Detection of Natural Hybridization between Pink Salmon (Oncorhynchus gorbuscha) and Chinook Salmon (Oncorhynchus tshawytscha) in the Laurentian Great Lakes Using Meristic, Morphological, and Color Evidence

Abstract

ciation (IGFA) as a world record pink salmon. The IGFA requested confirmation of the specimen's identification from G. Smith, Curator of Fishes at the University of Michigan's Museum of Zoology. Based on skeletal characters and color patterns, the specimen was identified as a hybrid between pink salmon (Oncorhynchus gorbuscha) and chinook salmon (0. tshawytscha; G. Smith, pers. comm.). Subsequent analysis of one nuclear DNA locus supported this conclusion (B. Shields, pers. comm.). Here, I report on meristic, morphological, and coloration patterns of suspected hybrids between pink and chinook salmon from the St. Marys River. Documentation of these characters and their inheritance patterns in hybrids may enable researchers and managers to detect and study hybridization between these two species. I also document the ranges of variation for meristic, morphological, and color characters in the St. Marys River populations of pink and chinook salmon. This information represents a benchmark against which to measure future changes in these populations. Some studies of morphological and molecular characters of Lake Superior pink salmon have been published (Berg, 1979; Gharrett and Thomason, 1987), but descriptions of subsequent pink salmon founder populations in the other Great Lakes are limited to discussion of abundance