Lake Whitefish in Lake Champlain after Commercial Fishery Closure and Ecosystem Changes

Abstract

Lake whitefish Coregonus clupeaformis were commercially fished in Lake Champlain until the 1913 fishery closure in U.S. waters. The only study of lake whitefish in the lake had been done in the 1930s. Our goals were to compare current biological parameters with historical information and to determine distribution and spatial differences in larval densities, with an emphasis on locating current spawning grounds, to gain insight on the current population in Lake Champlain. Adult lake whitefish (N = 545) were collected from 2006 to 2010 by using gill nets and trawls focused in the Main Lake. Larvae were collected extensively lakewide and intensively at Wilcox Cove and Rockwell Bay with an ichthyoplankton net. Population attributes (size, age, and sex composition; and growth, condition, and mortality) were typical of unexploited populations, as there was a wide range of length-classes (126–638 mm total length) and age-classes (1–26 years). Lake whitefish from the Main Lake had a high condition factor, and growth parameters were comparable with those of fish collected in the 1930s. Lake Champlain lake whitefish had greater asymptotic lengths than generally documented for the species. Larvae were found at sites throughout the Main Lake, and larval densities were among the highest recorded for the species (maximum = 2,558 larvae/1,000 m³); however, no lake whitefish were collected on the two historically documented spawning grounds. Lake whitefish in the Main Lake demonstrate characteristics of an unexploited population; however, evidence of spawning is absent or rare in portions of their historic range where habitat has been altered.

Received February 22, 2011; accepted August 24, 2011

ACKNOWLEDGMENTS

We thank Shawn Good (VTFWD) for access to laboratory equipment. We also thank Elias Rosenblatt, Neil Thompson, Josh Ashline, Kevin Osantowski, Lindsay Schwarting, and Joanna Hatt for assistance in the field and laboratory, and Richard Furbush, Joe Bartlett, and Rebecca Gorney for assistance with fish collection. We especially thank the National Oceanic and Atmospheric Administration for funding this project.