Selective Feeding by Atlantic Herring (Clupea harengus) Larvae on Zooplankton in Natural Assemblages

Abstract

The hypothesis that larval herring Clupea harengus select food by type as well a size was tested in laboratory experiments. Herring larvae were reared at 7 to 9ºC on wild zooplankton. The percentage of herring larvae with food at day's end increased from 4% (4 d) to 68% (9 d) and averaged 83% for larvae 25 to 74 d old. Larval herring selected aprticles according to type as well as size; this selectivity varied with larval age and hence size. Copepod nauplii and copepodites were prefered by larvae of all sizes. Among copepodites, Pseudocalanus sp. and Oithona sp. were preferred by smaller and larger larvae, respectively, while Acartia sp. was rarely ingested, even when of acceptable size. Mollusc veligers comprised a significant portion of the diet of young (4 to 24 d) larvae but were actevely rejected by older larvae even when perceived and of acceptable size. PArticles smaller than the largest acceptable size were consistently preferred, atypical of predation by vertebrates. These results indicate that larval herring select prey according to type as well as size and that this behavior is aquired through experience.