## 3 Results and Discussion  
### Biometric Parameters and VTG Concentrations  
The weight, length, HSI, K, and concentrations of vitellogenin in the trout coming from the Mavone and Ruzzo rivers are shown in Table 1.  
Comparing both the weight and length, the biometric parameters showed no significant differences (\(p\) > 0.05) between the male and female trout from both rivers. Positive correlations were also found for trout length and weight in both rivers (Tables 2 and 3).  
The trout sampled in this study all reported a K \(>\) 1, except for one sample that reported a value below 1. The K of fish species is a very important parameter for understanding fish biology and pathology. Many factors affect the growth condition of fish, including reproductive cycles and availability of food, as well as habitat and environmental factors [29], and K is a parameter that can be used as a good indicator of water quality or the general health of fish populations. In the present study, the K values suggest a state of wellbeing for this species, indicating that both rivers are a nutrient-rich environment with favorable conditions for brown trout.  
The results of the VTG levels are reported in Table 1. No significant differences in VTG levels (\(p\) > 0.05) were found when comparing male and female trout from the Mavone and Ruzzo rivers. Of particular interest are the VTG levels found in males from both rivers. Only one male reported a minimum value of 5.6 ng/mL, while the others showed concentrations from 26.1 ng/mL to 187.6 ng/mL (mean value of 74.67 ng/mL). These values could be interpreted as a sign of an estrogen-induced effect, and in this case,  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**River** & **Sex** & **Weight (g)** & **Length (cm)** & **HSI** & **K** & **VTG (ng/mL)** \\ \hline [PERSON] & F & 162.73 \(\pm\) 99.33 & 24.59 \(\pm\) 3.31 & 1.06 \(\pm\) 0.35 & 1.24 \(\pm\) 0.14 & 92.63 \(\pm\) 58.99 \\ \hline  & M & 258.44 \(\pm\) 362.04 & 26.00 \(\pm\) 8.86 & 0.87 \(\pm\) 0.31 & 1.23 \(\pm\) 0.10 & 84.49 \(\pm\) 64.21 \\ \hline [PERSON] & F & 182.13 \(\pm\) 122.83 & 25.38 \(\pm\) 4.98 & 0.98 \(\pm\) 0.19 & 1.12 \(\pm\) 0.19 & 88.23 \(\pm\) 72.43 \\ \hline  & M & 149.00 \(\pm\) 44.69 & 24.00 \(\pm\) 2.00 & 1.01 \(\pm\) 0.14 & 1.17 \(\pm\) 0.07 & 59.93 \(\pm\) 38.73 \\ \hline \end{tabular}
\end{table}
Table 1: Mean values and standard deviation of weight, length, hepatosomatic index (HSI), condition factor (K), and variation in vitellogenin (VTG) concentration in male and female trout.  
\begin{table}
\begin{tabular}{c c c c c} \hline  & **Weight** & **Total Length** & **HSI** & **K** \\ \hline
**Rank-Order Correlation** & **correlations** & **correlations** & **correlations** & **correlations** \\ \hline
**Weight** & 1.000 & & & \\ \hline
**Total length** & 0.980 * & 1.000 & & \\ \hline
**HIS** & 0.068 & 0.073 & 1.000 & \\ \hline
**K** & \(-\)0.354 & \(-\)0.449 * & 0.008 & 1.000 \\ \hline \end{tabular} \(\tau=p<0.05\).  
\end{table}
Table 2: Correlations among different parameters in the trout from Mavone river.  
\begin{table}
\begin{tabular}{c c c c c} \hline  & **Weight** & **Total Length** & **HSI** & **K** \\ \hline
**Rank-Order Correlation** & **Correlations** & **correlations** & **correlations** & **correlations** \\ \hline
**Weight** & 1.000 & & & \\ \hline
**Total length** & 0.935 * & 1.000 & & \\ \hline
**HSI** & 0.042 & 0.110 & 1.000 & \\ \hline
**K** & 0.482 & 0.236 & 0.038 & 1.000 \\ \hline \end{tabular} \(\tau=p<0.05\).  
\end{table}
Table 3: Correlations among different parameters in the trout from Ruzzo river.  
the VTG represents a biomarker of EDs exposure. The VTG levels in females ranged from 5 ng/mL to a maximum value of 202.6 ng/mL (mean value of 90.77 ng/mL), but the presence of high levels of VTG in females is a normal condition, and the highest levels could be an effective index of reproductive development. The VTG levels were not correlated with heavy metal concentrations, suggesting additional sources of contamination with estrogenic endocrine-disrupting chemicals.