62-6 The lake whitefish population in Lake Champlain: Past and present

Thursday, September 16, 2010: 3:20 PM
302 (Convention Center)
Seth Herbst , Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT
J. Ellen Marsden, Ph.D. , Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT
Lake whitefish support one of the most valuable freshwater fisheries in North America. Whitefish were commercially fished in Lake Champlain until the 1912 fishery closure in U.S. waters. The only whitefish study was done in the 1930s. Our goals are to compare current and historical biological parameters and determine distribution and spatial differences in larval densities, with an emphasis on locating current spawning grounds, to gain insight on the current whitefish population in Lake Champlain. Whitefish were collected in 2009 (N=223) using gill nets and trawls focused in the main lake, and ranged from 126-658mm TL.  Otolith ages ranged from 1-18, sex ratio was approximately 1:1 (M:F = 85:98), estimated von Bertalanffy growth parameters were K = 0.2 and L = 564, and mean Fulton’s K condition was 1.7. Fish collected in the 1930s using seines ranged from 356-663mm TL, scale ages ranged from 2-17, sex ratio was approximately 1:1 and Fulton’s K was 1.6 to 1.8.  Larval collections in 2009 showed that whitefish spawned throughout the main lake, but made limited use of northern and southern spawning sites, contradictory to historical records.  The absence of whitefish in these portions of their historic range may be cause for concern. 
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