Data from: Empirical verification of feeding selectivity of larval and juvenile pelagic fishes using in situ zooplankton communities

Most studies on the feeding ecology of larvae and juveniles of
commercially important pelagic fishes have used field-based approaches.
However, due to possible biases related to net sampling, it is uncertain
whether the results obtained from those studies truly represent the
situation of live fish in the sea. Here we investigated the feeding
ecology of pelagic fishes through a laboratory experiment minimizing the
biases inherent in field net sampling. In the experiment, hatchery-reared
juvenile chub mackerel (Scomber japonicus) and larval/juvenile Japanese
anchovy (Engraulis japonicus) were fed with wild-caught zooplankton
assemblages collected from around Hakatajima Island in the Seto Inland
Sea, Japan. The relationships between fish size and prey number in the
gut, and the selectivity on each prey organism were determined. As a
result, in both species, prey number and size increased with body size,
and the fish showed strong selectivity for crustaceans including
copepodites and adults of copepods. Our data has also clearly indicated
that both species can selectively prey on preferred foods that are rare
while avoiding non-preferred foods that are abundant. These results, which
substantially accord with reports from previous field studies, will not
only help field scientists make a convincing interpretation of their data,
but also open the possibility of further laboratory studies on detailed
mechanisms of the feeding selectivity of larval/juvenile pelagic fishes.

针对具有商业价值的中上层鱼类幼体及稚鱼的摄食生态学研究，大多采用野外采样方法。然而，由于网采样本可能存在系统性偏差，现有此类研究得到的结果是否能真实反映海洋中活体鱼类的真实摄食状态，仍未明确。为此，本研究通过实验室控制实验开展中上层鱼类摄食生态学研究，以尽可能规避野外网采方法固有的偏差。实验中，我们以人工繁育的日本鲭（Scomber japonicus）稚鱼，以及日本鳀（Engraulis japonicus）的幼体与稚鱼为实验对象，投喂采自日本濑户内海伯方岛周边海域的野生浮游动物群落。我们测定了鱼类体长与肠道内猎物数量之间的关联，以及对各类猎物的摄食选择性。结果显示，两种鱼类的肠道猎物数量与猎物体型均随自身体长增长而增加，且二者均对包括桡足类幼体和成体在内的甲壳类动物表现出强烈的摄食偏好。本研究数据同时明确证实，两种鱼类均可选择性捕食较为稀有的偏好性猎物，同时避开较为常见的非偏好性猎物。本研究结果与既往野外研究的报道基本一致，不仅可为野外研究者对其数据的合理解读提供支撑，同时也为开展针对中上层鱼类幼体与稚鱼摄食选择性详细机制的后续实验室研究开辟了可能。