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Desert Spring Fishes Scientific Name: Comanche Springs Pupfish – Cyprinodon elegans, Leon Springs Pupfish – Cyprinodon bovinus, Pecos Gambusia – Gambusia nobilis, Big Bend Gambusia – Gambusia gaigei Federal Status: All Endangered; 3/11/67, 8/15/80, 10/13/70, and 3/11/67, respectively • State Status: All Endangered Description of At present, the species occurs pri- and Species, Habitats, and marily in aquatic habitat fed by Present range for spring flow from Giffin, and San Pecos Gambusia Life History Solomon springs near Balmorhea, Comanche Springs pupfish Texas. The population at Phantom The Comanche Springs pupfish Lake Springs has been almost totally seldom exceeds 2 inches in total lost due to loss of length. It is gray-green above and spring flow. The pale yellow to white below, with clear areas of greatest to light orange fins. The sides are sil- abundance are in very white with blue-black blotches Balmorhea State forming a “stripe” along the side Park in the (often faint on the male). Males have refugium canal Present range for black speckling on the side and a (constructed in Comanche Springs Pupfish black edge on the caudal (tail) fin. 1974) and in San Present range for In contrast to other Cyprinodon Solomon Ciénega Leon Springs Pupfish species, this pupfish has a slender (created in 1996). Present range for Big Bend Gambusia body and lacks vertical bars. Additional habitat consists mostly of a system of concrete and earthen irri- grayish-brown on top, and lighter gation canals. The pupfish are often below. abundant in earthen ditches and con- The Leon Springs pupfish was crete flumes 4 inches or more deep first discovered in 1851 by members with bottoms covered with debris of the U.S. and Mexican Boundary and vegetation, such as muskgrass Survey. The fish was originally found (Chara spp.). They are rarely found at Leon Springs, a spring system that in concrete flumes where water depth once flowed in the Leon Creek is less than 4 inches and/or the bot- drainage about 6 miles west of Fort tom is scoured of debris. Stockton in Pecos County. Its historic Comanche Springs Pupfish The Comanche Springs pupfish range probably included all permanent © J.E. Johnson is known only from freshwater to waters within Leon Creek and the slightly saline habitats. The springs associated springs. In 1918, the area near Balmorhea have low salinities, where the fish was first collected was as did the now dry Comanche inundated by Lake Leon, an irrigation Springs. Other species of pupfish in and fishing impoundment. By 1938, the Pecos River system inhabit more the Leon Springs pupfish could no saline waters. Breeding is thought to longer be found in the area where it occur during most months of the was first discovered. Although Leon year, and spawning (egg-laying) Springs once produced a flow of about occurs in areas of flowing water as 20 cfs (cubic feet per second), the well as in stagnant pools. In irriga- springs produced no measurable flow tion canals, the pupfish prefer shal- by 1958 due to groundwater pumping Leon Springs Pupfish low areas with low current velocities. © TPWD in excess of aquifer recharge. Although they feed mostly on the bot- From 1958 until 1965, the Leon Historically, this pupfish tom, they also feed at the surface and Springs pupfish was thought to be occurred in two separate spring sys- at other levels in the water column. extinct. The fish were rediscovered tems of the Pecos River drainage. in 1965, when they were collected One was Comanche Springs, with Leon Springs pupfish from Diamond Y Spring, located headwaters (now almost always dry) The Leon Springs pupfish is a about 10 miles north of Fort within the city limits of Fort small (about 2 inches), robust pup- Stockton. The fish have since been Stockton, Texas, and the other was a fish, with a wider head and body found in Leon Creek, downstream group of springs near Balmorhea. than most pupfish. Breeding males from Diamond Y Spring in waters The pupfish population at Comanche are powdery blue-gray with fins of Springs were extirpated (lost) when varying shades of yellow edged with the springs first went dry in 1955. black. Females are grayish-yellow or Desert Spring Fishes 1 that are quite saline. The recent used for internal fertilization of localities are about 15 miles down- the female. stream from where the fish was origi- Historically, the Pecos gambusia nally found. was restricted to the Pecos River The Leon Springs pupfish basin in southeastern New Mexico presently occurs within two 3-mile and western Texas. The species spring-fed segments of Leon Creek occurred from as far south as Fort and Diamond Y Spring. Diamond Y Stockton, Texas to as far north as Draw is a tributary to Leon Creek. Fort Sumner, New Mexico. The popu- Pecos Gambusia These spring-fed segments are sepa- lations of