Juvenile pink salmon energy density, wet, dry, frozen weights from F/V Great Pacific, R/V Miller Freeman cruises in the Coastal Gulf of Alaska, NE Pacific, 2001-2003 (NEP project)

<p><strong>GLOBEC 2000: Feeding, growth, condition and energetics of juvenile pink salmon</strong><br />
<em>L. Haldorson [University of Alaska], D. Beauchamp [University of Washington], K. Myers [University of Washington]</em></p>

<p>The goal of this project is to determine how pink salmon in the northern Gulf of Alaska are affected by variation in the plankton production system during their first months at sea. This will be accomplished through an integrated project that includes field sampling, laboratory analyses and modeling. Pink salmon occupy surface waters of the continental shelf in the summer and fall after entering marine waters in the spring. In that period they grow rapidly and their feeding changes from small zooplankton in the summer to large zooplankton in the fall. This project will document temporal and spatial variation in prey use and availability, it will assess the effects of the shelf environment by measuring growth and condition of pink salmon, and it will use spatially-explicit foraging/bioenergetic modeling to understand observed patterns in feeding, growth and condition. Fish of hatchery origin, identified by thermal otolith marks, will be of particular interest, as the marine survival of each hatchery cohort will be available a year after those fish enter the marine environment.</p>

<p>Spatial and temporal variation in pink salmon diets and surface zooplankton will be described through laboratory analyses of field samples, and the basis for diet shifts to larger prey will be determined by calculations of prey selectivity. Standard length/weight condition measures will be calculated, and the energy content of salmon will be measured by calorimetry. Growth will be measured by size at age for hatchery fish and by scale analyses for all fish. The relationship between condition, growth and the environment will be examined. Habitat quality over the continental shelf will be assessed with spatially-explicit models with foraging and bioenergetic components that produce weight-specific estimates of growth potential. Bioenergetic modeling will also be used to estimate daily ration and seasonal consumption by pink salmon. The relationship between diets of pink salmon and other planktivorous fishes will be assessed.</p>

<p>This research will contribute directly to accomplishment of the GLOBEC program goal of understanding how production of upper trophic level species is linked to variation in oceanographic conditions. It is widely accepted that production of salmon in the GOA is determined by planktonic production. Detailed descriptions of spatial and temporal variation in diet, prey availability, temperature, growth and fish condition will substantially enhance our understanding of the connections between the marine environment and salmon production. (<em>project abstract</em>)</p>

<p><strong>GLOBEC 2000：幼年粉鲑（pink salmon）的摄食、生长、健康状况与能量学</strong><br /><em>L. 哈尔德森 [阿拉斯加大学]、D. 博尚 [华盛顿大学]、K. 迈尔斯 [华盛顿大学]</em></p>
<p>本项目旨在明确阿拉斯加湾北部海域的幼年粉鲑在入海后的最初数月内，如何受浮游生物生产系统变化的影响。研究将通过整合野外采样、实验室分析与模型构建三大模块完成。幼年粉鲑于春季入海后，在夏季与秋季栖息于大陆架表层水域；此阶段其生长速度较快，摄食对象也从夏季的小型浮游动物逐渐转变为秋季的大型浮游动物。本项目将记录猎物利用与可获得性的时空变化，通过测定幼年粉鲑的生长与健康状况评估大陆架环境的影响，并采用空间显式觅食/生物能量学模型解析其摄食、生长与健康状况的观测模式。本研究将特别关注通过热致耳石标记识别的孵化场繁育个体，因为这些孵化场种群的海洋存活率数据将在其入海一年后获得。</p>
<p>将通过对野外采样样本的实验室分析，描述幼年粉鲑食谱与表层浮游动物的时空分布特征，并通过猎物选择性计算明确其向大型猎物转变食性的内在机制。将计算体长/体重标准健康指数，并采用热量测定法测定粉鲑的能量含量。生长情况将通过孵化场繁育个体的年龄-体长关系，以及所有个体的鳞片分析进行测定。本研究将解析健康状况、生长与海洋环境之间的关联。将借助集成觅食与生物能量学模块的空间显式模型，评估大陆架栖息地质量，该模型可生成基于体重的生长潜力估算值。此外，生物能量学模型还将用于估算幼年粉鲑的日摄食量与季节摄食量。同时，本研究将评估幼年粉鲑与其他浮游食性鱼类的食谱重叠关系。</p>
<p>本研究将直接助力GLOBEC计划目标的达成——即明确高营养级物种的生物量如何与海洋环境变化产生关联。学界普遍认为，阿拉斯加湾（Gulf of Alaska，以下简称GOA）的鲑鱼生物量由浮游生物生产所决定。对食谱、猎物可获得性、水温、生长情况与鱼类健康状况的时空变化进行详细解析，将极大深化我们对海洋环境与鲑鱼生物量之间关联机制的认知。（项目摘要）</p>