Larval growth of the anchoveta Engraulis ringens during the winter spawning season off central Chile


Hernandez, Eduardo H., and Leonardo R. Castro
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Larval growth rates of the anchoveta Engraulis ringens were determined for two periods during the winter spawning season off Talcahuano, central Chile. Because winter is the season of minimum plankton production during the year, we hypothesized that larval growth rates during winter should be constantly low because of decreased larval fish food availability. Our results, however, indicate that 1) mean larval growth rates determined from three growth models in winter (mid-July through mid-September) were as high as in other periods of the year (linear, Gompertz, and von Bertalanffy; 0.47 mm/d, 0.50 mm/d, and 0.48 mm/d, repectively); 2) differences in larval growth rates occurred in two groups of cohorts spawned in the two periods during the spawning season (0.40 mm/d vs. 0.57 mm/d); and, 3) larval food (dinoflagellates, copepod eggs, and copepod nauplii) concentrations in the field were relatively high and not very variable during the study. Hydrography of the water column, however, varied throughout the season. During the last weeks of the study seawater temperature was higher, indicating intrusion of offshore warmer waters into the coastal zone. The presence of these warmer waters suggests that differences in growth rates between groups of cohorts may have resulted from larval development in water with different characteristics. Consequently, for a coastal upwelling species such as the anchoveta, increased growth rates in some cohorts may be advantageous considering that its main spawning season occurs in winter when the environmental conditions fluctuate markedly in short time scales.