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USGS at American Fisheries Society (AFS): From New List of Imperiled Fish Species to Fish and Natural Hazards and Contaminants


New Tally of Imperiled North American Freshwater Fishes: Report of the American Fisheries Society’s Endangered Species Committee. The American Fisheries Society’s Endangered Species Committee estimates that about 700 North American freshwater fishes are imperiled-regarded as vulnerable, threatened, endangered, or extinct. The new tally is nearly double that of the 1989 American Fisheries Society estimate of 364 taxa. The AFS Endangered Species Committee is composed of 3 U.S. Geological Survey scientists and 13 other colleagues. The increase in numbers of imperiled taxa results, in part, from increased taxonomic knowledge of the North American freshwater fish fauna. Increases in imperiled species over the past two decades corresponds to a revolution in the study fishes: advances in biological methods and concepts have significantly furthered knowledge of North American fishes, especially Mexican species. Also, the remarkable progress in biomolecular techniques is enabling scientists to document biological diversity at smaller scales with increasing precision. Examples of this are recognition of threatened and endangered salmon populations on the Pacific coast. The majority of taxa on the new list are species or subspecies; only 12 percent are distinct populations. The greatest cause of imperilment indirectly results from increases in the human population of North America. Humans are changing the landscape at the greatest rate of any time in recent human history. Many North American fishes simply did not evolve with the ability to adapt to relatively rapid changes to aquatic habitats created by modification, alteration, or transformation of landscapes. Because the current estimate is the third AFS list of imperiled North American fishes, the Committee is able to analyze trends in the data. The great majority of imperiled taxa, 80 percent, are endemic  restricted to one ecoregion or less (a single drainage, river, creek, lake or spring); 90 percent of taxa are restricted to two ecoregions or less. The Tennessee, Mobile, and Lerma-Chapala ecoregions have the greatest number of imperiled fishes. By threats, the major causes of imperilment are habitat loss and interactions with introduced fishes, both consequences of human activities. The current rate of extinction exhibits a positive linear trajectory, but the present decade is not over, and there are a significant number of highly vulnerable species that could disappear in the next several decades. Howard Jelks and Noel Burkhead, Sept 5, 8 a.m., Golden Gate A2. Howard Jelks: 352-264-3492, ; Noel Burkhead: 352-264-3499;

Natural Hazards, Fish Habitat, and Fishing Communities and Alaska. Fish and fishing communities are iconic symbols of Alaska; volcanoes, earthquakes, and tsunamis also stand out as processes that define or shape the Alaska landscape. In addition to commercial fisheries, regularly ranking among the top ten U.S. ports, subsistence fisheries and sport fishing play an important role in the economy and culture of Alaska. Alaska’s geographic location at one of the most active plate boundaries on the planet makes the region susceptible to a variety of natural hazards that can have an impact on these activities. USGS scientists examine the distribution of fishing communities and fish habitat with respect to volcanoes, earthquakes, tsunamis, and other natural hazards, and discuss the possible implications of natural hazards to fisheries. In addition to impacts on local fishing communities and commercial fisheries, these hazardous processes can impact fish habitat. The scientists examine the distribution of salmonids relative to earthquake and volcano hazards zones and discuss the potential impacts. Christian Zimmerman, Sept. 6, 1:20 p.m., Golden Gate Hall, Salon C3, 907-786-7071,

Status of Adult Lost River Suckers and Shortnose Suckers in Upper Klamath Lake and Its Tributaries, Oregon. Lost River suckers and shortnose suckers are both long-lived species native to the upper Klamath Basin of Oregon and California. Both species were listed under the Endangered Species Act in 1988. USGS scientists analyzed 13 years of data to assess the population dynamics and status of adult sucker populations in upper Klamath Lake, Oregon. These analyses indicate considerable variation among years in Upper Klamath Lake adult sucker survival rates, suggesting that survival rates differ not only between sucker species but also between reproductively isolated Lost River sucker spawning stocks. Research by the scientists shows that Lost River suckers had higher survival than shortnose suckers and that this population is stable or slightly increasing. However, the long-term dataset suggests that the shortnose sucker population is continuing to decline. Eric Janney, Sept. 4, 9:20 a.m., Salon 4, 541-273-8689 x 202,

