Substantial economic losses of farmed catfish to fish‐eating birds such as the double‐crested cormorant, Phalacrocorax auritus, continue to be reported on U.S. catfish farms. An economic analysis was conducted of the on‐farm effects of both the increased expenditures to scare fish‐eating birds from catfish farms and of the value of the catfish that were consumed by cormorants. A survey was conducted of U.S. catfish farmers in the Delta region of Mississippi and Arkansas, to obtain farm‐level data on expenditures to scare birds. Estimations of the lost revenue from catfish consumed by cormorants were developed from a concurrent study on cormorant distribution, abundance, and diet in the region. The economic effects of bird predation in terms of both fish consumption and management costs were evaluated across three farm sizes and nine catfish production practices. Catfish farmers spent on average $704/ha ± $394/ha to scare birds, making bird‐scaring costs one of the top five costs of raising catfish. The greatest cost components of scaring birds were manpower (39% of all bird‐scaring costs) and the variable and fixed costs of trucks used to scare birds (34% of all bird‐scaring costs). Losses were greater on hybrid than channel catfish fingerling ponds. Industry‐wide, the value of catfish losses averaged $47.2 million (range of $25.8–$65.4 million). Total direct economic effects (including both the increased costs to scare birds and the revenue lost from fish consumed by cormorants despite bird‐scaring attempts) averaged $64.7 million (ranging from $33.5 to $92.6 million). Profitability improved by 4% to 23% across the farm size/production strategies analyzed upon removal of the economic effects from bird predation, with greater effects occurring on smaller‐scale farms. One‐third of the farm size and production scenarios analyzed changed from being unprofitable to showing a profit in the absence of such negative economic effects associated with bird depredation. Overall, the combined effects of increased farm expenditures to scare birds from farms and the value of the catfish lost to predation by cormorants caused substantial negative economic effects on catfish farms.

中文翻译：

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cor捕食对cat鱼养殖场的主要经济影响

养殖cat鱼对以鱼为食的鸟类（如双冠mor，Ph）的重大经济损失，美国farm鱼养殖场继续有报道。对of鱼养殖场吓e食鱼鸟的支出增加以及cor消费的the鱼的价值对农场的影响进行了经济分析。对密西西比州和阿肯色州三角洲地区的美国cat鱼养殖者进行了一项调查，以获取农场级别的恐鸟支出数据。a虫消耗的cat鱼收入损失的估算是根据对该地区cor分布，数量和饮食的一项并行研究得出的。在三种养殖场规模和九种cat鱼生产实践中，评估了鸟类捕食对鱼类消费和管理成本的经济影响。farmers鱼养殖者平均花费704美元/公顷±394美元/公顷来吓birds鸟类，养scar成本是养cat鱼的前五项成本之一。吓鸟的最大成本构成是人力（占全部杀鸟成本的39％）以及用于吓鸟的卡车的变动和固定成本（占所有杀鸟成本的34％）。杂种的损失比沟channel鱼的鱼种塘更大。在整个行业范围内，losses鱼损失的平均价值为4720万美元（范围为25.8-6550万美元）。总的直接经济影响（包括吓birds鸟类的成本增加和尽管attempts鸟而造成的consumed消费鱼损失的收入）平均为6470万美元（从33.5美元到9260万美元不等）。在剔除鸟类捕食带来的经济影响之后，在整个农场规模/生产策略中，获利能力提高了4％至23％，而在较小规模的农场上则产生了更大的影响。在不存在与禽类掠食有关的负面经济影响的情况下，所分析的农场规模和生产情景的三分之一从无利可图变为盈利。总体而言，增加农场支出以吓退鸟类的农场支出和cor所捕食的fish鱼的价值加在一起，对cat鱼养殖场造成了重大的负面经济影响。