Fish Surveys and Research

An important objective of the Iowa Department of Natural Resources (DNR) Fisheries Bureau is to provide scientifically valid and defensible data for the effective and efficient management of Iowa’s aquatic resources. Fisheries management and research teams conduct scientific data collection and analysis across Iowa. 

Fisheries management teams are in charge of making decisions in their respective areas. They often conduct annual monitoring using a variety of survey approaches. The key to standard fisheries management is the collection of long-term data sets that help identify important trends in fish populations.  It's from long-term changes that biologists can best evaluate the needs of Iowa anglers and our fisheries.

  • Comprehensive surveys are used to collect standardized, comparable data from a wide geographic area. Standard protocols are shared across the state, allowing for fair comparisons across space and time. Comprehensive surveys must include spring electrofishing, summer hoop netting, and fall fyke netting. In addition to fish sampling, vegetation sampling is required for a complete comprehensive survey.

  • General surveys also collect similar data, but may not include all three requisite sampling approaches. They may also include other sampling methods or seasons, especially if targeting a particular fish species or size. Data from general surveys are not used in the same way as comprehensive surveys because of these differences.

  • Trend surveys use methods typically based on long-term historical approaches. Consistency is the key to trend surveys, allowing for comparison over time in a specific location. Trend surveys are often used to target a particular fish species and may yield results with higher-than-normal catch rates when compared to other surveys. When done consistently, this information can be used to answer specific questions. Examples include fall electrofishing to assess year-class strength of walleye populations, broodstock gill netting for walleyes and muskellunge, or early summer netting of riverine catfish species.

Fisheries management teams utilize all of these survey types to keep track of their fishery resources. The data they collect include fish species, length, weight, and health condition; overall catch rates (as a measure of abundance) and size structure; and presence of previously marked/tagged fish or spawning fish. It also includes water chemistry, boat ramp conditions, and fish habitat conditions. Iowa DNR strives to make much of this data available to anglers (and to anyone who is interested) through its website. Visit a particular lake or river’s detail page and scroll to the bottom under the section “Science and Conservation” to explore our public Fisheries Data Dashboard.

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Fisheries Research

In addition to all of this work, the Iowa DNR Fisheries Bureau also has dedicated research teams, who conduct special projects in support of existing and future changes in fisheries management in Iowa. These research projects may include the entire state, focusing on particular ecosystems. They are often designed to answer specific questions, requiring specific methods that may not be part of our comprehensive or trend surveys. They may be especially time-consuming or require collaboration with partners at universities or other agencies. Research projects are developed with (and sometimes by) fisheries management teams to ensure the research question is relevant, timely, and translates to useful management implications. The overall goal is to provide Iowans with the highest quality angling and aquatic resources as possible.

  • Intercept surveys are used to collect not only information about the fish, but about the people who use and enjoy the resource. This includes creel surveys, in which anglers are asked about their fishing day and catch, and aquatic invasive surveys in which boat ramp users are asked about their awareness of invasive species spread. Intercept surveys allow more personal, face-to-face conversation to help us stay in tune with the needs of those who want to use the aquatic resource.

  • Human dimensions surveys, along with a host of other social science approaches, are used to collect information about people’s needs, interests, and satisfaction. Sometimes these are mailed or conducted online, sometimes in person, but their purpose is to better represent the target population (for example, all Iowans) as a whole. Examples include the Iowa Lakes Survey and Trout Angler Survey.

Fisheries research provides the foundation of smarter, more efficient and effective fisheries management for Iowa’s resources. The DNR’s Fisheries Research program focuses on evaluating existing fisheries management practices, innovating new techniques, and advancing the science and technology used to improve fishing in Iowa’s lakes, rivers, and ponds. This focus helps the Fisheries Bureau ensure that fishing license dollars are spent wisely and as efficiently as possible. The research program accomplishes this with seven dedicated research stations: Natural Lakes, Large Reservoirs, Small Impoundments, Large Rivers, Interior Rivers and Streams, Fish Culture, and Data Science and Support. 

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Fisheries Research Dedicated Research Stations

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