Shark or sturgeon?

“Is that a shark?” visitors ask, pointing at a large, greyish fish hovering near the bottom of the Seattle Aquarium’s Underwater Dome exhibit. What they’ve noticed is one of our three sturgeons. No, they’re not sharks, but similar to them, sturgeons have a cartilaginous skeleton and an ancient appearance.

Some Aquarium guests are surprised to see a sturgeon in salt water, associating them more with freshwater sport fishing. Sturgeons are anadromous, migrating from freshwater to salt water and back, like our local salmon. Local sturgeons typically spend more of their lives in estuarine or marine environments, where they are less susceptible to rapid habitat changes, and return to freshwater only periodically to spawn.

Sturgeons are technically the most threatened group of animals on the International Union for the Conservation of Nature (IUCN) Red List of Threatened species. However, most of the critically endangered species are isolated to Europe and Asia, where females are harvested for their unfertilized eggs. Beluga sturgeons in the Caspian Sea are considered to the world’s finest producer of roe, or black caviar, in the luxury food market. Thankfully, U.S. Fish & Wildlife protections have thus far kept our endemic populations below the critically threatened level.

The Seattle Aquarium is home to two species of sturgeon: green and white. Keep reading to learn more about them!

green sturgeon

Green sturgeon, Acipenser medirostris

Distinguishing features: Darker, greenish coloration; barbells are located closer to the mouth. There is also a large scute (bony plate) behind the dorsal and the anal fin that the white sturgeon does not have. Typically has between eight and 11 dorsal scutes. Has a dark stripe along the underside.

Maximum size: 7 feet

Life span: up to ~70 years

Conservation status: IUCN Near Threatened

Fast fact: These two green sturgeons came to us from Washington Department of Fish & Wildlife (WDFW) in the early 1980s. They were already full-sized when they arrived at the Aquarium, so we do not know their exact ages. Their role at WDFW had been to help keep salmon pens clean by feeding on mortalities; however they had to be moved when they began also eating the live salmon!

white sturgeon

White sturgeon, Acipenser transmontanus

Distinguishing features: Paler, grey coloration; barbells (whisker-like sensors under their chin) are located closer to the snout than the mouth. Those taste-bud structures sometimes get them mistaken for catfish, another fish with large barbells. Typically has between 11 and 14 dorsal scutes.

Maximum size: 12 feet (official record)

Life span: >100 years

Conservation status: IUCN Least Concern

Insider fact: When our single white sturgeon arrived from a WDFW sturgeon hatchery in the early 1990s, it was only about two feet long. With continued health, it could still double its current size.

Look for the sturgeons on your next visit to the Underwater Dome Seattle Aquarium—and stop by the Life on the Edge tide pools or Puget Sound Fish exhibit to see sturgeon poachers, named for their resemblance to the much-larger sturgeon!

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