Day 390#: Russian Sturgeon
Today's animal of the day is the Russian Sturgeon (Huso gueldenstaedtii)!
Photo credit: Dennis Jacobsen
This species of critically endangered sturgeon spends most of its life swimming in the saline waters of the Black, Azov, and Caspian Seas. They are typically found near the sea floor, where they like to search the sand and mud for crustaceans, molluscs, and small fish to eat. They sense their prey from within the muck using three pairs of special barbels located on the tips of their snouts, which are super sensitive and can easily detect movement in the water. These sturgeon are capable of growing almost 7 ft long (around 83 inches)! However, these giant individuals are exceptionally rare, and most only grow to around 3 to 4.5 ft long.
Photo credit: gernotkunz on iNaturalist
While they spend most of their lives in saltwater, they're actually born in the freshwater lakes and rivers of Eastern Europe and Western Asia. Once they mature, the young sturgeon will make their way out to sea and live solitary lives until they reach sexual maturity. Starting in April, mature fish who are ready to spawn will form large schools and make their way upstream in order to reach the spawning grounds by June. Unlike salmon, which only spawn once and then die shortly after, sturgeon will return to the ocean after spawning and can spawn multiple times within their lifetimes. However, this does take up a lot of energy, so males usually only spawn once every other year, while females spawn once every two to three years.
Photo credit: Tennessee Aquarium
Sadly, spawning becomes harder and harder for these fish every year due to the construction of dams and pollution preventing them from traveling back and forth between the ocean and their spawning grounds. They are also regularly hunted for their unfertilized eggs, which are eaten as caviar. Usually, the female is killed in order to harvest her eggs, though there are non-lethal harvesting methods. Sadly, this is time-consuming and impractical for large-scale harvesting, so most fish caught are slaughtered. Thankfully, it is now illegal to hunt this species, and most caviar comes from farmed fish, which are somewhat better suited for the non-lethal harvesting method. Sadly, poaching still occurs, and even if it didn't, the various obstacles blocking their paths to the spawning grounds make it impossible for them to replenish their population.
A: Russian sturgeon, B and C: sturddlefish, D: American paddlefish / photo credit: Jenő Káldy and colleagues
Also, fun fact: in 2020, it was found out that the Russian sturgeon and American paddlefish are able to hybridize somehow. These hybrids are known as sturddlefish, which is an amazing name. I don't want to talk about these guys too much now, since they definitely deserve their own post someday, but it's so weird that these two species are even able to hybridize since they aren't even in the same family!
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