Distribution and Abundance of Umpqua Chub and Smallmouth Bass in the South Umpqua Basin Joe Tomelleri Cory Sipher 1, Casey Baldwin 2, Jim Peterson 3, 1 Bureau of Land Management, Roseburg, OR 97471 2 US Forest Service Tiller Ranger District, Tiller, OR 97484 and Paul Scheerer 4 3 USGS Oregon Cooperative Fish and Wildlife Research Unit, 104 Nash Hall, Oregon State University, Corvallis, OR 97331 4 Oregon Department of Fish and Wildlife, 28655 Highway 34, Corvallis, Oregon 97333
Overview Study objectives Umpqua chub background Potential limiting factors Previous surveys Study design Current distribution Factors affecting occupancy Next steps
Study Objectives Pilot study to assess the use of snorkeling to assess trends in Umpqua chub distribution and abundance in S. Umpqua subbasin o Tested the use of N-mixture and multi-state occupancy model with snorkeling data collected in summer 2015
Umpqua chub (Oregonichthys kalawatseti)
Umpqua chub habitat
Co-occurring Native Fishes Largescale sucker
Umpqua Chub Background Recognized as new species (Markle et al. 1991) State of Oregon sensitive and BLM Special Status Species Apparent range restriction and abundance decline coincided with expansion of smallmouth bass
Potential limiting factors Smallmouth bass o Predation o Competition Climate change (favors SMB?) Estuary salinity (fragmentation)
Historical Distribution Tiller
Previous chub surveys (snorkeling) 1987 1998 2006-07
Umpqua chub and smallmouth bass snorkel surveys Smallmouth bass Umpqua chub Simon et al. 2008
Study design Discussed need to reinitiate Umpqua chub monitoring at 2015 Umpqua Chub Working Group Meeting Describe current distribution in South Umpqua and Cow Creek Model population abundance and multi-state occupancy
Survey design 28 sites sampled on consecutive days Snorkel counts on right and left bank (~5 m band on each shore) Same surveyors on consecutive days Estimated abundance using a N-mixture model (based on count data) and described multi-state occupancy of both Umpqua chub and smallmouth bass
N-mixture model (Royle 2004) Uses repeated count data which minimizes handling (none with snorkeling) and requires no marking of animals Goal - find estimates of detection probability and average abundance across all sites that will generate results that closely match the field data Assumptions o Population closure between surveys o Spatial distribution (# individuals occurring at each site) follows a prior distribution (e.g. Poisson), which allows the detection probability to vary among sites o Whether or not an animal is detected at a site is a function of the number of individuals at site
Umpqua chub abundance
Smallmouth bass abundance
Multi-state occupancy model Goal- estimate the probability of occupancy (or proportion of sites occupied) for Umpqua chub and smallmouth bass Models both occupancy and detectability parameters 3 States: absent, present, or present and abundant Nondetection = species genuinely absent or present but not detected (imperfect detection) Assumptions: o Target species is never falsely detected at as site when it is absent (no mis-identification) o Site is closed to changes in the state of occupancy (repeated counts closely spaced in time) Can look at changes in occupancy states over time (versus changes in abundance over time) to assess trends in species status
Probability of occupancy Probability of abundant state Probability of Detection Occupancy Modeling Umpqua chub Probability of occupancy parameters o Percent aquatic vegetation Probability of detection o Aquatic vegetation Conditional probability of abundant o Cobble substrate, aq. vegetation 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 20 40 60 80 100 Percent vegetation 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 20 40 60 80 100 Percent vegetation 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 20 40 60 80 100 Percent Vegetation P(abund, cobble) P(abund, not cobble)
Occupancy Modeling Smallmouth Bass Probability of occupancy parameters o Average depth Conditional probability of abundant o Average depth Probability of detection o Intercept only (p = 0.77) 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Pr(occupancy) Pr(abundant) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Average depth (m)
Next Steps Conduct additional repeated surveys (more than 2 site visits) to describe seasonal changes in occupancy o One location had high abundance of Umpqua chub on first two visits but found no Umpqua chub on next two visits one month later Refine habitat occupancy relationships Identify overlapping habitat characteristics of Umpqua chub and smallmouth bass Estimate the power to detect changes in population abundance or occupancy?
Habitat management considerations Use modelling results to identify opportunities to improve habitat for Umpqua chub at occupied sites and restore habitat at unoccupied sites o Vegetation o Substrate o Depth Identify whether habitat partitioning occurs o Deep water for bass o Shallow shoals for cyprinids
Habitat management considerations Manage stream temperatures through riparian treatments on tributaries (esp. considering potential impacts from climate change) Instream temperature and/or flow modifications through dam releases Construct season migration barriers for smallmouth bass?
Acknowledgements Casey Baldwin Paul Scheerer Jim Peterson Steve Clark Jeff McEnroe Jason Wilcox Scott Lightcap Kelli Van Norman USFS field crew Gina Fritzman Joe Otto Lindsey Negherbon
Questions??
Questions??
Extra slides
4000 3500 Umpqua chub Smallmouth bass 3000 2500 2000 1500 1000 500 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Detection probability (percent) Population estimate Occupied sites (n = 28) Umpqua chub 6.1 9072 22 Smallmouth bass 3.0 4791 17
Abundance estimates Site Umpqua chub Smallmouth bass 1 1697 431 2 1218 326 2A 87 0 3 0 37 4 19 491 5 68 1191 6 3 598 7 105 88 8 722 350 9 0 220 10 13 82 11 0 70 15 0 0 16 37 0 Site Umpqua chub Smallmouth bass 17 3 133 18 392 3 19 273 0 20 313 0 21 322 0 22 183 0 23 0 0 24 371 0 25 1012 13 26 431 35 27 331 0 28 1131 0 29 341 53 31 0 670
Simon 2008
Umpqua chub abundance
Smallmouth bass abundance