Abundance of Engraulis ringens and other pelagic species in the Peruvian marine ecosystem determined by acoustic methods in 2021

Abstract

In 2021, two hydroacoustic cruises were conducted along the entire Peruvian coast to assess pelagic resources. The research was supported by industrial vessels from the Peru’s National Fisheries Society. The first cruise, 2102-07, took place from February 17 to April 1, and was completed from June 19 to July 13. The second cruise, 2109-11, was carried out between September 22 and November 3, 2021. This article presents the distribution and biomass of Engraulis ringens, as well as Trachurus murphyi, Scomber japonicus, Anchoa nasus, Galeichthys peruvianus, Pleuroncodes monodon, Dosidicus gigas, and Vinciguerria lucetia in the Northern Region of the Humboldt Current System (NRHCS). The results
indicate that E. ringens is the dominant species, with a healthy population benefiting from the slightly cool to neutral oceanographic conditions of the area. Its distribution showed seasonal patterns, with concentrations and a biomass of 12.03 million tons observed up to 80 nm offshore during cruise 2102-07, and a more scattered distribution with a biomass of 8.03 million tons observed up to 121 nm offshore during cruise 2109-11. Acoustic characteristics of E. ringens schools varied between surveys due to environmental variability and chlorophyll-a concentration. P. monodon was the second most abundant species in the coastal zone, sharing its
distribution with Engraulis ringens. Its biomass during cruises 2102-07 and 2109-11 was 1.50 and 1.20 million tons, respectively. T. murphyi and S. japonicus had limited and isolated distributions, with Scomber japonicus estimated at 0.82 million tons during cruise 2102-07 in areas of high school aggregation. Abundance of coastal species A. nasus and G. peruvianus was lower, while mesopelagic species D. gigas and V. lucetia were found in offshore areas. Only V. lucetia during cruise 2109-11 had a biomass estimated at 1.06 million tons.