Age and growth study of Fresh water shark, Wallago attu (Bloch and Schneider) from Manchar Lake, District Jamshoro, Sindh, Pakistan

Abstract

To study the age and growth of freshwater shark, Wallago attu (Bloch and Schneider) from Manchar lake district Jamshoro a total of 476 (367 and 109 male and female respectively) fish ranging in size from 15.0 to 65.0 cm and 159.3 to 1658.9 g in total length and weight respectively were collected from the catch of fishermen of the lake during March to August 2011. The relation between total length and weight of male, female and sexes combined were described by following equations. Log W = -2.30 + 3.10 Log L (for males) Log W = -2.14 + 2.90 Log L (for females) Log W = - 1.76 + 2.95 Log L (for sexes combined) It may be seen through regression equations that the values of (b) was practically identical in all cases and very close to ideal 3. The values in males were found better than females. The relative condition factor (Kn) values from this study Kn = 1.0, 0.99 and 1.0 for male, female and sexes combined respectively, represented fish in overall good condition. Males were found slightly better in condition than that of female from Manchar Lake District Jamshoro, Sindh, Pakistan. It was inferred from the length-frequency analysis that the model length 47.6 cm represents as 0+ age group and the subsequent model lengths 53.3 and 57.9 cm designated as 1+ and 2+ age groups respectively. The morphometric study of fresh water shark, Wallago attu revealed that there is no significant (P>0.05) difference among male and female was noticed from quite a good number of fish samples in the present study. It was concluded that the single population of this fish is available in Manchar Lake district Jamshoro, Sindh, Pakistan.