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Río Yaqui Fish Survey Shows Stable Populations on San Bernardino NWR
Southwest Region, November 5, 2010
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SCEP Diana Iriarte counts fish from one of the traps on San Bernardino NWR.  Photo by Chris Lohrengel, 11/5/2010, San Bernardino NWR, Cochise County, AZ
SCEP Diana Iriarte counts fish from one of the traps on San Bernardino NWR. Photo by Chris Lohrengel, 11/5/2010, San Bernardino NWR, Cochise County, AZ - Photo Credit: n/a
SCEP Diana Iriarte pulls nets set for catfish, while WRS Chris Lohrengel observes.  Photo by William Radke, 11/4/2010, San Bernardino NWR, Cochise County, AZ
SCEP Diana Iriarte pulls nets set for catfish, while WRS Chris Lohrengel observes. Photo by William Radke, 11/4/2010, San Bernardino NWR, Cochise County, AZ - Photo Credit: n/a

The fishes of the Río Yaqui - Yaqui topminnow, Yaqui chub, Yaqui beautiful shiner, Mexican longfin dace, Mexican stoneroller, and Yaqui catfish - are restricted in the United States to a small number of wetland sites in the Upper Río Yaqui basin.  Four of the six species are listed under the Endangered Species Act and are afforded legal protection in adjacent Mexico; these facts warrant the annual monitoring of the populations of these species.

The wetland impoundment monitoring effort resulted in 253 samples being taken from 14 sites; Leslie Creek, which is treated as a wetland habitat, was unable to be fully sampled this year, 15 traps were set as opposed to the normal 30, due to extremely low water levels.  Chub and topminnow were the only species considered in the analysis because they were the only species with a sufficient number for estimation, except in the case of Leslie Creek where longfin dace are considered with chub and topminnow; and North Pond, where beautiful shiner replace chub.  No longfin dace were captured in Leslie Creek.  The proportion of habitat occupied (PHO) for chub for twelve sites was 0.51 and for topminnow for fifteen sites was 0.75; the PHO of chub was up from last year slightly, while topminnow was down some.  The PHO of beautiful shiner was 0.20.

During monitoring of the riparian stream habitats in Black Draw, four locations were sampled.  Yaqui topminnow, Yaqui chub, and longfin dace were used for analysis.  No Mexican stonerollers were captured this year.  For the four sites sampled in Black Draw, the density rate per meter of stream length for topminnow was 2.23; chub was 0.06; and longfin dace 0.23.

Unlike the four small fish species that inhabit the upper Rio Yaqui in the United States, the large size of Yaqui catfish makes them suitable for mark-recapture methods.  Limited and sporadic trapping and marking has occurred between 2001 and 2004, and more effort has been expended since 2005 to assess the species' population.  As with last year, two 30-m trammel nets and one 50-m trammel net was used with a smaller mesh size (two inch compared to four inch).  All nets were set for two successive nights in House Pond, and were checked for captures at first light the following morning.  Twin Pond had two 30m nets set in it for two nights.  Captured catfish were removed from the net, massed and measured (total length), checked for a PIT-tag, and if not tagged, marked with a PIT and released.  There were seven fish captured, six of which were recaptures, from House Pond over the two nights for a capture rate of 0.12.  Two individuals were captured, both were recaptures, from Twin Pond for a capture rate of 0.03.


Contact Info: Christopher Lohrengel, 520-364-2104 x.106, chris_lohrengel@fws.gov



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