Increasing Water Temperature Trends in the Lower Klamath River, California. Elevated water temperatures have been implicated as a factor limiting the recovery of ocean-going fish populations in the Klamath Basin such as coho and fall Chinook salmon. USGS researchers examined a multi-decadal trend of increasing temperatures in the lower main-stem Klamath River above the ocean in meteorological records. Based on model simulations, this trend indicates a high probability that water temperatures have been increasing approximately 0.5°C per decade since the early 1960’s. The season of high temperatures potentially stressful to salmonids has lengthened by about one month over the period studied while the average length of the main-stem river with cool summer temperatures preferred by salmonids has declined by about 8.2 kilometers per decade. Water-temperature trends seem unrelated to any change in main-stem water availability, but are consistent with measured basinwide air temperature increases. Main-stem warming may be related to the cyclic Pacific Decadal Oscillation, but should this trend continue, it could jeopardize efforts to recover anadromous fish populations in the Klamath Basin. Sharon G. Campbell, Sept. 4, 9 a.m., Salon 4, 970-226-9331,

Hidden Fish Mortality Affects Fishery Sustainability and Performance. Though fisheries resource managers commonly use minimum length requirements as a tool to regulate both commercial and recreational fisheries, its efficacy depends on the mortality rate of those fish that are below the legal limit and are caught and released. USGS, University of Florida, and University of British Columbia researchers constructed a computer model to evaluate how “discard mortality” could influence the intent of minimum length regulations to conserve specific fish species. The researchers found that regulations such as length limits that can increase the amount of discard mortality reduced fishery yield and efficiency, potentially exposing the target species and ecosystems to increased negative effects from fishing activity. The findings suggest that for overexploited fisheries with moderate to high discard mortality rates, reductions in fishing mortality will be required to meet management goals. Thus, resource managers may want to carefully consider impacts of discard mortality on fishery sustainability. Lewis G. Coggins, Sept. 4, 8:20 a.m., Golden Gate B1, 928-556-7376,

Assessment of Fish Assemblages and Environmental Conditions in the Snake River, Idaho and Wyoming. The Snake River, the tenth-longest river in the United States, extends from Yellowstone National Park in western Wyoming to its union with the Columbia River in southeastern Washington. Historically, the river supported at least 26 native fish species including Chinook salmon, steelhead trout, Pacific lamprey, and white sturgeon. Today, of these four anadromous species, only the white sturgeon remains between the Hells Canyon Complex and Shoshone Falls, and much of the Snake River has been transformed into a river with numerous impoundments and flow diversions, increased pollutant loads, and elevated water temperatures. Studies by USGS researcher Terry Maret revealed a decline in the overall biotic diversity upstream to downstream in the Snake River and the Henrys Fork that correlates with increases in percentages of agricultural land, number of flow diversions, and number of constructed channels on the river. Fish assemblages in the Snake River now contain at least 19 native species and numerous alien ones. In the lower Snake River, there are more of the less-desirable species because they are better adapted for warm-water habitats found in the conditions created by impoundments. Terry Maret, Sept. 6, 8:40 a.m., Salon 13, 208-387-1328;

Sex and PCBs in Walleye: the ‘Hot Spot’ Effect. A previous investigation of polychlorinated biphenyl (PCB) concentrations in walleye from the Saginaw Bay (Lake Huron) population revealed that adult males were about 2.5 times higher in PCB concentrations than adult females. The researchers in that study concluded that this pronounced difference between the sexes was most likely due to males spending substantially more time in the highly contaminated Saginaw River system than females, thereby being exposed to higher PCB concentrations in their prey. Sediments near the mouth of the Saginaw River, which empties into Saginaw Bay, represent a PCB ‘hot spot,’ where contaminant concentrations are orders of magnitude higher than other locations in the bay. According to the conclusions from the previous study, there would be little difference in PCB concentrations between the sexes if the ‘hot spot’ was removed. We determined PCB concentrations in 15 adult female walleyes and 15 adult male walleyes from South Manistique Lake, a relatively pristine lake in the Upper Peninsula of Michigan with no point source inputs of PCBs. Results showed no significant difference in the walleye PCB concentrations between the sexes in South Manistique Lake. Thus, these results corroborated the conclusions of the previous study. Charles P. Madenjian, Sept 5, 9:20 a.m., Salon 3, 734-214-7259,

