Evaluation of length-weight and length-length relationships of some of the most abundant commercial fishes from the Couffo River basin (Benin, West Africa)

Abstract

The Couffo basin is not well known, and neither are its aquatic living resources, such as fish fauna, which are subjected to high exploitation rates. The objectives of this study were to establish length-weight ratios (LWRs) and length-length ratios (LLRs) for the most important species in the catches and those of certain economic value. A total of 12,191 specimens belonging to 40 commercial species of actinopterygian fishes were caught with several fishing gears and methods between February 2018 and March 2021. Allometric coefficient b of the LWRs (BW = a × TL b ) ranged from 2.194 for Enteromius callipterus to 3.673 for Protopterus annectens with a mean of 2.902 ± 0.315. The growth of thirteen species was isometric, that of fourteen species was negatively allometric, and that of the remaining thirteen species was positively allometric. Coefficient of determination r2 for the LLRs of 39 of the 40 selected species mentioned above was significant and ranged from 0.781 in Gobionellus occidentalis to 0.997 in Elops senegalensis with a mean value of 0.951 ± 0.049. The results will be useful for further studies on assessments of population dynamics and the sustainable conservation of the already limited fish stocks in the Couffo River basin.

On the occurrence and distribution of Synodontis nigrita and Synodontis violaceus (Siluriformes: Mochokidae) in the Nilo‐Sudan, and Upper and Lower Guinea ichthyofaunal provinces

“…data, DDW)] and number of mandibular teeth [32–43 vs . 21–31 in S. obesus (data: Lederoun et al ., 2018)], these specimens are here all re‐identified as S. melanopterus [77.2%–84.0% and 33–47 mandibular teeth (data: Poll, 1971)], although the colour pattern shows strong intraspecific variation. Moreover, further research is needed to assess their conspecificity.…”

“…cf. obesus (Lederoun et al ., 2018). Nonetheless, based on the combination of their IOW (% L SN ) [64.2%–86.4% vs .…”

“…Instead, in a recent checklist, these were listed as S. cf. obesus (Lederoun et al, 2018). Nonetheless, based on the combination of their IOW (% L SN ) [64.…”

Physicochemical Quality of the Water and Heavy Metal Contamination of the Sediment, Water, and Flesh of Some Fish in the Lower Reaches of the Mono River (Benin, West Africa)

“…The Mono River rises in the Koura Mountains at Alédjo (9°21'N01°27'E) in northwest Benin and drains a catchment area of around 22,000 km 2 (Lévêque and Paugy, 2006) between latitudes 6°10' and 9°00' North and longitudes 0°30' and 1°50' East (Lederoun et al, 2018). Most of the basin lies within Togolese territory, but its lower reaches form the natural border between Togo and Benin over a distance of around 100 km.…”

“…During each sampling event, fish from the artisanal catches were sorted, identified beforehand, counted, and weighed using an electronic balance with a capacity of 2,000 g and a precision of 0.01 g. Two sets of specimens of each species were prepared, with one set being tagged and fixed in 10% formalin. This was done for laboratory confirmation of identification, following the methods outlined in Paugy et al (2003a;2003b) and Lederoun et al (2018). The other batch was packed, tagged, and stored in a cooler box with ice for metal assay in the laboratory.…”