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首页> 外文学位 >Stock structure and environmental effects on year class formation and population trends of Pacific herring, Clupea pallasi, in Prince William Sound, Alaska.
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Stock structure and environmental effects on year class formation and population trends of Pacific herring, Clupea pallasi, in Prince William Sound, Alaska.

机译：在阿拉斯加威廉王子湾的太平洋鲱Clupea pallasi对年级形成和种群趋势的种群结构和环境影响。

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Fluctuating forage fish populations trigger large ecosystem responses in the North Pacific. A representative species, Pacific herring, Clupea pallasi, was chosen to model environmental effects on population fluctuations and recruitment with a case example in Prince William Sound (PWS), Alaska. A unique approach was used to (1) develop a spatially-explicit, life history-based conceptual stock model, (2) quantify population level effects of climatic trends, and (3) model key environmental factors affecting recruitment. Framed as a simulation model, the stock model was compartmentalized by life-history stages based on shared habitats and environmental forcing. Initial model conditions impacting year-class formation were adult size-at-age, spawn timing, location and spawner density, and conditions during egg incubation, all impacting a two-stage larval mortality rate. Larval survival probably dictates the extremes in year-class strength. Age1 abundance should reflect recruitment levels 2–3 yrs later, unless a predator pit exists. A metapopulation structure was proposed with at least two local population groupings with spatial complexity required to maintain stock levels. Herring abundance correlated with long-term climate trends supporting hypotheses of bottom up environmental forcing. Adult growth was oscillatory over a 13 yr period in phase with zooplankton production and climatic trends. Spawn timing occurred progressively earlier over the last 30 yr period with a concurrent regional spawn allocation shift and decrease in recruits per spawner. Incorporating local stock structure and local environmental variables into nonlinear herring recruitment models improved explanatory power over traditional models. Best-fit variables were eastern PWS SST, salinity, SST variance, and salinity variance from spring to fall. Eight critical life stage periods were defined based on the season and lag of the best-fitting varibles. Examining other variables in these critical periods led to defining potential key processes affecting year class formation. Allocation of spawn and age-3 recruits to metapopulation regions also impacted recruitment to PWS as a whole and these results supported the metapopulation theory. The results led to formulation of a new theory, entitled “opposing response”, explaining the mechanism producing the observed pattern of alternating strong and week year class strengths in northern Pacific herring.
机译：饲草鱼种群的波动引发了北太平洋地区对生态系统的巨大反应。在阿拉斯加威廉王子湾（PWS）的一个案例中，选择了具有代表性的物种太平洋鲱鱼 Clupea pallasi 来模拟环境对种群波动和募集的影响。一种独特的方法用于（1）建立基于空间历史，基于生活史的概念库存模型;（2）量化气候趋势对人口水平的影响;（3）对影响招聘的关键环境因素进行建模。以模拟模型为框架，将种群模型按基于共享栖息地和环境强迫的生命历史阶段划分。影响年级形成的初始模型条件是成年成年大小，产卵时间，产卵位置和产卵密度以及卵孵化期间的条件，所有这些都会影响两阶段幼虫的死亡率。幼虫的存活率可能决定了年级强度的极限。年龄1的丰度应反映2-3年后的征募水平，除非存在掠食者坑。提出了一个具有至少两个当地人口分组的种群结构，其空间复杂性要求维持种群水平。鲱鱼丰度与长期气候趋势相关，支持自下而上的环境强迫假说。在浮游动物产量和气候趋势变化的13年中，成年动物的生长是振荡的。产卵时间在过去30年中逐渐发生，同时出现区域产卵分配变化，并且每个产卵者的新兵数量减少。将本地股票结构和本地环境变量纳入非线性鲱鱼招聘模型可以提高对传统模型的解释能力。最佳拟合变量为东部PWS SST，盐度，SST方差和春季至秋季的盐度方差。根据最合适的变量的季节和滞后定义了八个关键的生命阶段。在这些关键时期检查其他变量可以确定影响年级形成的潜在关键过程。将子代和3岁新兵分配到超种群区域也影响了整个PWS的募集，这些结果支持了超种群理论。结果导致形成了一个新的理论，称为“对立反应”，解释了在北太平洋鲱鱼上产生观察到的交替的强和周年级强度模式的机理。

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