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ALEC G. MAULE 



■/ Cooperative Fisheries Research I 'nit 

 Department of Fisheries and Wildlife 

 Oregon State I 'nil ersity 

 Corvallis, OR 97331 



HOWARD F. HORTON 



Department of Fisheries and Wildlife 

 Oregon State University 

 CorvaUis, OR 97331 



BATHYMETRIC DISTRIBUTION, SPAWNING 



PERIODICITY, SEX RATIOS, AND SIZE 



COMPOSITIONS OF THE MANTIS SHRIMP, 



SQUILLA EMPUSA, IN THE NORTHWESTERN 



GULF OF MEXICO 1 



The mantis shrimp, Squilla empusa, ranges in the 

 western Atlantic Ocean from Maine through the 

 Gulf of Mexico (Gulf) to Surinam (Manning 1969). 

 This stomatopod occurs in high-salinity waters 

 (Gunter 1950; Franks et al. 1972) and is one of the 

 more common macrocrustaceans in the northern 

 Gulf (Hildebrand 1954). Squilla sp. may be impor- 

 tant predators of other crustaceans, polychaetes, 

 and fish (Camp 1973; Caldwell and Dingle 1976), 

 but they also serve as food for many fishes includ- 

 ing Rachycentron canadum, Lutjanus cam- 

 pechanus, Sciaenops ocellatus, Micropogonias un- 

 dulatus, and Rhomboplites aurorubens (Knapp 

 1951; Moseley 1966; Overstreet and Heard 1978a, 

 b; Grimes 1979). 



Despite its importance, little detail is known of 

 the life history of Squilla empusa. The pelagic 

 larval stages have been described (Morgan and 

 Provenzano 1979; Morgan 1980), and much infor- 

 mation has been published recently on the 

 worldwide zoogeography and distributional in- 

 terrelationships, evolutionary ecology, and life 

 history patterns of stomatopods, primarily coral- 

 dwelling taxa ( Reaka 1979, 1980; Reaka and Man- 

 ning 1980). However, the latter information does 

 not deal with S. empusa, and it may not be valid to 

 extrapolate to this species. Reaka (1979: table 5) 

 reported that the coral-dwelling taxa were long- 

 lived and gave estimates of 26-34 yr to reach me- 

 dian size (using mean growth increments and 

 mean molting frequencies), 12-14 yr (using mean 

 growth and maximum molting), or 4-8 yr (using 

 maximum growth and molting). Although we 

 could not determine age of S. empusa readily from 

 length-frequency analysis, a much shorter 

 maximum life span (1-3 yr) is part of what appears 

 to be a common pattern of population dynamics in 

 the white and/or brown shrimp communities 

 where S. empusa occur (Chittenden and McEach- 

 ran 1976; Chittenden 1977). 



This paper describes bathymetric distribution, 

 size at maturation, spawning periodicity, sex 

 ratios, size compositions, and morphometric rela- 

 tionships for S. empusa collected in the north- 

 western Gulf during routine trawling operations. 



418 



-</!(/ 



technical article TA 18359 from the Texas Agricultural Ex- 

 periment Station, Texas A&M University, College Station, TX 

 77843. 



FISHERY BULLETIN: VOL. 82, NO. 2, 1984. 



