Alaska Blackfish Facts, Adaptations, Diet, Size, Habitat, Lifespan

Alaska blackfish are small, rarely reaching lengths of more than 8 inches, however, specimens approximately 13 inches have been discovered. They can be distinguished from other varieties by their wide paddle-like pectoral (lower front) fins and tail, as well as their tiny ventral (lower middle) fins, the positioning of their dorsal (upper) and anal fins in the rear side of their bodies, and their wide, plain heads. 

Their front sides are deep greenish or brown, and their bottom sides are light, with uneven mottled skin regions. The appearance of a reddish fringe along the dorsal, caudal (tail), and anal fins differentiates fully grown males from females. In addition, the edges of the ventral fins in adult males grow considerably beyond the front of the anal fin, whereas females don't.

Alaska Blackfish Facts

The Alaskan blackfish is widely known for its adapted esophagus that allows it to breathe in air. Alaska blackfish's esophagus can be segmented into two sections one for non-respiratory functions and another for respiratory functions. The respiratory segment is distinguished by extended mucosal folding and vascularization, as well as by the presence of numerous small blood vessels throughout the epithelium. This respiratory system indicates selection pressures for pulmonary and hydrostatic organ growth. The availability of the hydrostatic swim bladder is an intriguing factor to consider because it appears to be pointless unless it is essential for maintaining neutral buoyancy during the cold winter months when the water is covered with ice.

Alaska Blackfish Adaptations

The blackfish, in addition to being able to "breathe" air oxygen, can also withstand in lakes and rivers with very low dissolved oxygen concentrations. This aids in the survival of blackfish during the winter months when they are trapped under ice in the lakes, ponds, and sloughs of Interior, Northern, and Western Alaska.

Alaska Blackfish Diet

Zooplankton, insects, and small fish are among the prey items that Alaska blackfish consume. It is well known that larger fish are opportunistically cannibalistic. The Alaska blackfish is prey for a wide variety of predators, including northern pike, other Alaska blackfish, birds, and humans.

Alaska Blackfish Habitat

Alaska blackfish were spotted only in Alaska and eastern Siberia. Lowland marshes, lakes, waterways, and ponds have thickly vegetated places where they reside. They're slow-moving bottom-dwelling fish with huge pectoral fins that paddle slowly through the vegetation in quest of food.

Alaska Blackfish Lifespan

The average lifespan of fully grown Alaska Blackfish is around 8 years depending upon the raising environment and quality of feed.