Seeb, J. E., L. W. Seeb, D. W. Oates and F. M. Utter (1987).  Genetic variation 
and postglacial dispersal of populations of northern pike Esox lucius in North 
America. Canadian Journal of Fisheries and Aquatic Sciences.  44:556-561.
	
The authors studied the genetic relationships and postglacial dispersal of 
northern pike Esox lucius populations in North America using allozyme data. 
Allelic products of up to 65 protein coding loci were examined in eight 
populations: five from drainages in western Canada; two from the Missouri River 
drainage, and one from the upper Mississippi River drainage. Only two 
polymorphic loci were identified, Est-1 and Ck-1, and the average observed 
heterozygosity was only 0.001. All of the populations from the drainages in 
western Canada and the Missouri River were genetically identical. The 
Mississippi River population was unique, expressing Ck-1(140), an allele nearly 
absent in all other populations, at a frequency of 0.99.