Interrelationships between morphometric variables and rounded fish body yields evaluated by path analysis

Abstract

-The objective of this study was to verify which morphometric measures and ratios are more directly associated with the weight and body yields of rounded fish. A total of 225 specimens of rounded fish (59 pacus, 61 tambaquis, 52 tambacus and 53 paquis) with average weight of 972.43 g (±115.52 g) were sampled, stunned, slaughtered, weighed, measured, and processed for morphometric and processing yield analysis. The morphometric measures taken were: standard length (CP); head length (CC); head height (AC); body height (A1); and body width (L1). For completeness, the following morphometric ratios were calculated: CC/CP, AC/CP, A1/CP, L1/CP, CC/A1, AC/A1, L1/A1, CC/AC and L1/CC. The yields of carcass, filet, rib and filet with rib were estimated after processing. Initially, a "stepwise" procedure was performed in order to eliminate multicollinearity problems among the morphometric variables, and the phenotypic correlations were then calculated for the dependent variables (weight and body yields) and independent variables (morphometric measurements and ratios). These correlations were later deployed in direct and indirect effects through path analysis, and the direct and indirect contributions of each variable were measured in percentage terms. The CC and A1 measures were important for determining the weight of rounded fish. The CC/A1 ratio was the variable most directly associated with carcass yield. For filet, filet with rib and rib yields, the L1/CC ratio was found to be more appropriate and can be used directly.

Ichthyometry and electrical bioimpedance analysis to estimate the body composition of tambatinga

“…Given the influence of other ichthyometric variables not studied here, on fish yield (Reis Neto et al 2012;Silva et al 2009;Leonhardt et al 2006), we suggest that its relations with the BIA data be further researched.…”

Imputation of genetic composition for missing pedigree data in Serrasalmidae using morphometric data

“…The presence of significant moderate to high correlation between genetic compositions imputed between the evaluated traits can be a function of these characteristics as correlation is found in fish (Reis Neto et al, 2012;Melo et al, 2013).…”

A suitable ichthyometer for systemic application

“…Many biological indices in live fish are derived by correlating morphometric, meristic, biometric and genetic variables, using both in situ and in vitro techniques (Hamza, 1999;Jones et al, 1999;González-Díaz et al, 2005;Gaspar et al, 2012;Reis-Neto et al, 2012;Muto et al, 2016). The modern methodology includes the use of high-definition cameras, sensors and specialized software (Harvey, 2003;Costa et al, 2006).…”

“…As well as estimating standard length (SL), this method, with the help of a digital image analyzer, allows estimation of other parameters such as size, shape of eyes and fins, and distances and proportions between biometric features; all important criteria in the optimum management of aquatic resources (Jawad et al, 2009;Gaspar et al, 2012;Reis-Neto et al, 2012;Yajing, 2012;Klima et al, 2013;Paiva et al, 2015;Muto et al, 2016). …”

“…Using the drift error for ±5°, the TL of a 20.84 cm fish is reduced on average to 20.74 cm and to a maximum of 20.60 cm. Perhaps these values do not generate significant differences; however, this level of error is not trivial, since according to Goodenough et al (2010) no matter how small the incidence of errors, it is magnified during calculation of biometric indices, and therefore it is important that this error, if present, is minimal (Hamza, 1999;Jawad et al, 2009;Rutjes et al, 2009;Masson et al, 2011;Gaspar et al, 2012;Reis-Neto et al, 2012).…”