group, as pointed out by Lunz (1958), repre- 

 sentatives were collected but were not identi- 

 fied positively. These individuals, primarily 

 juveniles, were too small (usually less than 

 100 mm.) to be of commercial importance and 

 were not marketed. Occasionally the stone 

 crab, Menippe mercenaria , and the portunid, 

 Arenaeus cribrarius , were taken in the pot 

 fishery. These forms were not culled from the 

 catch but were marketed as edible crabs. 



Sex Composition 



Females made up the majority of the com- 

 mercial catch in the fishery of the lower St. 

 Johns River and males dominated in the upper 

 river. In Area 1, the sex ratio varied with the 

 season and between the area's upper and lower 

 reaches. In the vicinity of New Berlin (fig. 1), 

 for example, females made up 60 to 90 percent 

 of the catch from January through September 

 but only 10 to 25 percent from October through 

 December. In the vicinity of Jacksonville, the 

 percentage of females decreased from 75 per- 

 cent in January and February to between 15 

 and 40 percent from April through October, 

 and increased again to 75 percent in December. 

 The ratios of females to males in Areas 2 and 

 3 varied little by location within the areas. 

 The percentage of females in Area 2 shifted 

 during the year from 10 to 35 percent, and 

 in Area 3 from 5 to 3 5 percent. 



Sponge crabs (females carrying an egg mass 

 on the abdomen) were not seen in Areas 2 and 

 3 and generally were not common in the vicinity 

 of Jacksonville in Area 1. Downriver from 

 Jacksonville in the vicinity of New Berlin, 

 however, the majority of the female crabs 

 caught from April through September had 

 sponges. 



Width Distribution 



Data on widths of crabs captured by pots, 

 grouped into 10-mm. size classes, indicated 

 that crabs 160-169 mm. were most commonin 

 catches from Area 1. Average widths of crabs 

 were 157.9 mm. for Area 1, 155.4 mm. for 

 Area 2, and 166.3 mm. for Area 3. The larger 

 crabs (greater than 169 mm.) were most 

 numerous in the pot catches of Area 3 and the 

 smaller crabs (less than 150 mm.) were most 

 common in the pot catches of Area 2 (fig. 7). 

 The width of 16.5 percent of the crabs from 

 Area 3 was 190 mm. or more. The largest 

 crab measured was .a 246-mm.-wide male 

 from Lake George. 



Widths of trawl- caught crabs had essentially 

 the same width-frequency distribution as the 

 crabs captured by pots in Area 1 (fig. 8). 

 Differences are primarily the result of a 

 greater percentage of crabs less than 120mm. 

 in the trawl catch. 



CARAPACE WIDTH (MM.) 



Figure 7. — Width distributions of blue crabs caught by the 

 pot fishery of Areas 1-3, St. Johns River, 1961-62. 



CARAPACE WIDTH (MM.) 



Figure 8. — Width distributions of blue crabs caught by the 

 trawl fishery, St. Johns River, 1961-62. 



Width-Weight Relation 



Crabs that were weighed from the commer- 

 cial fishery were grouped by 5-mm. width 

 intervals, and the average weight was deter- 

 mined for each group. Individuals 100-mm. 

 wide averaged 61 g. for males and 59 g. for 



