Status of westslope cutthroat trout (Oncorhynchus clarki lewisi) in the United States: 2002

Shepard, Bradley B.; May, Bruce; Urie, Wendi

doi:10.5962/bhl.title.45772

Cited by 15 publications

(17 citation statements)

References 24 publications

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“…We also recognize that our PVA modeling results assume that stream habitat conditions in the foreseeable future (which we define as roughly the next three decades; also see Shepard et al 2003) will not be radically and expeditiously altered by overwhelming wildfire, severe stream warming, or some other overarching ecosystem change that could sweep across the riverscape. Despite these assumptions, the weight of evidence from the present study suggests that most of the Bull Trout populations in Idaho are generally at low risk of extirpation in the foreseeable future.…”

Section: Projections Of Population Persistencementioning

confidence: 95%

Bull Trout Trends in Abundance and Probabilities of Persistence in Idaho

Meyer

Garton

Schill

2014

N American J Fish Manag

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We estimated the population growth rates of Bull Trout Salvelinus confluentus and used population growth models to evaluate observation error and estimate Bull Trout persistence probabilities by using 25 data sets (averaging 19 years of record) that indexed abundance across Idaho. These data sets were derived from a variety of fish sampling techniques, including weirs, screw traps, redd counts, daytime snorkeling, electrofishing, and angler creel. Bull Trout populations in Idaho were relatively stable prior to 1994, but after 1994, substantially more population growth rates trended statistically upward (n = 14) than downward (n = 3). Average intrinsic rates of population change were 0.01 (SE = 0.03) prior to 1994 and 0.07 (SE = 0.02) after 1994; across all years of data, the rate of change averaged 0.07 (SE = 0.02). Fifty‐nine percent of the data sets had zero to minimal observation error according to Gompertz state‐space model estimates; observation error was least common in data from screw traps and redd counts and most common in snorkel data. Gompertz‐type density‐dependent models were most often the best‐fitting models for Bull Trout population growth. Moreover, few of the most reliable modeling results (i.e., those from data sets estimated to have zero to minimal observation error) contained a period effect or time (i.e., year) effect, suggesting that carrying capacity generally did not differ between the pre‐1994 and post‐1994 periods and generally was not trending positively or negatively through time. Parametric bootstraps predicted that the mean probability of falling below the quasi‐extinction level of 20 adults in the next 30 years was 9.8% (median = 4.7%) for data sets estimated to have zero to minimal observation error. The weight of evidence from our modeling results suggests that for most Bull Trout populations in Idaho, abundance is stable or increasing and the risk of extirpation in the foreseeable future is low.Received March 12, 2013; accepted November 18, 2013Published online February 10, 2014

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Section: Projections Of Population Persistencementioning

confidence: 95%

Bull Trout Trends in Abundance and Probabilities of Persistence in Idaho

Meyer

Garton

Schill

2014

N American J Fish Manag

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“…In the Blackfoot Watershed, WSCT occupy -90% of historical range. The Blackfoot River also supports one of the larger fluvial meta-populations of genetically unaltered WSCT (upper drainage) in Montana (Pierce et al 2004), but at population abundance well below habitat capacity (Shepard et al 2003).…”

Section: Westslope Cutthroat Trout Conservationmentioning

confidence: 86%

“…WSCT, a Species of Special Concern in Montana, have declined over much of their historic range within the last century. These declines are most pronounced east of the Continental Divide in the upper Missouri River drainage (Shepard et al 2003). Reasons for the decline include habitat loss and degradation, genetic introgression with introduced rainbow trout and Yellowstone cutthroat trout, over harvest and competition with introduced brook trout and brown trout (Liknes 1984; AUendorf and Leary 1988 Shepard et al 2003).…”

Section: Westslope Cutthroat Trout Conservationmentioning

confidence: 99%

The Big Blackfoot River Fisheries restoration report for 2004 and 2005

Pierce¹,

Podner²

2006

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“…Historical populations in all remaining river drainages were classified as core. Recent assessment data (Shephard et al 2003) shows substantial disjunct peripheral population losses in all three areas as well as habitat fragmentation and isolation of remaining core populations in the following drainages: Clark Fork, Marias, Middle Missouri, Upper Missouri, and Madison. Remaining populations are now increasingly vulnerable because of the amount of habitat lost and the location of these areas outside of the remaining core.…”

Section: General Distributions and Declinesmentioning

confidence: 97%

Conserving Peripheral Trout Populations: The Values and Risks of Life on the Edge

Haak¹,

Williams²,

Neville³

et al. 2010

Fisheries

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Peripheral populations-generally defined as those at the geographic edge of the range-often have increased conservation value due to their potential to maximize within-species biodiversity, retain important evolutionary legacies, and provide the fodder for future adaptation. However, there has been little exploration of their conservation value in aquatic systems. Inland cutthroat trout (Oncorhynchus clarkii) subspecies provide a unique opportunity to evaluate the distribution of peripheral populations and patterns of persistence across a wide range of environmental conditions. Our assessment analyzed range-wide losses of peripheral and core populations since the 1800s, and evaluated the likelihood of persistence for remaining populations of five cutthroat trout subspecies: Bonneville, Colorado River, Yellowstone, Rio Grande, and westslope. For all five, we found that core and peripheral populations have declined substantially, but the amounts of habitat occupied by peripheral populations generally have declined at a greater magnitude. The more isolated peripheral populations typically exhibited the greatest declines. Remaining peripheral populations often failed to meet minimum persistence criteria. Our characterization of peripheral populations and their losses emphasizes the need for closer evaluation of conservation priorities and management actions for cutthroat trout and other fishes if the values of peripheral populations are to be maintained.

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Status of westslope cutthroat trout (Oncorhynchus clarki lewisi) in the United States: 2002

Cited by 15 publications

References 24 publications

Bull Trout Trends in Abundance and Probabilities of Persistence in Idaho

Bull Trout Trends in Abundance and Probabilities of Persistence in Idaho

The Big Blackfoot River Fisheries restoration report for 2004 and 2005

Conserving Peripheral Trout Populations: The Values and Risks of Life on the Edge

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