Juvenile Salmonid Monitoring In Coastal Oregon and Lower Columbia Streams, 2015 Report Number: OPSW-ODFW-2016-1

Identification Information

Citation

Originator: Suring, E., and R. Constable

Publish Date: 2015

Online Link: None

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Ronald Constable

Job Position: NRS-2 Assistant Project Leader

Telephone: 541-757-5107

E-Mail Address: ron.constable@oregonstate.edu

Description

Abstract: This report analyzes data from juvenile salmonid surveys in the three coho Evolutionarily Significant Units (ESU) and the four steelhead Distinct Population Segments (DPS) in coastal Oregon for 2015. Results from 2015 are compared to previous years and used to describe trends in distribution and abundance. To access prior reports visit https://nrimp.dfw.state.or.us/crl/default.aspx?pn=WORP. Coho: Density estimates in 2015 for the Oregon Coast Coho (OCC) ESU were higher than in 2014, but similar to the 1998-2014 average for the ESU. Abundance estimates in 2015 were similar to 2004-2014, but higher than those in1998-2003. Site occupancy rates appeared to be increasing for the ESU since the start of our monitoring in 1998, although the rate from 2015 was lower than in 2014. The average occupancy rate from 2010-2015 has been similar to the average from 2004-2009 and higher than the average from 1998-2003. In the ESU plots of parr abundance against female spawner abundance suggest limits in freshwater habitat to parr production when spawner abundance exceeds approximately 80,000 females. Parr production rates in the ESU typically decrease when female spawner abundance increases. The density, number of sites at full seeding, occupancy, and pool frequency estimates in 2015 for the Southern Oregon Northern California Coho (SONCC) ESU were the lowest recorded since our monitoring began. Abundance estimates of parr from 2013-2015 were lower than those from 2001-2012 and similar to those from 1998-2000. Occupancy estimates for the last 4 cohorts have been the lowest recorded since monitoring began. Density estimates in 2015 for the Lower Columbia River Coho (LCR) were higher than in 2014 but similar to the average from 2006-2014 for the ESU. Abundance estimates of parr in 2015 were similar to the estimate in 2014 and to the 2006-2014 average. Site occupancy rates in 2015 were similar to the 2014 rate and the average rate from 2006-2014. Steelhead: The density, abundance, and occupancy rate estimates in 2015 for Oregon Coast Steelhead DPS were lower than in 2014 and lower than the 2002-2014 average for the DPS. The four cohorts previous to 2015 have had the four highest occupancy rates. Density in 2015 for the Klamath Mountain Province was lower than in 2014 and lower than the 2002-2014 average for the DPS. The 2015 and 2014 abundance estimates were the 1st and 2nd lowest recorded in the DPS. Site occupancy in 2015 was similar to 2014 and to the 2002-2014 average for the DPS. As in past years, the 2015 metrics for the two steelhead DPSs in the Lower Columbia River had similar metrics. Densities, pool frequencies, and point estimates for site occupancy and abundance were the lowest recorded in 2015. The original pool depth criteria was =40cm in maximum depth. This was changed to =20cm in 2010. Analyses based on the =20cm maximum depth criteria typically produce larger abundance estimates with proportionately smaller confidence intervals than analyses based on the =40cm maximum depth criteria. Abundance estimate trends that included shallow pools tracked with those based on the former pool criteria.

Purpose:

Time Period of Content: 1998-2015

Geographic Extent: Oregon coast, Columbia River

Status: Final

Use Constraints:

Format: PDF File

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Is a physical copy maintained for reference at Headquarters? No