Geology topics

Paul C. Marsh

Publications and source records attributed to Paul C. Marsh.

4 recordsLinked to original sources

USGS2005

Cibola High Levee Pond annual report 2004

This represents the fourth and last annual report of a five year study investigating the early life ecology of the bonytail and razorback sucker at Cibola High Levee Pond. The work in 2004 included: telemetry studies, collection of physical water quality measurements, zooplankton samples, netting fish, the collection of scale samples for aging, predator/prey tank tests and a preliminary analysis of the data base. Juvenile bonytail and razorback suckers were collected this year, demonstrating that natural recruitment occurred for both species. Young from 2004, 2003, and 2002 were all represented in our sample. Unfortunately, we discovered that largemouth bass had also spawned. Approximately 100 young bass were observed during a snorkeling trip in late July. Bass ranged in size from an estimated 5 to 50 cm and were distributed throughout the pond. Attempts to determine the cover preference of 30-cm bonytail met difficulties. Spawning occurred a month earlier than previous years due to an unseasonably warm spring. The combination of warmer temperatures and the vigors of spawning attributed to higher stress and associated mortality of study fish. We replicated our procedures under hatchery conditions on the chance that transmitter attachment was at fault but we experienced similar post-release mortality, including the control fish. This supports the long held contention that bonytail are extremely fragile during and after spawning. In the predator-prey tests, young of every species tested ate razorback sucker larvae. The most aggressive predators tested in 2004 (n = 8 species) were young of the year green sunfish, channel catfish, and common carp. Bullfrog tadpoles and red swamp crayfish also ate razorback sucker larvae and eggs, showing predation is not limited to predatory fish. This work illustrates that early life stages are quite vulnerable to small predators that have easy access to shallow nursery habitats. Remaining work will be finished this coming summer and a final report describing CHLP and the ecology of these fish will be completed by the end of 2005. We offer our assistance to the Fish and Wildlife Service in the pond’s renovation and support for the creation of additional refuge ponds. Funding for this work ends September 2005.

Cibola High Levee Pond↗

USGS2002

Lost, a desert river and its native fishes: A historical perspective of the lower Colorado River

The Colorado River had one of the most unique fish communities in the world. Seventy-five percent of those species were found no where else in the world. Settlement of the lower basin brought dramatic changes to both the river and its native fish. Those changes began more than 120 years ago as settlers began stocking nonnative fishes. By 1930, nonnative fish had spread throughout the lower basin and replaced native communities. All resemblance of historic river conditions faded with the construction of Hoover Dam in 1935 and other large water development projects. Today, few remember what the Colorado River was really like. Seven of the nine mainstream fishes are now federally protected as endangered. Federal and state agencies are attempting to recover these fish; however, progress has been frustrated due to the severity of human impact. This report presents testimony, old descriptions, and photographs describing the changes that have taken place in hopes that it will provide managers, biologists, and the interested public a better appreciation of the environment that shaped these unique fish.

Colorado River↗

USGS1999

Spring-summer movements of bonytail in a Colorado River reservoir, Lake Mohave, Arizona and Nevada

The bonytail Gila elegans is a large-river minnow (Cyprinid) endemic to the Colorado River system of western North America. The species is federally listed as endangered, its biology poorly understood, and relatively little is known of its movements. Two short-term telemetry studies were conducted during 1996 and 1997 to assess spring-summer temporal and spatial movement patterns in Lake Mohave, Arizona and Nevada, where the largest remaining population of bonytail persists. A total of 20 bonytail were implanted with 90-day sonic transmitters. Ten fish (5 wild-caught from the Lake and 5 cove-reared: 5 females and 5 males) were implanted in May 1996 and additional 10 (7 wild-caught and 3 pond-reared: 2 females and 8 males) were implanted in April 1997, released into the lake immediately after surgery, and tracked approximately weekly through August of both years. Eight fish dispersed immediately after release in 1996, two moved up- and six moved down-lake. The five wild-caught fish moved down-lake as much as 42 km, and four of these (all males) remained in the lower most 5 km while the other (female) occupied an area about 10 km below the release site. Two cove fish moved up lake 15 and 43 km, respectively, while a third moved 4 km down-lake. Two fish were never contacted. Most locations were in shallow water along shorelines, in some instance within inundated stands of riparian vegetation. In 1997, three pond fish were surgically implanted with transmitters and released at Cottonwood Cove, Nevada. Two were not contacted again, and the other was lost 12 days post-release after moving approximately 1.4 km across the lake. Seven wild fish were captured and released at two sites in the lower portion of the lake, and all moved to downstream areas where they remained for the duration of study. Contact was lost with one fish after 3 days and another remained stationary after 13 days; the five others were tracked for 62 to 119 days. These last fish remained in the lower lake and had net movement (displacement from release site to last contact location) that averaged 5.4 km and ranged from 4.7 to 6.9 km. All net displacements were downstream. Cumulative distance traveled averaged 28.9 km and ranged from 19.9 to 33.0 km. Most fish locations during daylight hours were in deep water adjacent to the steep Nevada shore, while nighttime locations were in shallow water along gently sloping Arizona shorelines. Bonytail can move substantial distances in a short time (10s of km in a few days). Fish in both years apparently favored the same areas, where they may remain for weeks. Unmarked bonytail were observed or captured by setting nets in places favored by tagged fish, a significant result since future use of the technique may enhance our ability to monitor reintroductions, locate and document spawning, examine habitat use, and acquire desperately needed brood stock for this critically imperiled species. External tagging techniques developed for juvenile razorback sucker may provide a method of minimizing telemetry induced stress while allowing us to focus sampling on congregation sites.

Arizona, Nevada↗

USGS1994

Predation by odonate nymphs on larval razorback suckers (Xyrauchen texanus) under laboratory conditions

High larval mortality has plagued efforts to raise razorback suckers ( Xyrauchen texanus ) in a Lake Mohave, Arizona-Nevada backwater. Observations indicate odonate nymph densities may be high enough to impact larval survival. In laboratory tests conducted in aquaria, damselfly (Coenagrionidae: Enallagma sp.) and dragonfly (Libellulidae: Tramea sp.) nymphs consumed 81% and 76% respectively of 11.8 ± 0.7 mm total length larval razorbacks in 7 days compared to 12% mortality in controls. Larger razorback larvae (14 to 15 mm TL) were less susceptible than smaller fish, showing 53% mortality versus 18% in controls. Extensive growth of sago pondweed ( Potamogeton pectinatus ) may exacerbate predation effects in the backwater, by allowing odonates access to more of the water column.

Southwestern Naturalist↗