Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Wild Razorback sucker (Xyrauchen texanus) Spawning a Success
Southwest Region, March 17, 2005
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Roger Hamman, Assistant Director, Dexter National Fish Hatchery and Technology Center (Center) lead a crew of six in the annual spawning of the razorback sucker. Roger, a pioneer in spawning, established guidelines that have set precedence in spawning technique used at hatcheries for more than 24 years. This year was unique in that the broodfish selected to spawn were all wild. As fry they were collected in Lake Mohave, taken to a hatchery, reared until they were 10ยจ, and released back into Lake Mohave. Later, they were recaptured and brought to the Center for use as wild brood fish. These fish were able to be identified through a small microchip (PIT tag) that was placed in them before their release into Lake Mohave. The broodfish were brought in from the earthen ponds at the Center, identified and separated according to gender. The females were all given three hormonal injections (one-a-day for three days) speeding up ovulation and on the fourth day the spawning process began. A total of 11 pairs were spawned producing over 715,000 eggs. These eggs were placed in incubators, where water flows at a warm 70 degrees Fahrenheit temperature allowing the eggs to hatch in 4 to 5 days. Once hatched, the fry are placed in holding tanks and allowed to swim-up before being transferred to earthen ponds. The Center will stock 60,000 fry into two earthen ponds and culture until fingerlings attain a size of 200mm. The fingerlings will be transferred to grow-out ponds on the Navajo Reservation as part of the San Juan River Recovery Implementation Program. The success the Center has experienced in spawning the razorback sucker is evident in its distribution of this species to different lakes and rivers encompassing four Southwestern States. Without this type of intervention the chances of this species becoming extinct would almost be certain.

Contact Info: Martin Valdez, 505-248-6599, martin_valdez@fws.gov
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