Observations on the reproductive biology of the angular rough shark, Oxynotus centrina (Oxynotidae)

Some aspects of the reproductive biology of the angular rough shark are des cribed in this paper from specimens collected in the Mediterranean (Tunisia n coasts and Gulf of Lion, Southern France) and in the Eastern Tropical Atl antic (Cape Verde Peninsula, Senegal). At sexual maturity, males and female s have attained a total length (TL) of 600 and 650 mm, respectively. Adult females were generally larger than males. The maximum TL for males and for females was 640 and 780 mm, respectively. The smallest gravid female observ ed was 730 mm TL. The angular rough shark is an aplacental viviparous speci es with two ovaries and two uteri, both of which are functional. Ripe oocyt es ready to be ovulated were large and heavy. Their average diameter was 39 .31 mm and their average weight was 24.45 g. Vitellogenesis of maturing ooc ytes did not coincide with gestation. Reproductive cycle could last approxi mately one year. Average weight and average TL of full developed foetuses w ere 69.65 g and 221.33 mm. Average weight and average TL of new born pups w ere 69.83 g and 228.33 mm TL. Birth probably occurred at a TL between 210 a nd 240 mm. The computed chemical balance of development (CBD) based on mean dry weights of new-borns pups and fertilised eggs was 1.36. The low CBD va lue was due to the fact that the angular rough shark was strictly a lecitho trophic species. Increase in weight especially among adults was more rapid in females which were generally heavier than males. This characteristic was related to the reproductive activities of the females. The liver is heavy and the hepatosomatic index (HSI) reached high values in all specimens. HSI is not subject to change with size except in females where it increased at the end of maturation and slightly decreased from July to September. Liver plays an important role in buoyancy rather than in elaboration of gonadic products. The gonosomatic index (GSI) reached high values in adults especia lly in females from July to September. The sex ratio of the total sample sh owed that males were slightly more numerous than females. The changes in se x ratio are related to sampling as well as to segregation of the sexes at d ifferent depths during certain stages of the reproductive cycle rather to a high rate of mortality in juveniles and adults according to the sex.