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 (Lakes Monona and Fish from 1995). Sonar data were not collected in 2000, but collection resumed in 2001 on Crystal, Sparkling, and Trout and continues to the present (with the exception of Crystal in 2004). In 2005, data were also collected on Mendota. This dataset includes data from lakes Crystal, Sparkling, Trout and Mendota from 2001 through 2007. The data represent lakewide 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, the low volume sampled in shallower depths and the addition of shallow water species in density estimates. In addition, because of the near field acoustic later, the upper 2 meters of the watercolumn 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 lakes Sparkling, Crystal and Mendota are for the entire basin of each lake. The data shown for Trout Lake represent densities in the largest south basin only Number of sites: 4

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