Ecological Study on Carrying Capacity and Population Density-dependent Effect of Pacific salmon

研究了北太平洋太平洋鲑鱼的承载力和种群密度效应。1)通过Logistic方程和繁殖曲线计算的北太平洋粉鲑的承载力与阿留申低压指数（ALPI）显著相关。这表明，太平洋鲑鱼的承载能力可能会随着长期气候变化而变化。2)北海道大麻哈鱼成熟期的体尺在20世纪70年代末至90年代初呈显著下降趋势，自90年代末以来呈相对上升趋势。在北海道大麻哈鱼中，不仅种群数量与叉长呈显著负相关，而且种群大小与群体的平均成熟年龄呈正相关。从尺度反算的生长分析表明，北海道鲑在第二年以后，特别是在第三年的海洋生活中，生长量出现了下降 ...更多信息 三文鱼然而，最近的增长下降，没有显着影响其繁殖力和鸡蛋的大小。这表明，减少增长和成熟年龄的增加是由于密度依赖的种内竞争和高丰度的鲑鱼在北太平洋。3)在阿拉斯加湾，1994年至1996年和1998年期间，除了主要以凝胶状浮游动物为食的鲑鱼外，太平洋鲑鱼的主要猎物动物是鱿鱼（主要是银乌贼）。1997年，太平洋鲑鱼的摄食和生长受到厄尔尼诺事件的影响，鱿鱼从它们的胃里消失了。1999年以来，阿拉斯加湾6种太平洋鲑鱼的食物生态位没有明显差异，主要以磷虾类、端足类、桡足类和翼足类等浮游动物为食。稳定同位素分析结果表明，coho和Chinook鲑鱼，以及虹鳟鱼）的含量高于肉食动物（例如，红鲑、鲑鱼和粉红鲑鱼）。4)这些结果发表在许多科学论文上，并在国际研讨会和会议上提出。少

We investigated on carrying capacity and population density-dependent effect of Pacific salmon in the North Pacific Ocean. 1) The carrying capacity, which is calculated by the Logistic equation and the reproduction curve, of pink salmon in the North Pacific Ocean significantly correlated with the Aleutian Low Pressure Index (ALPI). This indicates that the carrying capacity of Pacific salmon may vary with long-term climate change. 2) Body size of Hokkaido chum salmon at maturity showed a significant decreasing trend from the late 1970s to early 1990s and relative increasing trend since the late 1990s. In Hokkaido chum salmon, not only significant negative relationship between population abundance and fork length, but also positive relationship between population size and average age at maturity of cohorts were observed. Growth analysis back-calculated from scales showed that a growth reduction occurred after the second year, especially in the third year of oceanic life of Hokkaido chum … More salmon. The recent growth reduction, however, had no significant effect on their fecundity and egg size. This suggested that reduced growth and increasing age at maturity were due to density dependent intraspecific competition and high abundance of chum salmon in the North Pacific Ocean. 3) In the Gulf of Alaska, a dominant prey animal of Pacific salmon except for chum salmon, which fed mainly on gelatinous zooplankton, was squids (mainly Berryteuthis anonychus) during years from 1994 to 1996, and 1998. In 1997, Pacific salmon was affected feeding and growth by the El Nino Event, and squids disappeared from their stomach. There is no difference of food niche among 6 species of Pacific salmon in the Gulf of Alaska since 1999, because all species fed mainly on zooplankton such as euphausiids, amphipods, copepods, and pteropods. The result of stable isotope analysis showed that trophic levels of nekton-feeders (e.g., coho and Chinook salmon, and steelhead trout) were higher than those of plankton-feeders (e.g., sockeye, chum, and pink salmon). 4) These results were published on many scientific papers, and presented at international symposium and meetings. Less