Description and Analysis of The Gambia Catfish Stock Assessment

The assessment compared the results of Yield per Recruit (YPR) and Spawning Stock Biomass per Recruit (SSBPR) analysis to establish overfishing reference points to the results of a length-based catch curve (LCCA) to estimate the fishing mortality rate. The catfish species are a major bycatch in the sole bottom gillnet fishery, with a long life span, slow growth, low fecundity, and large parental investment in care of young. The life history characteristics of the catfish species make it highly vulnerable to overfishing. The catfish are a major source of income for local fishermen, with 90% of the catch being sold in the local market and 10% being exported. The assessment used length frequency data collected from a gillnet study conducted in the Kartart area from May 25 to June 22, 2013. The study evaluated two mesh sizes, 84 and 92 mm stretched mesh, which is larger than the regulated size of 80 mm. A total of 1540 catfish were measured, consisting of two species: Arius latisculatus and Arius parkii. The growth parameters of the catfish species were estimated using the von Bertalanffy growth equation. The estimated growth parameters were L0 = 0, K = 0.2, and Lmax = 72 cm. The input function was linear between ages 2.1-3.0, with all year 3 and older fish being assumed to be mature. The catfish are assumed to recruit in a linear manner from age 4.6, with all fish 30 cm and above being assumed to be retained by the gear 100%. The LCCA analysis was used to estimate the total mortality (Z) and fishing mortality (F) of the catfish species. The predicted Z was estimated to be 0.6484, and assuming M = 0.2, then F = 0.45. The catch curve analysis showed a total mortality of 0.65. The results of the LCCA suggest that the catfish species experienced growth and recruitment overfishing in 2013. The reference points estimated in the YPR and SSBPR analysis were Fmax = 0.27 and F30% = 0.26. The fishing mortality (F) calculated for the catfish species was 0.45, which is above the reference points. Immediate action is recommended to reduce fishing mortality of the catfish species. A closed season/area from May-October should be implemented to protect the animals during their spawning season. An increased mesh size in the gillnet will also help to reduce the mean size of animals captured. A study to evaluate the selection of hook size in the longline fishery is also recommended. The National Sole Fishery Co-Management Committee (NASCOM) should carefully monitor this species and be prepared for further action in the future to continue protecting them. The catfish species are an important source of income for local fishermen, and their conservation is crucial for the sustainability of the fishery. The implementation of the recommended measures will help to reduce the fishing mortality of the catfish species and ensure the long-term sustainability of the fishery.