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Fish of the Day

Today's fish of the day is the green sturgeon!

The green sturgeon, scientific name Acipenser medirostris, is known for being one of the few sturgeon species in North America, and their distinctive color. Like many fish in the modern day, the green surgeon has both a historic range, and a far reduced current range. The historic range stretches the entire coast of California and Oregon, spawning in the Klamath river, and traveling in rivers between the two freely, but the modern range is only a fraction of what it once was.

The current populations are scattered between Southern Washington, Oregon, Pacific ocean, and Northern California. In the modern day they can be found along a number of rivers during their breeding season: The mouth of the Columbia river, Umpqua river, Klamath river, Rouge river, and Eel river to name a few, but these fish also have a section of their life spent along the coast line. Within these habitats, the green sturgeon can be found living along the bottom of rivers, preferring to spend time around the beds of environments.

Green sturgeon have a diet similar to that of other sturgeon: small invertebrates that it sucks up from the ocean bed, primarily shrimp, worms, crabs, and bugs. They eat prey with large lip-like structures around the mouth that are used for sucking up prey. Nearby their mouth is a set of sensitive barbells that determine where prey is. These barbells (located close to the mouth) also happen to be one of the defining features of the green sturgeon from their closely related and often range sharing relatives: the white sturgeon (whose barbells are located a bit farther from the mouth).

The lifecycle of the green sturgeon is simple. For the first 3 years of their lives after hatching, they will live within the rivers of their spawning. It was assumed that young green sturgeon would act similarly to white sturgeon, but the behavior of their juveniles are entirely different. When white sturgeon young are born, they move downstream and live along the surface of the water. However, green sturgeon have eggs that settle into the rocks below, seeking cover. Then, once they have aged 9 days and can forage appropriately, they then disperse up and downstream, giving each sturgeon a large area to forage independently. Interestingly, the green sturgeon juveniles forage exclusively at night for the first 10 months of their lives, and were found to have the most nocturnal behaviours of any sturgeon in North America. This nocturnal behavior continues into their first winter, where after migrating to wintering areas, they will only forage at night and hide in dark areas during the day.

After the three years living within their freshwater spawning rivers, the green sturgeon juveniles will make a trip to the coastline of the Pacific, already at a size of 1 foot in length. This is the second part of their lifespan, and the sturgeon will live along the coastline for around 10 years in females, and around 6 years in males. This part of their life is relatively unknown, as they tend to stray away from animals that aren't invertebrates and hide along the sea bed from anything resembling a predator. Leaving us in the dark to any interesting behaviors during this part of their lives. Then, in adulthood these fish will repeatedly travel back to the spawning rivers to have eggs during March-July having a breeding season every 3-5 years, returning back to the ocean once the breeding season ends. These fish will live around 60-70 years, going through over a dozen breeding seasons in a lifetime.