Comparative studies on feeding in larval anchoveta (Engralis ringens) and sardine (Sardinops sagax)
1989
Muck, P. | Rojas De Mendiola, B. | Antonietti, E. (Programa Cooperativo Peruano-Aleman de Investigacion Pesquera c/o IMARFE, Callao (Peru))
The diet and morphological parameters (mouth width, gut length, eye pigmentation, and mouth function) of larval anchoveta (Engraulis ringens) and sardine (Sardinops sagax) of the Peruvian upwelling system were studied, based on samples obtained in February/March 1982. The relationships body length/mouth width and body length/gut length showed significant differences: an anchoveta has a larger mouth than a sardine of the same size but a shorter gut; the two species also differed in a number of morphological characteristics. Species and size composition of prey in the guts of first feeding larvae (anchoveta: 3-3.5 mm; sardine: 4-4.5 mm) are significantly different: the former feeds almost exclusively on a pure phytoplankton diet (phytoflagellates, dinoflagellates; 30 micromole width) whilst the latter feeds almost exclusively on zooplankton (copepod eggs and naupli; 70 micromole width). These findings for first feeding larvae suggest a high larval mortality for anchoveta during El Nino periods when primary production is reduced drastically; they also agree with the hypothesis that differences in larval mortality during El Nino events are one of the decisive factors for the transition from anchoveta to sardine in the Peruvian upwelling system. For older anchoveta and sardine larvae (755.5 mm), there is a wide diet overlap for all stages of calanoid copepods, and phytoplankton becomes less important as an energy source.
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