3110

• UCREFRP Catalog Number: 3110
• Author: Sublette, J. E.
• Title: Survey Of The Fishes Of the San Juan River Basin, With Particular Reference To The Endangered Species.
• USFW Year: 1976.
• USFW - Doc Type: Albuquerque, New Mexico.
• Copyright Material: NO

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previously reported from the San Juan Basin,.
Salmo trutta Linnaeus - Brown trout (Figs. 2 and 3)

Salmo gairdneri Richardson - Rainbow trout (Figs. 4 and 5)

Two species of trout were collected during the survey, both in limited

numbers except immediately below Navajo Dam where they are the most significant

component of the fish fauna.. At least four other salm.onids occur within the

river basin: Salmo clarki pleuriticus Cope, Colorado River cutthroat (Behnke and

Zarn 1976); Oncorhynchus kisutch (Walbaum), Coho salmon; Oncorhynchus nerka

(Walbaum), Kokanee (New Mexico Department of Game and Fish, Wildlife News, various

issues; personal communication, Bob Patterson and Hike'Hatch). The absence'of

Salmo clarki from the collections is attributed to very sparce collecting at stream

elevations where the cutthroat trout is expected to occur. In addition at the

upper elevation stations the electrofishing equipment vas "down"; consequently,

only seine collections were made. Neither Wemsman (1973) nor Behnke and Zam

(1976) list any known populations of the native subspecies, ~. clarki pleuriticus,

from the San Juan basin. Salvelinus fontinalis (Mitcbill) brook trout, also
occurs in the Mancos, La Plata and Animas River drainages of Colorado (Smith

1976) but was not collected during this survey.
Very limited net sets were made in Navajo Reservoir with negative results

for Kokanee which are known to occur there. Coho sal80n have not been recently

collected in Navajo Reservoir by the New Mexico Departaent of Game and Fish but

are still believed to be present (Mike Hatch, personal communication).

DorOtlOm..l pet~'nen8-:' (Guntlwr) - Threadfin shad (Figs..6 and 7)

This introduced forage fish was very abundant 1D the San Juan Arm of Lake

Powell. Large numbers of juveniles were taken during the first week of August

indicating an excellent hatch during the earlier part of the year.

Catostomus (Pantosteus) discobolus Cope - Bluehead sucker (Figs. 8 and 9)

Among the endemic fish of the San Juan River Basin three species stand out

8S being highly successful in competition with many iBtroduced species. One of

these is the bluehead sucker, the second most abundant fish taken during the

survey. The co-extensive native sDecies. the'" flannehllourn Alldc.~l" _ CAtnA tnmllA