[2] 



tj- in «? i^- co en 



— m co ^ 



co tt m (O r— 



en o — cj co 



Total Length [mm) 



FKil'RK 6. Percentage of female Squilla empusa by size. Sam- 

 ple sizes arc 255-2.710 size class, except where indicated. 



50 60 70 80 

 Total Length (mm| 



Kiel KK i Length frequency imoving averages of three) and 

 cumulative percentage of all Squilla c/upusa collected off 

 Freeport, Tex. ..July 1979-June 1980. 



21-24 July 1980 day cruise when only one speci- 

 men was captured, mean sizes on each cruise 

 ranged between only 71 and 89 mm (Table 1). In 

 addition, 997c confidence limits for observations 

 also showed little variation during this period. 



Length-Weight- Width-Relationships 



Length-length, length-weight, and length- 

 width relationships are presented in Table 4. 

 Length-weight regression coefficients were sig- 

 nificantly different between the sexes (F = 5.03; 1, 

 9, 381 df; P < 0.051. However, the minor difference 

 ( b = 2.94 vs. 2.96) may have little biological mean- 

 ing, thus pooled regression statistics are also pre- 

 sented to simplify stock assessment. Calculated 

 length-weight regression coefficients significantly 

 exceeded (3 = 3.0 at a = 0.05 (data pooled, t = 

 -12.23; males, t = -5.89; females, t = -10.42). 



Discussion 

 Bathymetric Distribution and Diel Periodicity 



Squilla empusa occur on a mud or sandy-mud 

 bottom (Franks et al. 1972) as do several of its 

 congeners (Reaka and Manning 1980). This 

 species ranges on such bottoms across most of the 

 continental shelf in the northern Gulf. We cap- 

 tured S. empusa to depths of 86 m in agreement 

 with Hildebrand (1954) and Franks et al. (1972), 

 who captured specimens to 82 and 91 m, respec- 

 tively. Our findings that S. empusa were common 



TABLE 4. — Length-length, length-weight, and length-width regressions for Squilla empusa, sexes pooled unless 

 indicated, with supporting statistics. Measurements are in grams and millimeters. Size range for each equation is 

 26-132 mmTL. All regressions are significant at a = 0.001. Corrected total sum of squares is for y unless* is designated; ris 

 from Kicker's 1 1973 ) GM functional regression. See below for definition of symbols. 



'CL = Carapace length; TL = total length; AL = abdominal length; AW = abdominal wet weight; TW = total wet weight; AWD = abdominal width 



424 



