Ecology of larval fishes in the Independencia Bay, Pisco, Peru: Temporal and spatial relationships, taxonomic aspects

Abstract

The plankton of Independencia Bay was sampled during the year 2000. In total, 16,156 fish larvae, representing 34 families, 48 genera and 48 species were collected. 8 families numerically dominated the diverse larval fish fauna and comprised 96.8% of the larvae captured. The monthly mean density of total fish larvae showed two peaks (springtime and summer peaks). The greatest mean density during the spring peak was 7,492 larvae/100 m3, recorded in October. The greatest mean density during summer was recorded in February (2,493 larvae/100 m3). Abundance in October (spring time) at Santa Rosa was higher than at the other 3 stations, but abundance in those other 3 stations was higher in February (summer time). The spring and summer ichthyoplankton abundance peaks in Independencia Bay coincided with high zooplankton standing stocks and also coincided, approximately, with periods of increased upwelling in the area. The occurrence of high larval fish densities and the wide range of larval stages suggest that Independencia Bay is a regionally important spawning and nursery ground for marine fish. A Principal Component Analysis (PCA) showed that temperature and salinity accounted for the largest fraction (74.4%) of the variability in the observed larval fish assemblage patterns. Vertical distribution patterns of ichthyoplankton were examined from two depths (surface and 10 m) at two stations. There were no statistically significant differences between nighttime and daytime densities of fish larvae at either depth. Nevertheless, a small degree of vertical redistribution was apparent for some species that could be interpreted as nocturnal dispersal. Developmental series for individuals of Normanichthys crockeri and Prolatilus jugularis are presented using morphological features and pigmentation patterns. Larvae hatch sizes, information concerning the different stages, main diagnostic features of the larvae and meristic information including fin ray accounts are given.