In warmwater fishes, feeding during winter is often assumed to be negligible; however, there is growing evidence that juveniles will feed opportunistically even at cold temperatures. If fishes are able to effectively digest prey, then feeding during winter could supplement energy reserves and mitigate the risk of winter starvation. We use laboratory and pond experiments to determine whether feeding during winter can supplement energy reserves in a warmwater species. We compared juvenile Pumpkinseed ( Lepomis gibbosus ) from two cold-climate (native Canadian) and two warm-climate (non-native Spanish) populations raised in a common environment to determine whether winter feeding is more prevalent in populations that typically experience longer winters. Under simulated winter conditions, Pumpkinseed with access to prey readily fed and had greater lipid mass in spring than those without access to prey. Despite similar rates of consumption, winter feeding improved lipid mass to a greater extent in the Canadian populations, indicating that feeding benefitted the cold-climate populations more than the warm-climate populations. All populations of Pumpkinseed overwintering in outdoor ponds also fed regularly, with 88% of individuals collected mid-winter containing at least one prey item. The pattern of loss in energy reserves over time varied dramatically among populations suggesting that pond-specific environmental conditions were important in shaping how energy reserves were used. These results indicate that winter feeding may be more common in juvenile warmwater fishes than previously thought and that supplementation of energy reserves during winter should be taken into account when considering the factors influencing first year recruitment success.

中文翻译：

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冬季零食：整个冬季喂食在幼南瓜中很常见，可提高春季可用的能量储备

在温水鱼类中，通常认为冬季的摄食可以忽略不计；然而，越来越多的证据表明，即使在寒冷的温度下，幼鱼也会投机取食。如果鱼类能够有效消化猎物，那么在冬季喂食可以补充能量储备并减轻冬季饥饿的风险。我们使用实验室和池塘实验来确定冬季喂食是否可以补充温水物种的能量储备。我们比较了在共同环境中饲养的两个寒冷气候（加拿大本土）和两个温暖气候（非西班牙本土）种群的幼南瓜（ Lepomis gibbosus ），以确定冬季喂养是否在通常经历较长冬季的人群中更为普遍。在模拟冬季条件下，与无法接近猎物的南瓜相比，能够轻易获得猎物的南瓜籽在春季具有更高的脂质质量。尽管消耗率相似，但冬季喂养在更大程度上改善了加拿大人群的脂质质量，表明喂养对寒冷气候人群的益处大于温暖气候人群。在室外池塘越冬的所有南瓜籽种群也定期喂食，88% 的个体在冬季收集到的至少含有一种猎物。随着时间的推移，不同人群的能量储备损失模式差异很大，这表明池塘特定的环境条件对于塑造能量储备的使用方式很重要。