Status and restoration options for Atlantic sturgeon in North America

There is considerable interest in restoring stocks of Atlantic sturgeon (Acipenser oxyrinchus), one of only two dozen extant sturgeons worldwide. Populations of its two subspecies are found in large rivers along the North American coasts of the Atlantic (A. o. oxyrinchus) and the Gulf of Mexico (A. o. desotoi). Although these populations were severely reduced because of overfishing and, in some instances, blockage of spawning runs, their present statuses, vary from those that still support limited fisheries (St. John River, new Brunswick), to a large but apparently declining population (Hudson River), to relict-sized (Delaware River, Mobile River), to apparently extirpated (Maryland tributaries of Chesapeake Bay; St. Johns, river, Florida). There are two primary alternatives for restoring these populations: (1) eliminating harvest and allowing natural recolonization and increase and (2) hatchery-based stocking (reintroduction or supplementation). We performed genetic analyses aimed at guiding restoration efforts. Mitochondrial DNA analysis revealed strong stock structure along both coasts at eh regional and, in some instances, population levels. Estimates of gene flow rates were low and suggested slow natural recolonization rates. Thus, the first alternative avoids the genetic risks of interstock transfer and inbreeding depression that may result from hatchery-based programs, but given the low intrinsic rates of increases and recolonization of Atlantic sturgeon, recovery may take decades to centuries, if it occurs at all. Therefore,it is imperative that the restoration approach be tailored to the particular circumstances and demographics of each population; however, the characteristics of this species and poor funding prospects make this information difficult to obtain. It appears likely that initial Atlantic sturgeon stocking efforts will target systems where they are extinct, as recently occurred in the Nanticoke River of Chesapeake Bay.