November 2018
Pierina Mendoza, Juan Sánchez, Rony Riveros, Javier Velasquez, Edgard Dávila, Darwin Loja and Carlos Vilchez
Conference: 3rd Latin American Manatee Symposium - SILAMA 2018 and XII Congress of the Latin American Society of Specialists in Aquatic Mammals - SOLAMAC 2018
At: Lima, Peru
Photo by Pierina Mendoza
The knowledge of the parameters that affect the growth of the manatee in captivity is important in the conservation terms. This information is vital for make decisions about the nutritional management of rescued calves. During this work, the data of biometrics (total length) and body weight, from one Amazonian manatee of each sex in captivity, was recorded since their rescue to their pre-liberation (48.5±2.5 months). Two non-linear function were separately performed for both animals for each variable: Gompertz function BW = BWm*exp(-b*exp(-k*age)) and Von Bertalanffy function TL = TLm*(1-b*exp(-k*age))3, were delineated for body weight (BW) and total length (TL), respectively. The following parameters were obtained: BWm, TLm, k and b; where BWm and TLm are asymptotic parameters, k expresses the ratio of the maximum growth rate, and b is used to calculate the inflection point: ln(b)/k. Subsequently, the first derivative of both functions were adjusted for observe the growth’s variation of both variables in reference to age. Finally, the following function evaluation indicators were obtained: Adjusted coefficient of determination (R2aj), Akaike information criterion (AIC) and Bayesian information criterion (BIC). The data was obtained from the Gauss-Newton iterative method (P<0.001), using the R-Project statistical software. The functions obtained the follow indicators: AIC (250 and 234) and BIC (257 and 241) from Gompertz and AIC (274 and 246) and BIC (280 and 253) from Von Bertalanffy equations; in female and male growth curves, respectively. The function reached convergence and generated the follow parameters of estimation: BWm of 126.3 and 103.5; LTm of 248.8 and 267.0, for female and male; respectively. In conclusion, the non-linear Gompertz and Von Bertalanffy functions are suitable for describe the performance of the growth curve of Amazonian manatee in captivity and the body weight and total length dimorphism can be differentiated between both sex.
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