Empetrichthys latos

  Robert Miller described in his paper from 1948 in total three subspecies, according to the three populations he found in the three springs. The differences are morphological, mostly fin sizes and distances between fins and head profiles. Living in small populations in isolated springs may easily drive a population in a certain direction and cause morphological as well as genetical differences, for last ones, the populations haven't been studied (and it might be meanwhile impossible due to conservation practices). However, modern fish taxonomy inclines to refuse the taxon "subspecies", as either there are differences between populations that qualify for a separate taxon, then these populations are regarded species, or they do not. In this case, alternative expressions like clades, lineages, populations, subpopulations, or ESU's come in use. Anyway, we don't want to violate the existing situation in the Pahrump Poolfish, though we would also prefer to talk about lineages or ESU's instead of subspecies, so we decided to place the information we usually try to give about Holotypes, habitat and terrae typicae here in the chapter "Remarks".

  Empetrichthys latos concavus: University of Michigan Museum and Zoology, Cat. No. UMMZ-141857.

  The Holotype is an adult female of 39mm standard length, sampled by R. R. Miller and his wife Frances on October 5th, 1942. The Collection-numbers of the Paratypes are: UMMZ 140491 (21 specimens) and USNM 112071 (5 specimens), 17 to 40mm long. The type location was a spring on the Raycraft Ranch, about 0.5 miles (0.5km) north of the Pahrump Ranch, Pahrump Valley, Nye County, Nevada. The species epithet can be derived from the Latin with the prefix con- meaning "with" and cavus "the hollow", therefore concavus can be translated with "with a hollow", refering to the marked concavity of the top of the head.

  Empetrichthys latos pahrump: University of Michigan Museum and Zoology, Cat. No. UMMZ-141856. The Holotype is an adult female of 35mm standard length, seined by R. R. and F. H. Miller on May 5th, 1942. The Collection-numbers of the Paratypes are: UMMZ 140490 (originally 142, now 130 specimens); USNM 112073 (ex UMMZ-140490, 10 specimens), 14 to 36mm long. The type location is a marshy overflow of a spring-fed ditch on Pahrump Ranch, 6 miles (9.7km) northwest of Manse Ranch, in Pahrump Valley, Nye County, Nevada. This subspecies "is named pahrump after the valley in which it is found, and more particularly for Pahrump Ranch, which is the more precise type locality."

  The left picture shows an adult male Paratype of Empetrichthys latos concavus (UMMZ-140491), 34mm long, and the right one of Empetrichthys latos pahrump (UMMZ-140490), 32mm long:

   Poolfish occured exclusively in an area 50 to 100km west and northwest of Las Vegas. The map below shows the historic places where the genus Empetrichthys occured with red asteriscs marking the habitats of Empetrichthys latos in the Pahrump Valley, blue those of Empetrichthys merriami in Ash Meadows. A low rise separates both basins:

  Refuges of the Pahrump Poolfish - Los Latos Pool and Corn Creek Spring:

  The remaining subspecies latos could only survive through a couple of translocations starting in the 1970's before the Manse Spring dried up completely in 1975. The first translocation happened in June 1970, when the Los Latos Pool in an isolated canyon near Lake Mojave above the Colorado River was stocked (Soltz and Naiman, 1978). This site was flooded in the late 1970's, the population got lost and the individuals were never replaced. The second locality outside of the Pahrump valley receiving fish were the Corn Creek Springs, northwest of Las Vegas on the Desert National Wildlife Range (DNWR), Nye County. The transplant to Corn Creek Spring took place in August 1971 and involved 29 fish. David S. Soltz and Robert J. Naiman (1978) reported about a relatively large reproducing population there, but it was extirpated in the late 1990's due to the illegal introduction of crayfish and bullfrogs. The population was reduced to three fish in 1998 and was not found thereafter. In June 2003 fish from the State Park population were introduced to a refugium, a secure, but smaller part of Corn Creek Spring with visual surveys in July 2003 revealing eight young in the refugium. Another 30 adult Poolfish were added to the refugium from the State Park population in August 2003. The population seemed to be stable and was estimated at 141 fish in 2004. However, the Nevada Department of Wildlife opined in 2005 that the tanks would never be capable of sustaining the thousands of fish which formerly inhabited the springs. The Corn Creek refuge site itself went on without Pahrump Poolfish until 2015, after site restorations to the spring system were fully completed. The surviving Poolfish were removed and the site was poisoned with Rotenone to eradicate the non-native fish populations that had been introduced. In 2014, after they did that, but before they had a chance to put Poolfish back in, somebody had introduced non-native fish again, so they did another successful Rotenone treatment to eradicate those non-native fish. In the summer of 2014, they moved some Poolfish from other sites back into Corn Creek Spring and by 2018, the estimated Poolfish population was over 2,000 fish. However, the recent resurgence in the Pahrump Poolfish population was short-lived, as newly-introduced non-native fish once again appeared at Corn Creek by 2019 and the number of Poolfish dropped to less than 200. Meanwhile a plan exisist to poison the Corn Creek site again in 2021 and after that restock with Poolfish. 

