Sexual maturity, fecundity and embryonic development of the spiny dogfish, Squalus acanthias, in the eastern Mediterranean Sea

• Main Authors: Chatzispyrou, A., Megalofonou, P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: spiny dogfish; Squalus acanthias
• Online Access: https://pergamos.lib.uoa.gr/uoa/dl/object/uoadl:3010705

The reproductive biology of the spiny dogfish, Squalus acanthias, was investigated throughout a year, in the eastern Mediterranean Sea. One hundred and eighty specimens were sampled of which 119 were females and 61 males, ranging from 320 to 755 mm and from 350 to 820 mm total length (TL), respectively. The minimum size of mature females was 515 mm and 470 mm TL for mature males (smaller compared with sizes in other studies). Gonadosomatic index (GSI) and hepatosomatic index (HSI) were higher during June and August in female dogfish, respectively; in males GSI had a peak in July and HSI showed its highest value in April. A total of 39 gravid females was identified with TL ranging between 570 and 755 mm. Only 28 of them were bearing embryos; candled uteri were observed in the 11 other gravid animals. A positive relationship was recorded between maternal length and litter size. Ovarian fecundity ranged between 1 and 6 (mean 2.1 1.1); uterine fecundity ranged from 1 to 6 (mean 3.3 1.2). The size of the pups varied from 72 to 220 mm TL and their weight ranged between 1.6-48.5 g (mean 11.7 8.6). The spiny dogfish was compared with fish from other study areas and was found to be smaller in size in the eastern Mediterranean Sea, reaching maturity at smaller sizes and obtaining lower fecundity than female fish in other areas.