inshore of 24 m and most abundant at 9-16 m agree 

 with Camp's (1973) data off west central Florida, 

 but contrast with the data of Hildebrand (1954), 

 who found greatest abundance at 35-42 m off 

 Louisiana. Squilla empusa apparently reach peak 

 abundance in much deeper water in the north 

 central Gulf than off Texas, which may simply 

 reflect the phenomenon that the inshore white 

 shrimp community penetrates into deeper water 

 there than it does in the northwestern area (Chit- 

 tenden and McEachran 1976). 



We captured greater numbers of S. empusa at 

 night as did Hoese et al. (1968), who suggested that 

 S. empusa retreat to burrows during the day and 

 consequently are more likely to avoid trawls. 



Spawning Periodicity 



The prolonged spawning period of January to 

 July-August that we found agrees, in part, with 

 Franks et al. (1972), who collected stomatopod lar- 

 vae in the plankton from April through September 

 off Mississippi, and with Swingle (1971), whose 

 limited data from Mobile Bay, Alabama, suggested 

 winter and spring spawning. In addition, S. em- 

 pusa 10-25 mm long occurred May-December in 

 the stomachs of Centropristis philadelphica col- 

 lected in conjunction with our study (Pa vela and 

 Ross 3 ); S. empusa were most abundant in these 

 stomachs in September and October. About 4-5 mo 

 elapsed between our first collection of gravid S. 

 empusa and their first appearance in C. philadel- 

 phica stomachs. These data suggest S. empusa 

 spawn over an extended period of time and spend 

 an extended time in the egg mass, propelagic, or 

 pelagic stages of development, as occur in other 

 closely related stomatopod species (Reaka 1979; 

 Senta 1967 and Pyne 1972 cited in Morgan 1980). 



Sex Ratios and Maximum Size 



The change in sex ratio we observed at 80 mm, 

 which is about the size at which females mature, 

 may reflect different mortality rates between the 

 sexes after maturity or growth cessation in larger 

 males. Our data do not permit a choice between 

 these possibilities. 



The maximum size of 132 mm that we observed 

 is similar to other maximum sizes for this species 

 reported from the northern Gulf (Hoese et al. 1968, 



120 mm SL; Christmas and Langley 1973, 145 

 mm). Much larger specimens have been reported 

 from the Atlantic coast north of Cape Hatteras, 

 N.C. (Bigelow 1941, 180 mm, type of length not 

 given). These geographic differences in maximum 

 sizes of S. empusa appear similar to differences in 

 size that are found in many fishes (White and 

 Chittenden 1977; Shlossman and Chittenden 1981; 

 Geoghegan and Chittenden 1982; Murphy and 

 Chittenden 4 ). Therefore, our findings may reflect 

 the zoogeographic change in population dynamics 

 that these authors suggest occurs in the area of 

 Cape Hatteras. Fishes, and possibly other taxa, as 

 our data on S. empusa suggest, show smaller sizes, 

 shorter life spans, higher mortality rates, younger 

 age at maturity, more rapid turnover of biomass, 

 and greater ability to avoid growth overfishing 

 (see Gulland 1980) in the warm-temperate Caro- 

 linean Province waters of the Gulf of Mexico and 

 South Atlantic Bight than do their conspecifics 

 and congeners in the cold-temperate waters north 

 of Cape Hatteras. 



Acknowledgments 



We wish to thank M. Burton, T Crawford, J. 

 Pavela, J. Ross, B. Slingerland, H. Yette, and Cap- 

 tains P. Smirch and A. Smircic for their assistance 

 in field collections. R. Case, M. Cuenco, and J. 

 Cummings wrote and assisted with computer pro- 

 grams. Paul Haefner and Robert Stickney re- 

 viewed the manuscript. Financial support was 

 provided by the Texas Agricultural Experiment 

 Station; by the Strategic Petroleum Reserve Pro- 

 gram, Department of Energy; and by the Texas 

 A&M Sea Grant College Program, supported by 

 the NOAA Office of Sea Grant, U.S. Department of 

 Commerce. 



Literature Cited 



alverson, d. l.. and m. j. Carney. 



1975. A graphic review of the growth and decay of popula- 

 tion cohorts. J. Cons. Int. Explor. Mer 36:133-143. 



BIGELOW, R. P. 



1941. Notes on Squilla empusa Say. J. Wash. Acad. Sci. 

 31:399-403. 



Caldwell, R. L., and H. dingle. 



1976. Stomatopods. Sci. Am. 234(11:80-89. 



Camp, D. K. 



1973. Stomatopod Crustacea. Memoirs of the Hourglass 

 Cruises, Fla. Dep. Nat. Resour., Mar. Res. Lab., St. 



3 J. S. Pavela and J. L. Ross, Research Associates, Department 

 of Wildlife and Fisheries Sciences, Texas A&M University, Col- 

 lege Station, TX 77843, pers. commun. April 1982. 



4 Murphy, M. D., and M. E. Chittenden, Jr. 1982. Reproduc- 

 tion, movements and population dynamics of the Gulf butterfish, 

 Peprilus burti. Unpubl. manuscr. Florida Department of 

 Natural Resources, Marine Research Laboratory, 100 - 8th Ave. 

 SE, St. Petersburg, FL 33701. 



425 



