7354 - Laserfiche WebLink

Home Browse Search

%,1 P Table 2. liological Summary of Rare Colorado River Fish (continued) Item Razorback Sucker rauchen texanus Status/Distribution Rare; Absent from much of its former range; Reduced in number; See Figure 4 for summary of distribution and identification of sensitive areas. Colorado River Yampa-Green River n-42 n¦27 Age and Growth - - - (TL in mm) - - - - IV - 485 - 499 V 571 522 510 483 VI 561 S10 508 489 VII S83 - 515 - VIII 592 - - - Maximum Size 740 m TL in lower basin 662 m TL iln upper basin Maximum Age Estimateq to 22 years from otoliths; little growth after reaching maturity; one fish 1508 m TO grew only 8 m in 3.5 years; other recaptures of fish over 550 as TL exhibited no growth at all. Reproduction Size/Age About 460 m TL; Probably age 3 or 4 Hatchery males mature at 3S6 m TL at age 2 Hatchery females mature at 406 m TL at age 3 Fecundity wild fish; n•10; average 46.740 (maximum 76.576) hatchery fish; n-46; average 124.522 Spawning Period early May - mid-June Temperature at Spawning Average 15°C (10 - 18°C) Streamflow at Spawning Descending Hydrograph Average 26.100 cfs Food Habits Algae. plant debris. Insect larvae including midges, mayflies. and caddisflies; caught occasionally on bait by anglers fishing for catfish. Habitat Spawning - Bars with sand. gravel, or rubble substrate; water velocity about 1 m/s; in the lower basin this species spawns in reservoirs over rubble substrate at depths of 0.3 to 6 meters. Young - Unknown since very few young are collected; believed to use quiet backwater areas. Adults - Deeper waters (to 2 meters deep) along shorelines, main channels, and eddies with water velocities under 0.5 m/s; during the spring this species will enter quiet backwaters and have been observed to congregate at the mouths of streams or seeps that are somewhat warmer than the main channel. Movement Fish have moved up to 129 miles but usually remain in the same area or within 20 miles of where they have been tagged. 25