Sturgeon Caught in Yukon River

Observation by Sharon Alexie:

There were two sturgeons that were caught by two separate individuals fishing in different areas. Those are foreign fish that habitat in temperate seas. It's very curious. This individual was fishing up river and said he caught it around the surface, which is interesting because I thought they were bottom feeders? Another individual commented saying that there was another one caught down river during Y1 commercial fishing. People did eat the sturgeon and said it tasted very good. Observation shared via email with Erica Lujan.

Erin Larson, Assistant Professor of Environmental Science at Alaska Pacific University, writes:

To me, that looks likely like a green sturgeon, although it's potentially possible that it could be an Asian Sakhalin sturgeon. It sounds like those two species are really difficult to tell apart without using genetics. The northern range of green sturgeon isn't super well-defined, but they have been spotted in the Bering Sea and the Kuskokwim estuary previously. It's pretty interesting that this one was found so far upriver. Sturgeon spawn in freshwater, but right now, we only know about green sturgeon spawning in rivers in Oregon, Washington, and California. Similarly, we don't know a ton about their feeding habits, but sometimes adults will either feed on small, injured fish, or will display funny jumping behaviors when they're spawning, which might explain why this sturgeon was seen near the water surface.

I've attached a couple of publications about green sturgeon, including one specifically about reports of them in Alaska. It sounds like there might not be any tissue left from this sturgeon, but it could be cool to genetically test if it is in fact a green sturgeon or an Asian Sakhalin sturgeon, since they're difficult to tell apart by appearances alone!

Comments from LEO Editors:

This observation has been forwarded to the University of Alaska Fairbanks Museum of the North, as well as to the Alaska Department of Fish and Game. This observation is of particular interest because there is little information on sturgeon populations in Alaska.

There are 27 species of sturgeon that live in the Northern Hemisphere, but only two can be found along the west coast of North America - the green sturgeon (Acipenser medirostris) and the white sturgeon (Acipenser transmontanus). Sturgeon feed and mature in saltwater, and return to freshwater to spawn every 1-4 years.

In one of the papers that Erin forwarded , "Biology and life history of Green Sturgeon (Acipenser medirostris Ayres, 1854):state of the science" (available in the Documents section of this post), green sturgeon primarily spawn in the Sacramento, Klamath, and Rogue rivers in California and Oregon. As described in the paper, "Confirmed Records of Two Green Sturgeon from the Bering Sea and Gulf of Alaska," green sturgeon populations have been documented in the waters of Southeast Alaska and northern British Columbia, but (at the time of this publication) there have been only three reliable reports of green sturgeon in the Gulf of Alaska and Bering Sea, and two anecdotal reports from the Copper River and Unalaska areas. Complicating efforts to understand green sturgeon populations in Alaska are the similarities in appearance between green stugeon and the Asian Sakhalin sturgeon, described in more detail in the third paper Erin provided, "A comparison of meristic and morphometric characters of green sturgeon Acipencer medirostris."