Assessment of the fishery, growth and mortality characteristics of the cassava croaker, Pseudotolithus senegalensis (Sciaenidae) from coastal waters of Ghana
2020
Okyere, Isaac | Blay, John
This paper reports on the fishery and some population parameters of the cassava croaker (Pseudotolithus senegalensis) at Anlo Beach near Shama (5°01’ N, 1∘37’ W) in the Western Region of Ghana. The study was conducted from July 2012 to June 2013 to contribute to information on the dynamics of demersal stocks in the country. Beach seining was the prime fishing method in the area with the fishing season spanning July to March. Catch per unit effort (CPUE), determined as catch per net haul per day was 9.5 kg in July 2012, 110 kg in January–February 2013 and 47 kg in March 2013. The species was absent from the fishery from April 2013 to June 2013. Monthly catches varied from 2295 kg to 31,500 kg, and specimens of the fish measured 7.5 cm TL to 105.4 cm TL and weighed 2.9 g to 7634 g. The length–weight relationship of the population was described by the equation: BW = 0.005TL3.04 (r=0.99), and grouping the fish at 5 cm class intervals showed modal lengths at 15.0–19.9, 35.0–39.9 and 60.0–64.9 cm TL. Analysis of the length-frequency distribution using the ELEFAN programme indicated an asymptotic length (L∞) of 110.3 cm TL, a growth coefficient (K) of 0.2 yr⁻¹, and total (Z), natural (M) and fishing (F) mortality coefficients of 0.68 yr⁻¹, 0.42 yr⁻¹, and 0.26 yr⁻¹ respectively, for the population. Longevity of the fish was estimated to be 15 years. A low exploitation level of the stock is suggested by the calculated exploitation ratio, E=0.38. These population characteristics are compared with those of other West African P. senegalensis populations.
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