DETERMINATION OF AGE AND GROWTH OF Macrobrachium vollenhovenii CAUGHT IN WARRI RIVER, DELTA STATE, NIGERIA

Abstract

Data on length weight relationships are useful management characteristics for estimating age and growth, population structure and some aspects of prawns population dynamics. Samples of Macrobrachium vollenhovenii were obtained from artisanal fishers at their collection site (station C) between March and August 2010. Monthly abundance and size distributions of specimens were conducted. Age and growth of specimens were determined through carapace length frequency data. This was interpreted by Pauly?s integrated modal frequency distribution, where six modal classes, representing six age groups were plotted. Each peak (06, 40, 51, 56, 59 and 60 mm) represents different age derived from the carapace-frequency polygon. This observation suggests a reliable means of deriving the age of prawns. The sex ratio of (1:1.4) was observed in male and female specimens respectively. The growth pattern of specimens showed a negative allometric growth represented by a ‘b? value =2.638. Body weight and total length relationships were significant (P < 0.05) with value of Y = 2.638x-1.348 and value of r2 =0.812. Mean condition factor for fresh body weight was 3.24 for males and 3.11 for females. Both values were dependable and reliable management indices for prawns