Sablefish (Anoplopoma fimbria) or black cod, as they are commonly called, are not related to Pacific cod but are instead in the family Anoplopomatidae, a family with only one other species, the skilfish (Erilepis zonifer).
A sablefish is slim and long and covered with small scales. It is dark gray or grayish-green on its back and sides and light gray or white on its stomach. It has two widely separated dorsal fins and a tail which is lightly indented in the middle. Sablefish have large mouths with small teeth. They grow quite large and have been known to reach 45 inches (114 cm) in length and 50.5 lbs. (25 kg). An average-sized sablefish weighs 8.1 lbs, (3.7 kg) and is 27 inches (69.1cm) long.
Sablefish range from Alaska and British Columbia south to Baja, California, and west to Kamchatka and Japan, Alaska has the highest concentration of sablefish.
Adult sablefish live on the slopes of the continental shelf and are usually found at depths of 492 to 4921 ft. (150 – 1500 m), but they have been found as deep as 9842 ft. (3000 m). Juveniles live nearshore in much shallower water. Juveniles are pelagic, while adults live near the bottom.
Sablefish spawn in the winter, normally between January and March, but spawning is dependent upon location. They spawn along the continental shelf at depths greater than 3281 ft. (1000 m.) Sablefish become sexually mature between five and seven years, and once they reach sexual maturity, they spawn annually. A female lays 110 eggs per gram of body weight, so an average sized female weighing 3.7 kg will lay approximately 407,000 eggs.
Sablefish larvae drift inshore, and juveniles remain inshore until they reach a size of 12 to 16 inches (30 -40 cm) at the age of two to five years. They then begin to move into deeper water and settle near the bottom, where they continue to grow.
Juvenile sablefish eat zooplankton and small fish, and adults eat fish, squid, octopus, and crustaceans. Survival of juveniles varies greatly from year to year, and biologists believe this variability is linked to zooplankton abundance, which is in turn linked to environmental conditions. Zooplankton thrive during years when ocean temperatures and nutrients produce rich phytoplankton crops for them to eat, and juvenile sablefish then eat the zooplankton, such as krill. When conditions are not favorable, though, zooplankton numbers drop, and fewer sablefish survive.
Juvenile sablefish are prey for many fish species, including Chinook and coho salmon. Sperm whales are a major predator of adults. Sablefish often live as long as 40 years, and the oldest recorded in Alaska was 94-years-old.
Like halibut, sablefish bring a high price per pound to commercial fishermen, and the current value of sablefish in the U.S. fishery is approximately $50 million per year. Most of the commercial catch is exported to Asia, where it is considered a delicacy, but sablefish is gaining popularity in the U.S. Sablefish are primarily harvested by longline or trawling. A small but growing sport fishery for sablefish has developed in Southeast Alaska.
Sablefish abundance has dropped since the 1980s, but with stricter commercial regulations in place, fishery managers consider the population stable. Both state and federal agencies manage sablefish.
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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. If you like audiobooks, check out her audiobook version of Murder Over Kodiak. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.