Survival of razorback sucker stocked into the lower Colorado River (original) (raw)
Related papers
Transactions of the American Fisheries Society, 2010
We used tag-recapture data to estimate apparent survival and capture probability for 119,129 hatchery-reared, federally endangered razorback suckers Xyrauchen texanus stocked into upper Colorado River basin streams during 1995-2005. Effects investigated included reach, year, and season of stocking; fish total length (TL) at time of stocking; survival in the first year after stocking versus in subsequent years; and sampling effort. Recapture data were also used to describe poststocking movement. First-year survival rate for stocked razorback suckers of average TL (252.5 mm) was low: 0.05 (95% confidence interval [CI], 0.042-0.071). Total length at stocking and first-year survival were positively correlated; survival approached zero for fish smaller than 200 mm TL but increased to 0.75 or higher for the few fish larger than 500 mm. Season of stocking had a large effect on razorback sucker first-year survival; the predicted rate for average-length fish stocked in summer was less than 0.02 (
Razorback sucker recruitment in Lake Mead, Nevada–Arizona, why here?
Lake and Reservoir Management, 2010
Populations of the endangered razorback sucker (Xyrauchen texanus) have been reduced in the Colorado River during much of the last century. The inability of razorback sucker to recruit in the presence of nonnative fishes and altered flow regimes is thought to be the major factor contributing to their decline. Through funding from the Southern Nevada Water Authority and the US Bureau of Reclamation, we have conducted an ongoing razorback sucker research project on Lake Mead, Arizona and Nevada, since 1996. A major emphasis of this research has been to determine if natural recruitment was occurring in Lake Mead and identify reasons for that recruitment. Ages calculated using a nonlethal aging technique for 186 individual razorback sucker indicate the Lake Mead population is relatively young and that natural, wild recruitment has regularly occurred since the late 1970s. Comparisons of back-calculated ages of captured fish with historical Lake Mead water elevations provide evidence that a change in annual lake level fluctuations is the most likely mechanism that initiated this recruitment phenomenon. Lake level changes along with inundated terrestrial vegetation and turbidity in specific sites in Lake Mead may provide littoral nursery cover for larval and juvenile razorback sucker, allowing them to avoid predation.
The Nature Conservancy undertook restoration of the Williamson River Delta Preserve with a primary goal "to restore and maintain the diversity of habitats that are essential to the endangered [Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris)] while, at the same time, minimizing disturbance and adverse impacts" (David Evans and Associates, 2005). The Western Fisheries Research Center of the U.S. Geological Survey was asked by the Bureau of Reclamation to assist The Nature Conservancy in assessing the use of the restoration by larval and juvenile suckers. We identified five obtainable objectives to gauge the habitat suitability for young-of-year suckers in the permanently flooded portions of the two most recently restored sections (Goose Bay and Tulana) of the Williamson River Delta Preserve (hereafter referred to as the Preserve) and its effects on the distribution and health of larval and juvenile suckers. Several of these objectives were met through collaborations with The Nature Conservancy, Oregon State University, Oregon Water Science Center, and Leetown Science Center. Our findings were in concurrence with those of The Nature Conservancy, who found that the Preserve supported young-of-year suckers at least as well as adjacent lake habitats (Erdman and others, 2011) despite the prevalence of non-native and piscivorous species in the system. The Preserve was recolonized by all fishes in the regional species pool, both native and non-native, between the time each portion of the Preserve (Goose Bay and Tulana) was inundated in autumn and the following spring. A large number of fish capable of preying on endangered larval suckers and a few fish that could prey on juvenile suckers were captured in the Preserve, but these species were no more abundant in the Preserve than in adjacent lakes. Larvae and age-0, age-1, and age-2 juvenile Lost River and shortnose suckers were captured in the Preserve, Upper Klamath Lake, and Agency Lake, indicating that these species reared in restored and unaltered lake habitats. We captured too few larval suckers to examine patterns in spatial or temporal distribution. Once endangered suckers transitioned into juveniles, as defined by morphological development, they continued to disperse from shallow to deep water throughout the Preserve and into adjacent lakes. Age-1 and age-2 suckers captured throughout the Preserve and in adjacent lake habitats, especially in spring, show continued use of restored habitat by these species. 2 Quantitative examination of habitat use by age-0 juvenile suckers that accounted for imperfect detection indicated the portion of habitat used increased throughout July and August each year until the entire study area was used by one or more age-0 juvenile suckers by the end of August. Our rigorous evaluation showed both restored Preserve and unaltered lake habitats were equally used by age-0 juvenile suckers. Although all sampled habitats were used, multi-state occupancy models indicated that more age-0 suckers occupied shallow rather than deep habitats within the range of depths we sampled (0.5–4.3 m). We were unable to compare health and condition of juvenile suckers among habitats, due to their movement among habitats. However, documentation of length-weight relationships, afflictions and deformities, and histology indicated juvenile suckers captured in all habitats maintained a similar level of health among the 3 years of our study.
