Abstract
A study on the reproductive strategy of Chrysichthys nigrodigitatus was conducted from October 2015 to August 2016, in the Nkam River in Yabassi, Littoral Region of Cameroon. For this purpose, 154 specimens of C. nigrodigitatus with total mean weight of 829.96 ± 829.58 g and total mean length of 367 ± 156 mm collected from artisanal fishermen were used. Twenty-nine (29) females at stage V of sexual maturity were selected for the evaluation of the fecundity. It appears that the oogenesis in C. nigrodigitatus is of an asynchronous type with multiple laying spread over a long period. The gonadosomatic index (GSI) peaks in June (17.9 ± 7.1 for females and 1.06 ± 0.27 for males). Hepatosomatic index (HSI) was higher in females than in males throughout the year. The mean condition factor K was 1.07 ± 0.09%. The breeding season occurred from April to October during the rainy season. Gonadosomatic and hepatosomatic indices were positively correlated with rainfall, contrary to the K factor, which has been strongly and negatively correlated with this physical parameter. The sex ratio of 1M: 1.5F was in favour of females, thus reflecting an “r” type reproductive strategy. Absolute fecundity was estimated at 1374 ± 1022 oocytes for individuals of 107.3 ± 111.9 g mean weight. Mean relative fecundity was 14 ± 3 oocytes/g of body weight. It was recommended that future work focuses on the captivity of this species.
Highlights
Fish is an extremely nutritious food, a vital source of protein and essential nutrients, especially for many low-income people around the world [1]
60 species of fish have recently been identified by Ajonina and Tomedi [15] in the Nkam River, amongst which the most abundant and much appreciated species was Chrysichthys nigrodigitatus, locally called “mayepe.” is fish species is the subject of many traditional recipes in households and restaurants, according to Ajonina and Tomedi [15], the consequence of which is the decrease of wild stocks. erefore, studies on the biology of this species is essential to better develop its breeding captivated
Three (3) increasing peaks were successively observed: November (1.05 ± 0.21), March (1.24 ± 0.49), and June (1.78 ± 0.56), while in males two (2) decreasing peaks were observed in November (1.41 ± 0.33) and in April (1.01 ± 0.27). e minimum values of Hepatosomatic index (HSI) were reached in December (0.84 ± 0.32) and in February (0.88 ± 0.15) in females and in March (0.64 ± 0.15) and May (0.48 ± 0.20) in males
Summary
Fish is an extremely nutritious food, a vital source of protein and essential nutrients, especially for many low-income people around the world [1]. In Africa, and in Cameroon, as reported by Cacot [3], fish farming has remained focusing on three species of fish: Clarias gariepinus, Oreochromis niloticus, and Cyprinus carpio. Erefore, studies on the biology of this species is essential to better develop its breeding captivated. Aspects of the biology of C. nigrodigitatus have already been the subject of several studies in West Africa, more in Ivory Coast, where captive breeding trials have been successfully tested by Djehi [16]. The general objective of this study was to evaluate some elements of the reproductive cycle of C. nigrodigitatus in view of its domestication, and it was to determine in this species the breeding period, sex ratio, and fecundity of this species depending on the endogenous and exogenous factors of the Nkam River
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