North Temperate Lakes LTER: Pelagic Prey - Sonar Data 2001 - current

Total pelagic fish abundance data were collected annually in mid-summer using sonar along a set of transects in each of eight lakes (Allequash, Big Muskellunge, Crystal, Sparkling, Trout, Mendota, Monona, and Fish), from 1981-1999, and in Lakes Monona and Fish from 1995-1999. This data is not available online (contact [e-mail]). No data was collected in 2000. In 2001, collection resumed on Crystal, Sparkling, and Trout. In 2005, collection resumed on Lake Mendota. This data is included in this dataset as CSV files. The data represent lake-wide density estimates for abundant pelagic prey species in each lake. The sampling on each lake was conducted in depths greater than 5 meters to avoid hazards to equipment. In addition, because of the near field acoustic effects, the upper 2 meters of the water column is not represented in the data. Although they were rare, large targets representing predatory species were excluded from the density estimation for pelagic prey species using the proportion of large targets identified during single target analysis on each lake. Densities for Sparkling, Crystal and Mendota are for the entire basin of each lake. The data shown for Trout Lake represent densities in only the south basin. Number of sites: 41981至1999年，研究团队于每年仲夏时节，在8个湖泊（Allequash、Big Muskellunge、Crystal、Sparkling、Trout、Mendota、Monona及Fish）的预设样带上使用声呐（sonar）采集远洋鱼类总丰度数据；1995至1999年期间，额外补充了Monona湖与Fish湖的采样工作。本数据暂不支持在线获取，如有需求请联系[e-mail]。2000年未开展任何采样工作。2001年恢复对Crystal湖、Sparkling湖及Trout湖的采样，2005年则恢复对Mendota湖的采样。本数据集以CSV格式文件存储上述全部数据。 该数据为各湖泊内优势远洋猎物种群的全湖尺度密度估算结果。为规避设备作业风险，所有采样均在水深大于5米的区域开展。此外，受近场声学效应影响，水体上层2米范围的相关数据未纳入本数据集。尽管捕食性大型目标个体较为稀少，但研究人员通过对各湖泊开展单目标分析时识别出的大型目标占比，将其从远洋猎物种群的密度估算流程中剔除。 Sparkling湖、Crystal湖及Mendota湖的密度数据为对应湖泊的全流域尺度结果；本次公布的Trout湖数据仅涵盖其南流域的密度估算值。采样点位总数为4。