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首页> 外文期刊>Marine ecology progress series >Comparative analysis of the feeding ecology of two pelagic forage fishes: capelin Mallotus villosus and walleye pollock Theragra chalcogramma
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Comparative analysis of the feeding ecology of two pelagic forage fishes: capelin Mallotus villosus and walleye pollock Theragra chalcogramma

机译：两种中上层饲草鱼类：毛鳞鱼和壁角狭鳕Theragra蓝藻的摄食生态学比较分析

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摘要

Pelagic forage fishes are an important component in the transfer of trophic energy in marine ecosystems. Capelin Mallotus villosus and age-0 walleye pollock Theragra chalcogramma are pelagic forage fishes whose alternate fluctuations in abundance have been associated with system-wide biotic reorganization of the Gulf of Alaska (GOA) ecosystem. To better understand differences between these fishes, we compared their feeding ecology using samples of similar-sized (39 to 126 mm) individuals collected together in midwater trawl hauls during September 2000 to 2001 in the western GOA. Zooplankton samples were used to characterize prey availability. The comparative analysis focused on diet, feeding chronology, daily ration, and prey selectivity. The diet of both species mostly consisted of small copepods, large copepods, adult and juvenile euphausiids, thecosome pteropods, and larvaceans; consequently, the overall diet overlap was high. The diet overlap of fish from some samples, however, was low. Capelin fed mostly during crepuscular periods while pollock mostly fed at night. The daily ration estimate for capelin was low (1.8% body weight [BW]) relative to pollock (5.2% BW). Chesson's index of selectivity indicated preferential selection of euphausiids (adult and juvenile) by capelin and age-0 pollock. At euphausiid-poor locations, capelin stomachs were mostly empty while pollock stomachs contained alternate prey. Selectivity of amphipods, large copepods, larvaceans, and reptantians was higher for age-0 pollock than for capelin. Consumption of euphausiids increased with their abundance in the plankton, and consumption:biomass ratios indicate that localized depletion could occur. We hypothesize tthat capelin increase foraging mobility while age-0 pollock switch to alternate prey as a competitive response to limited euphausiid avail-ability.
机译：远洋饲料鱼类是海洋生态系统中营养能量转移的重要组成部分。 Capelin Mallotus villosus和0岁角膜白鲑Theragra chalcogramma是浮游性饲料鱼，其交替的丰度波动与阿拉斯加湾（GOA）生态系统的全系统生物重组有关。为了更好地理解这些鱼类之间的差异，我们使用2000年9月至2001年在GOA西部中部拖网拖网中收集的相似大小（39至126毫米）个体的样本，比较了它们的摄食生态。浮游动物样品被用来表征猎物的可用性。比较分析的重点是饮食，进食时间，每日定量和猎物选择性。两种物种的饮食主要由小型co足类，大型co足类，成年和幼年的足up，小体足类和幼体组成。因此，总体饮食重叠率很高。但是，某些样品的鱼的饮食重叠很低。卡普林（Capelin）大部分在夜间进行觅食，而鳕鱼（Palock）多数在夜间进食。相对于鳕鱼（5.2％BW），毛鳞鱼的日定量估计值低（1.8％体重[BW]）。 Chesson的选择性指数表明，毛鳞鱼和0岁的狭鳕对虾类（成人和青少年）的优先选择。在肠胃炎较差的地方，毛鳞鱼的胃大部分是空的，而狭鳕的胃中则有其他猎物。 0岁小孔雀的两栖类，大型pe足类，幼虫和re类动物的选择性高于毛鳞鱼。紫杉类的消费量随其浮游生物的丰富而增加，而消费：生物量之比表明可能发生局部枯竭。我们假设毛鳞鱼会增加觅食的活动性，而0岁的鳕鱼会切换为替代猎物，以竞争对有限的磷虾利用率的竞争。

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