2001 Rio Grande silvery minnow population monitoring

and Egg Salvage Site

This project has ended for the 2002 season.

        Back to Rio Grande silvery minnow Population Monitoring      

Map of Upper Corral Site


Photo of the site on 18 May 2002

Locality Description
click on map to enlarge

Socorro County, Rio Grande, ca. 18 miles downstream of the southern end of the Bosque del Apache National Wildlife Refuge.  Site is at approximately the same location as the Upper Corral Site.
SAN ACACIA REACH
River Mile 58.8

Rio Grande silvery minnow, Hybognathus amarus, is a member of a reproductive guild (group) of fishes characterized by pelagic-broadcast spawning and the production of semibuoyant eggs. Spawning by members of this reproductive guild is associated with high-flow events such as spring run-off or summer rainstorms. Upon release, eggs are about 1.6 mm diameter but quickly swell (ca. 3.0 mm) and remain suspended in the water column during development (see drawings and photos). Egg hatching time is temperature dependent but rapid occurring in 24-48 hours. Recently hatched larval fish remain a component of the drift until development of the gas bladder. This physiological development corresponded with a shift in swimming behavior as larvae actively seek low-velocity habitats.

The 3-5 days necessary for propagules to attain the developmental stage that allows them to freely disperse permits time for considerable downstream dispersal of eggs and larvae in the Middle Rio Grande. It is necessary for at least some portion of the displaced fish to move upstream to maintain those populations. Historically, there were no permanent barriers to upstream dispersal of fishes in the Middle Rio Grande. There are currently three instream diversion structures between Cochiti Dam and Elephant Butte Reservoir are barriers to upstream movement of fishes and fragment the once continuous range of the only remaining Middle Rio Grande (NM) member of this reproductive guild.

Currently over 90% of the catch of Rio Grande silvery is in the San Acacia Reach of the Middle Rio Grande. Multi-agency efforts in areas of habitat improvement, research, and propagation are underway in an attempt to increase population size and distribution with the ultimate goal being recovery of this species.

This study was designed to acquire information on the timing, duration, and magnitude of spawning by Rio Grande silvery minnow. Previous efforts indicated that Rio Grande silvery minnow spawning occurs over a relatively short period during spring run-off. This information will be useful in assessing progress of efforts towards recovery of this endangered fish. Additional goals of this study were to acquire Rio Grande silvery minnow eggs for rearing and use in propagation efforts and provide eggs for genetic analysis.

Spawning Periodicity of Rio Grande silvery minnow during 2002
Final Report by Steven P. Platania and Robert K. Dudley

Reports from Previous Project Years

Spawning Periodicity of Rio Grande silvery minnow during 2001
Final Report by Steven P. Platania and Robert K. Dudley

Spatial Spawning Periodicity of Rio Grande silvery minnow during 1999
Final Report by Steven P. Platania and Robert K. Dudley

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Egg-collecting in the river 2001
Egg-collecting in the river 		Egg-collecting in the LFCC 2001 Egg-collecting in the LFCC
 

Daily Updates - Current Flow Conditions at San Marcial gauge

  April
30 Site setup day - no eggs were collected in four hours of active sampling.

 

  May

1 No Rio Grande silvery minnow eggs at Upper Corral Site. Caught a few common carp eggs. Also sampled near San Acacia Diversion Dam - no eggs collected.
2 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
3 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
4 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
5 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
6 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
7 First catch of Rio Grande silvery minnow eggs in the river - about 75 total were collected.
8 No Rio Grande silvery minnow eggs were collected during a full day of (intensive) sampling.
9 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
10 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
11 Collected a cumulative total of 9 RGSM eggs during today's sampling effort
12 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
13 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
14 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
15 No Rio Grande silvery minnow eggs were collected during a full day of sampling. River has not yet risen from Cochiti release.
16 No Rio Grande silvery minnow eggs were collected during a full day of sampling. Reports have come in of eggs being collected upstream of the site. Discharge increase expected to reach the site late Friday (17 May) evening.
17 Thr first eggs arrived around 2:00 p.m.
18 Hundreds of thousands of eggs were collected.
19 Tens of thousands of eggs were collected.
20 Hundreds of eggs were collected.
21 A few Rio Grande silvery minnow eggs were collected during a full day of sampling.
22 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
23 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
24 No Rio Grande silvery minnow eggs were collected during a full day of sampling. Water levels have returned to pre-Cochiti release levels.
25 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
26 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
27 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
28 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
29 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
30 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
31 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
  June
1 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
2 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
3 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
4 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
5 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
6 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
7 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
8 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
9 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
10 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
11 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
12 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
13 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
14 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
15 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
16 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
17 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
18 No Rio Grande silvery minnow eggs were collected during a full day of sampling. We are waiting to see if the increase in flow that resulted from the rainstorm on Friday, 14 June will reach the site. Flow increased to approximately 300 cfs over San Acacia on Monday, 17 June.
19 No Rio Grande silvery minnow eggs were collected during a full day of sampling. Still waiting to see if the river level will rise.
20 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
21 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
22 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
23 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
24 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
25 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
26 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
27 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
28 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
29 No Rio Grande silvery minnow eggs were collected during a full day of sampling.
30 No Rio Grande silvery minnow eggs were collected during a full day of sampling.