Wednesday, December 8, 2010

Historic Abundance, Real Context for Recovery

While data on the past abundance of salmon and steelhead in our rivers can be hard to come by, it is generally acknowledged that there were alot more salmon in the past. Often we hear "salmon so thick you could walk across their backs" as a description of past salmon abundance. Unfortunately, most agency records date back only to the 1950s and the majority of monitoring efforts were not started until the 1970s or later, so we have mostly been left to speculate about exactly how productive our rivers once were, unitl recently.

In 2006 Bill McMillan published an analysis which he coauthored with Nick Gayeski of the Wild Fish Conservancy. The report, which predictably, was widely dismissed by WDFW officials, is the best attempt ever made to quantify historic abundance of steelhead in Washington State. Using early commercial fishing and cannery records they made the first robust estimates of steelhead abundance in many of Washington's Rivers. What the found was startling, many of the rivers in Washington State once supported tens of thousands of steelhead. In the heart of steelhead's range these rivers supported some of the most productive and diverse populations of steelhead in the North Pacific at the time of colonization. Historical records suggest the Stillaguamish River once supported a run of 60-90 thousand winter steelhead. Today the escapement goal is 950 fish, as little as 1% of historic abundance. In 2009 WDFW estimated that 125 winter fish returned to the entire Stillaguamish basin. On the Queets data shows that historically between 50 and 80 thousand fished returned annually. Today run sizes are depressed below 10 thousand fish and commercial harvest of steelhead continues to take a substantial portion of the run every year. In another recent analysis of the North Umpqua River canning records, McMillan uses information dating from 1919 to estimate historic abundance of steelhead on the Umqua well in excess of 100 thousand fish and possibly as high as 200 thousand fish.

Taken in the context of modern steelhead abundances where populations are most often counted in the few hundreds, tens of thousands of fish can seem difficult to imagine. How could we have possibly driven populations to such low levels, and why can't we recover some semblance of historic abundance. To fully incorporate historic abundance into our recovery goals we must first understand the process by which populations were so rapidly depleted. While historic records are undoubtedly patchy, the story they tell is one of fantastically abundant populations of salmon and steelhead in the period of the first american settlements in the Northwest. Within a few generations many populations had collapsed to much lower levels of abundance. This can be explained by a couple of mechanisms. With protracted freshwater rearing, steelhead are typically much less productive than their salmon cousins and intensive harvest likely meant that within a few generations, only the most productive portions of the stock complex remained.The rate at which agriculture and resource extraction changed the landscape also had profound impacts on steelhead populations. Clearing of forested floodplains for agriculture, diking of floodplain reaches, dredging for barge traffic, splash damming and extensive timber harvest, unregulated mining and the construction of irrigation dams which blocked fish passage all brought devastation to once pristine habitats. Even 100 years later, the legacy of these impacts remains.

While historic abundance numbers may paint a grim picture of devastation and loss in populations of salmon and steelhead, it also provides hope. Salmon and steelhead have throughtout their history recovered from catastrophic disturbances including glaciation, megafloods and volcanic eruptions. As our understanding of the linkages between intact habitat and the productivity of salmon and steelhead grows we are increasingly capable of undertaking restoration projects which can benefit wild fish. The next step however is changing the culture that surrounds salmon. With so many economic and cultural interests in play, moving away from the status quo of intensive harvest and large scale hatchery supplementation will be extremely difficult but not unattainable. We will never recover populations to historic levels, but by incorporating our knowledge of historic abundance and habitat loss we may someday be able to recover populations to a level beyond what our current management paradigms could ever imagine.

See the 2006 publication at Wild Salmon Center's website:

An interesting analysis reposted on the North Umpqua Fly Guide Blog:

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