Geology topics

Matthew R. Sloat

Publications and source records attributed to Matthew R. Sloat.

3 recordsLinked to original sources

USGS2016

Effects of stream-adjacent logging in fishless headwaters on downstream coastal cutthroat trout

To investigate effects of headwater logging on downstream coastal cutthroat trout ( Oncorhynchus clarkii clarkii ) populations, we monitored stream habitat and biotic indicators including biomass, abundance, growth, movement, and survival over 8 years using a paired-watershed approach. Reference and logged catchments were located on private industrial forestland on ∼60-year harvest rotation. Five clearcuts (14% of the logged catchment area) were adjacent to fishless portions of the headwater streams, and contemporary regulations did not require riparian forest buffers in the treatment catchment. Logging did not have significant negative effects on downstream coastal cutthroat trout populations for the duration of the sample period. Indeed, the only statistically significant response of fish populations following logging in fishless headwaters was an increase in late-summer biomass (g·m −2 ) of age-1+ coastal cutthroat trout in tributaries. Ultimately, the ability to make broad generalizations concerning effects of timber harvest is difficult because response to disturbance (anthropogenically influenced or not) in aquatic systems is complex and context-dependent, but our findings provide one example of environmentally compatible commercial logging in a regenerated forest setting.

Oregon↗

USGS2014

Ecological and evolutionary patterns of freshwater maturation in Pacific and Atlantic salmonines

Reproductive tactics and migratory strategies in Pacific and Atlantic salmonines are inextricably linked through the effects of migration (or lack thereof) on age and size at maturity. In this review, we focus on the ecological and evolutionary patterns of freshwater maturation in salmonines, a key process resulting in the diversification of their life histories. We demonstrate that the energetics of maturation and reproduction provides a unifying theme for understanding both the proximate and ultimate causes of variation in reproductive schedules among species, populations, and the sexes. We use probabilistic maturation reaction norms to illustrate how variation in individual condition, in terms of body size, growth rate, and lipid storage, influences the timing of maturation. This useful framework integrates both genetic and environmental contributions to conditional strategies for maturation and, in doing so, demonstrates how flexible life histories can be both heritable and subject to strong environmental influences. We review evidence that the propensity for freshwater maturation in partially anadromous species is predictable across environmental gradients at geographic and local spatial scales. We note that growth is commonly associated with the propensity for freshwater maturation, but that life-history responses to changes in growth caused by temperature may be strikingly different than changes caused by differences in food availability. We conclude by exploring how contemporary management actions can constrain or promote the diversity of maturation phenotypes in Pacific and Atlantic salmonines and caution against underestimating the role of freshwater maturing forms in maintaining the resiliency of these iconic species.

Reviews in Fish Biology and Fisheries↗

USGS2014

Influence of sex, migration distance, and latitude on life history expression in steelhead and rainbow trout (Oncorhynchus mykiss)

Abstract:In partially migratory species, such as Oncorhynchus mykiss, the emergence of life history phenotypes is often attributed to ﬁtness trade-offs associated with growth and survival. Fitness trade-offs can be linked to reproductive tactics that vary between the sexes, as well as the inﬂuence of environmental conditions. We found that O. my kiss outmigrants are more likely to be female in nine populations throughout western North America (grand mean 65% female), in support of the hypothesis that anadromy is more likely to beneﬁt females. This bias was not related to migration distance or freshwater productivity, as indicated by latitude. Within one O. my kiss population we also measured the resident sex ratio and did not observe a male bias, despite a high female bias among out migrants in that system. We provide a simulation to demonstrate the relationship between sex ratios and the proportion of anadromy and show how sex ratios could be a valuable tool for predicting the prevalence of life history types in a population.

California;Idaho;Oregon;Washington↗