Length-weight relationship of Macrobrachium lar (Fabricius, 1798), an endemic freshwater prawn in streams and ponds of Andaman and Nicobar Islands

Abstract

Macrobrachium lar (Fabricius, 1798) is a freshwater prawn species of Andaman and Nicobar Islands (A&N Islands) inhabiting streams, rivers, lakes and ponds. Length-weight relationships of this species collected from selected streams and ponds during the year 2008 were estimated. A total of 238 specimens in the size range 60-167 mm in total length (128 females and 110 males) collected from the various streams while 281 specimens in the size range 63-118 mm in total length (157 females and 124 males ) caught from the ponds were examined. As there was no significant difference in the slopes and elevations of both sexes from each source, data were pooled to arrive at a common equation for each source. The combined equations of length-weight relationship of M. lar were W = 0.00007 L2.6695 for streams and W = 0.000006 L3. 205 for ponds. The correlation coefficient ‘r’ was found to be 0.86 for streams and 0.89 for ponds. The regression coefficient b for this species was either marginally higher (ponds) or significantly lower (streams) than 3 (p<0.01), suggesting allometric growth. The present results indicated that prawns sampled from ponds are heavier than those from streams at any given length.