Plasticity in the shape and growth pattern of asteriscus otolith of black prochilodus Prochilodus nigricans (Teleostei: Characiformes: Prochilodontidae) freshwater Neotropical migratory fish

Abstract

Using morphometric measurements and wavelets functions, the asterisci otoliths of curimatã, Prochilodus nigricans were analysed to identify the variation in shape and growth increment of individuals from Solimões, Japurá and Negro rivers of the Amazon basin, Brazil. The morphometric and morphological analyses did not reveal evidences of population segregation among rivers, but variations were found in the estimation of otolith growth increment. Also, the otolith shape showed a high variability between individuals, identifying four morphotypes. Morphotype 1 shows a more oval shape with a posterior zone clearly rounded; Morphotype 2 shows the posterior zone rounded, but the anterior end is more elongated; Morphotype 3 shows a completely different shape, elliptic-pentagonal and Morphotype 4 shows the posterior zone rounded, but the anterior end is more elongated and it is the pattern with antirostrum and rostrum more pointed and a deep notch. Therefore, the otolith shape exhibited a phenotypic plasticity that it was not associated with the metabolism of otolith growth. Whereas the otolith shape indicated a homogeneity in the sound perception through Amazon basin, the growth rates revealed an adaptive mechanism to environmental conditions or migratory process of this species.

Paradox of otolith shape indices: routine but overestimated use

“…The AFORO database (http://aforo.cmima.csic.es/; Lombarte et al 2006), the world's largest marine fish otolith database consisting of more than 2000 species and 7000 images, operates with this technique and has the option of attaching images for the online classification of species based on the K-nearest neighbours (KNN) D r a f t learning algorithm (Parisi-Baradad et al 2010). The conceptual development and mathematical analysis of wavelets involved learning from the analysis of points (coefficients) (Sadighzadeh et al 2012) to all-signal processing by means of principal component analysis demonstrating the real power of this technique (Abaad et al 2016;Tuset et al 2016Tuset et al , 2018Costa et al 2018).…”

Otolith shape variations between artificially stocked and autochthonous pikeperch (Sander lucioperca)

“…Otolith shapes are species-specific conservative and have been successfully used in fisheries to discriminate fish stocks (Campana and Casselman, 1993;DeVries et al, 2002;Paul et al, 2013;Schulz-Mirbach et al, 2008). The otolith morphometry is influenced by both genetics and the environment where the fish lives (Vignon and Morat, 2010), with individuals from the same population but living in different localities having different otolith shapes (Cerna et al, 2019;Costa et al, 2018;Pérez and Fabré, 2013). Therefore, otolith shape is a powerful tool to identify spatial distribution and natal origin of fish, because it integrates multiple variables in one conservative structure.…”