THE VALUE OF IN-STREAM WATER TEMPERATURE FORECASTS FOR FISHERIES MANAGEMENT

I. INTRODUCTION This paper examines the economic value of short-term stream temperature forecasts for salmonid management. Factors inhibiting the growth and survival of Pacific Northwest salmonids have received extensive attention for over 50 years. Despite this attention and billions of dollars invested in salmon recovery (Wu et al. 2003). many stocks continue to decline. Current run sizes of wild salmon in the Northwest (California, Oregon, Washington, and Idaho) are estimated to be between 1.7% and 8% of historic (late 1800s) run sizes (Lackey 2003). Of the 17 Chinook salmon evolutionary significant units (ESUs) identified by the National Marine and Fisheries Service (NMFS), 9 are listed under the Endangered Species Act (ESA). Similarly, of the 15 steelhead ESUs identified by NMFS, 10 are listed. A recent NMFS review of the status of West Coast populations of Pacific salmon and steelhead concluded that all ESA-listed ESUs are either in danger of extinction or likely to become endangered in the foreseeable future (Good, Waples, and Adams, 2005). These declines have been caused by a combination of natural and anthropogenic factors, including agriculture, forestry, land and water development, grazing, harvest, hatcheries, dams, and changes in water flow and temperature. Efforts to rebuild salmon slocks began in the early 1980s at the local, state, and federal levels (Aillery et al. 1999). As a consequence of the broad geographic scope of salmon habitat, these efforts increasingly conflict with existing land and water uses within a watershed. A wide range of recovery actions have been implemented, including habitat rehabilitation, restrictions on recreational and commercial catch, changes in operations of hydroelectric power facilities and hatchery programs, logging restrictions, and stream flow augmentation (Bell, Huppert and Johnson 2003; Costello, Adams, and Polasky 1998; Jaeger and Mikesell 2002). Most streams in the Pacific Northwest have total maximum daily load (TMDL) restrictions related to temperature. Failure to meet water temperature standards is the most common water quality violation throughout the Pacific Northwest and one of the key factors affecting the productivity of freshwater habitat of salmonids (Oregon Department of Environmental Quality 1998). Hence, many recovery programs include current and future water temperature as a component of fish recovery.1 As cold water fish, salmonids are vulnerable to elevated water temperature in the freshwater environment. Prolonged exposure to elevated water temperatures may cause thermal stress, weight loss, and increased mortality rates (Su 11 ivan et al. 2000). High water temperatures can also decrease fecundity, reduce egg-to-fry survival rates, inhibit the growth and survival rate of pan" and smolts, lower rearing densities, and decrease the ability of young fish to compete with other species for food and reduce their ability to avoid predation (McCullough 1999). Additionally, elevated water temperatures increase the vulnerability of both juveniles and adults to disease (Udey et al. 1975). A well-known example of such a disease effect is the fish kill in the Lower Klamath River, where between 33,000 and 70,000 adult Chinook salmon died during their spawning migration in September and October of 2002 (California Department of Fish and Game 2004). Its primary cause was a disease outbreak that occurred under conditions created by a combination of warm water temperature, an above average number of fish, and low river flow, which created serious overcrowding. This event had important management implications because it led to significantly augmented water releases from Lewiston Dam during the following summer in order to ensure that another fish kill would not take place (Zedonis 2004). The tish kill also led to implementation of a "weak stock'-management policy that resulted in an estimated loss of over $100 million for the commercial salmon fishery (Pacific Coast Federation of Fishermen's Associations 2005)? …