Visitors to our Underwater Dome exhibit often ask, “What’s that funny looking gray fish?” Sometimes they’re asking about wolf eels (which aren’t eels, despite their name)—but more often, they’re referring to sablefish.
Despite sometimes being called “black cod” and having some similarities in appearance, sablefish are not a true cod. They’re one of only two members of the Anoplopomatidae family. True cod belong to the family Gadidae.
Name: Sablefish (Anoplopoma fimbria), also known as black cod
Habitat: Typically sandy or muddy seafloor areas deeper than 600 feet (adults)
Range: Throughout the North Pacific
Size: Up to 3 feet long and 55 pounds
Life span: Up to 90+ years*
Diet: Fish, crustaceans and cephalopods
Reproduction: Sablefish are typically reproductively mature at 5–7 years of age. They spawn in winter in deep water. Eggs develop for about two weeks before hatching. At this stage larvae rise toward the surface, where they may be carried long distances by currents (in some cases over 2,000 miles in six to seven years).
The sablefish in our Underwater Dome exhibit came to us from a NOAA research program in 2013. NOAA monitors both sablefish movement and abundance. Movement is tracked via tag and release programs and abundance via longline and trawl surveys. Sablefish have been evaluated by the Seafood Watch program and are currently listed as both a “Best Choice” and a “Good Alternative,” depending on the location and method used to catch them.
*Wait a minute, what? Sablefish can live to be over 90 years old?! It’s true. And how do we know that? Scientists typically use the otolith, or ear bone, to age fish. This structure is part of the acoustico-lateralis system, contributing to hearing and buoyancy in living fish. More of a stone than a bone, the otolith is formed from regular growth and hardening of layers of aragonite, a form of calcium carbonate, in the fish’s skull behind its eyes. Since the growth is regular, it can be counted under a microscope like rings in a tree. Similar to tree rings, the otolith growth can be challenging to interpret, depending on factors like ocean conditions, calcium carbonate availability, and the fish’s overall health. Because of this, additional means of aging fish have been used to predict the otolith’s rate of accuracy, including radio carbon dating. According to one study by NOAA, the otolith was highly accurate in predicting age with only a one percent chance of over-predicting the fish’s age by one or more years—that’s pretty impressive!