Abstract

Length-weight equations are available for a number of small cetaceans^1-4 including the rough-toothed dolphin.^5,7 However, whether due to inadequate sample size (n =15⁵, n = 10⁶) or statistical error,⁶ those models often produce unrealistic weight values. Here, we suggest a more accurate model for assessing rough-toothed dolphin weight using a larger sample size. Data were obtained from stranding data reported for rough-toothed dolphins from 1995-2009 for the Gulf of Mexico and the Atlantic Ocean (n=173, ranging from 53.5-269 cm in length and 11.34-179 kg in weight). Data from animals in permanent human care and rehabilitation with accurate length, weight, and girth measurements (n=37, length 195.98-250.19cm, weight 68.49-173.7kg, and girth 92.71-132cm) were used to evaluate length-weight, girth-weight, and length-girth-weight relationships. For both data sets a linear regression model for dolphins was fitted. The analysis suggested length to be a significant indicator for predicting dolphin weights, girth was more significant, and length and girth the most significant. The best model fit is given by:

W = 5.939 x 10^-5 x L^1.180 x G1^1.693

The significance of F (3.47716E^-15) shows the model is useful and coefficients are significant since p-values <0.01.

Acknowledgements

The authors thank the staff and trainers at Gulf World Marine Park for the excellent care they provide to all the animals. We also thank Kenny Kroell and Stephen D. McCulloch from Harbor Branch Oceanographic Institute at Florida Atlantic University, Florida and Elizabeth Tuohy-Sheen from NOAA, National Marine Fisheries Service for access to stranding data for the Gulf of Mexico and the Atlantic Ocean. The authors are also in debt to John D. Boston for his assistance with the manuscript.

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