Introduction
For the clinician, the question of whether a dolphin can endure a protracted illness that includes a poor appetite or whether a dolphin in training has an appropriate physique has not been fully investigated. Body condition of dolphins has been debated for years and although there are standards based on weight, girth, and length, none have adequately combined a visual examination and bubbler thickness to generate an objective score.1-4
Pairing body weight to a visual assessment of body condition is dependent on the assessor's perception, making it a non-objective approach to determining the ideal physique of an individual dolphin. Assuming that a change in body weight is primarily a result of a change in blubber, a more accurate measure of change should be a measurement of blubber thickness compared with body length.
Materials and Methods
Abdominal blubber thickness was measured on 121 adult and subadult dolphins (sexually mature) in six Caribbean locations during quarterly ultrasound examinations over a one-year period. Blubber thickness was measured using either a Sonosite Turbo or Edge and a 3–5 MHz transducer in a transverse section in above either the testicle or ovary on the left side at a depth of 4.7 cm. The measurements were compared with body lengths in the following equation:
BBI = Blubber thickness (mm)/body length (cm) x 1000
Each dolphin was visually assessed for body shape and given a score of convex (overweight), slightly convex (normal), parallel (thin), and concave (skinny) and compared with the derived number. The water temperature varied from 27–31°C year round allowing comparisons to be made.
Results
Not surprisingly, only 62% of the visual scores agreed with the BBI, indicating differences in perceptions by the evaluator. Taking into account body score and BBI, it appeared that a minimum score of 32 best aligned with a visual assessment at all temperatures of a good versus a thin physique. Body blubber indexes ranged from 20 to 113 between all six facilities and averaged 38 for facilities where 90% of the individuals had good physiques and 33 for facilities where a significant number of dolphins were considered thin.
Discussion
The goal of the study was to compare blubber thickness to a static parameter (i.e., length) that defined an ideal dolphin physique. The authors believe that BBI is superior to scale weight to assess physiques where limits of blubber thickness define the risk of being too thin and not having enough reserve to sustain weight during a protracted illness or too fat that generates confusion as to whether the individual is either sick or satiated.
Although the limits may vary between facilities and individuals, we propose that the limits of BBI are 32 to 50 to account for variations in Caribbean water temperatures. As a pilot study, much more data is needed to investigate ideal BBIs for different life stages such as early growth, trimesters of pregnancy, post-partum period, elderly, male vs. female, and different seasonal water temperatures.
Body Blubber Index is not intended to replace regular body weights for facilities that have scales but the authors believe BBI adds an objective measure to corroborate visual assessment, especially in facilities that lack scales or lack the experience to make accurate visual assessments. We are also evaluating BBI with a number of beluga whales, Pacific white-sided dolphins, and killer whales and are seeing similar results, but the data is too preliminary to present.
Acknowledgments
The author is grateful for the assistance from the Curaçao Sea Aquarium (Laetitia Smits van Oyen, Mike Schoon, George Kieffer, Anne van den Heuvel, Zenzi Willems, and Marie-Christine van Pallandt), Blue Lagoon at Dolphin Encounters (Robert Meister, George Rodgers and Sarah Buchanan), Ocean World, Dominican Republic (Stefan Meister, and Kees de Groot), Dolphin Explorer (Luis Jose Mendes, Eric Bogden and Mauricio Francia), Anthony's Key Resort, Roatan Honduras, and Balmoral Island, Nassau Bahamas (Samir Galindo, Eldon Bolton, and Teri Bolton).
* Presenting author
Literature Cited
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