Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print.
In subarctic Newfoundland, age-0 Atlantic cod (Gadus morhua) settle into coastal habitats in several summer–autumn pulses, resulting in broad length-frequency distributions before winter. Low winter temperatures and potential decreases in food availability pose challenges for young-of-year fish. To examine how size variation affects overwintering success under contrasting food scenarios, we conducted 114-day laboratory feeding trials at ambient overwinter sea temperatures, using demersal age-0 cod collected from Newman Sound, Newfoundland. We reared two size classes of juvenile cod under four daily ration levels (starvation, low, medium, high). We used Fulton’s K condition factor to interpret effects of food availability and fish size on survival over winter. We showed that small amounts of consumed food (<1% BW·day−1) maximized winter growth and condition potential of juvenile cod in Newfoundland waters. With no food, survival of small cod dropped below 80% on Day 47, whereas survival of large juveniles remained >80% until Day 74. Therefore, we expect higher survival of earlier settlers and increased size-selective mortality in age-0 cod during either unproductive or protracted winters, when food abundance is often low.

中文翻译：

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食物和初始大小会影响少年海鱼（0岁大西洋鳕鱼）的越冬存活率和状况

《加拿大渔业和水生科学杂志》，印刷前。
在北极的纽芬兰地区，0岁的大西洋鳕鱼（加德斯·莫尔华）在数个夏季至秋季的脉动中定居于沿海栖息地，从而导致冬季前的长频分布。冬季气温低和粮食供应量可能减少，对年幼鱼类构成了挑战。为了检查尺寸变化如何影响在不同食物场景下的越冬成功，我们使用从纽芬兰的纽曼桑德（Newman Sound）收集的0年代龄鳕鱼，在环境越冬海水温度下进行了114天的实验室喂养试验。我们在每日四个日粮水平（饥饿，低，中，高）下饲养了两种大小的鳕鱼。我们使用富尔顿的K条件因子来解释食物供应量和鱼的大小对冬季生存的影响。我们发现少量食用的食物（< 1％BW·day-1）最大化了纽芬兰水域的冬季生长和鳕鱼的条件潜能。在没有食物的情况下，小鳕鱼的存活率在第47天降至80％以下，而大龄幼鱼的存活率一直保持在80天以上，直到第74天。因此，我们期望早期定居者的存活率更高，而0岁鳕鱼的体型选择死亡率则在此期间增加。要么是无产或旷日持久的冬天，那时食物的丰度往往很低。