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Characterization of Rio Grande Silvery Minnow Egg and Larval Drift and Retention in the Middle Rio Grande

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Characterization of Rio Grande Silvery Minnow Egg and Larval Drift and Retention in the Middle Rio Grande Characterization of Rio Grande Silvery Minnow Egg and Larval Drift and Retention in the Middle Rio Grande Prepared for New Mexico Interstate Stream Commission Albuquerque, New Mexico Prepared by SWCA Environmental Consultants April 2007 Characterization of Rio Grande Silvery Minnow Egg and Larval Drift and Retention in the Middle Rio Grande Prepared for New Mexico Interstate Stream Commission Albuquerque, New Mexico Prepared by Ann M. Widmer1, Jon W. Kehmeier1, and Joseph J. Fluder, III2 1SWCA Environmental Consultants 295 Interlocken Blvd., Suite 300 Broomfield, CO 80021 2SWCA Environmental Consultants 5647 Jefferson St., NE Albuquerque, NM 87109 April 2007 Characterization of Rio Grande Silvery Minnow Egg and Larval Drift and Retention in the Middle Rio Grande EXECUTIVE SUMMARY Artificial eggs (gellan beads) were used to characterize the retention and transport of silvery minnow eggs through the Albuquerque and Isleta reaches during spring 2005. This project occurred as three experiments, which quantified the retention of artificial eggs 1) between Angostura and San Acacia during high flow immediately following the arrival of a flood pulse (high flow ascending limb); 2) between Isleta and San Acacia at high flow without an ascending hydrograph (constant high flow); and 3) between Angostura and South Diversion Channel at low flow (constant low flow). These experiments enabled comparisons of egg retention between the Albuquerque and Isleta reaches under three flow conditions. Retention of artificial eggs was highest during the high flow ascending limb experiment, when inundation of floodplain areas and in-channel features would have been greatest (range 1.9% to 13.8% beads retained per km). Retention was 1.07 times higher in the Albuquerque Reach compared to constant low flow and 3.19 times higher in the Isleta Reach compared to constant high flow. Average egg retention rates were higher in the Isleta Reach than the Albuquerque Reach at all flows sampled. Egg retention was 4.78 times higher in the Isleta Reach than the Albuquerque Reach during the high flow ascending limb experiment; the magnitude of this difference was likely due to floodplain connection in the Isleta Reach. Rio Grande silvery minnow distribution, as measured by catch per unit effort, appears to be roughly correlated with calculated bead retention rates. The majority of silvery minnow captured in the Isleta and Albuquerque reaches in April, May, and June 2005 were located in river kilometers 260 to 211, a section of the Isleta Reach that demonstrated consistently high rates of bead retention. Results suggest that egg retention habitat is limited in the Albuquerque Reach, consistent with the results of other studies. It may be worthwhile to repeat the study at flow rates similar to the 2005 flows to assess whether the habitat restoration work conducted and planned for the reach is successful in retaining a higher proportion of beads. At both the flows tested, egg retention habitat in the Isleta Reach appeared to be high quality; bead retention rates in this reach were comparable to the highest rates measured on the Pecos River (Kehmeier et al. 2004). A study to identify the habitat features that retain eggs in the Isleta Reach could be valuable to restoration efforts in the Albuquerque Reach and elsewhere. It may also be useful to identify the sections of the Isleta Reach that retain the greatest numbers of eggs to enable more focused conservation efforts. ii Characterization of Rio Grande Silvery Minnow Egg and Larval Drift and Retention in the Middle Rio Grande TABLE OF CONTENTS Page INTRODUCTION ..................................................................................................................... 1 METHODS ................................................................................................................................ 4 Artificial Eggs ........................................................................................................................ 4 Study Location and Timing.................................................................................................... 4 Bead Collector........................................................................................................................ 8 Hydrology Model................................................................................................................... 9 Bead Velocity and Retention Calculations ............................................................................ 9 Model of Egg Retention in the Albuquerque and Isleta Reaches ........................................ 13 RESULTS ................................................................................................................................ 15 Experiment 1: High Flow Ascending Limb......................................................................... 17 Experiment 2: Constant High Flow ..................................................................................... 22 Experiment 3: Constant Low Flow ...................................................................................... 27 Summary of Reach-wide Retention ..................................................................................... 32 Comparison of Bead Retention and Silvery Minnow Distribution...................................... 32 Comparison of Modeled Egg Retention Using Hypothetical Uniform Distribution ........... 32 DISCUSSION .......................................................................................................................... 35 CONCLUSIONS...................................................................................................................... 39 RECOMMENDATIONS ......................................................................................................... 39 REFERENCES......................................................................................................................... 40 LIST OF TABLES Table Page 1 Bead release and collection sites on the Rio Grande for the three egg retention experiments in 2005. ............................................................................................................5 2 Collection of silvery minnow eggs and fish by MECs during the three bead drift experiments. ....................................................................................................................... 16 3 Average bead velocities through study reaches during three sampling events in 2005 based on arrival of peak bead densities.............................................................................. 16 4 Total numbers of beads released and collected, estimated bead totals, and reach-specific retention rates during the high flow ascending limb experiment. Empty cells indicate no beads were released, collected, or estimated at that site. ................................................... 20 5 Distance (km) to retain different proportions of eggs at transport rates observed during the high flow ascending limb experiment. ......................................................................... 20 6 Total numbers of beads released and collected, estimated bead totals, and reach-specific retention rates during the constant high flow experiment. Empty cells indicate no beads were released, collected, or estimated at that site. ............................................................. 25 7 Distance (km) to retain different proportions of eggs at transport rates observed during the constant high flow experiment. .................................................................................... 25 8 Total numbers of beads released and collected, estimated bead totals, and reach-specific retention rates during the constant high flow experiment. Empty cells indicate no beads were released, collected, or estimated at that site. ............................................................. 30 iii Characterization of Rio Grande Silvery Minnow Egg and Larval Drift and Retention in the Middle Rio Grande LIST OF TABLES (continued) Table Page 9 Distance (km) to retain different proportions of eggs at transport rates observed during the constant low flow experiment. ..................................................................................... 30 10 Reach-wide retention rates calculated from the three bead retention experiments............ 32 LIST OF FIGURES Figure Page 1 Range of the silvery minnow and reaches of the Middle Rio Grande. ................................ 3 2 Mean daily discharge at Albuquerque during three egg retention experiments in 2005 and the mean daily discharge for years 1974 – 2005 for months April-August (USGS Albuquerque Central Gage). ................................................................................................ 5 3 Bead release and collection locations (river kilometer)....................................................... 7 4 Use of Moore egg collector (MEC) to sample beads........................................................... 8 5 Extrapolated rates of bead passage through the channel (beads/15 min) at Calabacillas collection site using both MECs (top) and with the faulty flow meter omitted (bottom).. 11 6 Extrapolated rates of bead passage through the channel (beads/15 min) at South Diversion Channel collection site using both MECs (top) and with the faulty flow meter omitted (bottom).............................................................................................................................. 12 7 Modeled hydrograph during the
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