As the largest thermokarst lake in the world as well as the largest lake in all of Arctic Alaska, Teshekpuk Lake is an incredibly unique and valuable sanctuary for a variety of endangered and watchlist species. This wetland, found in the North Slope region of Northern Alaska, is home to its own closely monitored herd of around 40,000 caribou.
Along with being at the center of these calving grounds, the Teshekpuk Lake area is a haven for tens of thousands of molting geese, including many threatened species. These waters supply shorebirds and waterfowl with an ample supply of fish to feast on while they are in the vulnerable position of replacing their worn flight feathers.
With a name derived from the Inupiaq term tasok-poh, translating roughly to “large coastal lake,” it comes as no surprise that this giant body of water is only 6 miles inland from the Beaufort Sea. With a healthy supply of brackish regions and cool, freshwater streams, Teshekpuk Lake is a choice spawning ground and nursery for a variety of sedentary and migratory fish.
With the threat of climate change and energy development on the rise in this delicate ecosystem, it’s more important than ever to celebrate the organisms that call Teshekpuk Lake home. In particular, this article will go over 8 major fish species that thrive in these remarkable waters.
Fish Species in Teshekpuk Lake
1) Broad whitefish (Coregonus nasus)
The broad whitefish is a large, silver salmonid that is highly associated with Teshekpuk Lake due to its role as an important sustenance fish for locals. It has a small, down-turned mouth that it uses for bottom-feeding on mollusks and a deeply forked tail.
Despite their prevalence, much of the life cycle of broad whitefish, including its diet, is unknown. In an effort to better understand the species, several specimens of broad whitefish have been radio-tagged since 1996. As demonstrated by these studies, broad whitefish populations in Teshekpuk do not interact or exchange with those in the central Beaufort Sea area.
It is unknown if the broad whitefish found in Teshekpuk Lake exclusively inhabit freshwater, but many members of the species are known to be amphidromous, meaning they move to and from freshwater and marine water throughout their lives.
In particular, broad whitefish typically hatch in late April or May, migrating into and out of brackish water as they mature. Broad whitefish do not begin to spawn until they are at least 5 years old, but those in more Northern latitudes such as Alaska may take as many as 11 years to mature.
After maturing, broad whitefish return to the waters they were hatched in to spawn randomly. This long-lived species often surpasses 20 years of age and rarely spawns every year due to the strain of spawning. Spawning takes place in the fall or early winter, with eggs overwintering in gravel without parental care.
2) Least cisco (Coregonus sardinella)
Although they may not be as associated with Teshekpuk Lake as broad whitefish, least cisco are likely a much more prevalent species. Per several surveys of Teshekpuk lake from 1990 to 2007, least cisco dramatically outnumber other species, consisting of over 50% of fish caught in these studies.
This silver salmonid has black fins, a creamy underbelly, and dark green dorsal coloring. It has a protruding lower jaw, a trait that is unique among cisco species. This upturned mouth allows least cisco to feast on prey above or in front of them, giving it a specific ecological niche.
As a species, least cisco has sea-going and non-sea-going variants. Those found in Teshekpuk are believed by many experts to be non-migratory, as they grow slowly compared to their sea-going counterparts.
Least cisco also have two major size variants, normal or dwarf. Dwarf cisco reach maturity at only 3 years of age and 3.3 to 5.3 inches in length, whereas normal-sized individuals reach maturity at 6 years of age and 8 to 13.4 inches in length. This early maturity comes with an ecological trade-off, however — dwarf least cisco often reach only 14 years of age, whereas normal least cisco reach 23 years of age as well as lay nearly 30 times as many eggs per year.
Regardless of size or migratory patterns, least cisco spawn in freshwater between September and October and hatch in early spring.
3) Arctic grayling (Thymallus arcticus)
Arctic graylings are a beautiful species of salmonid that are easily identified due to their massive, sail-like dorsal fins that feature red, aqua, and purple mottling. These large dorsal fins are used by males to court females and are braced onto during spawning. Along with these vibrant dorsal fins, Arctic graylings have brightly colored bodies, which are black, silver, gold, or blue with black freckling.
During the summer, Arctic graylings migrate to streams to feed heavily on anything they can, from larvae to fish. When possible, Arctic graylings are known to feast on small mammals such as shrews. For the cool months of the year, the species is semi-dormant, moving slowly and eating little. Arctic graylings preferentially overwinter in lakes and can thrive in poorly-oxygenated waters.
Arctic graylings normally live for 18 years, but Alaskan specimens regularly surpass 30 years. Despite their longevity, Arctic graylings become sexually mature at a young age, from 4 to 7 years. Arctic graylings migrate to small streams to spawn in late spring and spawn randomly. After hatching in 13 to 18 days, fry quickly move downstream to warmer waters along the shoreline.
The species exhibits a unique behavior of spreading out along streams by age, with older fish feeding further upstream than downstream juveniles. Some scientists theorize that the warmer downstream waters allow juveniles to grow more quickly, while others argue this situation allows upstream fish to have access to drifting insects first.
4) Ninespine stickleback (Pungitius pungitius)
The ninespine stickleback is a small, slender fish that is an abundant source of food for many birds and fish native to Teshekpuk Lake. Despite its name, this species can have anywhere from 8 to 11 distinctly separated dorsal spines, and is often referred to as the tenspine stickleback as a result. Its specific coloring depends on its sex and breeding status, with normal coloration being dark brown dorsally with dark mottling. During breeding season, males develop a black area on their belly and chin.
Despite its small size, the ninespine stickleback has an exclusively carnivorous diet, primarily eating insects and crustaceans. This species is very short-lived, with males maturing at 1 to 2 years and living only three years. Females are more long-lived than their male counterparts, typically reaching 5 or more years. The reason behind this discrepancy is often speculated to be due to the intensity of breeding for males.
