Morphological analyses of otoliths indicate a single population of invasive Arapaima gigas in tributaries of the Upper Madeira River (Amazon Basin)

Morphological analyses of otoliths indicate a single population of invasive Arapaima gigas in tributaries of the Upper Madeira River (Amazon Basin)

 

ABSTRACT

The present study aimed to evaluate the potential of the shape of the sagitta otolith to discriminate populations of Arapaima gigas outside their natural area of occurrence in different tributaries of the Madeira River. Otolith samples were collected at three locations along the Guaporé and Mamoré rivers. The shape of the otolith was described using 20 Fourier harmonics and five shape indices. No significant differences were found in the shape of the otoliths among the different sample areas, and no evidence of relevant differences between groups was observed graphically for the two methods used. The success of the global classification of the models was considered average, being 57.57% for the shape indices, and 55.54% for the Fourier coefficients. Thus, the results suggest a single population of pirarucu in different locations of the Guaporé and Mamoré rivers. However, multidisciplinary studies involving genetics, morphology, and ecology may provide more accurate guidance for determining pirarucu populations in the study region.

Keywords: Fourier analysis, Shape indices, Fish populations, Sagitta

Authors: Marcos de Almeida Mereles, Raniere Garcez Costa Sousa, Carlos Edwar de Carvalho Freitas

Journal: Vol. 50 (2024): BOLETIM DO INSTITUTO DE PESCA

 

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