Long-Term Ecological Research (LTER)/NTL010: Determination of Pelagic Fish Abundance in North Temperate Lakes Primary Study Lakes

LTER - Long-Term Ecological Research Program/North Temperate Lakes (NTL)

LTER/NTL010 [Summary adapted from the LTER Core Data Set Catalog]:

Data are collected along a set of transects in each of five lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout), using a Simrad 70 khz machine with the transducer suspended in front of the boat.

Transects are run on two nights and two days in late summer. The returning acoustic signal is recorded on audio tape, as well as on paper charts. The recorded signal is analyzed using the HADAS package to produce fish densities, by size, for each discrete depth in the lake.

The North Temperate Lakes (NTL) site is affiliated with the Center for Limnology at the University of Wisconsin, Madison. The NTL site focuses its research on north temperate lake ecosystems in the Northern Highland Lakes District of Wisconsin. The Northern Highland Lakes District, has an area of approximately 10,000 sq. km. and has one of the highest concentrations of lakes in the world. Lakes range in size from 0.1 to 1,500 ha, in depth from 1 to 33 m, and in fertility from oligotrophic to eutrophic. Other representative limnological conditions include: rainwater dominated, groundwater dominated and drainage lakes; dystrophic lakes; lakes with varved sediments, winterkill lakes, temporary and permanent forest ponds, and reservoirs. Lakes are influenced by strong seasonality and are usually ice covered from late November to late April. Lakes within the Northern Highland exhibit near-natural water quality conditions. Nearly 80% of the land area and two-thirds of the lake frontage are protected.

Information about LTER is also available on-line at 'http://lternet.edu/'