STATUS AND RESTORATION OPTIONS FOR ATLANTIC STURGEON IN NORTH-AMERICA

There is considerable interest in restoring stocks of Atlantic sturgeo n (Acipenser oxyrinchus), one of only two dozen extant sturgeons world wide. Populations of its two subspecies are found in large rivers alon g the North American coasts of the Atlantic (A. o. oxyrinchus) and the Gulf of Mexico (A. o. desotoi). Although these populations were sever ely reduced because of overfishing and, in some instances, blockage of spawning runs, their present statuses, vary from those that still sup port limited fisheries (St. John River, new Brunswick), to a large but apparently declining population (Hudson River), to relict-sized (Dela ware River, Mobile River), to apparently extirpated (Maryland tributar ies of Chesapeake Bay; St. Johns, river, Florida). There are two prima ry alternatives for restoring these populations: (1) eliminating harve st and allowing natural recolonization and increase and (2) hatchery-b ased stocking (reintroduction or supplementation). We performed geneti c analyses aimed at guiding restoration efforts. Mitochondrial DNA ana lysis revealed strong stock structure along both coasts at eh regional and, in some instances, population levels. Estimates of gene flow rat es 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, b ut given the low intrinsic rates of increases and recolonization of At lantic sturgeon, recovery may take decades to centuries, if it occurs at all. Therefore,it is imperative that the restoration approach be ta ilored to the particular circumstances and demographics of each popula tion; however, the characteristics of this species and poor funding pr ospects make this information difficult to obtain. It appears likely t hat initial Atlantic sturgeon stocking efforts will target systems whe re they are extinct, as recently occurred in the Nanticoke River of Ch esapeake Bay.