Young M.K.,U.S. Department of Agriculture |
Schmetterling D.A.,Montana Fish
North American Journal of Fisheries Management | Year: 2012
Electrofishing-based estimates of fish abundance are common. Most population models assume that samples are drawn froma closed population, but population closure is sometimes difficult to achieve.Consequently,we individually electrofished 103 radio-tagged trout of two species, westslope cutthroat trout Oncorhynchus clarkii lewisi and brook trout Salvelinus fontinalis, in five streams in western Montana to quantify the influence of habitat and fish size on capture efficiency and movement related to electrofishing with unpulsed DC. First-pass capture efficiency was 46% and declined on subsequent passes. No variables were related to capture efficiency, and only the percentage of cobble or larger substrate was related to the probability that uncaptured fish would move during the first electrofishing pass. About 20% of the uncaptured fish did not move, and 95% traveled less than 18 m. We concluded that for these streams, the bias in abundance estimates from disregarding movement would be relatively minor. © American Fisheries Society 2012.
Ellis B.K.,University of Montana |
Stanford J.A.,University of Montana |
Goodman D.,Montana State University |
Stafford C.P.,University of Montana |
And 5 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2011
Introductions or invasions of nonnative organisms can mediate major changes in the trophic structure of aquatic ecosystems. Here we document multitrophic level impacts in a spatially extensive system that played out over more than a century. Positive interactions among exotic vertebrate and invertebrate predators caused a substantial and abrupt shift in community composition resulting in a trophic cascade that extended to primary producers and to a nonaquatic species, the bald eagle. The opossum shrimp, Mysis diluviana, invaded Flathead Lake, Montana, the largest freshwater lake in the western United States. Lake trout had been introduced 80 y prior but remained at low densities until nonnative Mysis became established. The bottom-dwelling mysids eliminated a recruitment bottleneck for lake trout by providing a deep water source of food where little was available previously. Lake trout subsequently flourished on mysids and this voracious piscivore now dominates the lake fishery; formerly abundant kokanee were extirpated, and native bull and westslope cutthroat trout are imperiled. Predation by Mysis shifted zooplankton and phytoplankton community size structure. Bayesian change point analysis of primary productivity (27-y time series) showed a significant step increase of 55 mg C m-2 d-1 (i.e., 21% rise) concurrent with the mysid invasion, but little trend before or after despite increasing nutrient loading. Mysis facilitated predation by lake trout and indirectly caused the collapse of kokanee, redirecting energy flow through the ecosystem that would otherwise have been available to other top predators (bald eagles).
Harper D.D.,U.S. Geological Survey |
Farag A.M.,U.S. Geological Survey |
Skaar D.,Montana Fish
Environmental Toxicology and Chemistry | Year: 2014
Water produced during coal bed natural gas (CBNG) extraction in the Powder River Structural Basin of Wyoming and Montana (USA) may contain concentrations of sodium bicarbonate (NaHCO3) of more than 3000mg/L. The authors evaluated the acute toxicity of NaHCO3, also expressed as bicarbonate (HCO3 -), to 13 aquatic organisms. Of the 13 species tested, 7 had a median lethal concentration (LC50) less than 2000mg/L NaHCO3, or 1300mg/L HCO3 -. The most sensitive species were Ceriodaphnia dubia, freshwater mussels (Lampsilis siliquoidea), pallid sturgeon (Scaphirhynchus albus), and shovelnose sturgeon (Scaphirhynchus platorynchus). The respective LC50s were 989mg/L, 1120mg/L, 1249mg/L, and 1430mg/L NaHCO3, or 699mg/L, 844mg/L, 831mg/L, and 1038mg/L HCO3 -. Age affected the sensitivity of fathead minnows, even within life stage. Two days posthatch, fathead minnows were more sensitive to NaHCO3 and HCO3 - compared with 4-d-old fish, even though fish up to 14 d old are commonly used for toxicity evaluations. The authors recommend that ion toxicity exposures be conducted with organisms less than 24h posthatch to ensure that experiments document the most sensitive stage of development. The results of the present study, along with historical and current research regarding the toxicity of bicarbonate, may be useful to establish regulatory standards for HCO3 -. Environ Toxicol Chem 2014;33:525-531. © 2014 SETAC.
