Dl. Propst et al., Distribution and notes on the biology of Zuni bluehead sucker, Catostomus discobolus yarrowi, in New Mexico, SW NATURAL, 46(2), 2001, pp. 158-170
Zuni bluehead sucker, Catostomus discobolus yarrowi, is endemic to the Litt
le Colorado River drainage of west-central New Mexico and east-central Ariz
ona. The extent of its historical distribution is uncertain, but included s
everal tributaries of the Little Colorado River upstream of Grand Falls, Ar
izona; origin of the taxon is ambiguous and contributes to poor definition
of its former distribution. Fish eradication efforts in the 1960s eliminate
d the subspecies from portions of the Zuni River drainage in New Mexico. Su
rveys in New Mexico during 1990 through 1993 found it in about 15 km of Rio
Nutria headwaters. Zuni bluehead sucker persists where habitat degradation
(channel incision and sedimentation) is limited and nonnative fishes (part
icularly Lepomis cyanellus) are rare or absent. Seasonally dry channels and
low waterfalls limited movement among headwaters. We found the sucker most
commonly in low-velocity (<10 cm/sec), moderately deep (0.3 to 0.5 m) pool
s and pool-runs with seasonally dense perilithic and periphytic algae. Life
history studies (1994 and 1995) documented reproduction in spring (April t
hrough early June) when water temperature was 6 to 13<degrees>C. Based on l
ength-frequency data, some individuals matured by age 1 and most were matur
e by age 2. Females typically produced 400 to 600 ova annually; spawning ma
y be bimodal, with most occurring early in the season. Individuals may atta
in 50 to 60 mm SL in their first year (age 0), thereafter growth is about 3
0 to 40 mm per year. Few suckers were >150 mm SL and most individuals were
less than or equal to age 3; few survived to age 4. Survival of Zuni bluehe
ad sucker without intensification and expansion of current conservation eff
orts is doubtful.