Length and weight of farmed young Morelet's crocodiles (Crocodylus moreletii) as predictors of their future size

Abstract

The aim of the study was to determine the earliest time at which the future size (length and weight) of farmed Morelet's crocodiles (Crocodylus moreletii) can be accurately predicted, to establish selection criteria in these individuals. A total of 8040 crocodiles (7394 males and 646 females) hatched from artificially incubated eggs were included. In each crocodile the total length and weight were measured on days 1, 132, 248, 364, 500, 616, 750, and 878 of age. On day 878 crocodiles were classified into five size groups: runt (RT), small (SL), medium (MM), large (LG), and extra-large (EL). The association between evaluations for length and weight, the correlation between length and weight in each measurement, and the differences in length and weight between assessments and sex were determined. Analysis from day 132 through day 878 included both sexes together. Neither length nor weight on day one correlated (> 0.40) with any subsequent evaluation. There was no difference among groups (P > 0.05) between length on day one and size on day 878. Difference was found between length on day 132 and size on day 878 in RT (P < 0.05), and between length on days 248, 364, 616, and 750 and size on day 878 in all the groups (P < 0.05). Difference was found between weight on day one and size on day 878 only in SL (P < 0.05), and between weight on days 132, 248, 364, 616, and 750 and size on day 878 in all the groups (P < 0.05). The size farmed Morelet's crocodiles will have at 878 days can be predicted with weight at 132 and length at 248 days. Use of the ranges of the size groups as selection criteria for growth will allow selecting the future smallest and largest individuals early in the production cycle and to enhance sustainable management of this species.