Genetic diversity and structure of lake whitefish (Coregonus clupeaformis) 100 years after closure of the commercial fishery

Abstract

In small, inland fisheries even small perturbations to the ecosystem can quickly influence population abundance, size and age distribution, and genetic structure and diversity. In Lake Champlain, lake whitefish (Coregonus clupeaformis) experienced extensive commercial harvest from the mid-1800 s to1918 and habitat fragmentation due to the construction of multiple causeways between 1850 and 1899. We evaluated the influence these environmental perturbations had on lake whitefish population genetics 120 years later. We used historic catch records to determine whether fishing pressure could have been strong enough to reduce lake whitefish population abundance, and used genotype data from eight microsatellite loci to look for genetic signatures of population-sub structure and bottleneck. Catch records indicate lake whitefish were being harvested in Lake Champlain at a similar magnitude to the Great Lakes, and simulations suggest genetic diversity may have been lost as a result of harvest. However, we were unable to detect significant evidence of a genetic bottleneck, but we cannot conclusively suggest that harvest of lake whitefish did not result in a genetic bottleneck. Additionally, we found only slight evidence of population sub-structure among isolated basins, suggesting that either some gene flow among basins is possible, or that populations are just beginning to diverge and therefore differences in allele frequency were too small to detect. These data provide a perspective on effects of an inland lake commercial fishery that was closed prior to population collapse, and offer a comparison to the Laurentian Great Lakes where lake whitefish are still being harvested.