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Fishery Bulletin 103(3) 



Jan Feb Match April May June July Aug Sept Ocl Nov Dec 



Figure 2 



Monthly changes in male thorny skates (A. radiata): (A) The mean 

 percent of each stage of spermatogenesis (stages III through VI) 

 found along a transect line across one representative full lobe 

 cross section of a testis; (B) hepatosomatic index (HSI) and; (C) 

 gonadosomatic index (GSI). Sample sizes are indicated above each 

 month. Values are expressed as mean ±SEM. 



(Scyliorhinus canicula) (Henderson and Casey, 2001), 

 ovary weight and egg deposition peaked during spring. 

 Similarly, several morphological parameters and steroid 

 hormones have been shown to peak in female winter 

 skates (Leucoraja ocellata) during the summer, and 

 egg-case production is highest in the fall (Sulikowski 

 et al., 2004). Lastly, in L. erinacea, examination of fol- 

 licle dynamics and egg-case production indicated that a 

 higher proportion of females are reproductively active 

 during two periods of time in the reproductive cycle: in 

 the winter and in the summer (Richards et al., 1963). 



The fairly consistent pattern of HSI in female thorny 

 skates over the reproductive cycle indicated that liver 



reserves (such as lipids and proteins used for oocyte 

 growth) were stored and metabolized continuously 

 throughout the year without a significant change in 

 whole organ biomass. This is in contrast to other ovip- 

 arous species, such as S. canicula, which displayed 

 seasonal variations in liver mass as a result of lipid 

 deposition occurring during different times of the re- 

 productive cycle (Craik, 1978). 



The continual presence of mature spermatocysts with- 

 in the testes over the entire sampling period indicateded 

 that male thorny skates are also capable of reproducing 

 throughout the year. Information describing the annual 

 reproductive cycles of oviparous male elasmobranchs is 



