Understanding how environmental factors—here, light intensity and turbidity—influence the feeding, growth, and survival of larval Delta Smelt is critical for optimizing the culture of this endangered fish species. Three sets of rearing trials were conducted where larvae were cultured under different levels of turbidity and light intensity. Delta Smelt larvae feeding activity was observed throughout the initial adjustment of light and turbidity levels to ascertain feeding ability and behavior at the different levels. It was found that there is a minimum threshold of combined light and turbidity to generate their exogenous feeding response. At low turbidity conditions, early-stage larvae begun feeding and growing earlier when light levels were higher. The condition factor and survival of the late-stage larvae was increased with increased turbidity. The results suggest Delta Smelt larvae may be cultured under lower turbidity and light conditions rather than at the currently used levels. We conclude that the interaction between turbidity and light intensity plays an important role in the feeding activity, growth, and survival of larvae. The results here may inform fish culture lab methodologies, but may also provide useful baseline knowledge for light and turbidity preferences of Delta Smelt larvae in the wild.

中文翻译：

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光和浊度对 Delta Smelt（Hypomesus transpacificus、Actinopterygii、Osmeridae）幼虫的摄食、生长和存活的影响

了解环境因素（这里是光照强度和浊度）如何影响幼体 Delta Smelt 的摄食、生长和存活，对于优化这种濒危鱼类的养殖至关重要。进行了三组饲养试验，其中在不同的浊度和光照强度水平下培养幼虫。Delta Smelt 幼虫的摄食活动在整个光照和浊度水平的初始调整过程中都被观察到，以确定不同水平的摄食能力和行为。发现存在组合光和浊度的最小阈值以产生它们的外源摄食反应。在低浊度条件下，当光照水平较高时，早期幼虫开始摄食和生长更早。后期幼虫的条件因子和存活率随着浊度的增加而增加。结果表明 Delta Smelt 幼虫可以在较低的浊度和光照条件下培养，而不是在目前使用的水平下培养。我们得出结论，浊度和光照强度之间的相互作用在幼虫的摄食活动、生长和存活中起着重要作用。这里的结果可能会为鱼类养殖实验室方法提供信息，但也可能为野生 Delta Smelt 幼虫的光和浊度偏好提供有用的基线知识。