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Update on the Historical Columbia River Steelhead/Salmon Abundance Project

Category: Newsletter Articles | Posted by: Jonathan | 12/18/11 | Comments: 0

Summary: Bill McMillan was awarded a $5,000 grant from the Wild Steelhead Coalition (WSC) in early 2010 to continue research and develop an accurate historical baseline of what steelhead/salmon numbers and distribution were in the Columbia Basin prior to Euro-American contact. Funds for the WSC grant were secured from Patagonia's World Trout Grant program.  A previous update regarding this project was featured in the November 2010 issue of The Adipose.
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by Bill McMillan

Historical Columbia River salmon catch

Beach Seining Salmon at Sand Island, Columbia River (near Ilwaco) 1897. (WA State Archives, Digital Archives item # AR07809001-ph001915.)

It had been hoped by now that this project would be complete, but it is not. This has not been for lack of hours spent on the project since receiving the grant, thus far over 900 hours since May of 2010 through September of 2011.

This is a cooperative project involving me and three authors from NOAA. We have had two meetings about which of the extensive historical data collected for the project to use as the basis for an initial paper that can help to guide recovery of ESA listed steelhead and salmon in the Columbia basin. We initially planned to provide a map of the Columbia basin that would show the breadth and extent of historic distribution of each species/race of steelhead/salmon. I had previously expended long hours putting distribution dots determined for each species at the upstream extent of every tributary (large and small) of the Yakima, Walla Walla, and Umatilla River subbasins. These dots were placed on hard-copy maps showing small areas of each subbasin in detail. These maps were then given to a University of Washington GIS class project from which to make a digital map of these Columbia subbasins with appropriate latitude and longitude locations for each dot, some several thousand such dots in all. They did an exceptional job of doing so but they were time limited to completion of only the Yakima subbasin. I attended their final presentation at the UW on June 1st of 2010 at Meany Hall at which there was an audience of a couple hundred interested people.

Out of this project, over the summer of 2010 it became clear that a complete map of the Columbia basin above Bonneville with similarly digitized point placements was not going to be doable anytime soon due to increasing budget constraints within NOAA that have denied anyone being able to work on this project with any specific funding — except for me. Although a large scale map of the Columbia basin as formerly planned will not happen in the near future, a map of the Yakima basin can provide a significant story as one of the largest subbasins of the Columbia. I continue to hope the Yakima map will end up being an initial piece in what might become a publicly available website that can provide a gradually growing picture of what the basin once looked like for historical steelhead/salmon distribution and extent, but at this point the GIS person formerly working with us through NOAA is gone.

During the first of the two meetings with the other authors, we thought that perhaps the best way of fulfilling the Patagonia/WSC grant would be to create an internally reviewed paper providing a broad view of several differing means of measuring what historical steelhead/salmon abundance was prior to Euro-American contact. These differing measures were to include:

• early commercial catch data and other historical evidence of catch combined with computed escapement estimates (as has previously been done, but which relied too heavily on commercial catch data alone);

• computation of what the amount of salmon was required to sustain the estimates of aboriginal population sizes in the Columbia basin (also previously done but each likely underestimated the amount of pounds of salmon required to sustain each person);

• computation of what the salmon use was by the major wildlife predators that shared salmon harvest in the Columbia basin with aboriginal peoples (this has not been done before and would add a significant amount of salmon/steelhead harvested by seals, sea lions, bears, wolves, and etc. to that harvested by aboriginal peoples and which still resulted in sufficient spawning escapement of salmon/steelhead to sustain them at high levels prior to Euro-American contact);

• use some sort of habitat measure as a primary determinant of how many steelhead and salmon the Columbia basin above Bonneville could have once sustained, a most primary one being amount of available spawning gravel for which there were actual measures made throughout much of the Columbia basin between 1934 and 1944

As I collected data for these four methods of determining pre-contact steelhead and salmon abundance, it became clear that it was leading to a project that would take another year or two to create as envisioned. However, it increasingly stood out that a gravel-based estimate of historical salmon/steelhead abundance was within the scope of completion in several months. Furthermore, it could be of small enough size and scope for peer reviewed journal publication. We subsequently had another meeting in early June of this year with all agreeing on this reduced scope that would provide the most bang as a scientifically defensible paper in the least amount of time. This remains our plan.

The data for this paper is now fully collected. The draft Introduction is written. However, the primary person for making the data talk in a mathematical model designed to do so has also been the lead person for NOAA in Elwha dam removal and monitoring as well as juggling several other projects within NOAA the past year. With the Elwha now running free, a window will again be available to cooperatively work on the Columbia project over the coming winter months. Until the gravel data are run through the mathematical model to determine the resulting spawning number of each species that the historic gravel could support the Columbia project has been unable to move forward. Once that occurs he can write the vital Methods section of the paper. Once the data are run through the model we will have the nuts and bolts for the entire paper in place. The most time consumptive portion is done – the data collection. Once the model is run, things will go comparatively quick. Nevertheless, a draft of the paper for publication remains 2-3 months down the line.

I much appreciate the patience with the slow progress that has occurred. It will eventually result in an important piece of work that provides a new method for assessing recovery and recovery planning that has an historical basis with resulting measures that can currently be applied for developing habitat-based escapement goals.

Further discussion about the importance of gravel as a measure for steelhead productivity at the larger eco-system perspective in the Columbia and elsewhere:

The measure of gravel per stream width and stream length at spawning time can vary at differing times of year. For instance many interior Columbia River streams carry higher flows of water from April through July when steelhead spawn. This means that there is greater wetted width of gravel potentially available than during low flow periods that salmon commonly face in the fall. However, depending on specific stream channel conformation, it can also mean that the only usable gravel is at more limited areas of stream along the bank edges or pool tailings due to flow velocities being too high in other areas. So it is a mixed bag of balances.

