Coho Distribution

2011-2016 Salmonid Redd Abundance and Juvenile Salmonid Spatial Structure in the Smith River Basin, California and Oregon

This report summarizes five years of data collection on salmonid populations in the Smith River basin based on the California Coastal Monitoring Program (CMP). We conducted this effort for five years from 2011-2016 based on funding through the Fisheries Restoration Grant Program.

We continually investigated two population viability metrics of salmonids in the Smith River basin (California and Oregon), with ESA listed coho salmon (Oncorhynchus kisutch) as the focal species. First, we monitored we monitored adult salmonid escapement and distribution from 2011 to 2016 using live fish, carcass, and redd counts as defined in California’s Coastal Salmonid Monitoring Plan. The spawner survey sample frame includes 161.8 kilometers of potential spawning habitat divided into 68 reaches and 30 sub-reaches. Over the five years we completed 1896 spawning ground surveys across 87 survey reaches. During this time we made 1380 observations of live adult coho salmon ranging from 125 in 2015-2016 to 494 in 2013-2014, and recovered 196 coho salmon carcasses ranging from 15 in 2014-2015 to 82 in 2011-2012. Across all five years most coho salmon observations and carcass recoveries occurred in Mill Creek, the exceptions were eight live individuals and 4 carcasses in Rowdy Creek, one carcass in Morrison Creek, and one live individual in Hurdygurdy Creek. Last, we were able to verify 293 individual coho salmon redds throughout the five years of sampling.

Second, we estimated the summer spatial structure of juvenile salmonids and adult coastal cutthroat trout annually from 2012 to 2016 using multiple-pass snorkel surveys in an occupancy modeling framework. The spatial structure sample frame includes 167 reaches totaling 298.1 kilometers of summer rearing habitat in the Smith River basin. Over the five years we completed surveys of 323 reaches totaling 608 cumulative stream kilometers and a total of 7254 pools. We documented coho salmon occupying 64 of the 157 reaches individually surveyed at least once over the five years. Coho salmon maintained patchy distributions relative to the sampling frame over the five years. Based on the summer distribution data collected throughout the basin, we describe five extant juvenile coho salmon patches. Four of the five patches are maintained by independent spawning sub-populations and we consider the lower mainstem Smith River and tributaries to be the only significant non-natal coho salmon rearing patch.

The Smith River Alliance and the California Department of Fish and Wildlife launched a partnership in 2011 to assess and monitor coho salmon in the Smith River basin. Under a grant from the Fisheries Restoration Grant Program, SRA assembled a crew of experienced fish biologists to implement the survey plan designed by Justin Garwood, CDFW.

Over five years we implemented a project designed to further develop and implement a strategic, long-term population assessment and monitoring program for coho salmon using standardized methods defined in the Coastal Salmonid Monitoring plan (CMP), (Adams et al. 2011).

The primary objectives were: (1) to monitor the annual abundance of adult Coho Salmon in the Smith River population unit using spawning ground surveys; (2) to monitor the occupancy and spatial distribution of juvenile coho salmon via snorkel surveys in the Smith River population unit; and (3) to incorporate spawning ground surveys occurring in Mill Creek into meeting the goals of a Life Cycle Monitoring Station (LCS).

Project Background

Marked population declines of coho salmon populations in all freshwater habitats in California have led to both federal and state listings under the federal (ESA) and California (CESA) Endangered Species Acts (Federal Register 1997, CDFG 2002). Both listings have initiated the development of recovery plans which include delisting goals (CDFG 2004, NOAA (SONCC recovery document in review) for the Southern Oregon Northern California Coho (SONCC) ESU. This unit has been defined as the scale used to assess population viability (Williams et al. 2006).

NOAA established four viable salmon population (VSP) parameters to determine a population’s risk of extinction. These parameters include: abundance, productivity (population growth rate), spatial structure, and diversity in life history (McElhany et al. 2000). Trend monitoring for these VSP parameters within specific functionally independent populations is the tool used to minimize uncertainties around extinction risk and recovery status of the SONCC ESU as a whole. For a coho salmon population to meet or exceed a viable threshold, it must show a low risk of extinction over 100 years (McElhany et al. 2000). Therefore, to determine recovery for the SONCC ESU, numerous long-term population monitoring programs need to be established across the ESU. The Smith River basin has been identified as a functionally independent coho salmon population in the central diversity strata for the SONCC ESU by NOAA (McElhany et al. 2000, Williams et al. 2006, Williams et al. 2008) and is proposed to represent a “Core population” (NOAA SONCC recovery document in review).

