Lenght-weight relationship adapted to freshwater prawn Macrobrachium rosenbergii morphological types

The social organization in a Macrobrachium rosenbergii population involves the emergence of different subpopulations (blue and orange claws males, small males, berried and nonberried females).In a population, prawns of a same size can get different weights.So using a simple length-weight relationship doesn't provide a good accuracy on the calculated mean weight of the whole population.Therefore there is a need for adapted, precise and reliable length-weight relationships for each morphological type.These length-weight relationships have been adjusted at IFREMER's experimental station in Kourou, French Guiana.Equations between orbital length and wet weight have been obtained by linear regression on the logarithm transformed values.They take the form W = a.LB , with a = cst and B varying between 2,9 and 3,3."R" tests realised on correlation cofficients showed a significant correlation (P < 0,05).Used with size histogram for prawn morphological types, the length-weight relationships make easier the different subpopulations growth survey inside the whole population.Applyings are numerous in discontinuous systems as continuous ones.