Steelhead can also access small streams during spring/summer runoff and reach usable spawning gravel that is otherwise inaccessible to salmon that spawn from August through October when many streams are at their lowest flows. In fact, many smaller tributaries can have significant portions that run dry from late summer through the fall and only steelhead make use of them. One might wonder, if this is the case then why don’t steelhead return in larger numbers than salmon. One reason is that steelhead rear longer than most salmon within streams before reaching the necessary size for smolting after 1-4 years of freshwater rearing. Therefore the amount of spawning gravel available is counter-balanced by the need for sufficient rearing habitat and sufficient instream productivity to sustain juvenile steelhead for those variable freshwater years. Also, although there are many miles of small tributaries that steelhead can potentially use for spawning, the actual usable gravel area within their smaller wetted widths is not nearly as great per mile as a mainstem river.

As with all salmonids, available spawning gravel remains the most basic habitat bottom line. Without sufficient gravel for egg deposition steelhead productivity is greatly constrained. Everything begins with successful egg-laying and egg-to-fry survival.

Species like chum and pink salmon (and some Chinook) that quickly outmigrate toward the sea after emergence from the gravel depend little on freshwater habitat other than spawning gravel. This can similarly be the case with sockeye that may immediately migrate to a lake for rearing. But steelhead rearing productivity is also greatly increased by large amounts of available gravel that can sustain chum, pink, and sockeye with the added nutrients of their eggs and carcasses. In the case of the Columbia above historic Celilo Falls apparently chum salmon did once return to some areas and sockeye salmon were once very abundant in others. But on the whole it was the nutrients from Chinook and coho salmon that were dispersed more broadly over areas where rearing steelhead cohabited and benefitted.

In the case of Chinook, the Columbia is noted for the largest runs to have occurred in their native North Pacific Rim range. While not as abundant as chum, pink, and sockeye in some other North Pacific river basins, Columbia Chinook were of large average size and provided 2-5 times the bio-mass per average returning fish than other salmon species (historic Columbia sockeye averaged 4-5 pounds, coho 7-8 pounds, chum 10 pounds, and Chinook 20-22 pounds overall – variable between spring, summer, and fall races and specific populations). They were, and remain, vitally important for making larger mainstem habitats nutrient-rich and productive, and in the case of spring Chinook they frequented quite small tributaries in cold and what may otherwise be nutrient-starved habitats shared with steelhead/rainbow, bull trout, and in some areas westslope cutthroat trout.

Coho salmon frequently cohabited smaller streams with steelhead in the Columbia basin and braided channels of mainstems. They most commonly occupied tributary areas where beaver dams and related ponds and marshes sustained flows during the otherwise low water period of October to early December when the coho once abundantly spawned in those areas. These portions of smaller tributaries that benefitted from coho nutrients and sustained flows related to beaver dams, ponds, and wetlands may have been vital to steelhead juveniles that were driven from upstream tributary areas that increasingly went dry through the summer/fall and maybe even into early-winter. Coho made these important refuge areas nutrient-rich with their carcasses and subsequently more aquatic life than elsewhere to sustain both rearing coho (1-2 years of rearing) and steelhead (1-4 years of rearing with some extreme cold headwater areas requiring 5-7 years of rearing in the Methow and Wenatchee basins as “rainbow trout” before transformation to outmigrating steelhead smolts).

In this regard, spawning gravel available for multiple species ultimately benefits steelhead rearing and renders the amount of their own available spawning gravel that much more important. These are the basics of viewing river basins and multiple species from the interactive eco-system perspective. In other words, single species management has often plagued fisheries management as a whole with the resulting inability to sustain salmon/steelhead abundances that habitat may still provide the capacity for – but only if fully occupied by salmon.

When it comes to habitat and rearing for steelhead, they are noted as the great generalists. Highly adaptive, they can take advantage of a broader mix of habitats than any single Pacific salmon species. It may be one primary reason Alaska’s Situk River has so many steelhead per area of available habitat. Viewed from the perspective of what is considered classic steelhead rearing habitat commonly identified as boulder/cobble riffles, the Situk River has very little. But what the Situk does have is abundant spawning gravel for all Pacific salmonids, a great deal of large wood to help retain nutrients and to provide cover, salmon managed to bring back sustained large returns, and in the past 30 years more emphasis on protective wild steelhead management. Apparently Situk steelhead can sustain very little harvest in climate conditions that typically require 3-4 years of juvenile rearing compared to an average of 2 years in the Columbia.

Therefore, at the salmon-driven eco-system perspective available spawning gravel is a particularly vital criterion from which to make estimates for spawning escapements … not at the single species level alone, but as multiple species that make up the whole. Gravel is measurable. The number of species/specific fish that can use that gravel with sustained abundance has both historical and sometimes contemporary evidence from which to determine how many fish can and should use it. A certain area of available gravel for steelhead is often a meaningless measure if the rest of the gravel in the river basin is not abundantly occupied by salmon. There are sometimes large areas of river basins where some races or populations of summer-run steelhead are isolated from other anadromous fish, such as Wind River above Shepard (this is the oldest of several spellings) Falls once was. In these limited instances, single species management for steelhead/rainbow may be more applicable, but in the majority of instances we need to better expand our management view to that of restoring functioning eco-systems – not simply that of restoring steelhead, or Chinook, or coho, or any single species. Using spawning gravel as a measure to determine escapement targets for all species combined is one necessary component for moving us toward recoveries.

 

 

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