Reproductive Biology of the Spiny Eel Macrognathus Pancalus Hamilton, 1822 From Upper Assam, India

Abstract

Reproductive biology of spiny eel Macrognathus pancalus Hamilton, 1822 was studied from the waterbodies of upper Assam, India. Sexual dimorphism was easily distinguished based on their body shape and colouration. Among the 467 fish samples examined, 312 males and 155 females were identified and the Male:Female (M:F) ratio ranged from 1:0.08 in November to 1:2.17 in June with overall sex ratio of 1:0.5. Five maturity stages were identified in a year and percentage distribution of each stage was calculated. The gonadosomatic index (GSI) ranged from 0.42 to 8.08 for females and from 0.33 to 1.25 for males. The length at 50% of the fishes attained maturity (Lm50) was 9-12 cm in males and at 12-15 cm in females, indicating males matures at moderately smaller size than their female counterparts. Ova diameter ranged from 0.3 to 1.3 mm; absolute fecundity ranged from 765.48 to 1691.96 and relative fecundity from 57.9 to 152.17. M. pancalus spawned once in a year with peak spawning between June and August.

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

“…The present investigation indicated an annual synchronous breeding pattern in M. pancalus in the study area. Similar findings were also reported by Abujam and Biswas (2020) and Faridi et al (2020). Earlier studies by Abujam and Biswas (2020) revealed almost similar trends in GSI peak values in M. pancalus during May and June for males and females respectively.…”

“…It is a sturdy fish inhabiting a variety of habitats including 'beels'/wetlands, small rivers, streams, canals, inundated fields, river plains and estuaries of Pakistan, Nepal, Bangladesh and India (Rahman, 1989;Talwar and Jhingran, 1991;Galib et al 2009). The species commands considerable market value as both food and ornamental fish in domestic and international trade (Suresh et al 2006;Abujam and Biswas, 2011;Raghavan et al 2013). Their entire demands, however, are met through wild catches from their native habitats (Suresh et al 2006).…”

“…It has been observed that along with unregulated catching practices, the impact of different anthropogenic activities including habitat modifications, construction of dams, invasive species introduction, overexploitation, etc. has had a profound impact on population dynamics of many freshwater fishes around the world including M. pancalus (Maitland, 1995;Abujam and Biswas, 2011). The persistence of these problems highlights time-bound interventions to prevent further declination of natural stocks.…”

“…Many authors have carried out studies on sexual dimorphism, reproductive strategies, feeding habits, induced breeding, etc. up to some extent in M. pancalus (Swarup et al 1972;Serajuddin and Ali, 2005;Abujam and Biswas, 2020;Borah et al 2020). However, a detailed study on the histology of gonads of M. pancalus is still lacking.…”

Aspects of reproductive biology of the lesser spiny eel Macrognathus aculeatus (Bloch, 1786) from river Ganga, Uttar Pradesh, India

“…Male dominancy over female may be due to accidental or natural mortality such as spawning stress of females in the population. reported by Abujam and Biswas (2011) and Kashyap et al (2016). However, it is worth mentioning here that several other workers (Qayyum and Qasim, 1964;Cardoso et al 2019) recorded the dominance of females over males.…”