A Report on the Renovation of Big Tank, El Coronado Ranch, Arizona with Comments on Yaqui Catfish Ictalurus pricei Collected from Big Tank during 2014-2015.

Authors: C.O.* Minckley, David Ward, Chris Lohrengel

Year: 2015 (xlvii)

Abstract

Big Tank is located on the El Coronado Ranch in Cochise County, Arizona and is the site of a population of Yaqui catfish,Ictalurus pricei. Two introduced fishes, the green sunfish and black crappie were also present in the tank and were thought to be one of the factors in preventing the successful reproduction of Yaqui catfish. For that reason, it was decided to renovate the tank in 2015 to remove them. In April a large pump was used to remove water to a depth of two feet. The tank was then seined with a 120 ft. X 1/8 inch X 6 ft. seine, with a mud line. The fish collected and removed included 27 adult Yaqui catfish, 7 very large grass carp (20 kg), an estimated 1,000 green sunfish and black crappie, and thousands of bullfrog tadpoles. Seining was stopped when the catch rate dropped markedly (<10 seine hauls). The Yaqui catfish were taken to San Bernardino NWR; grass carp were put into another pond; introduced fish and tadpoles were destroyed. The tank was then treated with full strength ammonia hydroxide to renovate it. It was refilled with water from the inflow of Turkey Creek after 24 hours. Ammonia levels were monitored for a month. Then, 90 days later, 13 Yaqui catfish and 1000 Yaqui chub were reintroduced into the refilled pond.