PREY SIZE ANALYSIS IN THE DIET OF LARVAE OF 4 CLUPEIFORMS IN A COASTAL AREA OF CENTRAL CHILE

The food composition in diets of a group of clupeiform larvae constitu ted by Sardinops sagax, Strangomera bentincki, Ethmidium maculatum, an d Engraulis ringens, in a size range from 4,0 mm to 20,0 mm, is analyz ed in terms of type and size spectrum. Larvae were collected in Concep cion Bay between September and November of 1987. In the four species, larvae start to feed at distinct body lengths, involving different mou th widths. This allow them to ingest prey of different sizes, so there would be a partially differential utilization of food. E. ringens and E. maculatum are the species that capture larger and smaller particle s, respectively, with the other two species at intermediary positions. From gut content analysis it is shown that the diet of younger larvae is composed mainly of small prey, such as nauplii, copepod eggs, dino flagellates and mollusk larvae. In older larvae, besides the same kind of prey, larger prey like copedodites are found too. E. maculatum doe s not follow this pattern since, although it ingests larger particles at first feeding, it does not show a clear increase of prey size with larval size. Despite the: initial differences in larval size and mouth , the quantitative increment of mouth width with size is similar in th e four species. Moreover, the size ranges of particles in the diet in all the species overlap widely, indicating a similar utilization of fo od resources.