Population Dynamics and Sustainable Management of the Blue Runner Caranx crysos (Mitchill,1815) within Côte d’Ivoire’s Coastal Waters

Abstract

Background and objectives: The blue runner Caranx crysos is exploited by artisanal marine fisheries but the knowledge on its population dynamic, is still sketchy. The present work was conducted to obtain information on population parameters and assess the stock of the species within Côte d’Ivoire’s coastal waters. Methodology: Fish were caught using gill nets in several sampling sites and then measured to the nearest mm and weighted to the nearest g. Data on fish length measurement were recorded during the period from April 2022 to May 2023, followed by the analysis of the recorded values with FiSAT. Results: The asymptotic length (L∞), the growth rate (K), the growth performance index (Ø'), the theoretical age (t0) and the maximum age (Tmax) obtained from length frequency data were 38.85 cm, 0.70 per year, 3.02, -0.12 year and 4.18 year respectively. From the study the total mortality rate (Z) estimated was 2.33 year-1, the natural mortality rate (M) was 1.75 year-1 and fishing mortality (F) was 0.58 year-1. The current level of the exploitation rate (E) and the maximum exploitation rate (E max) were estimated as 0.25 and 0.42 respectively indicating a low exploitation of Caranx crysos within Côte d’Ivoire’s coastal waters. Conclusion: Although Caranx crysos was underfished, fishing effort must be carefully monitored as well as a policy of adherence to conventional mesh sizes for responsible management of the fishery.