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Person

Daniel A Isermann

Unit Leader - Research Fish Biologist
Cooperative Research Units

Email: disermann@usgs.gov
Office Phone: 715-346-3221
Fax: 715-346-3624
ORCID: 0000-0003-1151-9097

Location
College of Natural Resources U of W
College of Natural Resources
University of Wisconsin
Stevens Point , WI 54481-3897
US

Supervisor: Cyndy Loftin
Understanding age and growth are important for fisheries science and management; however, age data are not routinely collected for many populations. We propose and test a method of borrowing age–length data across increasingly broader spatiotemporal levels to create a hierarchical age–length key (HALK). We assessed this method by comparing growth and mortality metrics to those estimated from lake–year age–length keys ages using seven common freshwater fish species across the upper Midwestern United States. Levels used for data borrowing began most specifically by borrowing within lake across time and increased in breadth to include data within the Hydrologic Unit Code (HUC) 10 watershed, HUC8 watershed, Level III...
Categories: Publication; Types: Citation
Resisting ecosystem transformation through an intensive whole-lake fish removal experiment
Abstract (from Fisheries Management and Ecology): Lake ecosystems are shifting due to many drivers including climate change and landscape-scale habitat disturbance, diminishing their potential to support some fisheries. Walleye Sander vitreus (Mitchill) populations, which support recreational and tribal fisheries across North America, have declined in some lakes. Climate change, harvest, invasive species and concurrent increases in warm-water fishes (e.g. Centrarchidae) may have contributed to declines. To test the utility of an intensive management action to resist walleye loss, an experimental removal of ~285,000 centrarchids from a 33-ha lake over 4 years was conducted while monitoring the fish community response....
Categories: Publication; Types: Citation
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Adult walleye (10 females and 10 males) were caught in Fox River (Wisconsin) during April 2014. Total length, weight, and age were determined for each of the walleye. Whole-fish homogenates were prepared during 2017. Lipid concentration and polychlorinated biphenyl (PCB) congener concentrations were determined in each of the homogenates during 2017-2018. For each sample, PCB congener concentrations were summed to yield total PCB concentration. All lipid and PCB congener terminations were made at the University of Michigan School of Public Health in Ann Arbor, Michigan.
Walleye (Sander vitreus) and Yellow Perch (Perca flavescens) are culturally, economically, and ecologically significant fish species in North America that are affected by drivers of global change. Here, we review and synthesize the published literature documenting the effects of ecosystem changes on Walleye and Yellow Perch. We focus on four drivers: climate (including temperature and precipitation), aquatic invasive species, land use and nutrient loading, and water clarity. We identified 1232 tests from 370 papers, split evenly between Walleye (N=613) and Yellow Perch (N=620). Climate was the most frequently studied driver (N=572) and growth/condition was the most frequently studied response (N=297). The most commonly...
Categories: Publication; Types: Citation
Largemouth Bass (LMB) Micropterus salmoides is one of the most popular sport fish in the United States and is intensively managed across much of its range. Beginning in 1989, Wisconsin implemented more restrictive harvest regulations for LMB, including greater minimum length limits, reduced bag limits, and a catch-and-release-only season during the spawning period across much of northern Wisconsin. We tested for trends in LMB relative abundance, growth, and angler catch and harvest in relation to LMB management policies from 1990 to 2011. We also tested for potential sport fish community responses to changes in LMB abundances using Walleye (WAE) Sander vitreus as an example. Angler catch rates and electrofishing...
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