Some Population Parameters of the Sardinella maderensis (Lowe, 1838) in the Sombreiro River of Niger Delta, Nigeria

Özet

Öz A study was conducted to estimate the growth and stock characteristics of the Sardinella marderensis (Lowe, 1838) from Sombreiro River of Niger Delta, Nigeria. Result obtained revealed that mean total length and mean weight of S. marderensis ranged between 4.1cm to 18.5 cm and 5g to 55.5g respectively. The b value of the length-weight relationship was 2.58 thus, species could be categorized as displaying allometric negative growth and condition factor was very high, it ranged from 3.04 to 4.43. The estimated von Bertalanfy growth (VBG) parameters of L∞, growth coefficient (k) and age at zero length (t0) were 23.31cm, 0.54 and -0.03/year respectively. The species showed year round recruitment patterns having two peak periods during April and July. The total mortality (Z) was2.74 year-¹., the natural mortality rate (M) and fishing mortality (F) were1.32 and 1.42 respectively. The estimated fishing mortality (Z-M=F) stood at 0.518. The length-based index of growth performance (φ – phi prime) for S. maderensis was estimated at 2.46. The length at first capture L50 was 7.19cm. The exploitation rate (Emax) was 0.421 whereas (E0.1) was observed to be 0.355 indicating that that the level of exploitation is already high and to obtain the maximum sustainable yield, the present level of fishing effort should be reduced through appropriate fishing regulation techniques.