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首页> 外文学位 >The relationships between fluctuations in oceanographic conditions, forage fishes, predatory fishes, predator food habits, and juvenile salmonid marine survival off the Columbia River.
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The relationships between fluctuations in oceanographic conditions, forage fishes, predatory fishes, predator food habits, and juvenile salmonid marine survival off the Columbia River.

机译：海洋条件波动，觅食鱼，掠食性鱼类，捕食者的饮食习惯和哥伦比亚河外幼鲑鱼的海洋生存之间的关系。

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摘要

Salmonid run sizes are strongly affected by their early marine stage. Fully understanding the life history of salmonids means understanding how they interact with their marine environment and with other fishes. Changes in the biological and physical environment off the Columbia River region affects the distribution and abundance of predatory fishes and their feeding, forage fishes, and juvenile salmonid marine survival. From 1998--2004, forage fish and predatory fish distribution and abundance off the Columbia River was quantified by surface trawling at night during spring/summer. The effect of predation on salmonids was measured by stomach analysis of predatory fishes. During the study period (1998--2004), forage fishes increased in abundance by orders of magnitude and were strongly related to the abundance of cold-water copepods the previous year. Higher forage fish populations were also linked to cooler ocean conditions and perhaps fewer predatory Pacific hake (Merluccius productus). Most forage fishes were distributed nearshore while predators had a more offshore distribution. Pacific hake was most abundant in 1998, 2003, and 2004; warm ocean years. Jack mackerel (Trachurus symmetricus ) was most abundant during 1999--2002; relatively cool ocean years. Deep (50-m) ocean temperatures and the date of the spring transition, when nearshore currents switched from northward to southward, were good predictors of Pacific hake abundance in the study area. Forage fish or salmonid occurrence in a haul was negatively related to the occurrence of predators. Pacific hake and jack mackerel ate primarily euphausiids and small fishes. Salmonids were rarely eaten by either predator. However, because the Pacific hake population can be very large, hake predation can be a significant source of juvenile salmon mortality off the Columbia River during some years. A trophic model showed that marine mortality of Columbia River juvenile salmonids may be related to the abundance of Pacific hake and forage fishes. A multiple regression using the predictions from the trophic model of annual numbers of juvenile salmonids eaten by hake and Columbia River spring flows as independent variables, accounted for much of the variation observed in the annual marine survival of Columbia River coho (Oncorhynchus kisutch) and Chinook salmon (O. tshawytscha), the dependent variable. Future research should identify the physical and biological forces that alter the feeding habits, migration and movements of Pacific hake and jack mackerel off the Northwest, and how Columbia River flows affect trophic interactions.
机译：鲑鱼的游走规模受到其早期海洋阶段的强烈影响。充分了解鲑鱼的生活史就意味着了解鲑鱼如何与海洋环境和其他鱼类相互作用。哥伦比亚河地区以外的生物和物理环境的变化会影响掠食性鱼类的分布和丰度，以及它们的摄食，饲料鱼和幼鲑鱼的海洋生存。从1998年至2004年，通过春季/夏季夜间的拖网捕鱼对哥伦比亚河沿岸的饲草鱼和掠食性鱼类的分布和丰度进行了量化。通过捕食性鱼类的胃部分析来测定捕食对鲑鱼的影响。在研究期间（1998--2004），饲用鱼的丰度增加了几个数量级，并与前一年的冷水pe足类的丰富度密切相关。饲草鱼的增加也与海洋凉爽和捕食性太平洋鳕（Merluccius productus）较少有关。大多数饲料鱼分布在近岸，而捕食者的分布在近海。太平洋无须鳕在1998年，2003年和2004年最为丰富。温暖的海洋岁月。鲭鱼（Trachurus symmetricus）在1999--2002年间数量最多;海洋年相对凉爽。当近岸海流从北向南转换时，深海（50米）的海洋温度和春季过渡的日期可以很好地预测研究区域太平洋鳕鱼的丰度。拖网中饲料鱼或鲑鱼的发生与捕食者的发生负相关。太平洋无须鳕和鲭鱼主要食用鱼up和小鱼。鲑鱼很少被任何一个捕食者吃掉。但是，由于太平洋无须鳕种群可能很大，因此在某些年份中，无须鳕捕食可能是哥伦比亚河外幼鲑死亡的重要来源。一个营养模型表明，哥伦比亚河幼鲑的海洋死亡率可能与太平洋鳕鱼和饲料鱼的丰富性有关。使用营养模型预测的多元回归，将无须鳕和哥伦比亚河春季水流吞噬的年幼鲑鱼的数量作为自变量，解释了哥伦比亚河coho（Oncorhynchus kisutch）和Chinook的年度海洋生存中观察到的大部分变化鲑鱼（O. tshawytscha），因变量。未来的研究应该确定改变西北太平洋太平洋无须鳕和鲭鱼的取食习惯，迁移和运动的物理和生物力，以及哥伦比亚河的水流如何影响营养相互作用。

著录项

  • 作者

    Emmett, Robert L.;

  • 作者单位

    Oregon State University.;

  • 授予单位 Oregon State University.;
  • 学科 Biology Oceanography.; Agriculture Fisheries and Aquaculture.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 335 p.
  • 总页数 335
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 海洋生物;水产、渔业;
  • 关键词

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