ISSN: 2577-4050
Authors: Castillo PR*, Cuadros G, Grados D, Cruz LL, Díaz E, Pozada M, Valdez C and Cornejo R
The present study was to observe the healthy condition of the anchoveta population at the level of distribution, size structure, acoustic descriptors of the schools, and estimation of biomass by three acoustic stratification techniques investigated in the two research surveys carried out by the Instituto del Mar del Perú in 2021. The three techniques were: i) 10x30 mn isoparalittoral areas with size mode data (Biom 1), ii) transects proposed by Jolly & Hampton (Biom 2), and iii) in 10x30 mn isoparalittoral areas with modal size data (Biom 3). The results showed that in the 2102-07 survey, the anchoveta had a mainly concentrated spatial distribution with high abundances; while, on the 2109-11 survey, it was generally scattered by its longitudinal displacement towards areas far from the coast. At the vertical level it was found mainly in the surface layer of the 50 m, with greater depths between 14° and 16°S, which reached up to 99 m in survey 2109-11 due to good oxygenation at those depths. The structure of the sizes observed in both surveys was congruent, with latitudinal segregation between adult and juvenile specimens, and with the presence of juvenile cohorts. In the 2102-07 survey, higher values of the energy descriptors were obtained (NASC, average Sv and asymmetry), mainly of the adult specimens; while, in the 2109-11 survey, schools with greater morphometric dimensions were obtained (height, perimeter, volume, area and rectangularity) due to the wide distribution away from the coast. The biomasses estimated by the hydroacoustic methodology were similar in 2102-07 and 2109-11 surveys, determined at 12.03 and 8.03 million tons, respectively, being healthy and reflected in catches in the two fishing seasons of 2021. The three biomass estimation techniques were almost similar to those obtained in both surveys.
Keywords: Anchoveta; Distribution; Concentration; Schools; Abundance; Tons