Furthermore, the Smith River basin is recognized as a recovery unit by CDFG (CDFG 2004) in the SONCC ESU. With the exception of one long-term monitoring program in Mill Creek (McLeod and Howard 2010), sparse information exists regarding the distribution and abundance of coho salmon in the Smith River. All previous studies appear to be juvenile focused; with repeated adult counts having occurred only in index sections of Mill Creek (McLeod and Howard 2010). A review of coho salmon distribution by Garwood (in review) identified 34 streams as having historic occurrence in the Smith River.

Smith R. Surveys

Smith River Level II Stream Surveys

Thanks to a great team and sufficient funding, 2012 was another good year for completing stream habitat surveys. The purpose of the surveys is to identify existing stream channel, riparian and aquatic ecosystem conditions on a watershed scale. Periodic, recurring stream surveys are an integral part of the fish habitat and watershed management programs. These surveys generate the baseline information which is used to support a variety of management activities including watershed analysis, fish habitat and watershed restoration projects, and stream monitoring and evaluation programs.

As inventories are completed and repeated over time, the information generated by them can be useful in measuring changes in stream channel conditions. In 2012 surveys were completed on the upper Middle Fork and Griffin and Monkey Creeks which are tributaries to the Middle Fork. Survey work was also completed on Copper Creek which is a tributary to the lower Smith. Special thanks to our funding partners — the Resource Advisory Committee for Title II Secure Rural Schools Act funding, the California Department of Fish and Wildlife, Redwood National and State Parks, and Del Norte County.

Download completed stream surveys

Volunteer Summer Surveys of Adult Trout and Salmon

The Smith River is famous for the fall-run Chinook salmon and winter-run steelhead trout that support an outstanding fishery, yet few people experience spring-run Chinook salmon and summer steelhead. These other salmonids are too rare to support a fishery, but they are important components of the Smith River’s biodiversity. These large fish reside in the river throughout the summer months. Coastal cutthroat trout are also present in summer and with great abundance.

The exceptional clarity of the Smith River makes it possible to annually survey the abundance and distribution of fish in summer using direct observation (mask and snorkel). The Smith River National Recreation Area (USFS) and the California Department of Fish and Game have intermittently monitored summer adult fish populations of the Smith River since 1982. With the support of these agencies, the Smith River Alliance began in 2000 to sponsor and coordinate a volunteer-based survey of adult fish (aka “Fish Count”). This event has been successful in both contributing to a long term data set on summer fish populations and providing an exceptional educational experience for participants.

Download Fish Survey Results from past years:
2017 | 20162010 | 2009 | 2008 | 2007 | 2006 | 2005

Lifecycle Monitoring

Mill Creek Salmonid Lifecycle Monitoring Station Juvenile Coho Salmon Outmigrant Trapping Project 2014-2017, Smith River, California

This report primarily summarizes the Mill Creek Lifecycle Monitoring Station (Smith River basin, California) smolt outmigrant trapping program results from 2014-2017. Additionally, given this is one of the longest running smolt trapping programs in California (1994-2017), we provide an overall summary of annual Coho Salmon smolt estimates throughout the program’s history.

2016 Mill Creek LCM Station Juvenile Outmigrant Trapping Annual Report

This annual progress report describes out-migrant trapping data collected by Mill Creek Lifecycle Monitoring Station partners estimates the abundance of salmonid smolts emigrating from Mill Creek, Smith River (California) during the spring of 2015. The report also estimates the apparent overwinter survival probability of Coho Salmon (Oncorhynchus kisutch) marked in the Fall of 2014 in Mill Creek and its three primary sub basins.

We would like to thank the California Department of Fish and Wildlife for its continued commitment to and support of all aspects of the Coastal Salmonid Monitoring Program in the Smith River basin including the Mill Creek Life Cycle Monitoring Station. The California Department of Fish and Wildlife was instrumental in the development and implementation of the out-migrant trapping portion of the Mill Creek Life Cycle Monitoring program through contributions from Sportfish Restoration Act funds. Among the many contributions to the Mill Creek Life Cycle Monitoring Station by the California Department of Fish and Wildlife include the rotary screw trap. We also wish to acknowledge the critical support provided by the Save the Redwoods League for their generous contribution toward Fall tagging efforts necessary to better understand Coho Salmon Salmon survival and distribution in the Mill Creek Lifecycle Monitoring Station.

A hearty shout out goes to all of the exceptional field biologists who collected rigorous field data: Sunny Bourdon, Vimal Golding, Rachael McCain, Jesse Nolan, Marisa Parish and their leader Jolyon Walkley.

Beaver Study

Juvenile Coho Salmon Use of Beaver Habitat


The ecological engineering activities of the North American beaver (Castor canadensis) have been shown to provide beneficial habitat for salmonids species including coho salmon and to increase overall biodiversity of small streams and their surrounding ecosystems. However, data showing beaver importance in coastal rivers and large tributaries are lacking despite beavers being common in many coastal rivers. Furthermore, no previous research has focused on beaver bank lodge use, distribution, and influence on salmonid habitat.


