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Technical Announcement:
USGS at the American Fisheries Society: From Silent Streams to Invasive Species to Climate Change

Released: 8/31/2009 10:59:40 AM

Contact Information:
U.S. Department of the Interior, U.S. Geological Survey
Office of Communication
119 National Center
Reston, VA 20192
Catherine Puckett 1-click interview
Phone: 352-264-3532

The American Fisheries Society (AFS) is holding its 139th Annual Meeting in Nashville, Tenn., from Aug. 30-Sept. 3. This year’s meeting theme is “Diversity – the Foundation of Fisheries and of AFS: Are We Gaining Ground?” Below are highlights from U.S. Geological Survey research presentations at the conference.

Ninety-Two Percent Increase in Imperiled Inland U.S. Fish Species: In 2008, the AFS Endangered Species Committee reviewed the conservation status of freshwater fish and fish that live in both oceans and rivers of the continental U.S., Canada, and Mexico. Seven-hundred taxa were determined to be imperiled, which represents 133 genera of 36 families and is a 92 percent increase above the number considered imperiled in 1989. Of these, 230 are listed as vulnerable, 190 threatened, and 280 endangered. An additional 61 taxa are presumed extinct or extirpated from nature. Overall, about 39 percent of the approximately 1,200 described inland fish species of North America are imperiled. Hotspots of imperiled taxa are in the southeastern U.S., mid-Pacific basin, lower Rio Grande, and inland and coastal drainages of Mexico. North American fish, like inland faunas of other continents, are most at-risk due to habitat destruction and modification, non-native species, overexploitation, and disease. Contact Stephen Walsh, swalsh@usgs.gov,  352-2265-3512.

Inland Fisheries Become More Important and Global Marine Fisheries Decline: Global marine fisheries are in a well-known crisis, with the total production of marine fishes for human and other consumption expected to further decline. One possible source of fish to fill the gap left by declines in marine fisheries is production of fish from inland ecosystems. Unfortunately, a true accounting for global inland fisheries is not yet possible. Given the reliance on inland fish as a staple protein source for many in the developing world and as a key source of recreational services for those in the developed world, the inability to assess the global status of inland fisheries may hinder sustainable management of inland water ecosystems and may result in management decisions that adversely affect inland fisheries. Estimates of inland fisheries productions are needed for informed management decisions about inland water ecosystems. Contact Doug Beard,  dbeard@usgs.gov, 703-648-4215.

Silent Streams: 74 Percent Increase in Extinct Taxa of North American Freshwater Fish Since 1989: In 1989, 40 species and subspecies of North American freshwater fishes were considered extinct; by 2008, the total was 61 taxa. The net increase of extinct taxa since 1989 is 74 percent. Since 1890, the mean extinction rate is 5.5 taxa per decade. This rate greatly exceeds a widely cited published estimate of 2.4 extinct species per decade. Human activities are linked to all extinct North American freshwater fishes, predominantly through habitat loss and introduction of non-native fishes. The two largest shared attributes among extinct fishes are that they are narrowly restricted in geographic range and the lack of direct or indirect parental care. Contact Noel Burkhead, nburkhead@usgs.gov, 352-264-3499.

Invasive Species and a Changing Climate: Invasive Species and a Changing Climate: Ongoing global changes such as more frequent transcontinental and transoceanic trade and tourism, land- and water-use changes, and climate change are helping increase rates of establishment and spread of harmful, invasive plant and animal species worldwide. The growing threat of new introductions intensifies the need for land managers, researchers, and stakeholders to combine existing efforts to further the prevention, early detection, monitoring of invasive species, to determine their ecosystem effects, and to coordinate containment, control, as well as restoration of affected habitat. Examples of how the interaction of invasive species with global climate change and other drivers of ecosystem change affect natural resource management will be discussed. Contact Cindy Kolar, ckolar@usgs.gov, 703-648-4023.

Algal Toxins a Possible Reason for Poor Survival of Juvenile Endangered Suckers in Upper Klamath Lake: The largest remaining habitat for endangered Lost River and shortnose suckers is Upper Klamath Lake, a lake in southern Oregon that suffers from massive annual blue-green algae blooms. In addition to producing extreme dissolved oxygen and pH levels, these blooms can produce toxins potentially harmful to fish. Preliminary findings of USGS-led research indicate microcystin – a liver toxin – is present in the fish.  Additionally, some juvenile suckers in Upper Klamath Lake exhibit tissue damage consistent with toxin exposure.  These findings are of particular concern as poor juvenile survival may be a key factor in an ongoing lack of recruitment into adult populations. USGS is conducting research to determine which toxins are present and at what concentrations, as well as what effects these compounds may have on the health and condition of juvenile suckers. Contact Scott VanderKooi, svanderkooi@usgs.gov, 541-273-8689

Drifting Larval Pallid Sturgeon and Fragmented River Reaches Contribute to Lack of Fish: In the upper Missouri River basin, where main-stem dams have fragmented endangered pallid sturgeon habitat, there has been little to no evidence of young sturgeon during the last several decades despite the fact that spawning is known to occur. To thoroughly examine the drift dynamics of larval pallid sturgeon in a natural environment, USGS researchers released about 430,000 larvae in the main-stem Missouri River and recaptured the drifting larvae over several days throughout a 110-mile reach of the river.  Preliminary evidence indicates that larval pallid sturgeon exhibit long-distance drift as the larvae develop, and may drift in excess of 200 miles. Consequently, researchers suspect that the limited length of free-flowing riverine habitat between Missouri River dams and reservoirs disrupt the natural larval drift cycle, and provide a likely bottleneck for this federally endangered species. Contact Patrick Braaten, pbraaten@usgs.gov, 406-526-3253.

The Gulf Sturgeon: Some Populations Up, Some Down, and Some Unknown: Populations of endangered Gulf sturgeon were substantially depleted by over-harvest at the turn of the 20th Century, and later were further reduced by impoundments on coastal rivers in the Gulf of Mexico. Studies in the 1970s-1990s indicated that individual river populations numbered only in the few hundreds to few thousands of fish. For the Suwannee River, only 3,000 fish were estimated to inhabit the river in the early 1990s, with adults representing less than 10 percent of the population. In 2007, this population numbered 14,000 fish, with adults comprising 40 percent of the fish. Because of harvest prohibition, no impoundment or bycatch impacts, and high-quality habitat, the Suwannee population has increased to about 10 percent of its probable pre-1880s numbers. Also benefiting from limited habitat impacts, Gulf sturgeon populations in the Yellow-Escambia rivers appear healthy. Recruitment in the Apalachicola population has been erratic, with no demonstrable population recovery, probably due to the combined effects of impoundment and habitat modifications (channelization, dredging). The remaining Gulf sturgeon river populations have been less-well studied. Contact Ken Sulak, ksulak@usgs.gov, 352-264-3500.

Adaptive Management for Climate Change: Climate change poses major challenges to many ecological systems, fish and wildlife, and natural resources. Land and resource managers must find ways to deal with resulting changes to hydrologic systems, fish and wildlife populations, wetlands, and agricultural lands. One effective tool that can be used is adaptive management, a decision process that promotes flexible decision making and can be adjusted in the face of uncertainties, as outcomes from management actions and other events become better understood. Adaptive management uses an iterative process of monitoring and learning through results, and adjusting the management strategy or adaptation, according to what is learned. Contact Kevin Whalen, kwhalen@usgs.gov, 703-648-4062.

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