Life-history, reproductive biology and sexual pattern of the Creole fish, Paranthias furcifer (Valenciennes, 1828) (Pisces: Serranidae).

摘要

The overall objectives of this study were to determine the basic population parameters of the Creole fish, Paranthias furcifer (Valenciennes) (Pisces, Serranidae) from southwestern Puerto Rico, and to compare those with a generalized model and expected trends for groupers'. The specific objectives were to examine its sexual pattern, determine the age/size structure of the stock, derive back-calculated estimates of growth, provide information on the instantaneous rate of total and natural mortalities, and to characterize its reproductive biology (i.e. annual cycles of gametogenesis, sexual maturation and spawning, fecundity). A total of 921 specimens, ranging from 108 to 225 mm fork length (FL), were collected from March 1992 to December 1993. Color pattern, length, weight, and sex of each individual were determined. Out of 555 gonads histologically examined, 296 (53.3%) were ovaries, and 254 were testes (45.8%). Five gonads were in a mixed gametic stage (0.9%), but only two were considered as possible transitionals. The structural organization in all testes was very similar to ovaries, with a central lumen and aciniform arrangement of cysts, which strong!y suggests that these were derived from an initial ovarian stage. Length-frequency distributions of females (mean = 177 mm FL, N = 522), males (179 mm FL, N = 397), and possible transitionals (178 mm FL) overlapped, with no statistically significant difference in mean length between sexes, nor within sexes throughout the year. Females and males occurred at a ratio close to unity in most of the size classes and months sampled; however, the overall sex ratio was significantly female-biased (56.7%). An observed decline in sex ratio during the reproductive season (November-December) suggested sexual segregation associated with depth. There were notable and permanent differences between the sexes in coloration of the distal margins of medial fins: red in females and yellow in males. Group spawning was suggested by the presence of large testes when ripe (up to 15.7% of total body weight). Based on available evidence, gonochorism appears to be the main sexual pattern of the Creole fish, with the possibility that a small number of males were derived through sex change of adult females. A sample of 522 females and 397 males was used to characterize reproductive biology. Five stages of gonadal maturity were defined for each sex. The smallest mature female was 144 mm FL, while the smallest mature male measured 138 mm FL. Ripe females and males numerically dominated samples of November and December. Spent fish were captured in January and February. Sexually inactive specimens were noted from March to April. Spawning occurred in two peaks associated with full moons of November and December. Examination of oocyte-diameter frequency distribution and total fecundity data suggested that unyolked oocytes recruit into the early vitellogenic stock after the first spawning event; therefore, the Creole fish appears to be an indeterminate spawner. (Abstract shortened by UMI.).