The undammed Smith River is a unique setting to study relationships among beavers and salmonids. In 2014, Smith River Alliance initiated research on juvenile coho salmon use of beaver and non-beaver altered habitats in the Smith River coastal plain and estuary through a collaboration with California Department of Fish and Wildlife and Humboldt State University graduate student Marisa Parish. This research was an extension of our estuary monitoring, Inventory of Juvenile Salmonid Rearing Habitat in the Smith River Plain, which was supported with funding from the California Department of Fish and Wildlife Fisheries Restoration Grant Program and Smith River Alliance.

Marisa’s study is focused on beaver bank lodge site selection and distribution to better understand beaver habitat preferences in coastal rivers. This research also evaluated the influence of beaver bank lodges on salmonid summer and winter rearing habitat. Results from this study provide insight on how beavers influence coastal rivers and can inform management and restoration efforts to help promote healthy beaver populations and the various salmonid rearing habitats they create.

Estuary Monitoring

Posted December, 2016
New Study Released:

Winter Distributions, Movements, and Habitat use by Juvenile Salmonids throughout the Lower Smith River Basin and Estuary, Del Norte County, California

Properly functioning estuaries are complex systems where aquatic organisms benefit from a variety of spatial and temporal niches. This is especially evident for Pacific juvenile salmonids, where studies have shown estuarine habitats can be more productive and can lead to greater growth and survival compared to those derived from natal stream habitats occurring upstream. Habitats including low gradient streams, sloughs, backwaters, off channel ponds, and emergent tidal wetlands have been shown to be especially productive features for rearing juvenile salmon throughout California and the Pacific Northwest. Understanding the functional role of coastal streams and estuaries can aid management and restoration decisions in maximizing population resilience through protection of diverse life-history patterns expressed among various salmonid populations.

This study adds a second winter period to a two-year comprehensive fish and habitat inventory of the lower Smith River and its estuary. From January 7 to March 19, 2016 we surveyed a total of 200 winter salmonid rearing habitat across 35.9 km using minnow traps, beach seines, and snorkel surveys. We also evaluated migration timing and residence in coastal streams by utilizing PIT tag antennas located in Morrison Creek and Tryon Creek. We found coho salmon to be widely distributed throughout coast tributaries that are dry during some of the summer months. Our findings can help to guide restoration efforts to maximize the survival of estuarine rearing individuals and aid in the recovery and conservation of salmonids in the Smith River basin.

Posted June, 2015
2015 Study

Distribution of Juvenile Salmonids and Seasonally Available Aquatic Habitats within the Lower Smith River Basin and Estuary – August 2015

Studies have suggested that estuaries, sloughs, backwaters, off channel ponds, and beaver structures are productive habitat features for rearing juvenile coho salmon throughout the Pacific Northwest. Little is known about the degree to which habitat features are available and used by rearing coho salmon in the lower Smith River. This project was the first year of our efforts to identify, map, and monitor juvenile coho distribution and habitat in the main channel, sloughs, beaver sites, alcoves, backwaters, and tributaries within the lower Smith River. Results offer essential baseline information to aid in restoration efforts.


DIDSON-Bryant-AndersonDual Frequency Identification Sonar

Dual Frequency Identification Sonar (DIDSON) was used to count adult anadromous fish migrating through the lower Smith River, Del Norte County, California during the 2014-2015 spawning season — and in previous seasons as well. DIDSON is multi-beam, high-definition imaging sonar that transmits sound pulses and converts the returning echoes into digital images. The technology is becoming more widely used to count Pacific salmon returning to rivers to spawn.

The DIDSON (Dual Frequency Identification Sonar) project has been possible thanks to a grant from the CDFW Fisheries Restoration Grants Program to estimate Chinook and steelhead escapement in the Smith River. For the 2014-15 season, the DIDSON Fish Counting Station at Smith River mile 6 began recording the salmon and steelhead migrations during the first fall storm in late September 2014. The station recorded the migrations continuously until the end of March 2015. Estimates of Chinook salmon migrating upstream past the sonar site were between 15,000 and 16,000 fish. Estimates of steelhead migrating upstream were between 12,000 and 13,000 fish.

Visit the DIDSON Fish Counting Station! If you find yourself on the Smith during steelhead season, a visit to the DIDSON station can be educational and entertaining. The project operators are knowledgeable, enthusiastic and eager to show off the capabilities of this technology and talk about their findings. Plus most of them are anglers, passionate about the river and its steelhead. Check it out. You’ll learn something. The DIDSON is a cooperative project involving many partners including Zack Larson & Associates, Del Norte County, SRA, and others. For more information see the PDF PowerPoint or contact Zack Larson at