What fish are in the Great Salt Lake?

The Great Salt Lake in northern Utah is known for its extreme salinity, which can range from 5 to 27 percent, far saltier than ocean water. This hypersaline environment is inhospitable to fish, and as a result, no fish species live in the main body of the lake. However, some of the freshwater and brackish wetlands, river mouths, and peripheral bays connected to the lake do support fish. This distinction is critical when discussing aquatic life in the area.

Why the Great Salt Lake Cannot Support Fish

The salinity of the Great Salt Lake fluctuates depending on water inflow, evaporation, and the lake’s unique geography. In most of the lake, especially Gunnison Bay (the north arm), salinity levels are too high for any fish to survive. Fish require a relatively stable balance of salt and fresh water to regulate their internal chemistry, and the Great Salt Lake exceeds the tolerances of even the most salt-tolerant species.

Additionally:

1. There is no natural outlet, so salts accumulate over time.
2. The north arm is especially saline due to limited freshwater inflow, separated by a railroad causeway that restricts water exchange.

Where Fish Can Be Found: The Peripheries

Though the lake itself is fishless, some connected and adjacent water bodies support introduced and native fish species. These include:

1. Bear River Bay and Farmington Bay

These areas lie at the mouths of the Bear River and Jordan River, where freshwater inflow creates brackish water zones. Here, salinity is much lower than in the main lake, and certain hardy fish species can survive.

Common species:

1. Common Carp (Cyprinus carpio) – Highly adaptable, carp tolerate a wide range of water conditions. They are invasive and dominate many freshwater zones near the lake.
2. Channel Catfish (Ictalurus punctatus) – Found in the lower reaches of tributaries and the fringe wetlands.
3. Black Bullhead (Ameiurus melas) – Another hardy species that can survive in brackish conditions.

2. Great Salt Lake Marshes and Wetlands

The lake is surrounded by freshwater and brackish marshlands, especially to the north and east. These wetlands are part of the Bear River Migratory Bird Refuge and other wildlife management areas.

Fish species here include:

• Fathead Minnows (Pimephales promelas)
• Mosquitofish (Gambusia affinis) – Introduced to help control mosquito populations.
• Utah Chub (Gila atraria) – Native to the region and found in freshwater areas.
• White Bass (Morone chrysops) – Occasionally present in tributaries like the Jordan River.
• Carp hybrids and suckers – Found in river mouths and freshwater canals.

3. Tributaries and Upstream Waters

While fish don’t live in the hypersaline lake, the rivers that feed it — particularly the Bear River, Weber River, and Jordan River — support a wide range of fish species in their upstream reaches.

Notable upstream species:

• Rainbow Trout (Oncorhynchus mykiss)
• Brown Trout (Salmo trutta)
• Mountain Whitefish (Prosopium williamsoni)
• Cutthroat Trout (Oncorhynchus clarkii) – Native to the region.

These species are typically found in higher elevation headwaters and reservoirs, far from the saline reach of the lake.

The Role of Fish in the Ecosystem (or Lack Thereof)

In the main lake, the absence of fish creates an unusual ecological structure. Instead of fish-driven food chains, the lake supports a microbial-based food web centered on:

• Brine shrimp
• Brine flies
• Halophilic algae and bacteria

These organisms feed a wide array of migratory birds, such as eared grebes, phalaropes, and American avocets, which depend on the lake during their migrations. The lack of fish means less competition for brine shrimp and flies, allowing their populations to reach extremely high densities — a unique feature of this ecosystem.

Conclusion

While the Great Salt Lake proper does not support any fish species due to its hypersaline waters, fringe areas, wetlands, and inflowing rivers provide habitats for a variety of freshwater and brackish-water fish. These peripheral environments contribute to the region’s overall biodiversity and ecological complexity. However, within the lake itself, the ecosystem is dominated by invertebrates and microorganisms adapted to the harsh, salty conditions — making it one of the most unique aquatic environments in the Western Hemisphere.