Philip J. Howell
United States Forest Service
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Featured researches published by Philip J. Howell.
Forest Ecology and Management | 2003
Bruce E. Rieman; Danny C. Lee; Dave Burns; Robert E. Gresswell; Michael K. Young; Rick Stowell; John N. Rinne; Philip J. Howell
Conservation of native fishes and changing patterns in wildfire and fuels are defining challenges for managers of forested landscapes in the western United States. Many species and populations of native fishes have declined in recorded history and some now occur as isolated remnants of what once were larger more complex systems. Land management activities have been viewed as one cause of this problem. Fires also can have substantial effects on streams and riparian systems and may threaten the persistence of some populations of fish, particularly those that are small and isolated. Despite that, major new efforts to actively manage fires and fuels in forests throughout the region may be perceived as a threat rather than a benefit to conservation of native fishes and their habitats. The management of terrestrial and aquatic resources has often been contentious, divided among a variety of agencies with different goals and mandates. Management of forests, for example, has generally been viewed as an impact on aquatic systems. Implementation of the management-regulatory process has reinforced a uniform approach to mitigate the threats to aquatic species and habitats that may be influenced by management activities. The problems and opportunities, however, are not the same across the landscapes of interest. Attempts to streamline the regulatory process often search for generalized solutions that may oversimplify the complexity of natural systems. Significant questions regarding the influence of fire on aquatic ecosystems, changing fire regimes, and the effects of fire-related management remain unresolved and contribute to the uncertainty. We argue that management of forests and fishes can be viewed as part of the same problem, that of conservation and restoration of the natural processes that create diverse and productive ecosystems. We suggest that progress toward more integrated management of forests and native fishes will require at least three steps: (1) better integration and development of a common conceptual foundation and ecological goals; (2) attention to landscape and ecological context; and (3) recognition of uncertainty. Published by Elsevier Science B.V.
Forest Ecology and Management | 2001
Bruce E. Rieman; James T. Peterson; James L. Clayton; Philip J. Howell; Russell Thurow; William L. Thompson; Danny C. Lee
Abstract Aquatic species throughout the interior Columbia River basin are at risk. Evaluation of the potential effects of federal land management on aquatic ecosystems across this region is an important but challenging task. Issues include the size and complexity of the systems, uncertainty in important processes and existing states, flexibility and consistency in the analytical framework, and an ability to quantify results. We focused on salmonid fishes and their habitats as indicators of conditions in aquatic ecosystems and used Bayesian belief networks as a formal, quantitative framework to address the issues in our evaluation of land management alternatives proposed for the interior Columbia River basin. Because empirical information is limited at the scales relevant to our analysis, an ability to combine both empirical and more subjective information was key to the analysis. The representation of linkages through conditional probabilities made uncertainty explicit. We constructed two general networks. One represented the influence of landscape characteristics and existing and predicted management activities on aquatic habitats. A second represented the influence of habitat, existing biotic conditions, and for two anadromous species, ocean and migratory conditions, on the status of six widely distributed salmonid fishes. In the long term (100 years) all three land management alternatives were expected to produce positive changes in the status and distribution of the salmonids and their habitats. Trends were stronger for habitat than for the status of salmonids because of greater uncertainty in linking the fish and habitat networks and constraints outside spawning and rearing habitat on federal lands in the study area. Trends were stronger for resident salmonids than anadromous forms because of additional effects of the migratory corridor assumed for the latter. Alternative S2, which approached ecosystem restoration more conservatively, generally produced the strongest positive changes, and alternative S3, designed to promote more aggressive restoration, the weakest. Averaged across the basin, differences among the alternatives were small. Differences were greater at finer temporal and spatial scales. In the short term (10 years) alternative S3 was expected to lead to further degradation in some areas. By formalizing our understanding and assumptions in these networks, we provided a framework for exploring differences in the management alternatives that is more quantifiable, spatially explicit, and flexible than previous approaches.
