Status of Oregon Stocks of Coho Salmon, 2015, OPSW-ODFW-2016-3

Identification Information

Citation

Originator: Sounhein, B., E. Brown, M. Lewis and M. Weeber

Publish Date: December 2016

Online Link: None

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Matt Weeber

Job Position: OASIS Program Analyst

Telephone: 541-757-5120

E-Mail Address: Matt.Weeber@oregonstate.edu

Description

Abstract: This report summarizes the results of status and trend monitoring for Oregon’s naturally spawning coho salmon, Oncorhynchus kisutch, through the 2015 run year (October 2015 through February 2016). Monitoring results include: 1. Abundance of naturally spawning coho salmon 2. Density (fish/mile) of naturally spawning coho salmon 3. Coho salmon spawn timing and distribution 4. Proportion of hatchery (marked) coho salmon in naturally spawning populations Results in this report are based on data from randomly selected spawning surveys and other methods used in areas without adequate random surveys. Results for coho salmon standard spawning surveys and spawning surveys for other species are covered in data summaries and reports posted on an Oregon Department of Fish and Wildlife (ODFW) web page (see: http://odfw.forestry.oregonstate.edu/spawn/index.htm). Monitoring occurs at three hierarchical spatial scales, as defined by the National Marine Fisheries Service (NMFS): Evolutionarily Significant Unit (ESU); stratum; and coho salmon population. There are three coho salmon ESUs located entirely or partially within the State of Oregon: the Lower Columbia River (LCR) Coho ESU; the Oregon Coast (OC) Coho ESU; and the Southern Oregon/Northern California Coast (SONCC) Coho ESU. This report summarizes results for coho salmon populations in the portion of each ESU within the State of Oregon. In the Oregon portion of the LCR Coho ESU sufficient surveys were conducted in 2015 to meet the precision goal for the ESU, but not for any of the three strata or six sampled populations. The 2015 wild coho salmon spawner abundance for the LCR Coho ESU was the lowest observed in the 14 years of this monitoring effort, but only set new record lows for the Gorge Stratum and its two populations. The proportion of hatchery coho salmon on natural spawning grounds was 8.7% in 2015, a record low for the LCR Coho ESU. This is the third consecutive year of setting a new record low for hatchery fish. However, during the last three years we have not conducted random coho salmon surveys in the Youngs Bay and Big Creek populations, an area of traditionally high levels of hatchery spawners. Regional patterns in fish distribution, spawn timing, and hatchery proportion are apparent at both the stratum and population scales. Overall, coho salmon spawner run timing in 2015 was similar in duration and peak timing to previous years. In the OC Coho ESU sufficient surveys were conducted to meet the precision goal for the ESU, 3 of 4 strata, and 4 of 21 populations (Necanicum, Beaver, Alsea and Siuslaw). Wild spawner abundance in the OC Coho ESU in 2015 was the lowest observed since 1999, but was higher than the 1990 through 1999 average abundance. There were no new record lows or highs in wild coho salmon abundance for any of the 24 populations or 5 strata. The proportion of hatchery fish on natural spawning grounds was 1.2% for the ESU as a whole. All naturally spawning coho salmon populations contained greater than 98% wild fish except the Salmon (94.6%), North Umpqua (94.1%) and South Umpqua (92.8%) populations. In 2015, densities of wild coho salmon spawners in random surveys were lower than the 5 year average in all 21 populations. Percentage of random surveys occupied by wild coho salmon was below the 5 year average in 16 of 21 populations. Overall, coho salmon spawner run timing in 2015 was similar in duration and peak timing to long-term averages; with peak spawning in mid to late December. Inadequate funding and the need to update the sampling frame continue to hamper the monitoring of the Oregon portion of the SONCC Coho ESU. In 2015 no Generalized Random Tessellation Stratified (GRTS) surveys were conducted in the Oregon portion of this ESU. Monitoring of wild coho salmon spawners was based on the Huntley Park seining estimate. Wild coho salmon spawner abundance increased substantially in 2015 compared to the prior year, and was about a two thirds of the 1994 through 2014 average. The proportion of hatchery coho salmon spawning naturally in 2015 was higher than the previous six years, but below the 21 year average. Without GRTS surveys, fish distribution and spawn timing were not evaluated in 2015.

Purpose:

Time Period of Content: 1998-2015

Geographic Extent: Lower Columbia River Basin and Oregon Coast

Status: Final

Use Constraints: Citation: Sounhein, B., E. Brown, M. Lewis and M. Weeber. 2016. Status of Oregon stocks of coho salmon, 2015. Monitoring Program Report Number OPSW-ODFW-2016-3, Oregon Department of Fish and Wildlife, Salem, Oregon.

Format: PDF file

Data Quality Information

Lineage-Source: Funds contributed in part by: Sport Fish and Wildlife Restoration Program administered by the U.S. Fish and Wildlife Service; Pacific Salmon Treaty and Pacific Coast Salmon Recovery Fund administered by the National Marine Fisheries Service; and State of Oregon (General and Lottery Funds).

Data Information

No data information was supplied.

Entity and Attribute Information

Attributes Description: Field attribute information is available in the attached file(s).

Is a physical copy maintained for reference at Headquarters? No