Fish Survey Data

This page provides anglers and other users access to fish survey data collected by Iowa Department of Natural Resources (DNR) fisheries staff during electroshocking and netting surveys on lakes, rivers and streams. Information available includes survey summaries from individual lakes and rivers, fish species length across lakes, and fish length and weight data. Additional data and summaries will be available in the future.

Fish survey data listed here includes information from a variety of types of surveys.

• Comprehensive surveys collect comparable data from a wide geographic range. The major tenet of this standardized sampling is to sample at the “same time, place and gear, with the same effort.” Comprehensive surveys must include spring electrofishing, which targets bass and some panfish species; summer hoop netting, which targets catfish; and fall frame netting, which targets panfish.
• General surveys also collect comparable data, but do not include all three sampling types required for comprehensive surveys.
• Trend surveys are conducted based on past survey work, but must develop samples that are scientifically sound and defensible. Trend surveys are often targeted at a particular fish species, and may yield results which show higher catch rates for that species than other survey types. Examples include fall electrofishing to assess year class strength of walleye populations, broodstock gill netting for walleyes and muskies, or early summer netting of riverine catfish species.
• Research surveys are undertaken to determine specific attributes of a fish population, or to address a particular problem.  These targeted surveys are scientifically sound and defensible, but may yield radically different results that would not be appropriate to compare to regular, standardized sampling.