List of Common Great Salt Lake Fish Species [Updated]
The Great Salt Lake in northern Utah is the largest saltwater lake in the western hemisphere. It covers about 1,700 square miles (4,400 km2), but the surface area of the lake varies greatly between wet and dry years due to the low average depth. The lake is the remnant of the prehistoric Lake Bonneville, which covered a massive 20,000 square miles (51,800 km2).
Lake Bonneville was formed about 30,000 years ago. Periods of warming and cooling made the lake shrink and stabilize, which resulted in four different visible shorelines and the Bonneville Salt Flats in western Utah. The final period of heating resulted in the formation of the Great Salt Lake, as we experience it today. The Great Salt Lake does not have an outlet, and so the minerals it contained concentrated as it shrank, which gave the lake its high level of salinity that is seen today. The main basin, Gilbert Bay, fluctuates between 6% and 27% salinity, while the hypersaline northern arm, Gunnison Bay, hits 30% salinity.
The salinity in the lake is so high that you can easily float in it. However, it also makes the lake toxic for most fish species, and the ones frequenting in the lake can typically be found close to the freshwater lakes feeding into the Great Salt Lake. In years with high precipitation, parts of the lake might incorporate enough freshwater to support a fish population for a short time. The area is, on the other hand, well-populated with wildlife and is an important resource for nesting and migrating birds. The following list of fish species is therefore comprised of species that might flood into the Great Salt Lake, and not species with established populations.
List of Fish Species in Great Salt Lake
1) Brine shrimp (Artemia franciscana)
Albeit not a fish, a section must go to the sole permanent resident of the Great Salt Lake, the brine shrimp. The name is a catch-all for multiple species of artemia, a primitive arthropod, however the one in the Great Salt Lake, A. franciscana, is native to America but has later spread to most of the world. The brine shrimp is extremely tolerant to the chemical composition of the water and occurs in hypersaline habitats across North and South America.
This small aquatic crustacean is of great ecological importance for many migratory birds, serving as a substantial part of their diet on the go. They also served as the food source for the famous flamingo, Pink Floyd, that lived for many years in the Great Salt Lake. Likewise, the brine shrimp is a filter feeder, consuming green algae that they filter from the water using their legs.
The enormous quantities of A. franciscana in the Great Salt Lake support a $10 to $60 million USD industry, with 21 companies harvesting in the north and south arms of the lake. Brine shrimp are harvested in their cyst life stage and used for commercially-cultured fish and crustaceans. The commercial harvest of this highly nutritious food source has resulted in strong selective pressure on the species, leading to changes in their observable characteristics like cyst buoyancy and life-history traits.
2) Cutthroat trout (Oncorhynchus clarkii)
The cutthroat trout is a species in the Salmonidae family (salmon) and a member of the genus Oncorhynchus together with the rainbow trout, among others. The common name refers to the distinct red color lining the lower jaw. They are generally found in well-oxygenated, cool waters. They are known to be easily outcompeted by other similar species and can drop significantly in population numbers after intense harvest. They feed on small fish, crustaceans, and insects.
A subspecies of cutthroat trout, the Bonneville cutthroat trout (Oncorhynchus clarkii utah) is native to the tributaries surrounding the Great Salt Lake. In addition to being the official state fish of Utah, the Bonneville cutthroat descends from the population of cutthroat trout, inhabiting the prehistoric Lake Bonneville. Forced to leave their native range as the salinity in the lake increased, the Bonneville cutthroat now survives in fragmented populations in Utah, Idaho, Wyoming, and Nevada. In contrast to the main species, the Bonneville has a silvery grey body with large round spots sparsely scattered along the body and fins and lacks the striking red jawline that is seen in the cutthroat trout.
3) Common carp (Cyprinus carpio)
The common carp is a member of the cyprinids, famous for their lack of a stomach. Instead, food is digested as it passes through their intestines. The common carp is often mentioned as the first fish species to be cultivated for human consumption. The praxis originated 3,000 years ago in China. Today it is listed on the ‘100 of the World’s Worst Invasive Alien Species’ list, together with another species on this otherwise short species list. They have earned their place among the worst species due to their serious impact on biological diversity as they stir up the sediment on the bottom when they feed, uprooting plants, destroying fish eggs, and increasing bioturbidity.
The common carp was introduced to Utah in 1883 in Utah Lake. The species was originally introduced for commercial and recreational fishing as an alternative to dwindling native species. However, the common carp quickly proliferated and is today considered a pest. It is the third most widely introduced species of fish but is considered vulnerable in its native habitat. A great variety of methods have been developed to target fish this species, e.g. training the carp to aggregate in specific areas by using food to habituate them, which makes it possible to harvest them in great numbers.
4) Least chub (Iotichthys phlegethontis)
The least chub is a rare species belonging to the Leuciscidae (minnow) family and the sole member of the genus Iotichthys. They are endemic to Lake Bonneville, the prehistoric lake in Utah, and persisted in wetlands left behind when the lake receded. Today they inhabit marshes and ponds and may venture into the Great Salt Lake in periods where plenty of freshwater has lowered the salinity. They prefer areas with moderate to dense vegetation and little current. When disturbed, they will quickly hide. The least chub has broad tolerance limits, which is what allows it to survive close to the Great Salt Lake.
The least chub exists in four areas separated in six distinct wild populations and was most recently assessed by the IUCN Red List of Threatened Species in 2012, where it was listed as Endangered. They are subject to a decline in the quality of their native habitat, which has led to a decline in the species’ abundance and distribution. Management of the species includes reintroductions to their former range and control of invasive species that might outcompete or predate the least chub.
5) Rainbow trout (Oncorhynchus mykiss)
The rainbow trout is a member of the Salmonidae (salmon) family. They are considered native to the lakes surrounding the Great Salt Lake, even though Utah sits right on the edge of the original distribution of the species. They are regularly stocked in some of the springs surrounding the lake, as they prefer clear and cold waters. They feed on a variety of invertebrates and small fish. They are easy to transport and very successful in hatcheries, even though they are sensitive to water temperatures.
Like the common carp, the rainbow trout is listed on the ‘100 of the World’s Worst Invasive Alien Species’ list. It has landed its spot among the worst species due to being a transmitter of disease, an efficient predator, and its similarity to other trout, which can lead to hybridization. They have been widely introduced and continue to be stocked annually for the entertainment of anglers. In the US, the rainbow trout is suspected to drive the decrease of the humpback chub, suckers, and squawfish through direct predation and competition for feeding areas.
6) Rainwater killifish (Lucania parva)
The rainwater killifish is a small silver to olive-green fish. The males are more vibrant in color and have dusky orange fins, edged by a black line. Some males have a black spot on the front of their dorsal fin. They normally occur in schools and the males can be seen flaring their relatively large fins at each other in displays of dominance. The rainwater killifish is mainly found in salt marshes and brackish stretches of coastal streams, although it can also live in freshwater lakes and rivers. It was recently assessed by the IUCN Red List of Threatened Species (2019) and was listed as Least Concern.
The rainwater killifish’s native range extends along the Atlantic and the Gulf of Mexico. They are thought to have been incidentally introduced to the rivers near the Great Salt Lake as hitchhikers, when sportfish were stocked with less restrictive rules compared to the ones we have today. The rainwater killifish have now established themselves as permanent residents around the lake and were the only documented fish species in 1986 to ever breed in the Great Salt Lake. However, the following years saw a steady increase in the lake’s salinity that pushed the little hardy fish back into the rivers.