Pecos gambusia that once © Dave Schleser rated by about one mile of usually existed at Leon Springs and dry stream bed. The fish prefer Comanche Springs were lost when slow-flowing stretches of water, with these springs went dry during the a substrate of mud and aquatic plant mid-1950s. Presently in Texas, popu- roots. They are also abundant in lations of the Pecos gambusia occur natural spring-fed marshes (ciéne- near Balmorhea in aquatic habitat gas), channels, and pools along this supported by spring flow from watercourse. Phantom Lake, Giffin, San Solomon, The Leon Springs pupfish feeds and East Sandia springs. The largest primarily on the bottom, ingesting population is in San Solomon Ciénega Big Bend Gambusia large amounts of detritus (decom- at Balmorhea State Park. A substan- © TPWD posed organic material) and mud. tial population also occurs in Leon Food items include diatoms, algae, Creek and in Diamond Y Spring out- The Pecos gambusia is an oppor- and small invertebrates. “Pit dig- flow north of Fort Stockton. The tunistic feeder. Primarily a surface ging” has been observed, where the species also occurs in a limited num- feeder, major food items include fish (mostly males) rest on the bot- ber of locations in New Mexico. insects, other small invertebrates, and tom of the pool and undulate their The Pecos gambusia occurs abun- some filamentous algae. bodies to churn up the substrate. dantly in spring-fed pools, spring Competition with other This behavior is thought to be associ- runs, and downstream areas having Gambusia species is important in ated with locating buried food items. relatively constant temperatures, determining the relative abundance The Leon Springs pupfish abundant overhead cover, sedge-cov- of the Pecos gambusia. Studies have spawns throughout the year, with ered marshes, and in gypsum sink- shown that, over a period of years, females laying up to 10 eggs per day. holes with no surface flow. It is the western mosquitofish outcom- Spawning occurs on the bottom sub- capable of occupying a variety of petes the Pecos gambusia in isolated strate in territories aggressively habitats if factors such as tempera- pools and downstream waters well defended by individual males. ture and salinity are suitable. removed from spring influence. Shallow shelf areas with slow cur- The closest relatives of the Pecos Salinity seems to be important in rents, warmer than the deeper chan- gambusia are found in south Texas determining the influence of an nels, are preferred for spawning. and Mexico, so the species has a long introduced competitor, the large- This species is known to tolerate an history of adaptation to warmer cli- spring gambusia (Gambusia geiseri). unusually wide range of salinities and mates. The fish does not occur even Since the Pecos gambusia is tolerant temperatures. However, studies sug- in spring-fed waters at higher eleva- of a wide range of salinities, it can gest that the temperature range tions, presumably because water tem- outcompete the largespring gambusia required for successful reproduction peratures are too cold. Maximum in the saline waters of Leon Creek, may be quite narrow. The extended temperature is also important in while the largespring gambusia seems breeding season, wide salinity and determining suitable habitat. The competitively superior in the freshwa- temperature tolerances, and broad Pecos gambusia seems to be less toler- ters of the Balmorhea area. In areas food habits suggest that the Leon ant of variable temperatures than the where the two species are found Springs pupfish is a generalist that western mosquitofish (Gambusia affi- together, the Pecos gambusia inhabits does best in simple communities with nis), a major competitor. Studies indi- mid-water and bottom habitats and few competing species. cate that the Pecos gambusia is more the largepring gambusia is more abundant in spring-fed waters, but it often found at the surface near vege- Pecos gambusia may also do well in less spring-like tation. The Pecos gambusia is a small waters if there is enough cover from 1 (1 /2 inches long), live-bearing fish above to buffer temperature changes. Big Bend gambusia with a dark lateral stripe and a metal- Predation by green sunfish The Big Bend gambusia lic gray-blue color. Females have a (Lepomis cyanellus) and largemouth (Gambusia gaigei) is a small, live- black area on the abdomen that sur- bass (Micropterus salmoides) can bearing fish which reaches a maxi- rounds the anal fin and anus. The 1 become a major limiting factor in mum length of about 1 /2 inches. anal fin of males is modified into a areas where there is no submerged The fish is yellowish in color, with a gonopodium, a tube-like structure vegetation or enough shallow water faint lateral stripe and orange to yel- to provide protection from predators.

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