DOI: 10.5061/dryad.57b80
title: Data from: Summer stream temperatures influence sculpin distributions and spatial partitioning in the Upper Clark Fork River Basin, Montana

description: The upper Clark Fork River basin of western Montana supports a poorly
 understood sculpin (Uranidea spp.) fauna that has perplexed ichthyologists
 and fish ecologists since the late 1800s. During our study, the basin
 contained three sculpin taxa whose taxonomy was under revision. All three
 taxa were formerly referred to the genus Cottus but are now treated as
 Uranidea. Our goal was to improve understanding of the distribution and
 ecology of two of the taxa. From 2006 to 2009, we sampled 144 reaches in
 31 streams and rivers to determine distributions of each taxa across the
 study area and within streams. We collected habitat data in 2007 and
 stream temperature data from 2006–2009 to identify correlates of sculpin
 distributions. In streams where both taxa occurred, Rocky Mountain Sculpin
 Uranidea sp. cf. bairdii were downstream and Columbia Slimy Sculpin U. sp.
 cf. cognata were upstream with a syntopic zone in between. Summer stream
 temperatures strongly influenced sculpin distributions, with mean August
 2007 water temperatures increasing in order of reaches characterized as:
 Columbia Slimy Sculpin-dominated, syntopic, Rocky Mountain
 Sculpin-dominated, and no sculpin. Columbia Slimy Sculpin occurred in cold
 tributaries of the Blackfoot, Clark Fork, and Bitterroot rivers and in two
 coldwater refugia in the mainstem Bitterroot River. In contrast, Rocky
 Mountain Sculpin occupied warmer downstream segments of many Blackfoot and
 Clark Fork river tributaries as well as some mainstem reaches of both
 rivers but were absent from the Bitterroot River drainage. Persistence of
 the taxa will likely depend, both directly and indirectly, on future water
 temperatures, and thus, sculpins are appropriate targets for researching
 and monitoring biological changes resulting from climate change.
description: Table 1
 Adams_et_al_2015Table 1. Site locations,
 sampling dates and effort, numbers of sculpin captured, and habitat data
 for spring and summer samples from 2006 - 2009. For the Clark Fork River,
 we arbitrarily set "distance to mouth" = 0.00 for reach 1.
 Latitude and longitude are given in decimal degrees in the NAD83
 datum.Table 2
 Adams_et_al_2015Table 2.—Complete list
 of sample reaches, locations, and sculpin captured at each reach during
 summers 2007-9. Reaches sampled only in summer 2006 are included although
 not shown on maps. “Distance to mouth” is the stream distance (km) from a
 reach to the mouth of the stream or river on which the reach is located.
 For Clark Fork River reaches, distances are from the downstream-most
 reach. Reaches are numbered from downstream to upstream in each stream.
 Reaches where we recorded stream temperatures in either 2007 or 2008 are
 indicated in the thermograph column. Latitude and longitude are given in
 decimal degrees in the NAD83 datum. The total number of seconds shocked
 (Total seconds) and the number (N) of samples in which time was recorded
 are given. “Fish sample N” is the number of summer samples made during
 2007-9 (maximum = 3). Where values for “Fish sample N” exceed those for
 “Seconds N”, electrofishing time was not recorded for all samples at the
 reach. Reaches with N = 0 for fish samples were sampled either in summer
 2006 or spring 2007, but not in any summer from 2007-9. The numbers of
 Rocky Mountain Sculpin (RMS), Columbia Slimy Sculpin (CSS) and
 sculpin-present (not identified to taxon because of their small size or
 uncertainty due to the presence of Cedar sculpin [U. schitsuumsh]) are
 given. Percent (%) RMS and CSS are the percentages of each taxon,
 disregarding any unidentified sculpin. Sculpin status indicates the
 sculpin category to which the reach was assigned for temperature and
 habitat analyses. Reaches with both RMS and CSS are indicated as syntopic
 (Syn) and those with only unidentified sculpins as present (Pres). Other
 abbreviations are as follows: fishing access site (FAS); highway (Hwy.);
 Montana Fish, Wildlife, and Parks (FWP); US Forest Service
 (FS).Table 3
 Adams_et_al_2015Table 3. Minimum,
 average, and maximum daily water temperature values for each reach during
 summer 2007. Stream names and reach codes are as in Tables 1 and 2. Sites
 are organized by sculpin group: no sculpin (none); Rocky Mountain sculpin
 (RMS) or Columbia slimy sculpin (CSS) only; or both species (syntopic).
 Daily summary statistics (mean, sample size [N], SD, and SE) by group are
 given for each temperature metric. Numbers in blue were estimated based on
 linear regressions (see text).