Evolutionary Applications | 2008
Michelle M. McClure; Fred M. Utter; Casey Baldwin; Richard W. Carmichael; Peter F. Hassemer; Philip J. Howell; Paul Spruell; Thomas D. Cooney; Howard Schaller; Charles E. Petrosky
Most hatchery programs for anadromous salmonids have been initiated to increase the numbers of fish for harvest, to mitigate for habitat losses, or to increase abundance in populations at low abundance. However, the manner in which these programs are implemented can have significant impacts on the evolutionary trajectory and long‐term viability of populations. In this paper, we review the potential benefits and risks of hatchery programs relative to the conservation of species listed under the US Endangered Species Act. To illustrate, we present the range of potential effects within a population as well as among populations of Chinook salmon (Oncorhynchus tshawytscha) where changes to major hatchery programs are being considered. We apply evolutionary considerations emerging from these examples to suggest broader principles for hatchery uses that are consistent with conservation goals. We conclude that because of the evolutionary risks posed by artificial propagation programs, they should not be viewed as a substitute for addressing other limiting factors that prevent achieving viability. At the population level, artificial propagation programs that are implemented as a short‐term approach to avoid imminent extinction are more likely to achieve long‐term population viability than approaches that rely on long‐term supplementation. In addition, artificial propagation programs can have out‐of‐population impacts that should be considered in conservation planning.
Transactions of The American Fisheries Society | 2007
Erica A. Swenson; Amanda E. Rosenberger; Philip J. Howell
Abstract Fish maturity status, sex ratio, and age and size at first maturity are important parameters in population assessments and life history studies. In most empirical studies of these variables, fish are sacrificed and dissected to obtain data. However, maturity status and the sex of mature individuals can be determined by inserting an endoscope through a small incision in the body cavity wall and viewing the gonads. The objective of this study was to evaluate endoscopy in a field setting for gonadal assessment of stream-resident forms of salmonids that mature at small sizes. Ninety-one brook trout Salvelinus fontinalis (60–210 mm fork length [FL]) were obtained via electrofishing and anesthetized. Maturity status and sex of mature individuals were determined with an endoscope. After recovery, individuals were euthanized with anesthetic and were dissected to validate the endoscopic classification. Endoscopy correctly determined the maturity status and sex of mature individuals for 96% of the brook tr...
North American Journal of Fisheries Management | 2012
Philip J. Howell; Paul M. Sankovich
Abstract The use of redd counts to monitor abundance and trend of bull trout Salvelinus confluentus has been clouded by uncertainties concerning measurement error, life history variation, and correspondence of redd counts to adult population size. We compared census redd counts with population estimates of mature females for a migratory fluvial population of bull trout (primarily ≥ 300 mm fork length) and for a population of small (<200 mm), likely resident, bull trout. We also compared the measurement error of the experienced surveyors who conducted the redd counts to that of a group of inexperienced surveyors. Although the regression of redd counts on adult females for the migratory population was statistically significant, a large proportion of the variation in the relationship was unexplained (r 2 = 0.47). Despite that variation, redd counts accurately reflected a greater than 50% decline in the population over 10 years; however, 5-year trends in redd counts could be misleading. Power analysis paramet...
Transactions of The American Fisheries Society | 2016
Philip J. Howell; Michael E. Colvin; Paul M. Sankovich; David V. Buchanan; Alan R. Hemmingsen
AbstractTo describe the life histories and demography of a fluvial population of Bull Trout Salvelinus confluentus, we PIT-tagged and radio-tagged Bull Trout captured in Mill Creek, a tributary of the Walla Walla River (Washington–Oregon), during 1998–2009. Adult abundance declined 63% during 2006–2010, driven primarily by a 10-fold reduction in subadult-to-adult returns. Larger subadults and fall–winter emigrants survived at higher rates, but they were a small proportion of the subadult migrants. The survival rates of larger, generally older adults were also more than 40% greater than those of smaller adults. Changes in abundance influenced other characteristics of the population. For example, adult upstream movement into spawning areas during 1999–2005 peaked in late July, whereas the smaller runs observed during 2006–2010 peaked in early September, and the relationship between fish size and migration timing shifted. Unlike many adfluvial populations, more than 90% of the adults in Mill Creek spawned an...
Conservation Genetics | 2003
Paul Spruell; A.R. Hemmingsen; Philip J. Howell; Naohisa Kanda; Fred W. Allendorf
Ecology of Freshwater Fish | 2010
Philip J. Howell; Jason B. Dunham; P. M. Sankovich
Archive | 2002
James T. Peterson; Jason B. Dunham; Philip J. Howell; Russell Thurow; Scott A. Bonar
Redband Trout: Resilience and Challenge in a Changing Landscape. Oregon Chapter, American Fisheries Society. 19 p. | 2007
Russell F. Thurow; Bruce E. Rieman; Danny C. Lee; Philip J. Howell; Raymond D. Perkinson