Growth pattern and condition factor of <i>Brycinus nurse</i> (Ruppell, 1832) in the Goronyo Reservoir, Sokoto State, Nigeria

Studies on length-weight-relationship (LWR) and Fulton’s condition factor (k) aspects of stock assessment explain fish patterns of growth, estimation of fish biomass from length observations and understand the welfare status of a given fish species in the aquatic habitat. The paucity of information on growth patterns and k of Brycinus nurse species in the Goronyo reservoir makes it difficult to develop strategies for sustainable management of the species. Three (Rimawa, Katsira and Kaita) landing sites were selected for monthly data collection for two years. About 763 specimens were sampled for data collection on LWR and k using standard procedures. Data were analyzed descriptively using frequency distribution and regression analysis conducted in order to establish relationship between length and weight of the sampled fish. The results revealed that B. nurse total length ranged from 7.13 to15.47 cm with a mean weight ranging from 30.69 ± 7.43 g to a maximum of 113.36 ± 5.29 g among unsexed specimens in August. The mean seasonal b values of the LWR exhibited isometric (b = 3.00, male), positive (b = 3.88, female) and negative (b = 1.20, male) allometric patterns of growth. The goodness of fit of the LWR ranged from R2 = 0.90 to R2 = 0.94 in males and females respectively. The mean k values ranged from 0.16 to 1.80 in males in October. The study concludes that, majority of the species exhibited small to medium size ranges, isometric and allometric patterns of growth and are overfished in the reservoir. Therefore, the study recommends the suspension of catching the species by the fishermen for two years in order for the species to attain its full-size potential in the reservoir.