Length estimation of anchoveta (Engraulis ringens) using echosounder in difficult to access fishing areas in the Atacama Region, Chile

This study explores the use of hydroacoustic methods to estimate the size distribution of Peruvian anchoveta, offering an alternative to traditional biological sampling methods. Acoustic data were collected using two algorithms: Single Target and Tracked Target, along with aTS to length conversion model specific to Peruvian anchoveta. The results showed that the Single Target algorithm estimated sizes ranging from 8.5 to 16 cm, with a mode of 12.0 cm, while the Tracked Target algorithm identified a range of 9 to 14 cm, with a mode of 11.5cm. Juvenile anchovies represented 45.8% and 51.2% of the population in each algorithm, respectively. Additionally, the depth of the echoes ranged from 3.92 to 43.95 m, suggesting that larger Peruvian anchoveta tend to inhabit deeper coastal zones, possibly as a physiologicaladaptation to these environments. The study demonstrates the effectiveness of hydroacoustics for estimating fish sizes, especially in areas where traditional sampling is inaccessible or difficult to carry out. This approach contributes to understanding fish population dynamicsand opens the door to future studies.