2024/10/30 by Gandega, Cheikhna Yero, El Omrani, Nassima, Bensmira, Meriem +7
#fishing #pêche #reproduction
paper · doi:10.60881/bszf149-3-1
This study focuses on three fish species in Foum-Gleita Lake (Mauritania): Clarias gariepinus, Oreochromis niloticus and Bagrus bajad. Both growth and reproduction of these three species are investigated. Growth parameters are used to determine median sexual maturity size and the reproduction periods during an annual growth cycle. Knowledge of the population parameters of these fish is relevant to their exploitation, growth rate data is used to estimate size distributions and fishing impacts on each fish population. Catch seasons and the minimum catch size for populations of each species were obtained to assist in better stock management. The studied species stocks were sampled and caught specimens were measured for total length, fork length, and total body weight. Evisceration of fish enabled the determination of sexual maturity by examining and weighing the gonads; food availability was assessed from prey in the alimentary bolus. Male Clarias gariepinus growth rate (k=0.16) was higher than for females (k = 0.12). This growth difference was confirmed by the growth performance indicator, phi. The same scenario was observed in Oreochromis niloticus. However, the opposite scenario occurred in Bagrus bajad where female growth rate tended to out-perform that of males. Clarias gariepinus showed two well-marked seasonal growth modes with total lengths of about 40 cm during January to July and about 30 cm between September to December in males. But in females the two seasonal growth modes were around 43 cm from January to August and around 40 cm from September to December. For both sexes of Oreochromis niloticus, the two modes of seasonal growth were well marked at between 20 and 30 cm from August to December. Bagrus bajad did not show well marked seasonal growth modes at all; likely due to an artefact linked to the low numbers per size class of the male individuals sampled or to environmental factors. These results are compared to data from elsewhere and collectively they contribute useful biological indicator data relevant to supporting new policies for the rational management of freshwater fishery resources in Mauritanian lakes.