Early Development of the Sacramento Perch

摘要

Populations of the Sacramento perch Archoplites interruptus, California's only native centrarchid, are declining and early development of this imperiled species is poorly known. Therefore, the main objective of this study was to describe the early development of Sacramento perch from fertilization to initiation of exogenous feeding. Embryos were obtained in the laboratory by spawning induction via photoperiod-temperature control or gonadotropin-releasing hormone analog treatment. Gross morphology and histological analyses were integrated to describe the early development. Cleavage was synchronous until the 64-cell stage, which allowed us to calculate the duration of one mitotic cycle during early synchronous cleavage (蟿 sub(0)) as 10-16 min at 25.4-25.6 degree C. A description of histological events from time to morulation, gastrulation, hatch, and exogenous feeding larvae is provided. Yolk sac larvae tended to adhere to the spawning substrate or sediment during the critical organogenesis stages. Larvae swam up and began exogenous feeding within 4 d postfertilization. Primordial germ cells were observed in 10-d-old larvae, but sex differentiation occurred after 43 d. External sexual dimorphism was not observed in early life stages.