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Selenium in Razorback Sucker 197 Table 1. Selenium concentration and percent moisture in eggs and milt of razorback suckers collected from Razorback Bar (abort 20 km upstream of the mouth of Ashley Creek) in the Green River, Utah Se Se' Fish Collection Fish Fish (µg/g) (µg/g) number date S weight length Moisture dry ~, ex (g) (min) (%) weight weight 1 2 04/29/92 '~ F 1,798 549 67.6 3.7 4 37 3 04!29/92 F (,485 545 84.1 10.6 . 31 97 4 04/29/92 04/29/92 F 1,649 540 78.2 4.7 . 7.14 5 04/29/92 M M 1,814 546 9(.9 l.8 7.37 6 04!29/92 M 1,176 477 95.0 6.7 25.95 7 05/05!92 M l ,127 47 l 92.9 1.3 4.51 8 05/05/92 M 1,375 1 570 504 526 95.3 2.8 3.55 , 91. l < l . l 11.51 'Selenium in muscle plugs--data from B. Waddell and T. May (pers. comm. 1992) The high selenium concentration found in eggs collected in 1991 and the endangered species status of razorback suckers is cause for concern for their future. This investigation was under- taken to determine selenium concentrations in eggs and milt of razorback suckers in the middle Green River, compare these concentrations with those measured in muscle plugs from the same fish, and evaluate possible effects on reproduction. A small number of ferilized eggs were collected from three pairings of razorback suckers on April 29. F15h 1 was mated with 6, 2 with 5, and 3 with 4 (see Table 1). Eggs were transported in a twofer to the laboratory at the CRFP office in Vernal, Utah, and placed in floating trays in a waterbath filled with dechlorinated tapwater. About 50 to l00 .eggs were placed in each tray. The same techniques used to success- fuily hatch razorback sucker eggs in previous years at the CRFP office were used ($. Haines, pers. comm., 1992). Materials and Methods Three female and five male adult razorback sockets were captured at the Razorback Bar between April 29 and May 6, 1992, using either electrofishing equipment or trammel nets checked hourly. These were the only fish available, in part, because of the rarity of these Fsh and because of the earlier than expected spawning activity. Capture and handling offish were accomplished jointly by U.S. Fish and WildSfe Service petsoir-tel of the Colorado River Fishery Project (CRFP) and Fish and Wildlife Enhancement (FWE), Salt Lake City, Utah. Fish were sexed, measured for length and weight, examined for external or internal tags, and sampled for reproductive products if mature. Ap- proximately 2 g of unfertilized eggs and 2 nil of milt were twllected. Samples were stored on ice in coolers in the field, and then transferred to a freezer for storage. Egg and milt samples were shipped on tce to the Patuxent Analytical Control Facility, Laurel, Maryland for anal- ysis of selenium concentrations. Samples were analyzed for selenium according to the method de- scribed by ICrynitsky (1987). Each 0.5-g aliquot of tissue was digested in 5 ml of nitric acid and then analyzed by graphite furnace atomic absorption spectroscopy. The nominal detection-limit was 1: l µg/L on a dry weight basis. The procedural blank was <0.03 µg. The relative percent difference from duplicate sample preparation and analysis was 2.6%. Recovery of NRCC (National Research Council of Canada) reference material DOLT-1 (dogfish liver tissue) was 85°.6. Prediges- tion spikes had a recovery of 98%. Percent moisture was determined in a sample aliquot dried 24 h in an oven at 200°F. Reference eggs were shipped to the National Fisheries Contaminant Research Center, Yankton, South Dakota from Dexter National Fish Hatchery (NFH), New Mexico. Brood stock at Dexter NFH originated from Lake Mohave, AZ-NV, and had been held at Dexter NFH for several years. Concentrations of selenium were determined for repli- cate sets of eggs and 30-day-old fry as described above, but analyses were conducted at Yankton. The detection limit was 0.019 µg/g wet weigh[. The procedural blank was 0.004 µg/5. The relative percent difference from triplicate sample preparation and analysis was 7.6%. Recovery of NRCC reference material DOLT-1 was within the recom- mended range. Predigestion spikes had a recovery of 95%n. Results Eggs of razorback suckers collected from the Razorback Bar contained 3.7 to 10.6 µg/g total selenium dry weight (Table 1). Milt contained <1. I to 6.7 µg/g selenium dry weight. Reference eggs from Dexter NFH contained 2.8 µg/g sele- nium dry weight (assuming 75% moisture; measured as 0.69 µg/g selenium wet weight. 0.07 SD, n=2). The resulting fry were fed live brine shrimp nauplii that contained background concentrations of 1.2 µgJg selenium dry weight (assuming 75% moisture) and a commercial fish diet that contained background concentrations of 2.0 µg/g selenium dry weight (26.2% mois- ture, n=5). Thirty-day-old fry contained 2.2 µg/g selenium dry weight (assuming 75°!o moisture; measured as 0.54 µg/g sele- nium wet weight, 0.18 SD, n=8 composite samples). No fish hatched from any of the three spawns incubated at the CRFP laboratory (B. Haines, pers. comm., 1992). About 30% of the incubated eggs were believed to be fertilized, but none reached the eyed stage. Although selenium concentrations in muscle plugs are the subject of a separate report (B. Waddell and T. May, pers. comm. , 1992), we present them here for comparison to sele- nium concentrations in eggs (Table 1). Muscle plugs were taken at the same time and from the same fish when egg and milt samples were collected. Muscle plugs from the three fe- male fish contained 4.4 to 32 µg/g selenium dry weight, and the five males contained 3.6 to 26 µg/g selenium dry weight. Discussion The gonads of fish do not normally contain elevated amounts of selenium. [n all but one laboratory or field study of selenium exposure where residues were measured in gonads, selenium