Project Title: Establishment of an Australian centre for marine mammal age determination using tooth structure: a case study using bottlenose dolphin teeth to investigate the relationships of age, reproductive status and toxic contaminant levels in South Australia
Chief Investigators: Dr Catherine Kemper and Dr Karen Evans
The method of estimating marine mammal age using tooth structure is well established but little expertise on this technique exists in Australia. As a result, most researchers needing to use the method travel outside Australia for training. During 2007, four investigators (C. Kemper, K. Evan, R. McIntosh, J. McKenzie) established a Marine Mammal Aging Facility at the South Australian Museum, an institution with significant marine mammal collections and research programs that would benefit from knowing animal age. Funding was obtained from ACCAMS to set up a laboratory and conduct a workshop for 6 to 8 participants from around Australia to get initial training in preparation and evaluation techniques for aging marine mammals using tooth structure. An instruction manual was prepared for the workshop (and has since been refined as more knowledge is gained) and will be made available on the Museums website.
The workshop and manual concentrated on two commonly-used methods 1) decalcified, thin-sectioned, stained small to medium-sized teeth (e.g. dolphins and seals) and 2) acid-etching of larger teeth (e.g. sperm whales and killer whales). The manual goes through a step-by-step approach to each technique, from obtaining teeth (including how to extract from live animals) to aging the prepared specimens. It incorporates the extensive experience of the investigators in using these techniques on marine mammals in Australia. Both methods use Growth-Layer-Groups (GLGs) as a means of estimating the number of years that an animal has been alive. Interpreting these GLGs requires a great deal of experience and it is recommended that several readers (and several estimations per reader) are done in order to be confident that the age arrived at is as accurate as possible. A comprehensive reference list of papers on marine mammal aging using tooth structure is included in the manual.
It is intended that the facility be operated in several ways:
1. It be available for Australian researchers (trained in the techniques) to process marine mammal teeth
2. The South Australian Museum/Investigators listed above prepare and/or interpret teeth under contract for external researchers
3. The South Australian Museum/Investigators listed above train researchers on a one-to-one basis, for a fee
Although not part of the funding agreement, during 2008, a university student from Italy conducted a project in the facility under the direction of C. Kemper. About 80 Indo-Pacific Bottlenose Dolphins were aged and sexual maturity of males determined for about 50 animals. Preliminary information on the age of sexual maturity of females was also obtained. A subset of the animals was known age as a result of long-term studies in the Adelaide region.
