Spawning behaviour of barred spiny eel, Macrognathus pancalus, in the River Gomti, India

Abstract

SummaryThe present study investigated the spawning behaviour of the spiny eel, Macrognathus pancalus, and its relationship with the environment (photoperiod and temperature). The results show that M. pancalus breeds during February to September with peak spawning during February/March and July/August, indicating two main breeding periods. Initiation of breeding occurs during increasing day lengths in early spring (February/March), and regression during decreasing day lengths in autumn (September/October). The breeding status confirmed by gonadosomatic index (GSI) and ovarian histology showed six stages of ovarian maturation (viz. stage I: chromatin nucleaolar; II: perinucleolar; III: cortical alveolar; IV: vitellogenesis; V: ripe; and VI: partially spent), with predominance of one or more stages at a particular time of the year. Males also followed a similar seasonal pattern in gonadal maturation as reflected by their GSI. Results show that M. pancalus is a seasonal breeder with bimodal spawning activity. The breeding pattern suggests an influence of prevailing day length conditions at this latitude.

Investigations on Gonadosomatic Index and Gonad Histology of Barred Spiny eel Macrognathus pancalus Hamilton, 1822 from Upper Assam, India

“…Investigations on Gonadosomatic Index and Gonad Histology of Barred Spiny eel Macrognathus pancalus Hamilton... variations may be due to the influence of day length on spawning activity. The notion may hold true as the environmental conditions reported by Zahid et al (2013) are in contrast to our study and that of Abujam and Biswas (2020). Variations in reproductive traits in different geographical regions and habitats, therefore, warrant further studies to confirm their semelparous or iteroparous nature in M. pancalus.…”

“…However, their observation was based on specimens collected from different habits in contrast to the present study. Furthermore, contradictory results of the spawning period were reported earlier by Zahid et al (2013) in M. pancalus. They reported two main breeding periods in M. pancalus; one during February/March and the other one in July/ August.…”