Shortraker rockfish

The shortraker rockfish (Sebastes borealis) is an offshore, demersal species distributed from the southeastern Kamchatka Peninsula, Russia, to Fort Bragg, California. It attains lengths greater than one metre (>39 inches) and weighs up to 20 kg (44 pounds). In the Gulf of Alaska, shortraker rockfish are sampled annually during longline surveys and are most abundant between depths of .

The Shortraker rockfish lifespan is thought to average about 120 years, the second-longest of all varieties of rockfish to the rougheye rockfish, estimated at 140 years. This makes rockfish some of the world's oldest living fish.

Commercial harvesting in the Gulf of Alaska began in the early 1960s when foreign trawl fleets were targeting more abundant species. In recent years, high catch rates indicate that the domestic trawl fleet targets this species; shortraker rockfish comprised 14.9% of the species composition of slope rockfish harvested in 1990, although trawl survey data indicates they comprised only 2.5% of the biomass.

In 1991, catch limits were established for shortraker rockfish to prevent overharvesting of this species in the Gulf of Alaska. Catch limits are based on biomass estimates derived from bottom trawl catch rates. These biomass estimates are questionable, however, because the catch efficiency of bottom trawls on shortrakers is unknown. Fishermen report that shortrakers school off-bottom and above rugged habitat in steep-slope areas where bottom trawls cannot sample effectively.

Record specimens
Fish age is estimated by counting growth rings in its earbone, known as an otilith, similar to tree age dating.  However, the method is only accurate in temperate regions, where variances between warm and cool season growth rates create distinct ring borders.  In both tropical and arctic waters it becomes very difficult to distinguish such annual variations.  However, as shortraker rockfish caught off Sitka are regarded as coming from waters along the boundary of temperate and arctic regions annual growth rings can be slightly discernible.

The record for oldest shortraker rockfish is 175 years, established by a 32.5" specimen.

In 2007, fishermen caught a specimen that was estimated to be between 90 and 115 years old. The fish weighed in at  and was measured at . It was caught south of the Pribilof Islands at an estimated depth of .

In 2013, Henry Liebman, a sport fisherman from Seattle, caught a specimen from  below the surface and 10 miles offshore near Sitka, Alaska. Experts believed the 42-inch,  , shortraker was the oldest ever caught, with an estimated age of 200 years. It was later found that the fish was only 64 years old.

References

External links
Shortraker rockfish from the Alaska Fisheries Science Centre Guide to Rockfishes (National Marine Fisheries Service)

Category:Sebastidae
Category:Fish of the Pacific Ocean
Category:Fish described in 1970