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<br />12 Ecology of Bonytail and Razorback Sucker <br /> <br />Table 4. Capture rates of minnow traps, hoop nets, box traps, fyke <br />nets, trammel nets, and electrofishing used to capture razorback <br />sucker at Cibola High Levee Pond from 2001 through 2004. <br /> Razorback Tad- <br />Technique Effort (hI sucker RZB/h Crayfish" poles" <br />Minnow trap 286 0 0.0 251 421 <br />Hoop net 366 77 0.2 0 0 <br />Box trap 384 0 0.0 19 15 <br />Fyke net 642 27 <0.1 13 75 <br />Trammel net 214 188 0.9 0 0 <br />Electro- 4.6 282 58.5 0 0 <br />fishing <br />'Includes only partial counts. Initially these organisms were not counted. <br /> <br /> <br />Fig. 12. Razorback sucker captured from CHLP exhibiting a spinal <br />deformity. The exact cause of this fish's disfigurement is unknown, <br />but similar spinal damage can be caused by electrofishing. <br /> <br />Mortality Issues <br /> <br />Bony tail are successfully cultured and used in long-tenn <br />experiments (Marsh and Mueller, 1999; Badame and Hudson, <br />2003); however, they have a reputation for stress-related <br />mortality (Meyers, 1992; Chart and Cranney, 1993; Tyus <br />and others, 1999). Bony tail are susceptible to stress-related <br />outbreaks of the disease ich (Ichthyophthirius multifilis) even <br />under controlled hatchery conditions (Chester Figiel, USFWS, <br />oral commun., 2004). The loss of several large adults during <br />attempts to capture wild brood stock from Lake Mohave in the <br />late 1980's prompted the development of stringent handling <br />protocols designed to minimize netting and handling stress <br />(USFWS, 1998b). Protocols recommended that nets be <br />checked every 2 hours and when an entangled bony tail was <br />encountered, that they be gently lifted, net and all, into a <br />holding tank where the net is cut away to free the fish. Direct <br />handling of fish was simply avoided whenever possible. Hold- <br />ing water contains a solution of 0.5% NaCI (4.9 g!L), 25 mg!L <br />MS-222, 0.26 mLlL stress coat, and 0.8 mg/L Chloramine-T. <br />Hauling densities were recommended not to exceed 30 g!L of <br />fish to water. <br />We observed unusual symptoms on bony tail that were <br />held for extended periods of time. Bony tail captured at CHLP <br />were held in a floating live car to prevent their recapture <br /> <br />during the routine 3-day sampling effort. While initial mortal- <br />ity was low (< I %), surviving fish exhibited dark strangulation <br />marks which in time expanded beyond their dorsal fin toward <br />their tail (fig. 13). The fish appeared stiff, lethargic, and had <br />difficulty swimming, exhibiting symptoms I suspect to be <br />tissue damage that may have resulted from net strangulation. <br />In later experiments conducted at Willow Beach NFH, the <br />same dark banding and other symptoms were observed on fish <br />that were simply handled. The size of the blotching increased <br />with time (fig. 14). All 21 bony tail used in this experiment <br />(including controls) came down with ich and perished within 2 <br />weeks after being handled. <br />These symptoms and deaths suggest bony tail may be <br />susceptible to capture myopathy. It is also known as "white <br />muscle disease," which is a non-infectious disease character- <br />ized by muscle damage bought about by extreme exertion, <br />struggle, or stress. It is a common problem in capturing wild <br />birds and mammals, especially wild ungulates (Williams and <br />Thome, 1996) but to our knowledge has not been reported in <br />freshwater fish. It has been reported in capture and transport <br />of sharks (Greenwell, 2003). Death can occur immediately or <br />be delayed for weeks. Prevention of stress is the only way to <br />eliminate this disease. <br />We are aware of two studies that actually examined the <br />impact of post-handling stress on cultured bony tail. Craig <br />Paukert and others (2005) handled cultured bony tail from one <br />to seven times and monitored growth and weight gain over <br />an II-month period. These results were striking, with each <br />handling event decreasing fish growth by 9.5% and weight by <br />24.8%. Tyus and others (1999) examined the impact of acquir- <br />ing genetic tissue samples from bony tail, and delayed mortal- <br />ity of these fish reached 77%, including their controls. They <br />suggested mortality resulted from ich infections. Likewise, <br />Chart and Cranney (1993) reported 75% mortality in bony tail <br />used in telemetry studies. <br /> <br /> <br />Fig. 13. Captured bonytail that were held for a few days often <br />exhibited discoloration, swelling, stiffness, and subdermal <br />hemorrhaging of the tail musculature. These symptoms appear <br />stress-related and usually result in death. <br />