This weekend, CBC reported that father-son vacationers, Paul and Don Jarvis, caught a 3.5 meter (~12 ft) sturgeon weighing an estimated 400 kg (just under 900 lbs). Since the story made it to US national news, it doesn’t really fit my Meanwhile in Canada series, but I went down the internet rabbit hole to make it an Interesting Science subject.
The most accurate way to age a sturgeon requires that it be killed to count the layers (similar to tree rings) of the dorsal fin just behind the head or from the otoliths (literally, ear stone). To simplify matters, several organizations have made length charts to correlate the fish size to age. For example, see these from Minnesota (pdf) and Fraser River, BC (where this fish was caught, pdf). Neither of these give the age for the size of sturgeon caught, so they are only useful as general info. Plus, river sturgeon grow larger than lake sturgeon, so comparisons for different regions are troublesome.
Furthermore, a 2003 study from Idaho Fish and Game (pdf) summarized 23 years of research to correlate known fish growth over time to the fin ray method. They determined that the fin-ray method actually under estimated a sturgeons age. Newer information, like those from Wisconsin have applied a correction factor to improve the accuracy.
So, back to the question, how old is that sturgeon in the river? Nobody knows. The fish did not have a transponder tag to give any background information (although one was inserted in case it is ever caught again). General guesses range between the founding of the Dominion of Canada (1867) to the Yukon Gold Rush (late 1890s). Makes you feel young.