Maturation,fecundity, and spawning strategy of the thornback ray, <Emphasis Type="Italic">Raja clavata</Emphasis>: do reproductive characteristics vary regionally? |
| |
Authors: | Bárbara Serra-Pereira Ivone Figueiredo Leonel Serrano Gordo |
| |
Institution: | 1.Unidade de Recursos Marinhos e Sustentabilidade,Instituto Nacional de Recursos Biológicos I.P./IPIMAR,Lisbon,Portugal;2.Centro de Oceanografia, Departamento de Biologia Animal,Faculdade de Ciências de Lisboa,Lisbon,Portugal |
| |
Abstract: | In Portuguese waters, thornback ray Raja clavata spawns mainly between May and January, although females and males in spawning condition are found throughout the year. The
maturation process can be divided into three main phases by using information on gonad weight, oviducal gland and uterus width
in females and on gonad weight, clasper length and sperm duct width in males. Females attain length-at-first-maturity at 784 mm
and males at 676 mm, at ages of 7.5 and 5.8 years, respectively. In females larger than length-at-first-maturity, a resting
stage was identified characterized by low gonadosomatic index and well-developed oviducal glands and uteri. These results
along with the low proportion of adult females that are effectively reproducing per month demonstrated that the thornback
ray cannot be considered a continuous spawner as described in other studies. Fecundity was determinate with about 35 eggs
released per batch. During the spawning season, a total of four batch episodes occur indicating that the total fecundity was
approximately 136 eggs per female. Regional differences may exist in the reproductive strategy of the species, namely on the
duration of the spawning season, length-at-first-maturity, and fecundity, which can be related to a more intense fishing pressure
in northern European waters. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|