Investigation of Growth Phases for Bottlenose Dolphins using a Bayesian Modeling Approach

Authors

Wayne McFee, Center for Coastal Environmental Health and Biomolecular Research, National Ocean Service, NOAA, 219 Ft. Johnson Road, Charleston, South Carolina
John Schwacke, University of South Carolina
Megan Stolen, Hubbs-SeaWorld Research Institute
Keith Mullin, National Marine Fisheries Service
Lori Schwacke, National Centers for Coastal Ocean Science, National Ocean Service

Date of this Version

2009

Comments

Published in MARINE MAMMAL SCIENCE.

Abstract

The Gompertz function is the most commonly used growth function for cetacean studies. However, this function cannot represent multiple phases of growth. In this study, we present a Bayesian framework fitting parameters of a triple-logistic growth function to describe multiple phases of growth for bottlenose dolphins (Tursiops truncatus), simultaneously fitting and comparing all growth parameters between South Carolina (SC), Mississippi Sound (MSS), and Indian River Lagoon (IRL) cohorts. The fitted functions indicated a preliminary early, rapid growth phase, followed by a second phase of slower growth, and then a moderate growth spurt later in life. Growth parameters between geographic cohorts did not show obvious differences, although asymptotic length for SC dolphins was lower than MSS and IRL dolphins and significantly lower between females from SC and the IRL. Growth rate velocities between the sexes showed females exceed males initially (<1 yr), followed by males gaining an advantage around the ages of 3–4 yr until the age of around 15 yr when growth rates for both sexes approached zero (asymptotic length). This study demonstrates age-related changes in growth rates between bottlenose dolphin sexes and evidence of at least some differences (i.e., asymptotic length) across geographic cohorts.