FISHERY BULLETIN: VOL. 75, NO. 1 



mature ovary, usually brownish orange to brown- 

 ish purple, is the concentration of large ova 

 (484-788 /u.m) containing large yolk granules 

 which make sectioning difficult. The size range of 

 these ova overlaps the mean diameter range of 

 extruded eggs (638-817 fim). 



The ovary is subdivided into lobes and possesses 

 a central hollow shaft or lumen as described for 

 Callinectes sapidus by Cronin (1942) and for 

 Portunus sanguinolentus by Ryan (1967). An 

 irregular matrix of compact germinal tissue, 

 surrounded by less compact zones of large ova, 

 borders the lumen. 



Redeveloping Ovaries 



The presence of developing ova in germinal 

 zones of ovaries suggests that oogenesis continues 

 after ovulation. Such redevelopment is indicated 

 by the range of ovarian developmental stages 

 observed in crabs known to have ovulated. Ovaries 

 from seven ovigerous crabs with egg remnants 

 resembled the early to advanced stages described 

 above. Mean values and ranges of horn width, 

 ovary volume, and gonad index reflect the wide 

 variety of stages of redevelopment (Table 1). 



In ovaries from nine ovigerous crabs and seven 

 females with egg remnants on the pleopods, 

 germinative zones were clearly evident (Figure 

 4 A) but the ovary was less compact than that of the 

 mature or ripe ovary as the interstices were filled 

 with connective tissue (Figure 4B). The ova were 

 more variable in size within a given developmen- 

 tal stage. Relatively large ova (388 jitm) can be 

 found in an early stage ovary while unusually 

 small ova (168 /xm) are numerous in an advanced 

 ovary. 



Incidence of Ovarian Development 



A relationship exists between size of female and 

 ovarian development (Figure 5). Eighty-eight 

 percent of all crabs =£75 mm CL (91 mm CW) 

 possessed ovaries in early stages of development; 

 90% of the females >75 mm were in intermediate 

 to advanced stages of ovarian development. Early 

 developmental stages can occur in large crabs, 

 particularly after recent ovulation. This is evident 

 from the distribution of ovigerous crabs and those 

 with egg remnants on the pleopods. Such ovaries, 

 in redevelopment stages, can recede to early 

 developmental stages. 



Size at Sexual Maturity 



Hartnoll (1969) regarded a crab as mature 

 "when it enters the intermolt during which it is 

 first able to copulate successfully." It is generally 

 accepted that in brachyurans maturity in some 

 females cannot be determined from the condition 

 of the gonads because development and ovulation 

 often occur a considerable time after mating. 



In the case of red crabs, several criteria were 

 examined in an effort to define the size (age) at 

 which females mature. These included the size 

 distribution of ovigerous and nonovigerous fe- 

 males, the incidence of physical indicators of copu- 

 lation, and changes in the features of the vulvae 

 and abdomen. 



Ovigerous Females 



The size-frequency distribution of 755 females 

 captured in November 1974, September 1975, and 

 January 1976 reveals the incidence of ovigerous 

 individuals and those with egg remnants on the 

 pleopods (Figure 6). In November and September, 

 27.3% and 15.7%, respectively, of females 3=71 mm 

 CL (97 mm CW) were ovigerous; 9.0% of females 

 2*71 mm in September carried egg remnants. In 

 January, 25.5% of females 2=71 mm CL were 

 berried; two of these showed some evidence of egg 

 hatching. Most (94%) of the ovigerous individuals 

 and those with egg remnants were between 71 and 

 1 13 mm CL (97-131 mm CW); only four crabs were 

 smaller. 



Physical Evidence of Copulation 



In numerous species of crabs, recent copulation 

 by the female is indicated by the presence of a 

 hardened mass of spermatozoa and associated 

 secretions protruding from the vulvae (Hartnoll 

 1969). This so-called sperm plug does not occur in 

 Geryon quinquedens . 



The exoskeletons of red crabs that have not 

 recently molted are blackened or discolored in 

 abraded or damaged areas and are usually in- 

 fested with lepadid barnacles Trilasmis sp. The 

 association of lepadids and discoloration serves as 

 an indicator of a time lapse since the last molt, 

 although the exact length of time cannot presently 

 be determined. It was reasoned that abrasion and 

 damage of vulval margins due to copulation would 

 result in similar discoloration. This was verified 



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