From Home-Made Plastic Tags to 3-D Positions of Fish Sent by Satellite: the Evolution of Biotelemetry. The tools and techniques available for biotelemetry in fisheries have grown rapidly during the last half-century, born through advances in technology in areas such as batteries, transistors, and computer chips. As a result, biotelemetry studies have progressed from those determining locations of a few animals by manual tracking to those determining 3-D positions of thousands of individuals and transmitting the information via satellite platforms. Acoustic and radio transmitters are now available in very small sizes and weights allowing smaller animals to be studied effectively, while improvements in coding schemes allow hundreds or thousands of transmitters to be distinguished on a single frequency enabling many more animals to be studied simultaneously. These and other changes occurring primarily over the last 50 years will be discussed in a presentation by USGS researcher John Beeman. John Beeman, Sept. 5, Salon 12, 509-538-2299, x 257,

Gulf Sturgeon in the Suwannee River; Population and Mortality Estimates. Twenty years of tagging efforts in the Suwannee River, Fla., have allowed USGS researchers to determine population estimates for this imperiled species. From 1995 to 1999, USGS researchers conducted a population census by netting, tagging, and recaptures. Scientists repeated this census in 2006 and 2007. Preliminary results of this work are that the population appears to be stable at about 7,000 fish (of net-vulnerable size) and possibly increasing slightly. Michael Randall, Sept. 6, 4 p.m., Golden Gate C1, 352-264-3521,

Critical Winter Habitat of Juvenile Gulf Sturgeon. By using a network of automated sonic receivers and sonic-tagged sturgeon, USGS researchers assessed overwintering habitat use of juvenile Gulf sturgeon in the Suwannee (2005-06) and Appalachicola (2006-07) estuaries to help determine critical winter habitat. The scientists found different habitat use in the estuaries of the two rivers. In the Suwannee, a more natural river, the fish were solitary and stayed in the in-shore area, moving frequently into areas that contained potential prey food. In contrast, in the Appalachicola estuary area, a large seafood-production area, Gulf sturgeon gathered to feed in areas where seafood-processing occurs and where food is readily available. They also fed in larger numbers underneath a bridge in the estuary where seabirds congregate and where, presumably, guano is enriching the substrate, enhancing food production. Kenneth Sulak, Sept. 5, 2:20 p.m. Golden Gate C1, 352-264-3500,

Distribution of Fish and Associated Environment Variables in the Lower Boise River. Within the last century, the lower Boise River has been transformed from a meandering, braided, gravel-bed river that supported large runs of salmon to a channelized, regulated, urban river that provides flood control and irrigation water to more than 1200 square miles of land. USGS and Idaho Department of Fish and Game scientists analyzed fish community data from the lower Boise River and found that the river is experiencing a decline in biotic integrity in the downstream direction. As a direct result of this degradation, more introduced non-native fish and native fishes tolerant of more adverse conditions were found in the fish communities. These results reveal that changes in land-use, habitat, and water quality, as well as regulated streamflow have adversely affected the lower Boise River fish community. The loss of sculpin in downstream reaches of the lower Boise River also raises a red flag and documents the need for further study to identify reasons for their disappearance. To support ongoing management practices, managers need to understand the current status of the river’s fish communities and related environmental conditions. Dorene MacCoy, Sept. 6, 8:20 a.m., Salon 13, 208-387-1354,

Juvenile Salmonid Passage at Large Hydroelectric Dams Using Acoustic Telemetry. Acoustic telemetry to study the movements of juvenile salmon has allowed researchers and managers to gather data that was previously unattainable by using other methods. In addition to gathering general movement behavior, passage route, and survival of juvenile fish as they pass hydroelectric dams, acoustic telemetry allows three-dimensional location data to be obtained. This 3-D data greatly expands the knowledge of fish behavior in the complex environments upstream of hydroelectric dams in the Columbia River Basin. USGS scientists demonstrate how this technology has advanced knowledge of fish behavior and aided in the development of management strategies designed to improve survival of juvenile fish passing hydroelectric projects on the Snake and Columbia rivers. The scientists will review evaluations of dam bypass structures and the evaluation of a proposed forebay fish guidance curtain at The Dallas Dam. Surface-oriented passage routes and guidance structures have been evaluated to improve fish survival, reduce the delay in migration, and use water more effectively within the federal hydropower system. Noah S. Adams, Sept. 5, 1:20 p.m., Salon 12, 509-538-2299 x 254,


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