Temporal variation in length-weight relationship, growth and condition factor of Acentrogobius viridipunctatus in the Mekong Delta, Viet Nam

Abstract

The fish resource assessment has strongly related to their growth pattern estimated from fish length-weight relationship and condition factor, but these data on Acentrogobius viridipunctatus—a traded gobies in the Mekong Delta, Viet Nam have been limited. Consequently, the present study was performed for a year-round 2020 in order to provide knowledge on the length-weight relationship (LWR), growth and condition factor (CF) of this fish species. A total of 960 fish (432 females and 528 males) were caught at four coastal sites from Long Huu, Tra Vinh to Tan Thuan, Ca Mau. Due to high determination values of LWRs (r2 > 0.8), the fish weight could be estimated from a given fish length. Since the slope value (b= 2.64 ± 0.03) of LWR was <3 (p < 0.05), the goby exhibited negative allometry, implicating that practically fish was caught at a young age. The fish growth pattern did not vary with sex and size since males, females, immature fish, and mature fish displayed negative allometry. Likewise, this fish exhibited a negative allometric growth pattern in dry and wet seasons. The fish growth pattern did not vary with the studied site but changed with month, raging from negative allometry to isometry. The CF of males (1.04 ± 0.01) was significantly higher than that of females (0.99 ± 0.01) (t = 4.07, p < 0.001). Likewise, the CF in the wet season (0.96 ± 0.01) outnumbered in the dry season (1.09 ± 0.01) and was regulated by the season × site interaction (F = 53.60, p < 0.001). However, as the CF was close to 1⎯the well-being threshold, this fish adapted well to their habitat. The findings suggested that the size of fish caught should be increased for sustainable exploitation of this resource.