Male ninespine stickleback are dedicated caretakers throughout the biannual process of spawning. As with other sticklebacks, they bind plant fragments together and form a tunnel-shaped nest. Then, males attract females with quick dancing movements and lead them to their nests. Males may invite multiple females to spawn, and each female lays 50 to 80 eggs at a time.
After laying, the female departs the nest, leaving the male responsible for parental care. They carefully aerate eggs with their fins for 6 to 7 days until hatching, after which males remove the egg remains from their nests. The male will capture his larvae with his mouth and deposit them on the top of the nest, often building a nursery for his young offspring.
Once these offspring are independent, the male will repeat the process with a new nest until the breeding season ends. Females may spawn multiple times per season, feeding heavily between each spawning.
5) Burbot (Lota lota)
The burbot is a unique species known by many names, including the eelpout, link, poor man’s lobster, loche, and tittaaliq. Despite being the only freshwater cod, it is large and eel-like, with microscopic scales that give its skin a slimy feeling. When handled, it is known to wrap around its captor’s arms and produce strange noises.
This species has a large, pouting mouth filled with sharp teeth and large, tubular nostrils. It has a single chin barbel and has black mottling over a base color of gray, olive, or yellow. Despite their strange appearance, burbots are said to have excellent taste and have been hunted to extinction in many regions.
Burbots are slow-growing fish that typically live 15 years in the wild. Alaskan burbot regularly surpass 20 years in age due to ideally cool and clean waters. This nocturnal bottom-feeder requires extremely cool water to spawn, often spawning in the winter under ice. Females may lay as many as 1 million eggs depending on their size and breed in massive, aggregate groups that may consist of dozens or even hundreds of burbot.
These eggs, which are typically only 0.15 inches in diameter, are spawned randomly and without parental care. They hatch in 4 to 6 weeks and begin their carnivorous diet even at this small size. Adult burbot vary dramatically in size depending on location and have been known to reach 60 pounds in some locations and less than 10 pounds in others. The burbot is an opportunistic feeder regardless of its size, often eating lamprey and even cannibalizing.
6) Lake trout (Salvelinus namaycush)
Despite what its name would imply, the lake trout is the largest member of the char family. This distinction between it and true trout is based on it having light spots on a dark body rather than dark spots on a light body. In the case of lake trout, these spots are irregular cream or yellow splotches on top of their dark brown-green coloration.
This species is long-lived, with one specimen in the North Slopes region being 55 years old. Throughout this long life, slow-growing lake trout regularly exceed 50 pounds. Juvenile lake trout typically feast on zooplankton, but their diets become more fish-based as they get older.
Lake trout become sexually mature depending on size rather than age. In many bodies of water, lake trout mature at 5 to 8 years of age. Due to their slow growth rates, lake trout from Teshekpuk typically mature at ages 8 to 9.
Alaskan lake trout spawn in different frequencies depending on their location. Those in southern regions of Alaska spawn annually, but northern specimens such as those in Teshekpuk spawn every other year or less. Males enter spawning grounds before females and carefully fan silt away from lake bottoms. Females arrive at night and spawn without a nest, broadcasting their eggs randomly across the cleaned substrate.
7) Arctic cisco (Coregonus autumnalis)
Arctic cisco can be distinguished from their close relative, the least cisco, by their colorless fins. They are moderately-sized fish, reaching up to two pounds and 20 inches. Arctic cisco are primarily silver, with a dark back.
Unlike least cisco, this anadromous species does not spawn in Alaska. Instead, Arctic cisco spawn in Canadian rivers and move west into the Beaufort Sea and adjacent lakes to grow in freshwater. These juvenile cisco rely on western-flowing winds to travel to Alaskan waters efficiently, and it is believed their population could dramatically suffer if these winds are altered due to climate change.
Although it is known that adult Arctic cisco eat primarily crustaceans, the diet of these freshwater juveniles is unknown. Fully grown Arctic cisco are known to take refuge in inland brackish waters such as Teshekpuk during the winter.
The Arctic cisco may spawn multiple times throughout its life but rarely spawns more than 2 – 3 times due to its comparatively short-lifespan and late maturity.
Usually, Arctic cisco mature at 8 to 9 years of age and live until they are 10 to 12, but some individuals have been known to live as long as 20 years. In addition to this late maturity, females typically do not spawn two years in a row due to the intense nature of migrating and spawning.
8) Dolly Varden trout (Salvelinus malma)
This cod species is regularly confused with its close relative, the lake trout, but is considerably smaller and more colorful. In the ocean, Dolly Varden are silver-green with orange spots. As they enter freshwater, they turn greenish-brown with crimson spots. Spawning fish become even more vibrant, with red, black, and white bellies, bright red and orange spots, and black fins.
Dolly Varden have freshwater and amphidromous forms depending on their access to the ocean. Those in Teshekpuk are sea-going and therefore able to become large. Adult Dolly Varden regularly migrate to lakes to overwinter and return to the oceans to feed in the summer.
Alaskan Dolly Varden have northern and southern variants, each with a different number of vertebrae and even chromosomes. Northern Dolly Varden, such as those in Teshekpuk, become distinctly larger than their southern counterparts.
Dolly Varden are not a prolific species, as they take 5 to 6 years to mature. Southern Dolly Varden often only live until 8 years old and are unlikely to spawn more than once. Because they often live to be 16 years old, northern Dolly Varden often spawn multiple times throughout their life but are known to take breaks from spawning from year to year to recover from the intensity of migration.
Skipping years between spawning may be advantageous to future offspring as well, as larger females lay more robust eggs and stronger fry.
