(This article was featured in the November 2010 issue of WSC’s newsletter, The Adipose.)
By Chris Grieve
Most of the Wild Steelhead Coalition members are aware that the Sauk and Skagit rivers were closed early the last two years during the winter seasons. Many of you probably didn’t know that a small amount of fishing activity continued during the closure in an effort to collect data on hatchery and wild steelhead. For the last two years the Washington Department of Fish and Wildlife (WDFW), Skagit River Tribal Co-managers, and Seattle City Light have managed to obtain money to do genetic sampling of Skagit and Sauk River wild and hatchery steelhead.
As it turns out, the safest way to catch steelhead for DNA sampling and acoustic tagging* is by using hook and line (fishing). Brett Barkdull, the WDFW district biologist and harvest manager for the Skagit River, Dave Pflug, a senior fisheries biologist with Seattle City Light, in addition to biologists with Skagit River System Cooperative, Upper Skagit Indian Tribe, Puget Sound Energy, University of Washington, and a couple local Skagit River guides have been catching, obtaining genetic samples, and releasing steelhead in April and May for the last few years. The project is funded in part through the federal Saltonstall-Kennedy Grant program. Another portion of the money used to pay for this project is hatchery reform money that was acquired through the Northwest Indian Fisheries Commission by the Skagit River System Cooperative. The project is loosely referred to as the SK Grant.
The purpose of the SK Grant is to determine the extent of genetic mixing of Chambers Creek origin hatchery steelhead with the wild steelhead stocks in the Sauk and Skagit Rivers. (Geneticists refer to this as introgression.) The original intent was to get two years worth of information from each site so a comparison could be made between years on an individual site. The WDFW also intends to use the genetic samples to determine if there are separate populations of wild steelhead in these rivers.
The team of biologists and guides mentioned above attempted to collect a total of 50 genetic samples of adult wild steelhead over the two year study. Sample collection was attempted at the following locations on the Sauk and Skagit Rivers and their tributaries: Lower Skagit River, Upper Skagit River, Cascade River, Sauk River, Suiattle River, and Finney Creek. They also attempted to collect a total of 50 juveniles taken from these same sites as well as the smolt trap at Burlington, and Chambers Creek origin juveniles from the Marblemount hatchery, The team also collected DNA samples from adult steelhead captured in tribal fisheries.
In addition to DNA from wild and hatchery steelhead, the group also attempted to collect samples from two year classes of isolated resident rainbow populations at the following sites: Ross Lake, NF Cascade River, NF Sauk River, Clear Creek, Sauk River, Baker Lake, and Finney Creek above the migration barrier.
The research team has successfully achieved the majority of these sample collection objectives, with the exception of adult samples from a few locations. The winter of 2008/09 sample collection effort, conducted when the rivers were closed in April and May, was successful on the Lower Skagit, Upper Skagit, and the Sauk. However, the team was not able to collect the targeted number of samples from the Cascade River because the fishing conditions in May were difficult. Sample collection on the Suiattle and in Finney Creek was not successful. They had more success in these systems in the winter of 2009/10. These data compliment an existing WDFW scale DNA data set collected in the winters of 2006/07 and 2007/08 on the upper Skagit and Sauk rivers.
In addition, the group collected DNA samples of resident rainbows from several Upper Skagit tributaries. The list includes Goodell Creek, Bacon Creek, Diobsud Creek, and rainbows from the Blackwater River in British Columbia (Blackwater River rainbows have been planted into Ross Lake).
The genetic information provided by this research is needed on all Puget Sound rivers. It will establish a genetic baseline for specific stocks and help determine if introgression has occurred which would impact that stock’s DNA (such a change would undoubtedly lower the wild stock productivity as well as change its life history parameters). This baseline will also help in the future if new studies show further introgression and also help biologists and fisheries managers understand potential reasons for stock declines.
In addition to the DNA data, the SK team recognized and took advantage of an additional research opportunity provided by their capture and release sampling methods. The Skagit Basin has an extensive acoustical receiver array in place that is used to study smolt migration patterns. Seattle City Light generously provided additional research funding to the team, which they used to purchase 120 acoustical tags. These tags were implanted in adults captured in the Hamilton-Birdsview area for DNA sampling. These fish were tracked as they moved through the Skagit mainstem, providing valuable information on adult steelhead movement patterns in this river system.
Acoustic tagging studies of juvenile steelhead demonstrate the value of this kind of research. Recent tagging studies conducted by Seattle City Light, the Corps of Engineers, and several other research partners indicate that only about 10 percent of steelhead smolts tagged in the lower reaches of the Nooksack, Skagit and Green Rivers are making it through Puget Sound and into the Pacific. These findings inform hypotheses for new research. Are these survival rates the norm during early marine migration, or are poor conditions in Puget Sound a key factor in the decline of regional steelhead populations? Time will tell, and the answer will help to guide us toward more effective restoration efforts. Understanding how adult fish migrate to their spawning habitats will provide similarly valuable information about survival in freshwater.
Ongoing steelhead population monitoring efforts on the Skagit have indicated an encouraging trend. WDFW and the tribes annually count steelhead spawning redds in index reaches as a basis for estimating population strength. The recent trend in redd count data indicates that early run wild fish appear to be increasing in abundance. This may indicate that the “wild steelhead release” regulation that was instituted on the Skagit River in 2002 is having some success rebuilding this population. The SK group was able to collect DNA from both early and late fish, which will help to determine if these are actually separate spawning stocks or a single stock that is expanding its run timing. Regardless, these findings provide evidence that wild steelhead release is an effective tool for restoring population abundance and diversity.
There will be at least two papers written by the researchers. However, it will take a couple months to analyze the DNA samples collected this year and about 14 months before all the data is put together.
This article was written by Chris Grieve with input provided by Brett Barkdull, District Biologist for Skagit River north to the Canadian Border and San Juan Islands (Brett is also the Skagit River Regional Harvest Manager), Dave Pflug, senior fisheries biologist with Seattle City Light, Eric Doyle, biologist, and Dick Burge, retired WDFW fisheries biologist and WSC VP of Science.
*Acoustic tagging is a method of tracking fish movement by placing a small transmitter in a fish, releasing the fish, and tracking its movement as it swims by acoustic receivers that are currently set up in the Skagit River, Puget Sound, and the Straights.