Reproduction and Development of Sebastodes paucispinis and Comparison with Other Rockfishes off Southern California

The elongate paired testes of Sebastodes paucispinis consist of numerous tubules radiating from a single sperm duct that extends along the surface of each testis. The paired sperm ducts converge at the posterior ends of the testes to form a single median duct which continues into the urogenital papilla, a probable intromittent organ. The ovaries are paired fusiform structures consisting of dense stroma and ovigerous tissue surrounded by a thin-walled muscular sac that also serves as a gonoduct. These ducts unite posterior to the ovaries to form a duct which exits between the anus and the urinary papilla. An unusual vascular system insures that the gonads receive a large and even supply of arterial blood. The testes of S. paucispinis are small during the early stages of spermatogenesis which take place from January to May. During the final stages of spermatogenesis (June-September) the testes enlarge and become pale white. Spermatogenesis terminates in September at which time the mating period probably begins. The ovaries undergo greater seasonal changes than the testes. Ovaries are small during the post-extrusion period from March to June. Vitellogenesis, which begins in July and continues throughout the summer, causes the ovaries to enlarge and become opaque yellow. The first pregnant females appear in October. In early gestation ovaries are translucent yellow but gradually they become darker as the embryos develop melanistic pigment. Females begin to give birth to their first brood in November. Maturation, fertilization, and development of a second brood follows immediately. Most females have gestated and released their second brood by March. The embryonic stages of S. paucispinis are similar to those of oviparous marine teleosts and specialized structures for nutritional and respiratory exchange are not developed. Gestation lasts about one month and the young are born as hatched, yolkless larvae, 4-6 mm long, with well-developed eyes, jaws, and pectoral fins. The larvae occupy the upper mixed layer and have a wide geographical distribution. They transform into juveniles at about 30 mm SL and move into shallow waters (usually less than 20 m) where they spend their first year. The gonad cycles of other species of Sebastodes are similar to that of S. paucispinis. Although most of the species examined gestate and give birth to young during the winter off southern California, species of one group (S. rosaceus and relatives) gestate and extrude young during t