Aspects of the biology of the tiger shrimp Penaeus monodon (fabricius) offshore the Niger Delta Area of Nigeria

Abstract

The growth pattern, food habits and sex ratio of Penaeus monodon, an invasive shrimp in the Niger Delta of Nigeria were investigated. The total length of the examined specimens ranged from 19.5 cm to 34.4 cm (carapace length, 3.3 cm to 7.9 cm) and weighed 51.5 g to 303.4 g. The shrimps exhibited allometric growth with regression coefficient (b) of 2.89 for females and 2.95 for males. There was high correlation between length and weight of the shrimps with correlation coefficient (r) ranging between 0.8722 and 0.8822. The condition factor ranged between 0.58 and 0.79 and was higher in the females. The shrimps fed mainly on crustaceans and molluscs. Algae and diatoms were also encountered in the stomachs. The sex ratio was 1:1.36 (male/female) which was significantly different from the expected 1:1 sex ratio (p ˂ 0.05).The tiger shrimps attained bigger sizes and fed on the young of the indigenous pink shrimp, Penaeus notialis. It may soon displace the native pink shrimp.