Southwest Biological Science Center

Fish and Wildlife

Filter Total Items: 22
Image: A Rainbow Trout Rests Among Cobble Substrate in Panther Creek
Date Published: May 14, 2017

Just below Glen Canyon Dam on the Colorado River is a very popular Blue Ribbon trout fishery known for its rainbow trout. However, approximately 78 miles downstream, near were the Little Colorado River flows into the Colorado River, is a population of endangered humpback chub. The introduced rainbow trout can negatively affect native humpback chub by competing with them for food (immature...

Arizona map depicting the number of bat species found across Arizona.
Date Published: February 14, 2017

Renewable energy development is expanding in southwestern deserts, including in Arizona. Energy developers look to resource management agencies to provide siting guidance on public lands where there might be conflicts with wildlife. Often, agency guidance considers species of conservation concern and economic importance, but information on comprehensive vertebrate biodiversity has been hard to...

Parker Dam on the Colorado River near Parker, Arizona.
Date Published: February 9, 2017

Aquatic invertebrates are critical food for fish and other species that inhabit large rivers. In the Colorado River Basin, invertebrates that get transported down the river (“in the drift”) are particularly important to rainbow trout and other species of interest to recreational users. This research seeks to compare rivers downstream of large dams throughout the Colorado River Basin in order...

A boat on the Colorado River in front of a rock outcrop containing a concrete structure.
Date Published: January 18, 2017

Algae, phytoplankton, and rooted macrophytes represent the base of many aquatic food webs and are known as primary producers. Through photosynthesis, these organisms convert sunlight energy into chemical energy (i.e., carbon) that in turn fuels the growth of animals such as macroinvertebrates and fish. This project uses high frequency measurements of dissolved oxygen, which is a by-product of...

A view of the lower Little Colorado River showing the light blue color of the river, riparian grasses, and canyon walls.
Date Published: December 23, 2016

Construction of Glen Canyon Dam has led to large changes in environmental conditions of the downriver Colorado River. Whereas the pre-dam Colorado River experienced large seasonal variation in temperature and discharge and was highly turbid, the post-dam Colorado River is far less variable in terms of temperature and discharge and is frequently clear. Many nonnative fish species had already...

Two USGS researchers on a small boat in the Colorado River sampling aquatic insects with a net.
Date Published: December 23, 2016

Rainbow trout is a desirable sport fish that has been introduced in many locations around the world. Although introductions of rainbow trout and other nonnative fishes provide recreational fishing opportunities, they also pose threats to native fish populations. The Glen Canyon Dam Adaptive Management Program has tasked scientists and managers with identifying management options that allow...

Four glass containers showing low turbidity water to highly turbid (cloudy) water
Date Published: December 21, 2016

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...

Northern leopard frog floating in the water in Glen Canyon.
Date Published: December 15, 2016

Although it is not listed on the Federal Endangered Species list, there is considerable concern over northern leopard frog declines in western North America. It is listed as a “special concern” species by some state wildlife agencies (e.g., Arizona Game and Fish Department 1996) and declines have been reported in Arizona, Colorado, New Mexico, and other areas across the west.  Leopard frogs...

Island Night Lizard on San Nicolas Island
Date Published: December 15, 2016

The Island Night Lizard was removed from the Federal list of "Threatened" species in May 2014. This rare and unique species represents an ancient lineage whose members are now sparsely distributed across parts of the Southwest North America, south through Mexico to the New World Tropics. The Island Night Lizard has a very small world range, occurring only on three of the southern California...

Anglers departing the boat dock at Lees Ferry, AZ with canyon walls in the background.
Date Published: December 15, 2016

Economic research at Grand Canyon Monitoring and Research Center is used to determine economic benefits of outdoor recreation in Glen Canyon National Recreation Area below Glen Canyon Dam and in Grand Canyon National Park, as affected by operation of Glen Canyon Dam. This research identifies recreationists’ preferences for attributes associated with their trips, spending that occurs regionally...

Juvenile Chiricahua leopard frog at Buenos Aires National Wildlife Refuge, Sasabe, AZ
Date Published: December 9, 2016

Managing a species with intensive tools like reintroduction may focus on single sites or entire landscapes.  For mobile species like the federally-threatened Chiricahua leopard frog (Lithobates chiricahuensis [CLF]), both suitable colonization sites and suitable dispersal corridors between sites are needed. Following the eradication of the invasive American bullfrog (Lithobates catesbeianus)...

USGS researcher on small boat holding the end of a net used to capture insects in the water.
Date Published: December 9, 2016

All aquatic invertebrates drift downstream at some point in their life cycle. Invertebrates may drift to find more preferable habitats, to leave the water during their transition from aquatic larvae to terrestrial adults, or accidentally such as when swept off the river bed by a flood. Regardless, when they enter the drift, invertebrates become particularly susceptible to predation by several...