Unravelling the stock structure of the Persian brown trout by otolith and scale shape

Abstract

The simultaneous use of the scale and otolith morphometry was assessed as a potential tool for the identification of Persian brown trout Salmo trutta stocks of the Lar Lake and five rivers from Lar Basin, Iran. Fourier coefficients (FC) and circularity, rectangularity, roundness, ellipticity and form factor shape indices (SI) were calculated for otolith and scale. Several SIs were significantly different among sites for both structures. Permutational multivariate analysis of variance revealed significant differences between several pairwise comparisons for otolith and scale (FCs and indices separately). Discriminant analysis showed otolith FCs (cross-classification rates: 25-86%) and SI (20-45%) appear to be a relatively acceptable tool to discriminate between several locations. Comparatively, the scale morphometry showed lower discriminatory power (FC = 3-65%; SI = 15-34%), with the exception of SI for Elarm River (60%), Kamardasht River (56%) and Lar Lake (75%). Cross-classification rates improved up to 100% when discriminate analysis incorporating all variables for otolith and scale was performed. The results showed a potential segregation between some water bodies, suggesting that the otolith and scale morphometry could be a useful tool to delimit S. trutta populations in relatively close freshwater environments. K E Y W O R D Selliptic Fourier analysis, Lar National Park, morphometry, shape indices, stock identification

Mixed stock assessment of lake-run Caspian Sea trout Salmo caspius in the Lar National Park, Iran

“…In contrast, using morphological analysis of otolith and scale, Rashidabadi et al (2019) could not clearly delimit Dalichay population from other populations. Our observation parallels the results presented in Pettersson et al (2001).…”

Does Fish Conditioning in Aquaculture Increase Survival Success in the Wild? A Case Study on a Cyprinid Fish

“…Assessing survival to adulthood by detecting spawning individuals could therefore be more accurate than the methods used to collect the currently available data. Another tool that can be applied to identify the survival rate of stocked individuals is the analysis of the fish scale and otolith shape and chemistry, which are effective tools to determine the fish origin [12,69].…”

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

“…2) were computed using the package rgeos (Bivand et al, 2019). Eight different shape indices (Burke et al, 2008;Leguá et al, 2013;Rashidabadi et al, 2020;Škeljo and Ferri, 2012) were computed for each individual otolith (Table 1). The aspect ratio (SIAR) between the otolith length and width expresses the otolith elongation.…”

“…The number of harmonics used was defined by applying the calibrate_harmonicpower_efourier function. The Elliptical Fourier Analysis is commonly used to describe the fish otolith shapes with a high degree of precision and success in capturing the shape of the otoliths, even those with rough contours (Assis et al, 2020;Gagliano and McCormick, 2004;Karahan et al, 2014;Lestrel, 1997;Mahé et al, 2019;Mérigot et al, 2007;Rashidabadi et al, 2020;Rodgveller et al, 2017;Smoliński et al, 2019).…”