July 24, 2013
Species Under the Radar — In-Fisherman occasionally features lake sturgeon and white sturgeon, but we hear far less about green sturgeon, a large species (over 200 pounds) that inhabits West Coast rivers and bays, primarily in estuarine waters. Although the southern population is listed as a threatened species, there's been relatively little research devoted to them. Harvest is banned throughout the region.
Recently, a team of biologists tagged 355 green sturgeon with acoustic transmitters on their spawning grounds and in non-spawning areas and studied their movements from Grays Harbor, south of Puget Sound, to San Pablo Bay near the Golden Gate Bridge. Fish were located with automated data-logging hydrophones placed in spawning rivers and various estuaries.
Results supported delineation of green sturgeon into discrete southern and northern population segments, as no fish from the Rogue or Klamath rivers ventured into the Sacramento River basin, and vice versa. During summer, sturgeon moved into estuaries not used for spawning, particularly Willapa Bay, Grays Harbor, the Umpqua River, and the Columbia River estuary, presumably to feed.
Some sturgeon moved through the Sacramento River to spawn upstream, while spawning migrations into the Klamath and Rogue rivers also were suspected from tracking locations. Researchers noted that movement patterns for the populations seemed entrained, and habitat degradation could disrupt key life history functions of this already scarce, but magnificent species.
*Lindley, S. T., and 11 coauthors. 2011. Electronic tagging of green sturgeon reveals population structure and movement among estuaries. Trans. Am. Fish. Soc. 140:108-122.