Comparison of Juvenile Alewife Growth and Movement in a Large and a Small Watershed

The freshwater behaviors of juvenile alewives Alosa pseudoharengus and the variables affecting their survival to recruitment are relatively unknown, even though recruitment to marine populations is critical to sustaining and restoring populations. Fish were collected in fall 2009 from a large watershed (the Hudson River, New York; N = 10) and a small watershed (the Peconic River, New York; N = 14), otolith chemistry was used to associate the fish to groups, and growth rates were compared both within and between rivers. Otolith Sr:Ca and Ba:Ca were measured along growth transects, and significant changes in these values were determined. In many instances, changes in these values are associated with changes in daily otolith growth increments. More variation was observed in the Ba:Ca ratios and daily growth rates of Hudson River alewives, possibly because they had more available nursery habitats. While there was variation in otolith chemistry and daily growth within Peconic River fish, fewer otolith chemistry patterns were observed in this group. Comparison of cumulative daily growth rates between the two groups showed that Hudson River alewives were smaller at younger ages but that their growth rate increased and their size at age eventually surpassed that of the Peconic River alewives. The results presented here provide the foundation for future work investigating the abiotic and biotic variables influencing juvenile alewife growth, behavior, and survival in different-size watersheds. Received March 21, 2011; accepted September 26, 2011