Estimating the Size of Historical Oregon Salmon Runs

Abstract

Increasing the abundance of salmon in Oregon's rivers and streams is a high-priority, public policy objective. Salmon runs have been reduced from predevelopment conditions (typically defined as prior to 1850), but it is unclear by how much. Considerable public and private resources have been devoted to restoring salmon runs, but it is uncertain what the current recovery potential is because much of the freshwater and estuarine habitat for salmon has been altered and there is no expectation that it will be returned to a predevelopment condition. The goals of all salmon recovery efforts are based on assumptions about the size of the runs prior to significant habitat alteration, coupled with an estimate of the amount and quality of freshwater and estuarine habitat currently available. We estimated the historical aggregate salmon run size in rivers along the Oregon coast (excluding the Columbia River) using two methods: (1) converting estimated aboriginal population levels into numbers of salmon; (2) extrapolating cannery pack into numbers of salmon. Annual aboriginal harvest of all salmon species is estimated to have been approximately 10 million pounds per year (4,500,000 kg) or 1.75–5.36 million salmon, a harvest level similar to that occurring during the height of commercial fishing on Oregon's coastal rivers in the late 1800s and early 1900s. Extrapolating cannery pack data, the estimated size of the late 1800s aggregate runs of coho salmon (Oncorhynchus kisutch) was 1.5–2.5 million. The estimated size of aggregate runs of chinook salmon (Oncorhynchus tshawytscha) runs was 290,000–517,000. Compared to our estimates of mid-1800s coho salmon levels, early 2000 runs (during favorable ocean conditions), were 11–19% of the historical level. During poor ocean conditions (1990s), current coho salmon runs were 3–6% of the historical size.

Keywords:

• salmon
• Oregon
• Pacific Northwest
• endangered species
• ecological restoration

Acknowledgments

The views and opinions presented are those of the authors and do not necessarily represent those of any organization.

Notes

Note: The data are calculated as follows: First, divide per capita consumption estimate in lbs (b) by the migration calorie loss factor (c) to obtain an estimate of salmon consumption(d). Second, divide the weight estimate (d) by 0.8 to obtain the per capita annual consumption weight estimate (e). Third, multiply the annual consumption weight (e) by the estimated number in each population group (a) to estimate the salmon harvest. Finally, sum the harvest levels to estimate the total annual harvest (in pounds) of salmon along the Oregon coast (f).

Entries listed as “Bay” represent all streams and rivers entering into that bay.