Growth curve of free-ranging Trichechus inunguis

Abstract

. Based on these equations, length at birth for the Amazonian manatee is estimated at 133.2 cm (average = 113.0 cm; SD = 34.4 cm) for males, and 131.0 cm (average = 124.7 cm; SD = 22.0 cm) for females. Among the males, the annual growth rate was 0.09 cm (95% CI: ± 0.002), with a maximum length of 299.4 cm (95% CI: ± 2.039), while females presented a growth rate of 0.24 cm per year (95% CI: ± 0.004), reaching up to 256.1 cm (95% CI: ± 0.4832) of total length. Even though von Bertalanffy's equation is not commonly used for sirenians, and considering that when previously applied it did not obtain satisfactory results, in this study it proved adequate for the establishment of the growth curve for free-ranging Amazonian manatees. Resumo: O objetivo deste trabalho foi descrever curvas de crescimento para peixes-boi-da-Amazônia de vida livre no Brasil. Foram utilizados dados etários e biométricos de 60 peixes-boi-da-Amazônia, 33 machos e 27 fêmeas, capturados entre 1993 e 2006 por pessoas ribeirinhas do médio Solimões e do Rio Pirativa, na região Amazônica, oriundos do Instituto de Desenvolvimento Sustentável Mamirauá e do Centro Nacional de Conservação e Manejo de Mamíferos Aquáticos/ICMBio. O modelo matemático não-linear utilizado para análise desses dados foi a equação derivada de von Bertalanffy, sendo calculadas duas equações de crescimento, uma para os machos L(t) macho = 299,4 [1-e -0,0897507(t+6,55696) ], e outra para as fêmeas L(t) fêmea = 256,1 [1-e -0,23731(t+ 3,01921) ]. Com o desenvolvimento dessas equações, o comprimento do peixe-boi-da-Amazônia ao nascer foi de 133,2 cm (média = 113,0 cm; SD = 34,4 cm) quando macho, e 131,0 cm (média = 124,7 cm; SD = 22,0 cm) quando fêmeas. Nos machos a taxa de crescimento anual obtida foi de 0,09 cm (IC 95%: ± 0,002), atingindo uma envergadura máxima de 299,4 cm (IC 95%: ± 2,039), enquanto as fêmeas apresentaram uma taxa de crescimento de 0,24 cm ao ano (IC 95%: ± 0,004), podendo alcançar até 256,1 cm (IC 95%: ± 0,4832) de envergadura. Apesar da equação de von Bertalanffy não ser comumente utilizada para sirênios, e quando aplicada anteriormente não ter obtido resultados satisfatórios, neste estudo apresentou-se adequada para a elaboração da curva de crescimento para peixe-boi-da-Amazônia de vida livre. Palavras-chave: peixe-boi-da Amazônia, estimativa de idade, von Bertalanffy, sirênios.

Prediction Equation of Body Weight of Amazonian Manatee (Trichechus inunguis) Calves in Captivity Using Biometry

“…According to Rose (1994) [3], the total curved length is not a reliable variable because individuals with the same total length may have different curvilinear lengths depending on their nutritional status. However, in this study the total curved length was the second variable with the highest coefficient of determination with respect to body weight; which is consistent with that described by Colares (2002) [28] and Vergara-Parente et al (2010) [30], who concluded that the total curved length is an important measure to describe the growth of manatees. The close relationship between this parameter and the body weight is evidenced by the high coefficient of correlation and determination in the linear regression, being a variable of great utility for the prediction of body weight.…”

Assessment of sexual maturity in captive Amazonian manatees (Trichechus inunguis)

“…() did not observe differences in body size between the sexes in captive Amazonian manatees, Vergara‐Parente et al . () observed differences in growth rates between the sexes of free‐ranging Amazonian manatees, with females growing faster than males, corroborating the results of this study.…”

Weight and morphometric growth of Pacu (Piaractus mesopotamicus), Tambaqui (Colossoma macropumum) and their hybrids from spring to winter

“…Among the tested models, the Logistic was the one which presented smaller values for AIC and larger values for R 2 in all studied variables and genetic groups. Therefore, it was the model best adjusted to the data and, thus, selected for comparing the growth parameters (Garcia et al 2011, Vergara-Parente et al 2010.…”