Origin and Movements of Young-of-the-Year Striped Bass in the Southern Gulf of St. Lawrence, New Brunswick

Abstract

Young-of-the-year (age-0) striped bass Morone saxatilis have been observed during late summer and fall in southern Gulf of St. Lawrence estuaries that may not support striped bass spawning. In this study, we tested the hypothesis that age-0 striped bass in the Richibucto and Kouchibouguac rivers disperse there from the Miramichi River, which is located approximately 35 km north of the Kouchibouguac River and 55 km north of the Richibucto River. Beach seining of the coastline between these three rivers during summer in 1997 and 1998 confirmed the presence of age-0 striped bass in the latter half of August but not before. Age-0 fish distributions over time were consistent with movement from the Miramichi River to the Kouchibouguac and Richibucto estuaries. Microsatellite nuclear DNA and mitochondrial DNA analyses were performed to determine the genetic relatedness among striped bass from these estuaries. Age-0 striped bass from the Shubenacadie River population in the Bay of Fundy, which is known to be genetically distinct from Gulf of St. Lawrence populations, and the Hudson River, New York, were used as out-groups in the analyses. In all comparisons, significant haplotype and allelic differences were found between Gulf of St. Lawrence samples and the Shubenacadie River and Hudson River populations. However, significant haplotype or allelic differentiation was rarely observed in comparisons among samples from rivers within the Gulf of St. Lawrence. These results suggest that some of the age-0 striped bass spawned in the Miramichi River leave their natal estuary in late summer and disperse through shallow coastal waters to other estuaries in the southern Gulf of St. Lawrence.