The Great Salt Lake in Utah is an aquatic environment where fish generally do not inhabit the main body due to extreme conditions. Its high salinity levels prevent most fish species from surviving. However, areas connected to the lake, especially freshwater inflows, do support various fish populations.
The Lake’s Unique Environment
The Great Salt Lake is one of the saltiest inland bodies of water globally, with salinity levels significantly higher than oceans. As a terminal lake, rivers flow in, but water only leaves through evaporation, accumulating dissolved minerals and salts. Salinity varies widely, from around 5% in Farmington Bay to 28% in the North Arm, compared to the ocean’s 3.5%. This variation is partly due to a railroad causeway that restricts water flow between the northern and southern arms, leading to different salt concentrations.
This extreme salinity creates an osmoregulatory challenge for most fish. Osmoregulation is the process by which organisms maintain a stable balance of water and salt within their bodies. In highly saline environments, fish constantly lose water to their surroundings through osmosis because the external water has a higher salt concentration than their internal fluids. While saltwater fish adapt by drinking seawater and excreting salt through gills, the Great Salt Lake’s concentrations are too high for these adaptations to be effective, preventing most fish from surviving.
Life That Thrives in the Great Salt Lake
Despite the harsh conditions, specialized organisms have adapted to the Great Salt Lake’s saline environment. Brine shrimp (Artemia franciscana) and brine flies (Ephydra hians and Ephydra cinerea) are the main macroinvertebrates thriving here. These species possess physiological adaptations that allow them to tolerate high salt concentrations; brine shrimp, for instance, survive in salinities from 3% to 33%.
Brine shrimp are crustaceans that feed on algae and bacteria, which also flourish in the lake. They reproduce by laying hardy, dormant eggs called cysts, which can withstand extreme temperatures and desiccation, hatching when conditions become favorable. Brine flies also have specialized organs to remove excess salt from their bodies, and their larvae consume algae and detritus. Both brine shrimp and brine flies play an important role in the lake’s ecosystem, serving as a food source for millions of migratory birds that visit the Great Salt Lake annually.
Fish in Connected Waters
While the main body of the Great Salt Lake is largely devoid of fish, freshwater tributaries and less saline bays connected to the lake do support various fish species. Rivers such as the Bear, Jordan, Weber, and Ogden flow into the Great Salt Lake, providing areas with significantly lower salinity. These freshwater inflows create diluted zones where fish can survive. For example, Farmington Bay and Bear River Bay, which receive substantial freshwater input, can host fish during periods of higher freshwater runoff.
Fish species found in these connected, less saline areas include carp, various minnow species, and trout such as the Bonneville cutthroat trout and rainbow trout. The Bonneville cutthroat trout, for instance, is native to the tributaries surrounding the Great Salt Lake. Certain springs and ponds located near the lake, like Locomotive Springs, also contain year-round fish populations, including carp, rainbow trout, and Least Chub, with some even stocked regularly. These fish generally remain in the fresher waters, avoiding the highly saline main lake.