The study evaluated some population parameters of Polydactylus quadrifilis within Ebrié lagoon (Potou sector). Samples were obtained using artisanal gillnet fishery from April 2004 to March 2006. A total of 741 individuals of P. quadrifilis ranged from 11 to 70 cm were examined. Population parameters were estimated where asymptotic length (L∞) was found 60 cm, growth rate (K) 0.33 per year, the longevity (T max) 9.09 years, and growth performance index (Φ′) 3.06. The length at first capture (Lc50 = 10.60 cm) was lower than the length at first maturity (Lm50 = 40 cm). Total mortality rate (Z) was calculated as 1.10 per year including natural mortality and fishing mortality. The exploitation rate (E=0.36) was found to be less than the maximum exploitation rate (E max = 0.44) and indicated that P. quadrifilis is not overexploited. The current exploitation rate should be maintained by sustainable fisheries measures including monitoring of fishing effort.

Background and Objectives: Marine catfish are abundant in the bays of Tabounsou and Sangareah in Republic of Guinea, but the knowledge on their biology is still scanty. The reproductive biology of Arius latiscutatus Günther, 1864 and A. gigas Boulenger, 1911 was studied through monthly sampling, from January to December 2016. Methodology: Fish were caught using gill nets in several sampling sites. Five gonadal stages were described, based on macroscopic observation of gonad form, size, weight, color and oocyte diameter. Results: The population was dominated by males (61%) in A. latiscutatus and females (53%) in A. gigas, showing a sex-ratio of 1:1.54 (Chi-square, P < 0.05) and 1:0.88 (P > 0.05), respectively. The length-weight relationship was a positive allometry for A. latiscutatus and A. gigas, and males (35.37 and 35.47 cm, respectively) reached first maturity earlier than females (39.7 and 40.8 cm, respectively). Changes in the gonadosomatic index (GSI) and in stages of gonadal development showed that A. latiscutatus spawned between April and October, while A. gigas spawned in May to November. The peak of condition factor was observed in June (0.68±0.05) and July (0.55±0.04) in females of A. latiscutatus and A. gigas, respectively. Conclusion: Both species, having only one annual breeding season, A. latiscutatus spawns earlier than A. gigas. Coastal fisheries should be restricted in cold season to preserve the ability of broodstock renewal for these species.

Aims: This study investigated Length-weight relationships and condition factors of fish species in Ebrie Lagoon (Aghien-Potou sector, Côte d’Ivoire) Place and Duration of Study: Ebrie Lagoon (Aghien-potou sector) from April 2019 to March 2020. Methodology: study was conducted during 3 to 4 days continuously in Ebrie Lagoon (Aghien-Potou Sector). Furthermore, monthly fish samples were collected from commercial fishing area at random using gillnets, cast nets, traps, hooks and beach seines. Results: All Length-Weight regressions were highly significant with the coefficient of determination (r2) ranging from 0.61 in Schilbe mandibularis to 0.90 in Monodactylus sebae and Chrysichthys maurus. An isometric growth was observed for most of species except three of them namely Ethmalosa fimbriata, Pseudotolithus elongatus, and polydactylus quadrifilis. The k values varied from 0.19±0.001 in S. melanotheron to 6.10±0.3 in Monodactylus sebae. The values of b and k denote that the Ebrie lagoon could provide a favourable environment and suitable habitat for the growth of those fish species. Conclusion: The study provides basic information on length-weight parameters for twenty major fish species collected from Ebrie lagoon (Aghien-Potou sector). Three species namely Ethmalosa fimbriata, Pseudotolithus elongatus and Polydactylus quadrifilis exhibited a trend of positive growth whereas seventeen fish species showed isometric growth. The condition factor k was superior to 1 for 75% of the fish species and inferior to 1 for 25 % of the fish species. These growth trends denote that the lagoon could provide a favourable environment and suitable habitat for the growth of those fish species. Thus it would be interesting to create a protected area near the lagoon in order to ensure the protection of fish species.