  Refuges of the Pahrump Poolfish - Shoshone Pond and Lake Harriet:

  Back to 1970, the Bureau of Land Management designated the Shoshone Ponds and 1,240 surrounding acres as the Shoshone Ponds Natural Area, White Pine County, about 40 miles southeast of Ely. The ponds were stocked in March 1972 with 16 Empetrichthys latos from Corn Creek or Manse Ranch Spring, but the fish were extirpated in 1974 due to vandalism when the water source was intentially turned off. In August 1976, another 50 fish were transplanted to the site (from the Las Vegas holding facility, University of Nevada) after modifications were made to the ponds' water system to prevent future vandalism. This population counted 1989 about 450 individuals. Since then the population was growing and remained stable since the 1980s with only natural population fluctuations affecting its status. However, surveys in 2003 indicated a significant decrease in the population to less than 1,000 individuals. Because this habitat is considered less than optimal, U. S. Fish and Wildlife Service biologists consider the site a temporary holding pool. In order to replace the lost Los Latos Pool population, besides the Corn Creek and Shoshone pond sites, a third population of Poolfish was established in the irrigation reservoir (Lake Harriet) at the State of Nevada's Spring Mountain Ranch State Park (State Park) in western Clark County after the eradication of exotic species. A number of 426 individuals of Poolfish from Corn Creek Springs were transplanted to the State Park location in June 1983. Since then, this was the largest and most stable population of Empetrichthys latos. Over 500 fish were present between 1985 and 1993 and population estimates were 24,800 fish in 1989, 16,775 in 2003 and 29,876 in 2004. Lake Harriet has historically hosted one of the biggest refuge populations for the Pahrump poolfish. But once non-native crayfish, goldfish and mosquitofish populations were found in the lake, Pahrump Poolfish populations dropped from over 12,000 fish to just a couple hundred within a year (2017). Eradicating these non-native species called for more extreme measures at Lake Harriet, which meant completely drying out the lake. Lake Harriet was refilled early in spring 2019, with the plan for a reintroduction of Pahrump Poolfish shortly thereafter. That plan, however, was further complicated by the COVID-19 pandemic that shut down the country in March. A reintroduction of Pahrump Poolfish to Lake Harriet finally in June 2020 has been successful so far, with reports that thousands of larval, newly hatched Poolfish can be seen around the shorelines. Estimations in 2020 talk about 6,000 individuals among all the sites in total. 

  The U.S. Fish and Wildlife Service approved the Pahrump Killifish Recovery Plan (Recovery Plan) on March 17, 1980 (Service 1980). The Recovery Plan recommended the establishment of at least three populations of Poolfish as the primary objective for the species' recovery efforts, preferably including a population at Manse Spring. The idea about that was, that the species is less likely to be threatened simultaneously at three or more separate sites than at a single location. The Recovery Plan also stated that the species could be considered for reclassification to threatened status when each of the three populations contained at least 500 adults for 3 years, and each habitat was free of immediate and potential threats.  A proposed rule to reclassify the Pahrump Poolfish from Endangered to Threatened Status was withdrawn in 2004 as a reclassification at this time seemed to be not appropriate, causing in the temporary loss of Corn Creek and the 2003 population decline at Shoshone Ponds. However, population developments over the last decades will not push the Fish and Wildlife Service to make another attempt to reclassify the Pahrump Poolfish. 

  The left picture shows the type locality of the Pahrump Poolfish (Manse Spring) and the four localities it was transfered to, the right picture the stocking and population history of this species until 2013. Both illustrations out of the doctoral thesis of S. C. Goodchild:

  Carl Hubbs (1932) when describing Crenichthys nevadae, enrolled a bit what was known about the relationship of the genus Empetrichthys before it was finally discovered of being related with the Mexican Splitfins. Here his thoughts: "In describing Empetrichthys, Gilbert (1893) remarked that it "seems most nearly allied to Orestias, of which numerous species have been described from lakes in the high Andes of South America." Garman (1895) regarded the genus as "allied to Fundulus through the more compressed species," though he approximated and compared Empetrichthys with Orestias in his key. Jordan and Evermann (1896) placed Empetrichthys in the Orestiinae. Eigenmann (1920) commented at some length on the possible relationships of the two genera, concluding that: They are so similar that they might readily be considered as forming but one genus. The double series of teeth in the jaws and the terminal though oblique mouth and the slightly more posterior position of the dorsal are the only characters distinguishing Empetrichthys from all of the species of Orestias. Myers (1931) finds, however, that Empetrichthys lacks skeletal features supposed to characterize the Orestiatinae (Orestiinae), and concludes that "it appears to have nothing to do with Orestias." Species of the subfamily Empetrichthyinae are oviparous fishes and share the lack of pelvic fins, while the subfamily Goodeinae is livebearing. Lynne Parenti (1981) finally proposed this subfamily as sister group to the Goodeinae and encompassed both in the family Goodeidae. Meanwhile the monophyly of the family Goodeidae and the narrow relationship between both subfamilies has been supported through several studies since the 1980's and is not doubted any longer, and meanwhile science is sure, that the resemblance of the genus Orestias is only superficial.