Reproductive Potentials of Brycinus nurse (RUPPELL, 1832) in Goronyo Reservoir, Sokoto State, Nigeria

A reproductive study is an important aspect of stock assessment. It describes the reproductive strategy and potential of fish in the aquatic ecosystem. Nearly all fish reproduce sexually, and most species have separate sexes (male and female). Those without separate sexes avoid self-fertilization by producing sperm and eggs at different times. Fecundity is described as batch fecundity, breeding season fecundity, life time fecundity, relative fecundity, or absolute fecundity in the stock assessment studies. The objective of this study was to describe the reproductive potentials of B. nurse in Goronyo reservoir, Sokoto state, Nigeria. The ovarian maturation stages of Brycinus nurse specimens were determined by using a single standard protocol. The gonads were removed and weighed, and the fecundity and GSI estimations were carried out. Data was analyzed in descriptive statistics, t-test, and compared using ANOVA at (P< 0.05) level using Excel sheets and SPSS version 25. The study revealed a sex ratio dominated by bigger males sampled between June and August, with more male specimens at Stage III and female specimens at stages IV and VI of gonad maturation. Similarly, the highest mean Gonado-somatic Index (GSI) values were recorded in June to September in male Brycinus nurse specimens, and lower mean GSI values were recorded in August, indicating this was the period the species spawns. The mean fecundity was highest from August to October in gravid Brycinus nurse specimens. In conclusion, this species spawns in August and has high reproductive potential in the Goronyo reservoir. The study revealed a strong fecundity and total somatic weight relationship in Brycinus nurse, therefore confirming somatic weight as the best indicator of fecundity. The study recommends the adoption of a closed season management strategy between June and October to allow an uninterrupted breeding activity of this species in Goronyo reservoir.