David Ward
Science and Products
Effects of Water Clarity on Survival of Endangered Humpback Chub
Introduced rainbow trout and brown trout are considered a threat to the endangered humpback chub in the Colorado River in Grand Canyon. These introduced species eat native fish, but impacts are difficult to assess because predation vulnerability depends on the physical conditions under which predation takes place. We studied how predation vulnerability of juvenile humpback chub changes in...
What's in the hump of the humpback chub?
The function of the nuchal hump on adult humpback chub (Gila cypha) has been the subject of longtime conjecture. Hypotheses about the purpose of the hump range from it being a feature that confers hydrodynamic advantages in swift water to speculation about how the hump may have reduced predation vulnerability to Colorado pikeminnows (Ptychocheilus...
Ward, David; Ward, Michael B. Viability of Razorback-Flannelmouth Sucker hybrids
Razorback sucker (Xyrauchen texanus) and flannelmouth sucker (Catostomus latipinnis) live in sympatry in the Colorado River basin. Although morphological intermediates have been described since 1889, hybrids were seemingly rare. Rarity of hybrids was likely attributed to razorback suckers' ability to find conspecific mates throughout the basin....
Wolters, Pilar N.; Rogowski, David L.; Ward, David; Gibb, Alice C. An evaluation of sedatives for use in transport of juvenile endangered fishes in plastic bags
Trucks and aircraft typically transport rare or endangered fishes in large unsealed tanks containing large volumes of water (typically hundreds of liters) during conservation efforts. Ornamental fishes, however, are commonly sent by mail in small sealed plastic bags filled with oxygen, minimal water, and a small amount of sedative to reduce weight...
Tennant, Laura A.; Vaage, Ben M.; Ward, David L. Geographic variation in the intensity of warming and phenological mismatch between Arctic shorebirds and invertebrates
Responses to climate change can vary across functional groups and trophic levels, leading to a temporal decoupling of trophic interactions or ‘phenological mismatches.’ Despite a growing number of single-species studies that identified phenological mismatches as a nearly universal consequence of climate change, we have a limited understanding of...
Kwon, Enubi; Weiser, Emily L.; Lanctot, Richard B.; Brown, Stephen C.; Gates, H. River; Gilchrist, H. Grant; Kendall, Steve J.; David B. Lank; Joseph R. Liebezeit; McKinnon, Laura; Erica Nol; Payer, David C.; Jennie Rausch; Saalfeld, Sarah T.; Rinella, Daniel J.; Senner, Nathan R.; Ward, David; Smith, Paul A.; Wissman, Robert C.; Sandercock, Brett K. What environmental conditions reduce predation vulnerability for juvenile Colorado River native fishes?
The incompatibility of native Colorado River fishes and nonnative warm-water sport fishes is well documented with predation by nonnative species causing rapid declines and even extirpation of native species in most locations. In a few rare instances native fishes are able to survive and recruit despite the presence of nonnative warm water...
Ward, David L.; Vaage, Benjamin Are hatchery-reared Rainbow Trout and Brown Trout effective predators on juvenile native fish?
Hatchery‐reared Rainbow Trout Oncorhynchus mykiss and Brown Trout Salmo trutta are typically fed exclusively on commercially prepared pelleted feeds and have no experience catching or consuming live fish at the time of stocking. Despite this lack of predation experience, it is commonly assumed that stocked Rainbow Trout and...
Ward, David L.; Morton-Starner, Rylan; Vaage, Benjamin Key morphological features favor the success of nonnative fish species under reduced turbidity conditions in the lower Colorado River Basin
As a result of anthropomorphic alterations to the lower Colorado River basin and other southwestern rivers, water turbidity has been greatly reduced and introduced, nonnative fishes thrive in these waterways. To quantify key morphological features that may allow nonnative fishes to displace native fishes, we compared eye diameter (a proxy for...
Moran, Clinton J.; Ward, David L.; Gibb, Alice C. Can data from disparate long-term fish monitoring programs be used to increase our understanding of regional and continental trends in large river assemblages?
Understanding trends in the diverse resources provided by large rivers will help balance tradeoffs among stakeholders and inform strategies to mitigate the effects of landscape scale stressors such as climate change and invasive species. Absent a cohesive coordinated effort to assess trends in important large river resources, a logical starting...
Counihan, Timothy D.; Waite, Ian R.; Casper, Andrew F.; Ward, David L.; Sauer, Jennifer S.; Irwin, Elise R.; Chapman, Colin G.; Ickes, Brian; Paukert, Craig P.; Kosovich, John J.; Bayer, Jennifer M. Does bioelectrical impedance analysis accurately estimate the condition of threatened and endangered desert fish species?
Bioelectrical impedance analysis (BIA) is a nonlethal tool with which to estimate the physiological condition of animals that has potential value in research on endangered species. However, the effectiveness of BIA varies by species, the methodology continues to be refined, and incidental mortality rates are unknown. Under laboratory conditions we...
Dibble, Kimberly L.; Yard, Micheal D.; Ward, David L.; Yackulic, Charles B. Long-term fish monitoring in large rivers: Utility of “benchmarking” across basins
In business, benchmarking is a widely used practice of comparing your own business processes to those of other comparable companies and incorporating identified best practices to improve performance. Biologists and resource managers designing and conducting monitoring programs for fish in large river systems tend to focus on single river basins or...
Ward, David L.; Casper, Andrew F.; Counihan, Timothy D.; Bayer, Jennifer M.; Waite, Ian R.; Kosovich, John J.; Chapman, Colin; Irwin, Elise R.; Sauer, Jennifer S.; Ickes, Brian; McKerrow, Alexa J.
Scientific monitoring plan in support of the selected alternative of the Glen Canyon Dam Long-Term Experimental and Management Plan
IntroductionThe purpose of this document is to describe a strategy by which monitoring and research data in the natural and social sciences will be collected, analyzed, and provided to the U.S. Department of the Interior (DOI), its bureaus, and to the Glen Canyon Dam Adaptive Management Program (GCDAMP) in support of implementation of the Glen...
Vanderkooi, Scott P.; Kennedy, Theodore A.; Topping, David J.; Grams, Paul E.; Ward, David L.; Fairley, Helen C.; Bair, Lucas S.; Sankey, Joel B.; Yackulic, Charles B.; Schmidt, John C. Effects of turbidity on predation vulnerability of juvenile humpback chub to rainbow and brown trout
Predation on juvenile native fish by introduced rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta is considered a significant threat to the persistence of endangered humpback chub Gila cypha in the Colorado River in Grand Canyon. Diet studies of rainbow and brown trout in Glen and Grand canyons indicate that these species eat native...
Ward, David L.; Morton-Starner, Rylan; Vaage, Benjamin M.