The multi-scale aggregative response of cormorants to the mass stocking of fish in rivers
The multi-scale aggregative response of cormorants to the mass stocking of fish in rivers
复制标题
鸬鹚对河流鱼类大量投放的多尺度聚合响应
DOI：
10.1016/j.fishres.2012.09.005
复制
发表时间：
2013
影响因子：
2.4
通讯作者：
M. Fujioka
中科院分区：
文献类型：
--
作者：
Naoko Kumada;T. Arima;J. Tsuboi;A. Ashizawa;M. Fujioka
在日本的河流中，大鸬鹚（Phalacrocorax carbo hanedae）和渔业之间存在着严重的冲突。这场冲突的基础是，鸬鹚以阿尤鱼为食，这是一种重要的商业鱼类，主要用于休闲捕鱼。为了了解鸬鹚如何改变其觅食栖息地与放养鱼类和捕捞活动的关系，我们使用两种不同空间尺度的方法研究了在4 - 7月的鸬鹚繁殖季节，鸬鹚丰度与ayu生物量之间的关系。首先，我们比较了不同河段的鸬鹚数量，这些河段是根据ayu放养确定的。鱼饵放生期间，鱼饵放生区域的鸬鹚数量呈增加趋势，而其他区域的鸬鹚数量没有明显的季节变化规律。其次，我们测试了鸬鹚数量是否与渔网捕获的阿渔生物量相关。在鱼样点900m、1km和2km范围内，阿育鱼生物量与鸬鹚数量呈显著正相关；然而，在采样点的100 - 800米范围内没有观察到这种相关性。4 ~ 6月，尽管有鸬鹚捕食，但鱼网捕捞的阿玉生物量仍在稳步增加；然而，这种生物量在7月捕鱼季节开始时急剧减少。该研究表明，尽管鸬鹚根据日本河流中大量的ayu种群改变了它们的觅食区域，但仍然保持了足够数量的ayu供垂钓者使用。
In Japanese rivers, there is a serious conflict between the great cormorant (Phalacrocorax carbo hanedae) and fisheries. The basis of this conflict is that the cormorants feed on ayu (Plecoglossus altivelis), a commercially important fish that is stocked primarily for recreational fishing. To understand how cormorants alter their foraging habitats in relation to the stocked fish and fishing activities, we examined the relationship between cormorant abundance and ayu biomass during the cormorant breeding season (from April to July) using two approaches that differ in spatial scale. First, we compared cormorant numbers in different river sections that were defined based on ayu stocking. The cormorant numbers in the sections stocked with ayu increased during the ayu release period, whereas the cormorant numbers in other sections showed no clear seasonal patterns. Second, we tested whether cormorant numbers were correlated with the biomass of ayu caught with cast nets. Positive correlations were observed between the biomass of ayu and the number of cormorants that were within 900m, 1km, or 2km of fish sampling points; however, such correlations were not observed within 100–800m of the sampling points. The biomass of ayu caught with cast nets increased steadily from April to June despite predation by cormorants; however, this biomass decreased sharply in July when the fishing season opened. This study indicates that although cormorants altered their feeding areas in accordance with the mass stocking of ayu in a Japanese river, sufficient numbers of ayu were still maintained for anglers.