Fishermen are not the only ones harvesting lower Columbia sturgeon.
Steller sea lions in the past decade have become a substantial threat, particularly in the 10 miles immediately downstream of Bonneville Dam.
Predation on sturgeon by sea lions happens elsewhere, too.
In 2009, the Oregon Department of Fish and Wildlife estimated the total annual predation on sturgeon in the entire lower Columbia and lower Willamette rivers at 6,700.
The estimate increased to 10,600 sturgeon by 2014.
The loss of adult fish reduces the productivity of the population, while the loss of juveniles may be reducing the number of sublegal (smaller than 38 inches) sturgeon.
