Notropis orca

phantom shiner

Type Locality

Rio Grande at El Paso, Texas (Woolman 1894).

Etymology/Derivation of Scientific Name

Notropis – ridged or keeled back; a misnomer, probably due to the shrunken specimen used by Rafinesque when establishing this genus for N. atherinoides; orca – killer whale, the head of N. orca said to resemble that of a dolphin (Scharpf 2005).

Synonymy

Notropis orca Woolman 1894:56; Chernoff et al. 1982:15; Hubbs et al. 2008:23.

Orcella orca

Orcula orca

Nototropis orca

Notropis simus

Notropis simus orca

See Chernoff et al. (1982) for detailed synonymy.

Characters

Maximum size: 74.4 mm (2.93 in) SL (Chernoff et al 1982).

Coloration: Generally pallid with little pigmentation; Chernoff et al. (1982) suggested common name of “phantom shiner” based partly on coloration of this species. Preserved specimens: pale; sides with broad silvery band, as broad as length of snout, bordered above by narrow plumbeous line; back sparsely covered with fine dark punctulations, median line of back with a faint plumbeous band; top of head dark, remainder silvery; pale underneath; fins pale (Woolman 1894). No prominent lateral stripe extending through eye; no caudal spot; no paired dots along lateral line (Hubbs et al. 2008). Peritoneum silvery (Chernoff et al. 1982).

Pharyngeal teeth count : 2,4-4,2.

Counts: Usually 8 anal fin soft rays; 9 or 10 gill rakers on 1^st arch; 14-16 gill rakers on 2^nd arch; 10 or 11 rakers on 3^rd arch; fewer than 45 lateral line scales (Hubbs et al. 2008).  8 anal fin soft rays; 7 dorsal fin soft rays (Woolman 1894).

Mouth position: Terminal and oblique (Hubbs et al. 2008). Subterminal, slightly oblique, lower jaw slightly included (Woolman 1894).

Body shape: Snout blunt; top of head unusually high and transversely rounded.  Plump body, slightly compressed, with broad back and belly; (Woolman 1894).

Morphology: Posterior edge of jaw does not reach pupil.  Eye small, slightly shorter than snout, contained about 3.5-4 times in body depth (measured over curve). dorsal fin insertion well behind insertion of pelvic fin, nearer base of caudal than snout; depth at occiput more than width at occiput (Hubbs et al. 2008).  Lateral line complete, usually not decurved, either straight or with a broad arch; premaxillaries protractile; upper lip separated from skin of snout by deep groove continuous across the midline (Hubbs et al. 2008). Fins moderate; dorsal fin high and falcate; pectorals slightly falcate, almost reaching ventrals, one and one-half in head; ventrals short, not reaching vent. Breeding adults with many, irregularly arranged tubercles on head, snout, lips, gular and branchiostegal regions, and breast; breeding males with well developed tubercles over outer nine fin rays of pectoral fin, and tubercles may be present on the thickened interradial membrane between these rays (after the outermost ray) and small tubercles sometimes found on anterior edge of dorsal and pelvic fins; breeding females sometimes with well developed, irregularly placed tubercles on upper surface of pectoral fin (Chernoff et al. 1982).  Intestinal canal short, forming simple S-shaped loop (Hubbs et al. 2008).

Distribution (Native and Introduced)

U.S. distribution: Endemic to the Rio Grande from the mouth of the river at Boca Chica Beach, Texas, to central New Mexico, including the mouth of the Pecos River (Chernoff et al. 1982; Miller et al.1989).

Texas distribution: Originally found throughout the Rio Grande (Chernoff et al. 1982; Edwards 2004).

Abundance/Conservation status (Federal, State, Non-governmental organizations)

Believed to be extinct (Miller et al. 1989; Bestgen and Platania 1990; Propst 1999; Edwards et al. 2004; Scharpf 2005; Hubbs et al. 2008); however, it has been suggested that species may still be extant as it was once widely distributed (Scharpf 2005). This species extirpated in the Rio Grande, New Mexico (Bestgen and Platania 1990; Platania 1991); may have been prevented from migrating to secure areas as a result of river desiccation, extreme distance, or habitat desiccation due to construction of dams and were unable to survive in reservoirs (Bestgen and Platania 1990). Miller et al. (1989) noted that dams, water diversion, pollution and increased salinity along with an abundance of introduced fishes brought about a significant decline in abundance of Notropis orca, especially after 1940. The species was considered endangered by Chernoff et al. (1982). Notropis orca was last seen in 1975 when a single adult was collected from the Mexican side of the lower Rio Grande (Chernoff et al. 1982; Miller et al. 1989).

