Body Condition Scoring the Sea Turtle

Body weight and measurements

Weight trends can be a helpful indicator of hydration and nutritional status. Upon presentation of a sea turtle, obtain body weight and standardized measurements, including maximum and minimum curved and straightline carapace length (SCL) and width (Fig 1) (Table 1). If possible, a maximum depth or body depth, measured after the animal inhales, is also useful. Take the depth measurement three times; the average is a good measure with which to track change.

Figure 1. Measurement of straightline width (SLW). Photo credit: Dr. Terry Norton. Click image to enlarge.

Subjective body condition scoring

At the Georgia Sea Turtle Center (GSTC), a body condition scale based on a 1-5 scoring system is used. A turtle that is emaciated with sunken eyes, that has a loss of shoulder and neck musculature as well as poor muscle tone would score a 1 on the scale. There is also loss of inguinal fat in the inguinal space, prominent skeletal elements on the skull and plastron, as well as loss of soft tissue between the carapace and plastron (Fig 2). The plastron may be slightly sunken in or concave (Fig 3). A body condition score (BCS) of 2 indicates that the turtle is thin (Fig 4). The neck muscles are pronounced and the shoulders are thin and wrinkled. A BCS 3 is normal (Fig 5), while 4 is robust (Fig 6) and 5 is obese.

Figure 2. An emaciated sea turtle with a body condition score of 1 out of 5. Photo credit: Dr. Terry Norton. Click image to enlarge.

Figure 3. The sunken or concave plastron of an emaciated turtle. The head is to the right, and the proximal hind limbs can be seen on the left. Photo credit: Dr. Terry Norton. Click image to enlarge.

Figure 4. Sea turtle with a body condition score of 2 to 2.5 out of 5. Photo credit: Dr. Terry Norton. Click image to enlarge.

Figure 5. Sea turtle with a body condition score of approximately 3.5 out of 5. Photo credit: Dr. Terry Norton. Click image to enlarge.

Figure 6. A robust sea turtle with a body condition score of approximately 4 out of 5. Photo credit: Dr. Terry Norton. Click image to enlarge.

Body condition scoring should be based on physical examination and not just observation. Edema of the subcutaneous tissue is not uncommon in debilitated turtles with hypoalbuminemia and can make the turtle falsely appear more robust.

Objective body condition scoring

An objective assessment of body condition uses a standard formula. To calculate a body condition index (BCI) requires two measurements where BCI = [weight (kg)/straight carapace length (cm³)] X 10,000 (Table 2).

Carapace length and sexual maturity

Age of sexual maturity varies among sea turtle species and within different populations of the same species. For example, loggerhead sea turtles (Caretta caretta) reach sexually maturity between 25 to 35 years of age, whereas the more recent research on leatherback sea turtles (Dermochelys coriacea) indicate they become sexually mature at approximately 11 to 25 years of age (Connet 2009, TEWG 2007, Snover 2002).

Onset of sexual maturity is related to carapace size. The turtle enters puberty when carapace length is approximately 75% of adult carapace length. Although there is considerable variability, approximate carapace size for mature turtles ranges from greater than 55 cm curved carapace length (CCL) in Kemp’s ridley (Lepidochelys kempii) and olive ridley turtles (Lepidochelys olivacea) to more than 130 cm CCL for leatherbacks (Table 3, Table 4).

For additional information on physical evaluation of the sea turtle, visit Sea Turtle Physical Examination Part 1: Eyes-Ears-Nose-Throat and Sea Turtle Physical Examination Part 2.

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