Linking Hydroclimate to Fish Phenology and Habitat Use with Ichthyographs

<div><p>Streamflow and water temperature (hydroclimate) influence the life histories of aquatic biota. The relationship between streamflow and temperature varies with climate, hydrogeomorphic setting, and season. Life histories of native fishes reflect, in part, their adaptation to regional hydroclimate (flow and water temperature), local habitats, and natural disturbance regimes, all of which may be affected by water management. Alterations to natural hydroclimates, such as those caused by river regulation or climate change, can modify the suitability and variety of in-stream habitat for fishes throughout the year. Here, we present the <i>ichthyograph</i>, a new empirically-based graphical tool to help visualize relationships between hydroclimate and fish phenology. Generally, this graphical tool can be used to display a variety of phenotypic traits. We used long-term data sets of daily fish passage to examine linkages between hydroclimate and the expression of life-history phenology by native fishes. The ichthyograph may be used to characterize the environmental phenology for fishes across multiple spatio-temporal domains. We illustrate the ichthyograph in two applications to visualize: 1) river use for the community of fishes at a specific location; and 2) stream conditions at multiple locations within the river network for one species at different life-history stages. The novel, yet simple, ichthyograph offers a flexible framework to enable transformations in thinking regarding relationships between hydroclimate and aquatic species across space and time. The potential broad application of this innovative tool promotes synergism between assessments of physical characteristics and the biological needs of aquatic species.</p></div

Location of Winchester Dam, OR, and upstream drainage basin.

<p>Winchester Dam was built in 1890 and upgraded in 1907 and now includes a timber-crib structure that is 4.9 m in height. While the dam does impound a shallow upstream reservoir, it is considered a “run-of-river” dam. A fish ladder allowing fish passage was installed in 1945 with a viewing window to monitor the upstream passage of all fishes past the dam. Continuously collected fish passage data at this location from 1992 and 2013 was used to develop the Winchester Dam ichthyograph.</p

Daily streamflow, water temperature and fish counts for Winchester Dam, North Umpqua River, Oregon, USA from 1992 to 2013.

<p>Streamflow (top graph) from USGS gage station No. 14319500. Stream temperature (second graph from top) and fish counts courtesy Oregon Department of Fish and Wildlife for, in order: steelhead (anadromous <i>Oncorhynchus mykiss</i>), sucker (<i>Catostomus macrocheilus</i>), Chinook Salmon (<i>Oncorhynchus tshawytscha</i>), lamprey (<i>Entosphenus tridentatus</i>), cutthroat trout (<i>Oncorhynchus clarkii</i>), and Coho Salmon (<i>Oncorhynchus kisutch</i>). Fish count data unavailable for Jan–Oct 1998. This figure shows a multi-year timeline plot of environmental conditions (daily streamflow and water temperature) and the community of fishes moving upstream past Winchester Dam. Darker colors are associated with higher numbers and show strong seasonal patterns over time for all species. Some species have narrow upstream migration windows (i.e. Coho Salmon) while others move upstream during a wider time window (i.e. steelhead).</p

Streamflow and stream temperature related to fish passage timing at Winchester Dam, OR.

<p>Multiple years of streamflow and stream temperature, when plotted against one another on a graph, may show a cyclical pattern. Such is the case at Winchester Dam, OR when streamflow and stream temperature for the period of record (1992–2103) is plotted as: (a) average daily values; inset) generalized seasonal relationship creating an annual cycle of hydrologic conditions. When fish passage is overlaid on the framework of discharge and temperature, an ichthyograph is created: (b) ichthyograph of daily fish use at Winchester Dam based on data from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168831#pone.0168831.g001" target="_blank">Fig 1</a>. Various other phenological traits could be plotted in this way, with ideal data based on empirical observation, as is the case at Winchester Dam, OR.</p

Conceptual ichthyographs for Coho Salmon.

<p>Conceptual ichthyographs for Coho Salmon use by life stage of: (a) a mid-river location such as Winchester dam, and (b) throughout the river network with generalized patterns of streamflow and stream temperature for different drainage areas. These conceptual ichthyographs are based on the empirical data available in this system (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168831#pone.0168831.g001" target="_blank">Fig 1</a>), but also incorporate informal data collected as part of ongoing fish management in this system, and the description of life-stage specific habitat characteristics that can be taken from the peer reviewed literature. Other species specific traits could be mapped in this way, as could other interpretations of fish habitat use beyond specific life stages. Empirical ichthyographs that map daily discharge, temperature, and fish use could also be mapped where data are available.</p