Assessment of reproductive organs of Varanus salvator harvested from Riau Province, Indonesia

Abstract

Background More than half of Indonesia’s national harvest quota for Varanus salvator originates from Sumatra, with Riau Province ranking among the top five contributors on the island. BRIN research has been conducted in two major provinces in Sumatra (North and South Sumatra), but not yet in Riau. The limited research on V. salvator in Riau prompted the authors to examine whether commercial monitor lizard harvesting in Riau is sustainable.
Objective This study aimed to examine the sexual dimorphism, reproductive organs, population reproductive rates, and body size morphometrics of V. salvator from Riau Province, Indonesia.
Methods A total of 660 V. salvator were measured for snout–vent length (SVL) and body mass. For reproductive conditions, we conducted direct gonadal inspections after the animals were slaughtered and skinned. The recorded parameters included sex and gonadal condition (testes or ovaries) to assess sexual maturity and reproductive trends within the harvested population. All animals were euthanized following standard animal welfare procedures by staff at the slaughterhouse.
Results The sex ratio of the study population was 58.48% males (n = 386) and 41.52% females (n = 274). Analysis of reproductive organs, including SVL and body mass, showed that males were larger than females. Females reached reproductive activity at approximately 40 cm SVL, as indicated by the presence of developing follicles. Males of similar SVL exhibited enlargement of the right testis, suggesting the onset of reproductive maturity.
Conclusion Assessment of the reproductive organs of V. salvator harvested from Riau Province, Indonesia, the larger the male body size, the longer the SVL and the larger the testis size, likewise for females, the larger the body size, the longer the SVL and the larger the secondary follicles obtained.