Ten years of hydroacoustical observations of the behavior and distribution of small pelagic fish in the west coast of Baja California, Mexico

Abstract

The main goal is to present results on the behavior and distribution of small pelagic fish on the west coast of Baja California, Mexico using hydroacoustics and related to oceanographic parameters. From December 1993 to September 2002, 20 oceanographic surveys have been done off the west coast of Baja California, Mexico aboard the R/V ‘‘El Puma.’’ Two areas are covered, a Northern area from Punta Colnet to Punta Baja (30 54′, 116 40′ W to 29 26′ N 115 29′ W) and a Southern area from Punta Eugenia to Bahia Tortugas (27 29′ N 115 22′ W to 26 47′ N 113 55′ W). Results show that since 1993 echo-counting has been reduced significantly in both areas. Results are discussed in terms of oceanographic parameters and the presence of the 1997 El Niño. Before the 1997 El Niño, echo-counting was high in both areas. The behavior is reversed during El Niño. However, in the central area results from March 2000 may suggest a possible change in this tendency.