Geology topics

Russell F. Thurow

Publications and source records attributed to Russell F. Thurow.

5 recordsLinked to original sources

USGS2024

Evaluating streamflow and temperature effects on Bull Trout migration and survival with linear spatial capture-recapture models

Objective In the U.S. Pacific Northwest, climate change is increasing air temperatures, decreasing warm season (April–September) streamflow, and increasing cool season (October–March) streamflow. Warmer water temperatures may alter conditions for migratory coldwater fishes like the Bull Trout Salvelinus confluentus . Consequently, an understanding of Bull Trout migration and survival is critical for species conservation and restoration. In the Salmon River basin, Idaho, 1992 and 1993 transpired to be two of the most opposing extreme years among the past three decades for warm season water temperature and streamflow. These extremes provided a unique opportunity to retrospectively compare Bull Trout survival and migration under potential climate change scenarios. Methods We evaluated prespawning and postspawning migrations and survival of fluvial Bull Trout that were radio-tagged and tracked from 1992 to 1994. We used a Cormack–Jolly–Seber linear spatial capture–recapture model to simultaneously model the migration and survival of radio-tagged prespawn ( n = 58) and postspawn ( n = 23) Bull Trout among weeks and river reaches with streamflow, water temperature, and habitat covariates. Result Most individual prespawning migrations were similar among tagged fish, whereas postspawn fish adopted multiple migration and overwintering strategies. Movements of prespawn Bull Trout were larger when (1) weekly average daily maximum streamflow increased and (2) weekly average daily maximum water temperature increased. The model estimated that at least 52% of spawners survived to spawning, and mean weekly prespawning apparent survival was higher in the low-streamflow year (1992) than in the year with higher and more variable streamflow (1993). Survival of 1992–1994 fish during the 38-week postspawning period was intermediate to that in the prespawning period. Detections of prespawn Bull Trout were generally higher at sites with more complex habitats, less large woody debris, and fewer undercut banks. Conclusion We found that the prespawn life stage can represent a shorter time frame (14–18 weeks) with increased mortality compared to the longer postspawning period (38 weeks). Bull Trout apparent survival increased with lower streamflow variability, indicating that expected future changes in climate may adversely affect Bull Trout.

Idaho↗

USGS2024

Coldwater fish in wadeable streams

Although we are consistent with the past edition of this volume regarding standard sampling techniques for wadeable, coldwater streams, this edition reflects recent literature, advances in calibrating numbers, and obtaining lengths of fish collected and provides additional clarity regarding effort. We also specify a minimum of two netters and one electrofisher operator for backpack electrofishing to allow capture of fish that “roll” downstream without surfacing (e.g., fish like sculpins, which lack swim bladders); however, as in the past edition, a minimum of one netter and one operator may be used on studies focused on fish with swim bladders, like salmonids (salmons and trouts). Finally, this chapter mentions specifically what factors should lead to standard adjustments to techniques to account for the range of habitat features typically encountered in headwater streams. Small, wadeable streams comprise most habitats available to fish in fluvial networks. Wadeable streams are generally less than 1 m deep, and fish can be sampled without the use of float craft. Cold waters are generally defined as having mean 7-d summer maximum water temperatures less than 20°C, providing habitat for coldwater fishes. Fish fauna of small, coldwater North American streams typically include salmonids, sculpins, minnows, sticklebacks, suckers, or lampreys (Hocutt and Wiley 1986). Standard sampling protocols provided herein apply most readily to salmonids because of their sport and commercial values (Johnson et al. 2007). Salmonids also have cultural values, are well studied and widely distributed, and act as predators, competitors, and prey (Lee et al. 1997). However, many of these methods can also be applied effectively to sample nonsalmonids. As interest in nonsalmonid species grows, further development and investigation of sampling methods for a broader diversity of species is expected (see section 8.5).

Book chapter↗

USGS2020

Concealment of juvenile bull trout in response to temperature, light, and substrate: Implications for detection

Bull trout ( Salvelinus confluentus) are challenging to detect as a result of the species cryptic behavior and coloration, relatively low densities in complex habitats, and affinity for cold, high clarity, low conductivity waters. Bull trout are also closely associated with the stream bed, frequently conceal in substrate, and this concealment behavior is poorly understood. Consequently, population assessments are problematic and biologists and managers often lack quantitative information to accurately describe bull trout distributions, estimate abundance, and assess status and trends; particularly for stream-dwelling populations. During controlled laboratory trials, we recorded concealment, resting, and swimming behavior of juvenile wild bull trout in response to: (1) constant and fluctuating water temperature, (2) presence or absence of light, and (3) substrate size. Light level had the strongest influence on wild fish concealment and more fish concealed as light levels increased from darkness to daylight. Wild fish were 14.5 times less likely to conceal in constant darkness and 4.1 times more likely to conceal in 12 h light x 12 h darkness compared to constant light. Wild fish were 6.2 times less likely to conceal in small (26–51 mm) substrate compared to larger (52–102 mm) substrate. As water temperature increased, fewer wild fish concealed. Knowledge of wild bull trout concealment will improve field sampling protocols and increase detection efficiencies. These data also enhance knowledge of bull trout niche requirements which illuminates ecological differences among species and informs conservation and restoration efforts.

PLoS ONE↗

USGS2011

Native fish conservation areas: A vision for large-scale conservation of native fish communities

The status of freshwater fishes continues to decline despite substantial conservation efforts to reverse this trend and recover threatened and endangered aquatic species. Lack of success is partially due to working at smaller spatial scales and focusing on habitats and species that are already degraded. Protecting entire watersheds and aquatic communities, which we term "native fish conservation areas" (NFCAs), would complement existing conservation efforts by protecting intact aquatic communities while allowing compatible uses. Four critical elements need to be met within a NFCA: (1) maintain processes that create habitat complexity, diversity, and connectivity; (2) nurture all of the life history stages of the fishes being protected; (3) include a long-term enough watershed to provide long-term persistence of native fish populations; and (4) provide management that is sustainable over time. We describe how a network of protected watersheds could be created that would anchor aquatic conservation needs in river basins across the country.

Fisheries↗

USGS2009

Coldwater fish in wadeable streams

Standardizing sampling methods for fish populations across large regions is important for consistent measurement of large-scale effects of climate or geography. In addition, pooling samples creates larger sample sizes and can facilitate data sharing among scientists and land managers. Sampling freshwater fish has largely not been standardized due to the diversity of fish and habitats. USGS aquatic ecologist Jason Dunham and co-authors contributed a chapter about sampling coldwater fish in wadeable streams to a new book that details common methods, protocols, and guidelines for sampling fish across North America. Topics include three common sampling methods: electrofishing, snorkeling, and nest counts. Each method provides complementary information about different species and life stages. The information will be useful for initiating new or fine-tuning ongoing sampling programs.

Book chapter↗