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San Bernardino National Wildlife Refuge Completes Annual Native Fish Monitoring on Refuge and Private Lands
Southwest Region, November 7, 2011
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Yaqui Topminnow (female)
Yaqui Topminnow (female) - Photo Credit: William R. Radke
Yaqui Chub
Yaqui Chub - Photo Credit: William R. Radke

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 220 samples being taken from 13 sites; Leslie Creek, which is treated as a wetland habitat, was unable to be fully sampled this year, five traps were set as opposed to the normal 30, due to extremely low water levels. Chub and topminnow are the only species considered in the monitoring analysis because they are 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 or chub were captured in Leslie Creek this year, but chub were observed. The proportion of habitat occupied (PHO) for chub for twelve sites was 0.42 and for topminnow for fifteen sites was 0.67; the PHO of chub and topminnow was slightly down from last The PHO of beautiful shiner in North Pond was 0.53. On the sites located on private lands, all had increases in PHO for chub and topminnow, the two species found in all five sites. In fact, for the first time since the implementation of the Safe Harbor Agreement in 2008, Yaqui topminnow breeding and recruitment was documented in one of the sites. All other topminnow captures had been from introducing individuals during the summer.

During monitoring of the riparian stream habitats in Black Draw, four locations were sampled. Yaqui topminnow, Yaqui chub, beautiful shiner, 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 3.38, chub was 0.679, shiner was 0.05, and longfin dace 0.033. All of which are up except longfin dace.

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.  Unlike last year, where two 30-m trammel nets and one 50-m trammel net were used, one 30-m and 50-m trammel net were used in House Pond. Twin Pond had the same net set as House Pond for two nights. All nets were set for two successive nights, and were checked for captures at first light the following morning. 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 no captures from House Pond over the two nights. However, in March 16 catfish were captured, twelve of which were recaptures, in one night, and relocated to the Arizona-Sonora Desert Museum for a captive breeding program. One individual was captured from Twin Pond for a capture rate of 0.03125.

 


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



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