Food habits of great cormorant Phalacrocorax carbo hanedae at Lake Biwa, Japan, with special reference to ayu Plecoglossus altivelis altivelis
Food habits of great cormorant Phalacrocorax carbo hanedae at Lake Biwa, Japan, with special reference to ayu Plecoglossus altivelis altivelis
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日本琵琶湖大鸬鹚 Phalacrocorax carbo hanedae 的饮食习惯，特别是香鱼 Plecoglossus altivelis altivelis
DOI：
10.1111/j.1444-2906.2006.01175.x
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发表时间：
2006
影响因子：
1.9
通讯作者：
T. Nakajima
中科院分区：
文献类型：
--
作者：
Tetsumi Takahashi;K. Kameda;M. Kawamura;T. Nakajima
近年来，由于琵琶湖附近的大鸬鹚Phalacrocorax carbo hanedae的数量增加，影响了香鱼Plecoglossus altivelis的商业捕捞。1998年和2001-2002年对66个胃的食性进行了研究，并观察了食物含量的季节变化。香鱼在胃中的比例在4月以后逐渐增加，7 - 8月占优势（重量比为0.62，出现频次为0.85）。相比之下，10月下旬之后，在胃中没有发现香鱼。春季香鱼个体数和密度的增加被认为是香鱼食性改变的触发因素。大鸬鹚对琵琶湖香鱼的摄食影响在46月约为46 t，在7 ~ 8月约为310 t。在香鱼商业捕捞的主要时期（11月至次年6月），与商业捕捞量相比，香鱼消耗的估计质量要小得多。
The recent increase in numbers of individuals of a piscivorous bird, the great cormorant Phalacrocorax carbo hanedae, around Lake Biwa has affected the commercial catch of ayu Plecoglossus altivelis altivelis. The food habits of the bird were studied based on 66 stomachs in 1998 and 2001–2002, and a seasonal variation in food contents was observed. The proportion of ayu in stomachs increased after April, and became most dominant during July and August (0.62 in proportion of weight, 0.85 in frequency of occurrence). In contrast, ayu was not found in the stomachs after late October. The increase of ayu in individuals and density in the surface layer of the pelagic zone of the lake during spring was considered as a trigger for the change of the food habits of the birds. The feeding impact of great cormorant on ayu in Lake Biwa was estimated to be approximately 46 t during April to June, and 310 t in July and August. During the main period for the commercial ayu catch (November to the following June), the estimated mass consumed by the bird is much smaller in comparison with the commercial catch.