Katie Brill

Life history is a key component in manatee research and it helps address important management needs, particularly of endangered populations. Tools to collect this information include growth-layer counts from earbones, these layers have been shown to reflect the age in years for manatees. Manatees are polyphyodont; therefore, teeth are not adequate for ageing manatees. Instead of a tooth, part of the earbone complex is used to count growth-layers to determine postmortem manatee age… Show more

Life history is a key component in manatee research and it helps address important management needs, particularly of endangered populations. Tools to collect this information include growth-layer counts from earbones, these layers have been shown to reflect the age in years for manatees. Manatees are polyphyodont; therefore, teeth are not adequate for ageing manatees. Instead of a tooth, part of the earbone complex is used to count growth-layers to determine postmortem manatee age. With increasing awareness of the importance of sample collection from manatee carcasses, a skillful earbone removal will be helpful. Improved knowledge of the skull anatomy will facilitate extraction of the earbone. Unfortunately, it is easy to recover the wrong bone or break/chip the portion to be aged. Thus, having familiarity with landmarks and orientation will assure the collection of the correct earbone piece (periotic bone rostral - "dome portion"). This presentation will discuss the techniques for earbone removal from the skull, as well as preservation of the bone until it can be sent to a laboratory for analysis. It is essential for all stranding members to receive earbone removal training to increase the number and quality of earbones collected. This enables more manatee carcasses to be aged from all regions. To date, only 34 African manatee earbones from Benin, Mali, Angola, Cameroon, Ghana, Gabon, and Senegal have been aged. It is imperative to understand how crucial it is in collecting these samples that provide insight in understanding African manatee life history and management needs.  Show less

Manatees are routinely aged by counting Growth Layer Groups (GLGs) in periotic bones (earbones). Manatee carcasses recovered in Florida between 1974 and 2010 provided age-estimation material for three readers and formed the base for a retrospective analysis of aging precision (repeatability). All readers were in good agreement (high precision) with the greatest apparent source of variation being the result of earbone remodelling with increasing manatee age. Over the same period, methods of… Show more

Manatees are routinely aged by counting Growth Layer Groups (GLGs) in periotic bones (earbones). Manatee carcasses recovered in Florida between 1974 and 2010 provided age-estimation material for three readers and formed the base for a retrospective analysis of aging precision (repeatability). All readers were in good agreement (high precision) with the greatest apparent source of variation being the result of earbone remodelling with increasing manatee age. Over the same period, methods of sample preparation and of determining a final age estimate changed. We examined the effects of altering methods on ease of reading GLGs and found no statistical differences. Accurate age estimates are an important component for effective management of the species and for better models of population trends and we summarize the currently recommended methods for estimating manatee ages using earbones. Show less

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