Are Marine Migrations of Striped Bass Genetically Pre-determined? : An investigation of Albemarle Sound-Roanoke River Striped Bass Migratory Patterns

Abstract

Striped bass, Morone saxatilis, is one of the most thoroughly studied anadromous fish species in the United States, with records governing the management of the species dating back to the late 1600s. However, management of this species has been difficult because of the species' anadromous behavior that takes it between fresh and marine waters, crossing numerous geopolitical boundaries. In the 20th century, the fishery experienced two dramatic declines in abundance. Studying the fishery after the declines resulted in major advancements in scientific understanding and management for this species, and striped bass is now an example of a successfully rebuilt fishery, key questions about population dynamics and migration patterns still persist. These unanswered questions reduce confidence in managing the species as a whole, and instead encouraging precautionary measures applied to small geographic areas, such as a natal river. This dissertation begins with a thorough review of the history of striped bass, including the key scientific findings and management measures instrumental in its recent recovery. Chapter 2 explores how scientists have approached the major challenge in striped bass management: defining the management unit so allocations can be made fairly and sustainably. The array of genetic techniques that have been employed, their limitations, and the populations studied with those techniques, is reviewed. Among the studies reviewed is one suggesting North Carolina striped bass migration may be genetically linked; this suggestion forms the basis for this dissertation's hypothesis. Answering this question can help resource managers better understand population dynamics, genetic interplay, and migration patterns - important for creating effective management and fair allocation between states. Chapter 3 explores the biotic and abiotic factors that can influence the results of an otolith microchemistry analysis, and Chapter 4 contains the discussion of the findings about the 112 striped bass examined. With biases accounted for, this dissertation concludes that marine migration was not linked to the genes examined. However, an interesting post-hoc observation can be made: though the behavior was not found to be genetically linked, striped bass in the first year of life proved to be residents, stagers, or sprinters, with different growth rates associated with these behaviors.