Reproductive biology of the crab Matuta planipes (Fabricius, 1798) in the coastal waters of the Persian Gulf (Hormozgan province)

Abstract

Introduction: This research was conducted in order to estimate the homogeneity, determine
the sex ratio and determine the spawning season of the crab M. planipes in the waters of the
Persian Gulf (Hormozgan province).
Materials & Methods: In this study, 286 samples of Matuta planipes crabs (Fabricius,
1798), including 136 male crabs and 150 female crabs in the coastal waters of the Persian
Gulf (Hormozgan province), were collected monthly from July 2018 to May 2019 and It was
recorded biometric data and some aspects of its reproduction were studied.
Results: The results showed that the annual male: female sex ratio of this species is not 1:1
and female crabs were more dominant with 52.3%. Also, the sex ratio of male: female crabs
in different carapace width classes had significant differences. All stages of ovarian
maturation were observed throughout the year. The abundance of egg-bearing crabs (stage 5
of ovarian maturity) in all months of the year indicates that this species is capable of
continuous spawning year around, but according to the abundance of female crabs in stage 4
of maturation, as well as the gonadosomatic index, the peak of spawning for this species, in
the region is from end of winter to spring. The homogeneity rate of egg-bearing females
showed that in this species, each female with a carapace width between 22-50 mm can
produce 5972-357110 eggs. The average number in this study was estimated to be 87996
eggs. The results also showed that the minimum size of this species that reaches sexual
maturity is 33 mm in carapace width and the length at which 50% of female crabs reach
sexual maturity is estimated to be 37 mm in carapace width.
Conclusion: Given the recorded results of this study, the ovigerous females are seen
throughout the year and the monthly changes of gonadosmatic index in the female indicate
that spawning peak occurred in the spring.