Arizona / Nevada regional report: Spring 1997.

Peter J. Unmack

Since this is my first report I figure a brief introduction is appropriate. I hale from Australia and have been living in the US since September 1994. I am presently a Masters student at Arizona State University working on the biogeography of freshwater Australian fishes under Dr. W.L. Minckley (that's right, that cichlid). One of my main interests is desert fish and desert springs in particular. I try and get out in the field occasionally and have been spending some time lately in Ash Meadows Nevada working on exotic fish reproduction during winter under thermal conditions. I also arrange two trips per year to southern Nevada for Tropical FishKeepers Exchange and the Bay Area Killifish Association to undertake conservation work on threatened and endangered fish populations under the direction of Nevada Division of Wildlife biologist Jim Heinrich. The first portion of this report is the results of the latest trip followed by brief notes on additional collecting I have been undertaking.

March 14-16 was our conservation weekend in southern Nevada. First stop was the Virgin River at Mesquite where we were monitoring reintroduced Endangered woundfin (Plagopterus argentissimus) populations. Native fish were not very common, a few flannelmouth suckers (Catostomus latipinnis), desert suckers (Pantosteus clarki), 2 Endangered Virgin chubs (Gila seminuda), 1 speckled dace (Rhinichthys osculus), and around 20 woundfin. Exotics included one carp (Cyprinus carpio) and literally thousands of red shiners (Cyprinella [Notropis] lutrensis). Next day we headed to a local park for some hard labor adding rocks to a half mile of artificial stream being developed for native fish conservation in Boulder City. Thanks to Jim Heinrich for allowing us to contribute.

From here we headed to Ash Meadows for a day and a half. We removed all the encroaching reeds (Typha) from two springs to try to open up Threatened pupfish (Cyprinodon nevadensis mionectes) habitat and reduce habitat for the exotic species there. We also removed around a thousand exotic fish (sailfin molly and damnbusia), crayfish, and bullfrogs. During a 6 month project there I have removed over 8000 exotics in 5-6 trips. Pupfish numbers appear to be improving, especially juveniles. Of course, one needs to keep removing exotics for the effect to continue. All collecting was done in conjunction with USFWS staff on the refuge. We also collected a bunch of shortfin molly and convict sicklids (including albinos) from Roger's Springs by Lake Mead, one of the other sites I am studying.

The day after returning from that trip it was off with my ichthyology lab that I teach to Lake Mohave on the Colorado River. The primary purpose was to collect Endangered razorback suckers (Xyrauchen texanus) as part of a larger annual sampling effort to monitor the population that has continued to document their decline since collecting began in the late 1960's. It is pretty impressive to able to view and hold a fish that is over 40 years old, few folks get to experience that! We also caught a single bonytail chub (Gila elegans), probably the most Endangered fish in the country. It was probably a hatchery release (they have to check the tag number). Exotics were also abundant including carp, largemouth bass, bluegill, striped bass, channel catfish, and rainbow trout. During the night teams went out collecting larval razorback suckers. This is part of the recovery effort as the last time recruitment occurred in the lake was 40-50 years ago (the age of the present group of adult fish)! Unfortunately, they don't live much longer than this, thus the population (and virtually the species) is almost gone. To prevent this, larvae are collected at night, as they are attracted to a light source. They are then taken to a hatchery and from there shortly after released into exotic fish free backwaters in the lake. No larvae are ever found over half and inch long in the main lake due to predation by exotics. So far this year over 75,000 have been collected. Once they reach 10-12 inches (big enough to avoid exotic predators) they are released back into the lake. It is still too early to tell if this will be successful although results to date are encouraging. On the way up to the lake we collected in three streams in the Bill Williams drainage, a tributary to the Colorado River in Arizona. The Santa Maria River had abundant longfinned dace (Agosia chrysogaster) and a single redshiner and a few bluegills. Burro Creek only contained red shiners and bluegills. Big Sandy River had only longfinned dace. All in all a busy week of activity that was great fun for all involved.

The following weekend I visited Fossil Creek in the upper Verde River near Payson. The whole creek is springfed. Native fish were abundant including speckled dace, desert suckers, and an enigmatic chub (Gila "robusta") population. Fossil Creek has one of only a few populations of this chub which is morphologically intermediate between roundtail chub (Gila robusta) and Gila chub (G. intermedia) whose taxonomy is yet to be resolved. It is indeed a rare treat in Arizona to be able to sit and observe an intact native fish fauna without many exotic fishes [only a few bluegills (Lepomis macrochirus) were observed]. At this moderate altitude, three species is the normal diversity that would be expected to occur (seven species is the highest native fish diversity still found in any waterbody in Arizona—unfortunately, it is not uncommon to find more that seven exotic fishes in many waterbodies). The next day I headed out to collect genetic samples for a fellow graduate student. First destination was the upper Santa Maria River to sample Date Creek. Here the creek has perennial water (note: the only water present) for about three quarters of a mile as it passes through a gorgeous little canyon. Longfinned dace were abundant, both adults and juveniles. For the first time I observed their breeding pits. These consist of small dug out depressions in the sand. Males don’t guard territories, when a female passes by, several males chase her and spawn in one of the many depressions. There is no parental care. Exotic fathead minnow (Pimephales promelas) had been previously recorded here. It is not uncommon in canyons for exotic fish to be present until the first larger flood. Native fish are adapted to survive the torrential flows through the canyon, the exotics get washed downstream to desiccate in the desert. The Hassayampa River was the other site sampled that day. Young longfinned dace were abundant, only a few adults were found.

The next weekend it was off into the wilds again! This time to Aravaipa Creek with students from the ichthyology class. Aravaipa is a rather special place in Arizona as it contains seven native species and exotics are rare. Dr Minckley has been sampling Aravaipa Creek for over 35 years! This data is used to look at changes in relative species abundance over time and identifying causes such as variation in stream discharge. The reason that fishes exist here is because the creek flows through a major canyon. Various geomorphological factors that make up a canyon force water to the surface, thus water exists perennially. The canyon is approximately 20 miles in length. Above and below the canyon water is not usually present. The class split into three groups to allow the nine sites to be sampled over the weekend. The seven native species recorded include desert suckers, Sonoran suckers (Catostomus insignis), Threatened spikedace (Meda fulgida), Threatened loach minnow (Tiaroga cobitis), speckled dace, roundtail chub, and longfinned dace. Exotic fish collected include green sunfish (Lepomis cyanellus) and yellow bullheads (Ameiurus natalis) while additional records exist for red shiner, fatheads, largemouth bass, black bullhead (A. melas), carp, and damnbusia. These exotics either don’t survive long term or build up large populations due to either marginal habitat or the huge flood in 1983 that removed most exotics, though interestingly none of the natives were effected, even their abundance didn’t change. The occurrence of exotic fish has increased after the 1983 flood in the lower portion of Aravaipa Creek as it now flows further, allowing exotics to migrate from the San Pedro River.

I don't formally organize NANFA trips at this stage due to the lack of local members, however, anyone from within or out of state should feel free to contact me if interested in coming along on any trips. Again, we have two trips per annum to southern Nevada that I would really encourage folks to get involved in. If interested, you should contact me ahead of time as sometimes I don’t get announcements out in time to meet publication schedules.


Peter Unmack
PO Box 1454
Tempe AZ 85280