Fish Ecology Field & Laboratory Assistant

Employer:  Joe Mrnak (; he/him)


I am seeking 2 motivated and independent undergraduate students to assist on two whole-lake manipulation experiments (invasive species removals, native species introductions) in northern Wisconsin.  Broadly, this research/project attempts to serve as an extension of efforts to restore ecosystems and(or) manage fisheries using a food web and ecosystem context.

Invasive species are a global concern, particularly for aquatic ecosystems.  In Wisconsin, invasive rainbow smelt (Osmerus mordax) negatively affect ecosystems that they colonize through competitive and predatory interactions with native species.  Negative effects include shifting food webs, altering zooplankton communities, and the decline or extirpation of native cool- and cold-water fishes (e.g., yellow perch Perca flavescens, walleye Sander vitreus, cisco Coregonus artedi).  Understanding and mitigating these effects and associated consequences are of primary interest to stakeholders, managers, and ecologists alike.  Research will focus on characterizing the abundance, distribution, diets, and population dynamics of several fish species across multiple lakes.  The work will primarily be composed of:

Field work: ~70% of time (work will be conducted BOTH during the day and at night)

  • Hydroacoustic fishery surveys
  • Fish sampling (e.g., vertical/horizontal gillnets, fyke nets, boat electroshocking, etc.)
  • Fish processing (length, weight, sex, diets, age structures, isotopes, etc.)
  • Basic limnological and zooplankton sampling

Laboratory work: ~30% of time

  • Sample processing (e.g., fish diets, age structures, zooplankton, isotopes, etc.)
  • Data entry

Most of the work will be based in the field and may require long hours under sometimes adverse conditions.  Fish sampling and habitat characterization will all be done via boat.  Technicians will gain experience with several fish, limnological, and habitat sampling methods.  Aside from this main project, there will be multiple opportunities to assist on and gain experience with other fisheries-based projects/groups (e.g., Wisconsin Department of Natural Resources-Escanaba Lake Research Station, UW-Stevens Point, North Temperate Lakes Long Term Ecological Research).

Having students with different life experiences and backgrounds is critical to ensure the exchange of diverse ideas which is necessary in training tomorrow’s scientists. Because we are actively working to increase diversity and inclusivity in our discipline, underrepresented groups are especially encouraged to apply.


  • Respectfully interacting with members of the public at field sites
  • Safe operation of UW – Madison boats and vehicles
  • Launching and towing boats
  • Careful and accurate data collection and sample processing
  • Deploying and retrieving sampling equipment
  • Handling and measuring fish
  • Conduct habitat surveys
  • Assist with field and lab equipment maintenance
  • Entering data into database


  • Must be eager to learn and have a genuine interest in aquatic ecology and(or) fisheries management
  • A unique aspect of this position will be an opportunity to conduct an independent research project (including giving an oral presentation) using data you collected!
  • Maintain positive attitude while conducting work
  • Must be willing to work under sometimes adverse conditions (i.e., nighttime, hot sun, cold, wind, rain, biting flies, etc.) for long hours
  • Be able to lift and carry a moderate amount (~30-50 lbs) of gear over short distances
  • Must be able to swim
  • Valid driver’s license which meets UW Risk Management standards is required.


  • Number of positions: 2 @ ~40 hrs/week
  • Start date: early to late May 2024
  • End date: late August to early September 2024
  • Pay:  $14.50 no experience; $14.75 some experience; $15.00 very experienced


These positions are located at the CFL’s Trout Lake Station in Boulder Junction, WI in northern Wisconsin.   Dormitory style housing (not food) is provided free of charge. Enjoy swimming, hiking, fishing, biking and shoreline campfires while gaining valuable research experience!

How to apply:

  • Application link
  • Priority consideration deadline:  February 21, 2024
  • We accept applications until all positions are filled.
  • Indicate preference for Fish Ecology Field & Laboratory Assistant on your application and contact Joe Mrnak if you have any questions.

The CFL is an equal opportunity employer and is dedicated to an inclusive and positive working environment for all.