are most abundant be- 

 tween September and December (Robblee et al. 1 991 , 

 Schmidt 1993). 



Habitat 



Ty pe: Eggs and early planktonic larval stages are 

 oceanic. Postlarval and juvenile stages occur in 

 oligohaline to euhaline estuarine waters and bays, and 

 adults occur in estuaries and nearshore waters to 64 m 

 depth. Mature pink shrimp inhabit deep offshore 

 marine waters with the highest concentrations in depths 

 of 9 to 44 m. Largest numbers of pink shrimp occur 

 where shallow bays and estuaries border on a broad 

 shallow shelf (Perez-Farfante 1 969, Costello and Allen 

 1970, McKenzie 1981, Bielsa et al. 1983, Williams 

 1 984). Costello et al. (1 986) indicate optimum habitats 

 have daily tidal flushing with marine water and large 

 seagrass beds with high blade densities. Protozoeal 

 and mysis stage larvae on the Tortugas Shelf were 

 found in depths of 14.6 to 47.6 m (Jones et al. 1970). 

 Larvae most generally occurred at depths of 18.3 to 

 36.6 m. Older pink shrimp occurred almost entirely in 

 inshore waters, and in Florida Bay appeared to be most 

 abundant in shallow water habitats (Jones et al. 1 970, 

 Robblee et al. 1 991 ). Optimum catches in Texas occur 

 in secondary bays, but this species occurs from sec- 

 ondary estuarine channels out to the continental shelf 

 (Copeland and Bechtel 1974) 



Substrate : Pink shrimp inhabit a range of bottom sub- 

 strates including shell-sand, sand, coral-mud, and 

 mud. Immature pink shrimp prefer shell-sand or loose 

 peat, and adults prefer shell-sand over loose peat 

 (Williams 1958, Williams 1984). Juvenile shrimp are 

 also commonly found in estuarine areas with seagrass 

 where they burrow into the substrate by day and 

 emerge and are active by night (Perez-Farfante 1 969, 

 Costello and Allen 1970, Williams 1984). Juveniles 

 have been frequently associated with seagrasses, and 

 it has been suggested that the distribution of seagrasses 

 may influence the geographic distribution of pink shrimp 

 populations (Costello and Allen 1970). In inshore 

 Florida waters, small juveniles were found close to 



shore in beds of shoal grass, Halodule wrightii, while 

 large juveniles occurred in deeper waters in turtle 

 grass, Thalassia testudinum (Robblee et al. 1991, 

 Schmidt 1993). Turtle grass has also been found to 

 provide a suitable habitat for many organisms that 

 penaeids and other species utilize as food (Moore 

 1963). 



Physical/Chemical Characteristics : 

 Temperature: One laboratory study found larvae 

 showed normal growth at 21° and 26°C, but died at 

 temperatures exceeding 31 °C (Williams 1 955a). While 

 larval development may be restricted to a narrower 

 range, juveniles may be fairly tolerant of a wide range 

 of temperatures (Williams 1955a). Juveniles tolerate 

 temperatures between 4° to 38°C, but extended peri- 

 ods of low water temperatures may result in death. In 

 Texas, they become more abundant with increasing 

 temperature, and optimal catches occur between 20° 

 and 38°C (Copeland and Bechtel 1974). Adult pink 

 shrimp tolerate temperatures between 10° to 35.5°C 

 (Williams 1955a), and temperature may be a limiting 

 factor in the northern part of their range (Hettler 1 992). 



Salinity: Pink shrimp show different degrees of salinity 

 preference at different life stages (Bielsa et al. 1983). 

 Postlarvae have been observed in salinities ranging 

 from 12 to 43%» with little apparent differences in their 

 growth (Williams 1 955a). At a constant temperature of 

 24°C postlarvae showed no difference in growth at 

 salinities ranging from 2 to 40% o (Zein-Eldin 1963). 

 Juveniles have been observed between <1 to 47%o 

 although they prefer salinities greater than 20%o 

 (Costello and Allen 1 970, Copeland and Bechtel 1 974). 

 Optimum catches in Texas occur between 20 and 35%o 

 (Copeland and Bechtel 1974). Salinity does not ap- 

 pear to be a major factor in the distribution of adults or 

 in controlling spawning activity (Roessler et al. 1969). 

 Adults are generally found in 25 to 45%o, although they 

 have been found in salinities as high as 69%o. Abun- 

 dances are reduced above 45%o. At their lower salinity 

 tolerance, pink shrimp have been observed in 2.7%o in 

 the western Gulf of Mexico; and close to 1%o in the 

 Caloosahatchee estuary and Ten Thousand Islands of 

 Florida. One study indicates a possible positive rela- 

 tionship with freshwater runoff in the Everglades and 

 landings in the Tortugas shrimping grounds (Browder 

 1 985). Salinity requirements or preferences vary with 

 geographic area and shrimp size (Costello and Allen 

 1970). The pink shrimp appears to have superior 

 osmoregulatory capabilities to those of the brown 

 shrimp during periods of low water temperature, and 

 thus shows a greater capability for overwintering in 

 estuaries in the northern part of its range (Williams 

 1955a). 



66 