Habitat Associations

Macrohabitat: No information at this time

Mesohabitat: Collected from shallow riffle over rocky streambed (Woolman 1894).

Biology: Biology unknown as the last specimen was taken in 1975 (Miller et al. 1989; Bestgen and Platania 1990; Edwards et al. 2004).

Spawning season: No information at this time

Spawning habitat:  No information at this time

Spawning Behavior:   No information at this time

Fecundity:  No information at this time

Age at maturation:  No information at this time

Migration:  No information at this time

Growth and Population structure: Specimens from the two largest New Mexico collections had mean lengths of 53.1 mm (2.09 in) SL and 61.8 mm (2.43 in) SL, representing from two to three year-classes (Age I-III; Bestgen and Platania 1990).

Longevity: Age I - III present in New Mexico collections (Bestgen and Platania 1990).

Food habits: No information at this time

Phylogeny and morphologically similar fishes

Subgenus: Alburnops (Scharpf 2005). Notropis orca closely related to the Pecos bluntnose shiner (Notropis simus pecosensis) and the Rio Grande bluntnose shiner (N. s. simus; Hubbs et al. 2008). Notropis orca differs from Notropis simus in having 8 (usually) anal fin rays, 9 or 10 gill rakers on the 1^st arch, 14-16 gill rakers on the 2^nd arch, 10 or 11 gill rakers on the 3^rd arch, slender pharyngeal arch, and the posterior edge of jaw not reaching the pupil; while Notropis simus has 9 or 10 (usually) anal fin rays, 6-8 gill rakers on the 1^st gill arch, 11-13 gill rakers on the 2^nd arch, 8 or 9 gill rakers on the 3^rd arch, pharyngeal arch broad, and the posterior edge of jaw under the pupil (Hubbs et al. 2008).

See Chernoff et al. (1982) for comparison of morphological characteristics of Notropis orca and other species including: Notropis simus pecosensis, Notropis s. simus, the Rio Grande shiner (N. jemezanus), the sharpnose shiner (N. oxyrhynchus), the silverband shiner (N. shumardi), the river shiner (N. blennius), and the chub shiner (N. potteri).

Notropis orca known to hybridize with the Rio Grande bluntnose shiner (N. s. simus; Chernoff et al. 1982).

Host Records

 No information at this time

Commercial or Environmental Importance

Hybridization between Notropis orca and the Rio Grande bluntnose shiner (N. simus simus, subspecies of Notropis simus) may have occurred as a result of the reduction in spawning sites and/or rarity of both species; whether hybridization influenced the decline of this species is not known (Chernoff et al. 1982; Miller et al. 1989).

References

Bestgen, K.R., and S. P. Platania. 1990. Extirpation of Notropis simus simus (Cope) and Notropis orca Woolman (Pisces: Cyprinidae) from the Rio Grande in New Mexico, with notes on their life history." Occasional Papers, The Museum of Southwestern Biology (6): 1-8.

Chernoff, B., R.R. Miller, and C.R. Gilbert. 1982. Notropis orca and Notropis simus, cyprinid fishes from the American Southwest, with description of a new subspecies. Occasional Papers of the Museum of Zoology, University of Michigan 698:1-49.

Edwards, R.J., G.P. Garrett, and N.L. Allan. 2004. Aquifer-dependent fishes of the Edwards Plateau region. Chapter 13, pp. 253-268 in: Mace, R.E., E.S. Angle, and W.F. Mullican, III (eds.). Aquifers of the Edwards Plateau. Texas Water Development Board. 360 pp.

Hubbs, C., R.J. Edwards, and G.P. Garrett. 2008. An annotated checklist of the freshwater fishes of Texas, with keys to identification of species. Texas Journal of Science, Supplement, 2^nd edition 43(4):1-87.

Miller, R.R, J.D. Williams, and J.E. Williams. 1989. Extinctions of North American fishes during the past century. Fisheries 14(6):22-38.

Platania, S.P. 1991. Fishes of the Rio Chama and upper Rio Grande, New Mexico, with preliminary comments on their longitudinal distribution. Southwestern Naturalist 36(2):186-193.

Propst, D.L. 1999. Threatened and endangered fishes of New Mexico. Tech. Report No.1. New Mexico Dept. of Game and Fish., Sante Fe, NM. 84 pp.

Scharpf, C. 2005. Annotated checklist of North American freshwater fishes, including subspecies and undescribed forms, Part 1: Petromyzontidae through Cyprinidae. American Currents, Special Publication 31(4):1-44.

Woolman, A.J. 1894. Report on a collection of fishes from the rivers of central and northern Mexico. Bull. U.S. Fish Comm. 14(1895):55-66.