Morphological Differentiation of Lake Sturgeon (Acipenser fulvescens) from the St. Lawrence River and Lac des Deux Montagnes (Quebec, Canada)

Abstract

We investigated the degree of morphological differentiation of lake sturgeon (Acipenser fulvescens) from the St. Lawrence River (Lacs Saint-Pierre and Saint-Louis and the river itself downstream from Lac Saint-Pierre) and from Lac des Deux Montagnes. Forty-one morphometric characters (traditional and truss network) and two meristic traits were used on 200 sturgeon (890–1010 mm total length) from five sites. The study of the meristic characters showed a difference of 1.5 gill rakers between Lac Saint-Louis sturgeon and those from Lac Saint-Pierre and Lac des Deux Montagnes although the range was identical in all groups. Principal components and discriminant analyses performed on morphometric characters showed that Lac des Deux Montagnes sturgeon differ markedly from the St. Lawrence River fish by their proportionally higher and longer head (correct reclassification 89%). The more discriminant descriptors show a difference ranging from 4 to 16 mm between Lac des Deux Montagnes fish and those from the St. Lawrence River. The multivariate analyses also revealed significant morphometric differences between fish in different sectors of the St. Lawrence River. However, the absolute differences are rather tenuous and are not adequate to designate separate stocks based solely on morphology.