Transactions of the American Fisheries Society, 2009
Radiotelemetry was used to investigate the summer distribution and diel habitat associations of endangered adult Lost River suckers Deltistes luxatus and shortnose suckers Chasmistes brevirostris in northern Upper Klamath Lake, Oregon. From 2002 to 2004, Lost River and shortnose suckers were tracked by boat, and water depth and water quality were measured at each fish location. A series of water quality monitors were deployed in northern Upper Klamath Lake to provide temporal information on ambient temperature, pH, and dissolved oxygen, and water samples were collected to assess chlorophyll a concentration. Suckers moved into northern Upper Klamath Lake during June and began to leave in late September each year. Kernel density estimates revealed differences in the distribution in the northern portion of Upper Klamath Lake in 2002 and 2004. In 2003, however, both Lost River and shortnose suckers were commonly located within and offshore from Pelican Bay, a shallow (1.0-2.0 m), groundwater-influenced area of Upper Klamath Lake. This was especially obvious beginning in late July of 2003, concurrent with reduced dissolved oxygen levels (,4.0 mg/L) in the northern portion of Upper Klamath Lake that resulted from a dieoff of the cyanobacterium Aphanizomenon flos-aquae. Both Lost River and shortnose suckers were generally associated with water depths greater than the mean depth (2.8 m) of northern Upper Klamath Lake. Evidence ratios did not suggest diel differences in depth, temperature, dissolved oxygen, or pH at sucker locations. Both Lost River and shortnose suckers generally occupied depths greater than 2.0 m, except when suckers sought refuge in Pelican Bay during periods of poor water quality. Despite the potential for increased avian predation, suckers appeared to benefit from moving into Pelican Bay rather than staying in areas where dissolved oxygen was low. Pelican Bay appears to be an important refugium and thus may be important for sucker conservation.
Blue sucker habitat use in a regulated Texas river: implications for conservation and restoration
Environmental Biology of Fishes
Species conservation requires a clear understanding of habitat availability and subsequent use of those habitats. In cases where species declines have occurred and gone undetected by conservation managers, habitat alteration, fragmentation, and loss are often the largest contributors. River fragmentation often results in altered flow regimes, subsequently impacting the availability of riverine habitats. Blue sucker (Cycleptus elongatus) is associated with riffle and run habitat, which is especially impacted when river flows are altered. The goal of this research was to identify the extent of blue sucker habitat and mobility of the species in the Colorado River, Texas. To understand habitat selection and use, blue suckers (N = 49) were surgically implanted with telemetry tags. During 2015-2017, thirty-eight attempts were completed to relocate individuals. Optimized hotspot analysis identified three river reaches critical for blue suckers that accounted for 20% of the study area. Blue suckers used these locations year-round including during spawning. Habitats used by blue sucker were composed of gravel, cobble, boulder, and bedrock typically in riffle and run habitat. Mobility, as measured by home range size, increased as riffle density decreased. Larger home ranges were presumably necessary to find habitat to complete aspects of their life history. Results of this study suggest suitable habitats are limited throughout the fragmented riverscape. Conservation action in the form of habitat construction or increased stream connectivity through barrier mitigation could have positive impacts on the future of blue suckers in the lower Colorado River, Texas.
The Southwestern Naturalist, 2012
We compared two populations of the bluehead sucker (Catostomus discobolus) during [2007][2008][2009] in the Weber River, Davis, Summit, and Weber counties, Utah. We estimated 225 and 546 individuals in these populations. Based on recaptured, PIT-tagged fish, annual survival of adults (202-575 mm total length) was high (77%); however, our top model indicated mortality increased with size (i.e., senescence). We documented movements 15 km downstream and 5 km upstream and 88% of detections from a stationary antenna occurred at night. Despite high rates of survival of adults, recruitment appeared minimal in one of the populations because it was composed primarily of mature adults. Recruitment potentially was limited by interactions with a high density of brown trout (Salmo trutta) and combined effects of an altered hydrograph (magnitude, duration, and timing) and thermal regime. If conservation of these populations is a priority, recruitment must be increased immediately in one of the populations to avoid extinction.
USGS professional paper
Poor recruitment appears to limit the recovery of Lost River and shortnose sucker populations in Clear Lake Reservoir, California, but the cause is unknown. Adult suckers migrate up Willow Creek and its tributaries to spawn in some years, but low flow in Willow Creek may inhibit spawning migrations in other years. It is unclear whether spawning is successful, larvae survive, or juveniles persist to adulthood. Environmental variables associated with successful spawning or young-of-year survival have not been identified and early life history for these populations is poorly understood. The U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service and Ruby Pipeline L.L.C. Corporation (El Paso, Tex.) initiated a study in 2011 to better understand juvenile sucker life history in Clear Lake Reservoir, and to identify constraints in the early life history that may limit recruitment to the adult spawning populations. This is a report on the 2011 pilot study for this proj...