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Morphometric body condition indices of wild Florida manatees (Trichechus manatus latirostris)

December 6, 2016

In many species, body weight (W) increases geometrically with body length (L), so W/L3 provides a body condition index (BCI) that can be used to evaluate nutritional status once a normal range has been established. No such index has been established for Florida manatees (Trichechus manatus latirostris). This study was designed to determine a normal range of BCIs of Florida manatees by comparing W in kg with straight total length (SL), curvilinear total length (CL), and umbilical girth (UG) in m for 146 wild manatees measured during winter health assessments at three Florida locations. Small calves to large adults of SL from 1.47 to 3.23 m and W from 77 to 751 kg were compared. BCIs were significantly greater in adult females than in adult males (p < 0.05). W scaled proportionally to L3 in females but not in males, which were slimmer than females. The logarithms of W and of each linear measurement were regressed to develop amended indices that allow for sex differences. The regression slope for log W against log SL was 2.915 in females and 2.578 in males; W/SL2.915 ranged from 18.9 to 29.6 (mean 23.2) in females and from 24.6 to 37.3 (mean 29.8) in males. Some BCIs were slightly (4%), but significantly (p ≤ 0.05), higher for females in Crystal River than in Tampa Bay or Indian River, but there was no evidence of geographic variation in condition among males. These normal ranges should help evaluate the nutritional status of both wild and rehabilitating captive manatees.

Publication Year 2016
Title Morphometric body condition indices of wild Florida manatees (Trichechus manatus latirostris)
DOI 10.1578/AM.42.4.2016.428
Authors Lauren T. Harshaw, Iskande V. Larkin, Robert K. Bonde, Charles J. Deutsch, Richard C. Hill
Publication Type Article
Publication Subtype Journal Article
Series Title Aquatic Mammals
Index ID 70178720
Record Source USGS Publications Warehouse
USGS Organization Wetland and Aquatic Research Center