Aspects of the Biology and Population Dynamics of Sphyraena Sphyraena (Linnaeus, 1758), Apsilus Fuscus (Valenciennes, 1830) and Cynoglossus Senegalensis (Kaup, 1858) in Ghanaian Waters
Despite the commercial relevance of the S. sphyraena, A. fuscus and C. senegalensis to the Ghanaian fisheries there is paucity of information on the growth, population dynamics and exploitation rates of the three stocks, as such making it nearly impossible to sustainably exploit these species in Ghana. Therefore it was reasonable to investigate aspects of the biology and population dynamics of these species as the findings would help boost management measures. A total of 420, 423 and 562 specimens of Sphyraena sphyraena, Apsilus fuscus and Cynoglossus senegalensis respectively were studied. Total length (TL) ranged from 12.5 cm to 66.5 cm for S. sphyraena, 20.3 cm to 50.9 cm for A. fuscus and 11.0 cm to 56.4 cm for C. senegalensis. A significant relationship and a strong correlation between total length (TL) and body weight(BW) was exhibited by the three species. The growth of S. sphyraena and A. fuscus were allometric (b = 2.75 ±0.11; P<0.05 for S. sphyraena and b = 2.84 ±0.12; P<0.05 for A. fuscus) while C. senegalensis showed an isometric growth pattern (b = 3.08 ±0.11; P>0.05). Condition factor range for pooled specimens of S. sphyraena was 0.41 (±0.03) to 0.60 (±0.02), 0.37 to 0.72 for males and 0.38 (±0.04) to 0.54 for females. For A. fuscus, condition factor for pooled specimens ranged from 0.93 to 1.09 (±0.03), 0.94 to 1.09 and 0.94 to 1.08 (±0.03) for females. The condition factor ranged from 0.39 to 0.68 for pooled specimens of C. senegalensis. The exploitation rate were estimated at 0.62 for S. sphyraena, 0.56 for A. fuscus, and 0.52 for C. senegalensis. In conclusion, all three species exhibited exponential growth and the condition factor recorded was higher in smaller size groups than in the larger size groups.