Endangered Species in Fish Slough

The Owens pupfish is a small fish whose vast numbers throughout the Owens Valley wetlands were reported in 1859. They were still abundant in 1916, when large schools were observed in numerous sloughs and swamps between Laws and Bishop. However, during the 1920's to 1940's the number of Owens pupfish and their habitat declined rapidly. The wetlands shrank as they and creeks were diverted for farming, water was exported and dams were built. Non-native fish that prey on the pupfish were also introduced, further shrinking their numbers. By 1948, it was believed the species was extinct.

In 1964, a small population of Owens pupfish was rediscovered in Fish Slough. Pupfish feed on insect larvae and aquatic plants. Some species can survive in warm, salty water that has low levels of oxygen. Pupfish are extremely territorial, and the males will fight aggressively to protect the area they claim. Spot the two-inch pupfish by their distinctive "stop-start" swimming style.

The Owens tui chub is a species that survives in the quiet, sluggish waters of the slough. Chubs feed primarily on insects and aquatic plants. Spawning occurs from late April through June, in shallow areas with lots of vegetation. Like the Owens pupfish, the species is endangered mainly because of loss of habitat and the introduction of exotic fish species that prey on the chub.

The Owens speckled dace (a fish) is a subspecies of speckled dace found locally in a few sites within the Owens River drainage. It was last recorded in Fish Slough in 1938. The Owens sucker is also unknown in Fish Slough today. Both may have been eliminated due to the introduction of non-native fish species. Biologists hope to reintroduce the Owens sucker and the Owens speckled dace to Fish Slough.

Though not endangered, the Fish Slough springsnail can be found only in the waters of the marsh. While this tiny snail occurs in specific locations within the wetland, little is known about its biology.

Unwanted intruders to this complex environment include non-native species such as largemouth black bass, carp and mosquitofish. They disrupt the fragile and natural balance of the wetland habitat. Their introduction is a continuing problem today.