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~~~~ !~~~~~ ~U~~ Arch. Environ. Contain. Toxicol. 27, 195-201 (1994) ~~~~ ARCHIVES O F Environmental Contamination and TOXICO~Og~/ ® 1994 Springer-Vaiag New York Inc. Selenium in Eggs and Milt of Razorback Sucker (Xyrauchen texanus) in the Middle Green River, Utah S. J. Hamilton', B. WaddellZ ' U.S. Fish and Wildlife Service, National Fisheries Contaminant Research Center, Field Research Station, RR 1 Box 295, Yankton, South Dakota 57078-9214, USA a U.S. Fish and Wildlife Service, Ecological Services, 2060 Administration Building, 1745 West 1700 South, Salt Lake City, Utah 84104-5110, USA Received: 30 September 1993/Revised: 3 February 1994 Abstract. Eggs from three female and milt from five male endangered razorback suckers (Xyrauchen texanus) were col- lected from the Razorback Bar (about 20 km upstream of Ash- ley Creek) in the Green River of northeastern Utah. Eggs, but not milt, had concentrations of selenium that were above the range of selenium concentrations in control fish from laboratory studies or reference fish from field studies. The concentrations, however, were below those reported in selenium-exposed fish that had reproductive problems in laboratory studies or field investigations. Tests with three streamside spawned pairs of razorback suckers, which were sampled for eggs and milt in this study, resulted in no hatching of fertilized eggs. Concentra- tions of selenium in eggs and milt were significantly correlated with selenium concentrations in muscle plugs taken from the same fish, but egg and milt concentrations were not signifi- cantly different from muscle plugs. Selenium concentrations in eggs of razorback suckers in the Green River maybe suffi- ciently elevated to cause reproductive problems that are con- tributing to the decline of this species in the upper Colorado River basin. The razorback sucker (Xyrauchen texanus) was listed as a fed- erally endangered species in 1991 (U.S. Fish and Wildlife Service 1991). Studies of razorback suckers in the Green River, Utah, between 1979 and 1986 reported low numbers of adults, little growth, and no apparent recruitment (Tyus 1987). The decline of the species throughout its range in the Colorado River system has been attributed to dam building, habitat de- struction, habitat alteration, impairment of water quality, and interactions with non-native fishes (Minckley er al. 1991). De- spite the presence of irrigated agriculture in the Green River Correspondence to: S. J. Hamilton drainage, little attention has been given to contaminant impacts from irrigation projects. Razorback suckers historically have been found in the Green River in northeastern Utah, immediately adjacent to Stewart Lake and the confluence of Ashley Creek and the Green River (Figure 1). The soils in this area are derived from Mancos shale which contains about i ,100 µg/kg selenium (Stephens et al. 1992). Ashley Valley contains about 28,000 A of irrigated agricultural land, and drainwater is discharged via surface flow or rile drains to either Ashley Creek or Stewart Lake with outflow to the Green River (Stephens et al. 1992). Low-inten- sity inigation activities have occurred in this area for 60 years, whereas intensified irrigation and drainwater disposal have oc- curred only since about 1979. Concentrations of selenium found in the water from Ashley Creek ranged from 59 µg/L in 1987 to 78 µg/L in 1988 (Peltz and Waddell 1991). Selenium concentrations in whole-body fish collected from Ashley Creek in 1989 during a study of the middle Green River ranged from 40.1 µg/g dry weight in black bullhead (Ameiurus melas) to 122 µg/g in fathead minnow (Pimephales promelas) (Peltz and Waddell 1991). Ashley Creek had the largest concentration of selenium of all tributaries to the Green River sampled. Stewart Lake receives substantial amounts of irrigation drainage water and discharges about 25% of its selenium into the Green River. Selenium concentrations in drainwater collected in 1988-89 on the north shore of Stewart Lake ranged from 13 to 26 µg/L in drain J1, 29 to 35 µg/L in drain J3, and 67 to 85 µg/L in drain J4. Selenium concentrations in the outlet of Stewart Lake on the south shore were L 1-12 µg/L during the same time period. Concentrations of selenium in whole-body fish collected in 1989 from the outfall of Stewart Lake ranged from 11.2 µg/g dry weight in green sunfish (Lepomis cyanellus) to 24.8 µg/g in fat- head minnows (Peitz and Waddell 1991). The presence of razorback suckers at the confluence of Ash- ley Creek and the Green River was clearly documented during a time period immediately prior to spawning (Tyus 1987; Tyus and Karp 1990). Large numbers tagged at that site were later found both upstream and downstream in spawning conditions (Tyus 1987). Most spawning occurs approximately 20 km up-