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Fish face many anthropogenic stressors. Authorities in marine, estuarine, and freshwater realms often share interdependent fisheries management goals, but address singular stressors independently. Here, we present a case study suggesting that coordinating stressor relief across management realms may synergize conservation efforts, especially to actualize restoration benefits. Major efforts are underway to restore juvenile salmon habitat across California’s Central Valley landscape, but it is unclear how fisheries and flow management will influence juvenile salmon occupancy of restored sites. Leveraging monitoring data, we find that for juvenile salmon (

Ecologists are pressed to understand how climate constrains the timings of annual biological events (phenology). Climate influences on phenology are likely significant in estuarine watersheds because many watersheds provide seasonal fish nurseries where juvenile presence is synched with favorable conditions. While ecologists have long recognized that estuaries are generally important to juvenile fish, we incompletely understand the specific ecosystem dynamics that contribute to their nursery habitat value, limiting our ability to identify and protect vital habitat components. Here we examined the annual timing of juvenile coldwater fish migrating through a seasonally warm, hydrologically managed watershed. Our goal was to (1) understand how climate constrained the seasonal timing of water conditions necessary for juvenile fish to use nursery habitats and (2) inform management decisions about (a) mitigating climate-mediated stress on nursery habitat function and (b) conserving heat-constrained species in warming environments. Cool, wet winters deposited snow and cold water into mountains and reservoirs, which kept the lower watershed adequately cool for juveniles through the spring despite the region approaching its hot, dry summers. For every 1°C waters in April were colder, the juvenile fish population (1) inhabited the watershed 4-7 d longer and (2) entered marine waters, where survival is size selective, at maximum sizes 2.1 mm larger. Climate therefore appeared to constrain the nursery functions of this system by determining seasonal windows of tolerable rearing conditions, and cold water appeared to be a vital ecosystem component that promoted juvenile rearing. Fish in this system inhabit the southernmost extent of their range and already rear during the coolest part of the year, suggesting that a warming climate will truncate rather than shift their annual presence. Our findings are concerning for coldwater diadromous species in general because warming climates may constrain watershed use and diminish viability of life histories (e.g., late springtime rearing) and associated portfolio benefits over the long term. Lower watershed nurseries for coldwater fish in warming climates may be enhanced through allocating coldwater reservoir releases to prolong juvenile rearing periods downstream or restorations that facilitate colder conditions.

River restoration plans often propose multiple rehabilitation actions to address key habitat impairments, but they rarely attempt to quantify the potential benefits of alternative sets of actions for targeted biota. We use geomorphic and biological analyses to estimate restoration potential under three alternative scenarios for a 64-km section of the Trinity River, California, between the North Fork Trinity River and Lewiston Dam, which is the focus of habitat rehabilitation efforts under the Trinity River Restoration Program. The three scenarios are (1) increasing habitat quality by wood additions and alcove construction, (2) increasing habitat quantity by increasing sinuosity and side-channel length, and (3) increasing both habitat quality and quantity. For each scenario, we used existing stream habitat and juvenile salmonid data from previous studies to estimate potential improvements in fry or pre-smolt production. The potential increase in Oncorhynchus tshawytscha (Chinook salmon) and O. mykiss (steelhead) fry rearing capacity was 62 and 67%, respectively, for Scenario 1 (increasing habitat quality), and 36 and 44% for Scenario 2 (increasing habitat quantity). Only the most optimistic Scenario 3 (increasing both habitat quality and quantity) more than doubles potential juvenile salmonid production (112% increase in Chinook fry capacity and 107% increase in steelhead fry capacity). These quantitative predictions are useful in developing realistic restoration targets and evaluating whether proposed restoration actions can achieve the aims of a restoration program. [ABSTRACT FROM AUTHOR]

We carried out this study to clarify the relationships between the seasonal changes of bark stripping and food quality, and between bark-stripping intensity and bark nutrition with age of veitch fir ( Abies veitchii) by sika deer ( Cervus nippon) in the northern Mount Fuji district, from June 2000 to July 2003. We found that sika deer gnawed and ate all of the bark stripped, and a seasonal change in bark stripping occurred from December to May or June with a peak in March–April. The stripping period largely overlapped with the periods of low food availability and poor food nutrition (indicated by fecal chemical component index) of sika deer, from January to April. Both bark nutritional quality and bark-stripping intensity related to stand age and tree size of veitch fir negatively. Consequently, bark-stripping intensity related to bark nutritional quality positively. February is the worst forage period in terms of both quantity (due to deep snow) and quality (indicated by fecal chemical components). There was a time lag of 1 to 2 months in the peak of bark stripping in March–April when compared with the poor forage period in February. This time lag may suggest that sika deer need more nutritious and easily digested food from March due to increased nutrient demands that result from depleted body condition in both sexes, gestation of pregnant females, and the recovery of active metabolism. [ABSTRACT FROM AUTHOR]