Restoring an Ancient Fish in a Modern World

Sturgeons are unique among the world’s c. 27,000 fishes: ancient in origins, limited in species diversity, morphologically specialized, ecologically generalized, long-lived and slowly reproducing, both freshwater dwelling or anadromous and, concerning humans, of considerable commercial, public, and scientific interest.  The sustainability of freshwater and anadromous fishes is challenged by the usual litany of overfishing, pollution, and habitat alterations, with blockage of migration to historical spawning grounds by dams being the chief hindrance to anadromous fish populations.  More recent impediments include climate change, hatchery and aquaculture effects, and the consequences of alien species. But many of the characteristics that combine to make sturgeons unique also influence the relative effects of all of these challenges to their survival. The status of freshwater-resident forms of sturgeon is chiefly beholden to the history of harvests.  Compared with other freshwater-sea migratory fishes, anadromous sturgeons, with their tendency to inhabit the lower mainstem reaches of rivers, have suffered less from damming.  Sturgeons also appear reasonably resilient to contamination.  But all sturgeons appear to be acutely sensitive to overharvest, whether intentional or as bycatch. (However, many exceptions exist to these overall conclusions.)  Given their life history characteristics and the typical management options available, there are relatively few international success stories—most recoveries occur slowly, if at all. A surprising aspect to sturgeon conservation is how cryptic populations can be, meaning that some circumstances are not as impoverished as they first appear. Sturgeons are also highly charismatic and restoration efforts may benefit from public support if they are presented as iconic species.