Date of Award

Fall 2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Ian Bartol

Committee Member

Mark Butler

Committee Member

A. Ann pabst

Call Number for Print

Special Collections LD4331.B46 L96 2012

Abstract

Little is known about the life history and overall ecology of bottlenose dolphins that strand in Virginia. In this study, I examined archived life history samples and stranding data from bottlenose dolphins found in Virginia waters to (1) develop growth curves based on ages from sectioned teeth, (2) document characteristics of male and female reproductive organs, and (3) define the relationship between age/length and presence of neonatal characteristics during the first year of life. The Gompertz growth model provided the best fit of growth data for stranded T. truncatus in Virginia. Length at birth and asymptotic length for males were 119.4 cm and 253.9 cm, respectively, and for females were 118.8 cm and 241.6 cm, respectively. The oldest male was 35 years and the oldest female was 48 years. The youngest sexually mature female was ten years, while the youngest sexually mature male was nine years. High variability in the presence of spermatozoa, seminiferous tubule diameter and percent Interstitial tissue was observed for males between the ages of 10 and 14, suggesting that these years represent a pubertal or transitional stage. Quantitative measurements of postnatal dentinal growth provided higher temporal resolution than visual methods traditionally used to assess age during the first year of life. Rostral hair loss, disappearance of fetal folds, and eruption of teeth all represent reliable ontogenetic transitions during year one of life, with the loss of rostral hairs occurring earliest and disappearance of fetal fold/lines occurring latest. This study provides the first comprehensive data set on age, reproduction, and neonatal characteristics for dolphins in Virginia waters and should be of high relevance for cetacean researchers, stranding coordinators, and population dynamicists.

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DOI

10.25777/5741-pn15

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