Crenichthys nevadae

Goodeid
Goodeid
Goodeid
Goodeid
Goodeid
Goodeid
Original Description: 

  HUBBS, C. L. (1932): Studies of the fishes of the order Cyprinodontes. XII. A new genus related to Empetrichthys. Occasional Papers of the Museum of Zoology University of Michigan. Nr. 252: pp 1 - 5

Etymology: 

This species' name nevadae refers to the state of Nevada (USA) where this species can be found.

Holotype: 

  Collection-number: Museum of Comparative Zoology - Harvard University, Cat. No. MCZ-32948.

  The Holotype is an adult female, 44mm SL, collected by C. T. Brues and his wife on 21.07.1930. The Collection-number of the Paratype is: University of Michigan Museum and Zoology, Cat. No. UMMZ-95024

English Name: 
Railroad Valley Springfish
Synonyms: 

none

Karyotype: 

 The Karyotype describes the number and appearance of chromosomes during the phase of condensation, classified by the position of the centromere (Levan et al., 1964).

The following abbreviations are employed:

 

M = large metacentric chromsome (a result of Robertsonian fusion)

m = small metacentric chromsome (centromere at medium position)

sm = submetacentric chromsome (centromere at submedian position)

smst = submetacentric-subtelocentric chromosome (continous series)

st = subtelocentric chromosome (centromere at subterminal region)

stt = subtelocentric-acrocentric chromosome (continous series)

t = acrocentric chromosome (centromere at terminal region)

 

The Karyotype of Crenichthys nevadae has not been ascertained.

Size: 
The maximum known TL is 72mm. The total length is depending on the spring it occupies. Populations of the northern distribution area are said to be generally larger than the ones of the southern area.
Terra typica: 

The Holotype comes from an isolated warm spring at Duckwater, Nye County, Nevada, near the north end of Warm Spring Valley, 16 miles east and 46 miles south of Ely.

Status after IUCN: 

Vulnerable

Distribution and ESU's: 

Crenichthys nevadae is located in the range of the ancient Lake Railroad (Nevada, USA). Desiccation of this lake isolated the species in two areas in Railroad Valley: The northern area is situated on the Duckwater Shoshone Indian Reservation containing Big Warm Spring and Little Warm Spring. The southern area lies approximately 43 km apart and consists of four springs near Lockes Ranch, Nevada (Big, North, Hay Corral and Reynolds Spring). The population of Big Warm Spring was extirpated in the late 1990' s and has been re-established in 2007, but it no longer occurs in the headspring pool or in much of the outflow where it was once observed.

   With respect to the vulnerable habitats, two additional populations have been established outside of the species' historical range in 1947 and 1978. Four formerly unknown populations were determined in 1977, 1992 and 2003 - 2005.

Habitat: 

This species lives in thermal springs and their outflows, which mostly are grown with filamentous algae and lined by overhanging or overgrowing vegetation. The temperature ranges from 29°C to 36°C. 

Colouration: 

The colouration of Crenichthys nevadae seems to be quite similar to Crenichthys baileyi: Sexually active males' flanks are coloured brigthly golden, with the lateral blotches forming a dark band. The colouration is intensifiing in excitement, a medial band on the back of the fish is shown, extending from the mouth to the dorsal fin origin. The edges of the fins become blackish to black in males, some males can turn nearly totally dark during courtship. With regard to the limited information available, a distinguishing character of Crenichthys nevadae is a distinctive row of dark blotches in the midline, with pale bars in between in adults, shown when not courting and that no ventral row of blotches or a line is present as it is in Crenichthys baileyi.

Biology: 

Breeding occurs year-round but ovary production documented from Big Warm Spring was greatest during the summer, declined in spring and fall, and was poorly developed in winter. When water temperatures were especially high, no larval fish were produced in any season. Reproduction seems to be severely restricted in water temperatures above 95°F (35°C). The ratio of males to females is even in the spring but the number of females almost doubles in the summer and fall.

 

Diet: 

Primarily feeding herbivorous in spring, observations in summer show that Crenichthys nevadae from Big Spring at Locke's Ranch is then carnivorous, preferring ostracods (WILLIAMS & WILLIAMS), but regarding the feeding habits of closely related inhabitants of thermal springs, Crenichthys nevadae probably is an opportunistic omnivore, with animal food representing around 2/3 or more of its consumption during the summer, primarily consisting of gastropods. Plant consumption is mostly filamentous algae. While the intestine length is consistent with an omnivore, Sigler & Sigler suggest that the high water temperatures of the springfish habitat may demand the higher energy available with animal food.

Remarks: 

Although the Railroad Valley springfish is not currently threatened with extinction, its extremely limited range makes it vulnerable to competition from introduced species and to habitat modifications. For instance, it was nearly eliminated from Duckwater Spring in the early 1980s by introduced Ictalurus punctatus. The springfish has been introduced to Chimney Springs (10km S of Lockes Ranch) and into springs in the source of Hot Creek Canyon (65km W of Lockes Ranch) in Mineral County, Nevada. In 1981, the introduced springfish population at Chimney Springs was lost after spring discharge ceased altogether. Springfish were reintroduced into Chimney Springs when flows resumed. Several other springs in the region have also failed. Nevertheless, it is absolutely worth considering, why several organisations introduce game fish to habitats and others have to transplant the native fish to the next one to keep them alive.

   Species of the subfamily Empetrichthyinae are oviparous fishes. PARENTI (1981) proposed this subfamily as sister group to the Goodeinae and used the family name Goodeidae to encompass the two subfamilies. This narrow relationship has been supported by several studies since the 1980's (WEBB, DOMINGUEZ).

   Both genera of this subfamily share the lack of pelvic fins.

   In its natural habitats Crenichthys nevadae is threatened by nonnative aquatic species, channelisation of spring outflows, ground water depletion, fragmentation of habitat and alteration of the spring sources and outflows for agricultural practices. Actions have been taken to preserve the remaining populations and to restore the habitats in the species' historical range, including an agreement with the Indian Shoshone tribe and acquiring a Wildlife Management Area at Locke's Ranch. 

   In cooperation with the US Fish & Wildlife service, the Duckwater Shoshone tribe has received three grants to restore the habitat of the "Railroad Valley Spring Fish" that has been listed as threatened species. These small fish were a traditional food source for the Shoshones in this area prior to non-native settlement in the late 1800's. The plan calls for putting in walkways and signage to restrict public access and provide interpretation as well as returning the spring to its natural meandering channels. To facilitate the restoration and prevent the introduction of non-native species, the tribe will purchase an existing catfish farm business located near the spring.

   According to the Nevada Department of Wildlife, Crenichthys nevadae is subject to protection and may not be possessed by a person. Obviously, at present, this species is not available in Europe. A former introduction is uncertain.

   Available information about this species' life history is rare and reports about maintenance in captivity are unknown.

First Describer: 
Hubbs, 1932
Photos: 

Image 1: Immature male from Duckwater

Copyright: Aaron Ambos

Image 2: Group at Locke's Ranch

Copyright: Aaron Ambos

Images 3 - 6: large female and males

Copyright: Kevin Guadalupe