Flatfish

Arrowtooth Flounder (Alaska Fisheries Science Center – NOAA)
Arrowtooth flounder (Atheresthes stomias) are a relatively large flatfish. At present, data on many basic aspects of arrowtooth flounder life history such as size and age of sexual maturity are lacking. However, spawning fish have been observed from December through February. In Alaska waters, arrowtooth flounder are distributed over the continental shelf through age 4 and then at older ages disperse to occupy both the continental shelf and the slope.

Arrowtooth flounder range from central California to the eastern Bering Sea and currently are the most abundant fish in the Gulf of Alaska. The huge increase in biomass observed in the 1990s resulted from strong year-classes produced in the 1980s. Because of their abundance, arrowtooth flounder are of substantial ecological importance at higher trophic levels in the Gulf of Alaska food web and have been identified as a significant food source for Steller sea lions, occurring in their diet 21%-35% of the time in the area around Kodiak Island. Arrowtooth flounder are also known to be voracious predators of juvenile walleye pollock.

Rock Sole (Alaska Fisheries Science Center – NOAA)
Two species of rock sole in Alaska were distinguished in 2000, the northern and southern rock soles (Lepidopsetta polyxystra and L. bilineata). Adults of the northern rock sole are found from Puget Sound through the Bering Sea and Aleutian Islands to the Kuril Islands, while the southern rock sole is known from the southeast Bering Sea to Baja California. The northern rock sole spawns in winter and spring, and the southern rock sole spawns in summer. The rock soles, along with other small flatfishes, represent an important trawl fishery in the Bering Sea and Gulf of Alaska. The Fisheries Behavioral Ecology Program primarily works with the northern rock sole.

Rock soles grow to approximately 60 cm and live 15-20 years. Maturity occurs in 4-7 years. Adhesive eggs are laid on the bottom and hatch in 6-25 days, depending upon temperature. The larvae develop in the upper water column consuming small zooplankton. Metamorphosis occurs at about 15 mm, and small juveniles can be very abundant in shallow, near-shore waters where they consume polychaetes and small crustaceans. Age-0 northern rock sole is the most abundant flatfish in fine-mesh trawl collections in Kodiak (1-30 m depth), sometimes reaching densities of several per square meter. The rock soles are highly cryptic in coloration and movement, and continue to eat small invertebrates throughout their lives in the benthos.