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132 The Southwestern Naturalist vol. 30, no. 1 TABLE 2.-Broodstock and indivduals used in temperature experiments Ra-rback 11-'ta61 Humpback squawfish (1) Squ Int, (11) TYPE Wild Wild Wild Hatchery Hatchery SOURCE L. Mohave, L. Mohave, Little WBNFH WBNFH Arizona Arizona Colorado River, Az. YEAR 1981 1979,80,81 1978,79,80 1974 1974 NUMBER FEMALES I 1 1 2 1 TL (mm) 620 490 413 485,490 496 WT (kg) 3.3 1.0 0.9 LI,L1 1.2 HCG' (IU/kg) 91 0 91,182 45 45 NUMBER HCG INJECT. 3x 0 3x,lx 3x 3x CPb (mg/kg) 0 0.45 1.81 0.91 0.91 NUMBER OF MALES 3 4 2 4 3 DATE SPAWNED 2/20 4/25 4/30 5/04 5/10 NO. OVA (est.) 104k 30k 20k 90k 45k WATER HARDENED (hrs) 1-2 1-2 I-L5 2-2.5 1-1.5 PERCENTAGE FERTILIZATION 90 76 95 95 83 ° Human chorionic gonadwropin ° Carp pine tary Broodstock and Experimental Individuals.-Broodstocks were obtained from wild populations in Lake Mohave, AZ-NV, and Little Colorado River, AZ, or as hatchery-bred fish from Willow Beach National Fish Hatchery (WBNFH), AZ (Table 2), and subsequently transferred to outdoor ponds at DNFH. As fish began to develop secondary sexual characteristics. 1-2 females and 5-20 males were tran- ferred from ponds to indoor tanks and held at 17.5-I8°C for 3-6 d. Size of brood fish and limited facilities precluded acclimation of spawners to test temperatures. Adults were injected with one or both of Human Chorionic Gonadotropin (HCG) or acetone-dried carp pituitary (CP) (Table 2). Eggs were hand stripped, fertilized immediately by sperm from one or more males, and water har- dened for I to 2.5 h at 17.5-18°C. After hardening, 100 fertilized ova were siphoned into each of 18 to 36 incubation chambers, and 3 to 6 replicate chambers were randomly placed into each of 6 aquaria. Embryos of razorback sucker were treated daily with 1.0% formaldehyde for 10 min (Inslee, 1982) until embryo motility was observed within the chorion. Other species were not so treated because protocols were unknown. Two trials (I, II) were conducted on Colorado squawfish because of unusual initial results. Data from both those trials were poled for analytical purposes. Data Aquisition and Analysis.-Incubating eggs were examined (40X) within 2 It of spawning to determine percentage fertilization (Table 2) and at approximately 12-h intervals thereafter through hatch or swimup. Dead eggs were removed, live embryos enumerated and staged (Solberg, 1938; Lagler et al., 1977; Minckley and Gustafson, 1983), and newly-hatched fry measured (total length [TL] to nearest 0.1 mm). Time to first hatch, peak hatch, 50% hatch, last hatch, and swimup were recorded and mean percentage survival and hatch were computed. Swimup was defined as attainment of neutral buoyancy. Representative samples of normal and anomalous fry were preserved in 5% formaldehyde and are housed at Arizona State University. Temperatures were measured 6-10 times daily and dissolved oxygen once daily in each aquarium. Development rate (V = 1000/p, where p = hrs to 50% hatch) was determined for each replicate at each temperature (Lagler et al., 1977). The development rate: temperature relationship is appar-