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P.A. Bisson

Publications and source records attributed to P.A. Bisson.

4 recordsLinked to original sources
USGS2003

Fire and aquatic ecosystems of the western USA: Current knowledge and key questions

Understanding of the effects of wildland fire and fire management on aquatic and riparian ecosystems is an evolving field, with many questions still to be resolved. Limitations of current knowledge, and the certainty that fire management will continue, underscore the need to summarize available information. Integrating fire and fuels management with aquatic ecosystem conservation begins with recognizing that terrestrial and aquatic ecosystems are linked and dynamic, and that fire can play a critical role in maintaining aquatic ecological diversity. To protect aquatic ecosystems we argue that it will be important to: (1) accommodate fire-related and other ecological processes that maintain aquatic habitats and biodiversity, and not simply control fires or fuels; (2) prioritize projects according to risks and opportunities for fire control and the protection of aquatic ecosystems; and (3) develop new consistency in the management and regulatory process. Ultimately, all natural resource management is uncertain; the role of science is to apply experimental design and hypothesis testing to management applications that affect fire and aquatic ecosystems. Policy-makers and the public will benefit from an expanded appreciation of fire ecology that enables them to implement watershed management projects as experiments with hypothesized outcomes, adequate controls, and replication.

Forest Ecology and Management↗
USGS1988

Channel hydraulics, habitat use, and body form of juvenile coho salmon, steelhead, and cutthroat trout in streams

Habitat use by juvenile coho salmon Oncorhynchus kisutch , steelhead Salmo gairdneri , and the coastal subspecies of cutthroat trout Salmo clarki clarki in small streams in western Washington was influenced by hydraulic characteristics of different types of channel units. Coho salmon preferred pools with average velocities less than 20 cm/s; very few fish were found in riffles with high current velocities. Steelhead occurred in riffles and also utilized deep pools with relatively high velocities along the center of the channel. Cutthroat trout were intermediate between coho salmon and steelhead in their use of swiftly flowing habitats. Variation in body shape and fin size among the three species generally fit the predicted morphologies that would be favored in different locations within the channel. Coho salmon possessed a deep, laterally compressed body with large median and paired fins. These features are believed to facilitate rapid turns and quick but transient burst swimming. Steelhead possessed a more cylindrical body shape with short median fins and relatively large paired fins, attributes that appear well adapted to holding a position in swift water. The cutthroat troutˈs lack of morphological adaptation to either fast or slow water may help to explain why this species is dominated by coho salmon and steelhead in areas of sympatry.

Transactions of the American Fisheries Society↗
USGS1988

Summer production of coho salmon stocked in Mount St. Helens streams 3-6 years after the 1980 eruption

We monitored habitat use and summer production of stocked underyearling coho salmon Oncorhynchus kisutch from 1983 to 1986 in three streams affected by the 1980 eruption of Mount St. Helens, Washington. Two streams were in the blast area and one was on a volcanic mudflow terrace, Midsummer water temperatures frequently exceeded presumed stressful thresholds and occasionally surpassed the incipient lethal limit. Temperatures at the study sites (up to 29.5°C) may have been the highest ever recorded in small streams in western Washington. In addition, there was relatively little submerged cover and limited pool habitat. Despite the severe conditions created by the eruption, production rates of stocked coho salmon at all sites ranged from 15.1 to 143.8 mg/m 2 ·d (2.3–21.6 g/m 2 over an average 150‐d summer period) and were equal to or greater than those measured in other streams of comparable size in the region. Coho salmon production in the streams was more strongly influenced by population biomass and density than by average individual growth rate. Production was also influenced by timing and average weight at stocking; larger fish stocked later in the summer had higher survival than smaller fish stocked earlier. Apparent summer mortality (true mortality plus emigration) may have been influenced by the presence of other salmonids. Coho salmon density at the end of summer was consistently lowest in the mudflow stream, the only site to have a large population of steelhead (anadromous rainbow trout Oncorhynchus mykiss , formerly Salmo gairdneri ). We suspected that an abundance of both terrestrial and aquatic food was partly responsible for the high summer production of stocked coho salmon in what was an otherwise hostile environment.

Washington↗