Fishing guides and rafting operators who run businesses along the river said the move could be catastrophic to the area's sizable outdoor industry, which depends heavily on the busy summer season. The closure could last for months if river conditions don't improve and fish keep dying, according to officials from Montana Fish, Wildlife and Parks. It extends to hundreds of miles of waterways that feed into the Yellowstone, including the Boulder, Shields and Stillwater rivers. Even when the river reopens, there are fears the fish die-off could deal a lasting blow to the Yellowstone's reputation as a world-class trout fishery that draws visitors from around the world. "This kill is unprecedented in magnitude. We haven't seen something like this in Montana," Fish, Wildlife and Parks spokeswoman Andrea Jones said. By Friday, roughly 4,000 dead fish had been counted, but the total number is estimated to be in the tens of thousands, including fish that sank to the bottom, officials said. Most have been mountain whitefish, a native game species, but reports emerged that the die-off has affected some rainbow trout and Yellowstone cutthroat trout—species crucial to the fishing industry. No dead fish were found inside Yellowstone National Park, where a celebration of the National Park Service's 100th anniversary is set for next week. Officials said they had no plans to close waters inside the park. The closure on the Montana portion of the river aims to stop the spread of the parasite, which causes fish to contract a fatal kidney disease, as well as protect the fishery and the outdoor economy it sustains, officials said. The disease was previously documented just twice in the state over the past 20 years but more recent outbreaks have occurred in Washington, Oregon and Idaho. Officials said it does not pose a health risk to people. Low water levels and warm temperatures are making the problem worse by adding to the stresses faced by cold-water species such as trout and whitefish, officials said. In other rivers, outbreaks of the disease persisted until water temperatures dropped months later. On the Yellowstone, fishing, wading, floating, boating and other activities are banned until further notice. Numerous fly fishing outfitters and rafting companies operate in the closed stretch of river, which extends from Yellowstone National Park's northern boundary to the city of Laurel, along with all tributaries in those areas. Fishing guide Dan Gigone, who owns the Sweetwater Fly Shop in Livingston, said one of his guides reported seeing hundreds of dead fish, including some trout, in the river Thursday. Gigone called the closure catastrophic but said he would not fight it. "We have trips on the books through September," Gigone said. "It's definitely a big part of the Livingston and area economy. But we need to protect the resources as best we can for future years." Yellowstone Raft Co. owner Robin Trotter said she had started calling hundreds of customers with reservations in coming weeks to let them know their trips could be canceled. Fish, Wildlife and Parks Director Jeff Hagener said the agency had to balance economic consequences with the risk to the fishery, given that recreational activities disturb fish and exacerbate the effects of the disease. The parasite is not native to the area, meaning it was introduced by people via a contaminated boat, fishing waders or other means—or possibly by birds that transported it from another waterway, officials said. The wildlife agency set up two decontamination stations to try to reduce the chance of equipment spreading the parasite to other rivers. The agency urged the public to clean equipment properly before moving between bodies of water. "There's not a lot known about how this moves through the environment," said Dan Garren of Idaho Fish and Game who dealt with a 2012 whitefish die-off blamed on the parasite. "It's easy to overlook a dead whitefish. It's true for biologists, it's true for anglers. They don't carry the same weight as trout."
Thirty animals have been shipped to slaughterhouses, and officials plan to send an additional 63 in the next few days. The bison were weighed and tested for disease for research purposes, and the remaining animals were crowded into holding pens to await shipment. The park's actions are driven by an agreement in 2000 with Montana officials that requires it to control its bison herds. The meat will be distributed to American Indian tribes that traditionally subsisted on bison. "Nobody here wants to be doing this," park spokeswoman Jody Lyle said after the bison were prodded into trailers for shipment. "It's time for a change." About 150 of the animals have been captured this winter trying to migrate out of the park in search of food at lower elevations in Montana. Ranchers worry about bison infected with brucellosis, a disease that can cause cattle to abort their young. There have been no recorded bison-to-cattle transmissions of brucellosis, and critics say the slaughters are unnecessary. Captured bison that test negative for it are not spared. "This is not OK. It's really that simple," said Stephany Seay with the Buffalo Field Campaign, a bison advocacy group. Rick Lamplugh said he moved last May from Oregon to the small town of Gardiner, at the northern entrance to the park, in large part for the wildlife viewing opportunities. The park and state agencies need rethink their policies on bison so they can be "treated like any other wildlife," he said. Tens of millions of bison, also known as buffalo, once roamed North America. Commercial hunting drove the species to near-extinction in the late 1800s before conservationists—including former President Theodore Roosevelt—intervened when only dozens were left. Yellowstone is home to one of the few remaining wild populations. Millions of tourists visit the park each year to see the animals, a top attraction at the nation's first national park. The animals also are the symbol of the National Park Service. Since the 1980s, worry over brucellosis has prompted the killing of about 8,200 park bison, most of them sent to slaughter. In recent years, state, federal and tribal agencies have tried to emphasize public hunts that occur just outside the park's boundaries. Hunters so far this winter have killed more than 400 of the animals, said Andrea Jones with Montana Fish, Wildlife and Parks. That's the most since 1989. The vast majority were shot by members of American Indian tribes that have treaty hunting rights in the Yellowstone region. Detracting from the hunt's success has been an unprecedented number of animals that were merely wounded and retreated to the park after being shot. Up to 50 wounded bison were killed by state and federal wildlife agents, Jones said. The park had 4,900 bison at last count, well above the 3,000 dictated under the agreement. Park officials set a goal this year of removing 600 to 900 of the animals. More shipments to slaughter are possible in coming weeks if large groups of bison move into Montana, although a mild winter has reduced this year's migration compared with previous years. During the past decade, Montana Gov. Steve Bullock and his predecessor moved to allow bison into areas adjacent to the park. Yellowstone administrators have supported those efforts, but they say they are bound under the 2000 agreement to keep the bison herds in check. Alternatives—such as transferring some Yellowstone bison to lands outside the park—are under consideration but unlikely to take effect soon. Park workers are holding back from slaughter 57 bison calves and yearlings for potential future placement elsewhere if the opportunity arises, park spokeswoman Amy Bartlett said. If that doesn't happen, the animals will be slaughtered, she said. Explore further: Bison transferred to reservation from Yellowstone