Behaviors of Southwestern Native Fishes in Response to Introduced Catfish Predators

Transcription

1 Notes Behaviors of Southwestern Native Fishes in Response to Introduced Catfish Predators David L. Ward,* Chester R. Figiel, Jr. D.L. Ward U.S. Geological Survey, Grand Canyon Monitoring and Research Center, 2255 N. Gemini Drive, Flagstaff, Arizona C.R. Figiel, Jr U.S. Fish and Wildlife Service, Warm Springs Fish Technology Center, 5308 Spring Street, Warm Springs, Georgia Abstract Native fishes reared in hatcheries typically suffer high predation mortality when stocked into natural environments. We evaluated the behavior of juvenile bonytail Gila elegans, roundtail chub Gila robusta, razorback sucker Xyrauchen texanus, and Sonora sucker Catostomus insignis in response to introduced channel catfish Ictalurus punctatus and flathead catfish Pylodictis olivaris. Our laboratory tests indicate these species did not inherently recognize catfish as a threat, but they can quickly (within 12 h) change their behavior in response to a novel predator paired with the sight and scent of a dead conspecific. Chubs appear to avoid predation by swimming away from the threat, whereas suckers reduced movement. Effects of antipredator conditioning on survival of fish reared in hatcheries is unknown; however, our results suggest some native fish can be conditioned to recognize introduced predators, which could increase poststocking survival. Keywords: Catostomus insignis; Gila elegans; Gila robusta; Ictalurus punctatus; predation; Pylodictis olivaris; Xyrauchen texanus Received: September 26, 2012; Accepted: June 10, 2013; Published Online Early: August 2013; Published: December 2013 Citation: Ward DL, Figiel Jr. CR Behaviors of southwestern native fishes in response to introduced catfish predators. Journal of Fish and Wildlife Management 4(2): ; e x. doi: / JFWM-084 Copyright: All material appearing in the Journal of Fish and Wildlife Management is in the public domain and may be reproduced or copied without permission unless specifically noted with the copyright symbol ß. Citation of the source, as given above, is requested. The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service. * Corresponding author: dlward@usgs.gov Introduction Many endangered-species recovery programs rely on hatcheries for supplementation of rare fishes into areas with depleted populations. Bonytail Gila elegans and razorback sucker Xyrauchen texanus are two endemic fishes of the Colorado River that have experienced severe declines in number and distribution since being listed as endangered (ESA 1973, as amended) in 1980 and 1991 respectively (USFWS 2002a, 2002b). Causes for declines are linked to abiotic and biotic changes in the Colorado River and its tributaries that resulted from construction of large hydroelectric dams. These changes include alteration of flow and thermal regimes, as well as introduction and establishment of nonnative fishes (Minckley and Marsh 2009). Thousands of bonytail and razorback suckers are reared annually at hatcheries and stocked into the Colorado River and its tributaries as part of ongoing recovery efforts for these species (Minckley et al. 2003; Schooley and Marsh 2007). These native fishes reared in hatcheries typically suffer high mortality rates when stocked into natural environments with established populations of introduced fishes (Brown and Day 2002; Mueller and Marsh 2002; Myers et al. 2004; Marsh and Pacey 2005; Mueller 2006). For example, attempts to reintroduce captive-reared juvenile razorback sucker into the Gila River (Arizona) were unsuccessful at least in part because of predation by flathead catfish Pylodictis olivaris and channel catfish Ictalurus punctatus (Marsh and Brooks 1989). Poor survival of razorback sucker and bonytail stocked into Lake Mohave, presumably due to nonnative predators such as striped bass Morone saxatilis, has prompted recommendations to stock only large adults at a size that are less vulnerable to predation Journal of Fish and Wildlife Management December 2013 Volume 4 Issue 2 307

2 (Mueller 2005; Marsh et al. 2005; Schooley and Marsh 2007; Karam and Marsh 2010). Minckley and Douglas (1991) suggested that southwestern native fishes lack predator-avoidance defenses because they evolved in systems with few, if any, predators. Others have suggested that animals reared in artificial environments without predators must learn predator-avoidance skills to effectively cope with predators (Olla and Davis 1989; Brown and Smith 1998; McLean et al. 2000; Alvarez and Nicieza 2003). We exposed hatchery-reared juvenile bonytail and razorback sucker and wild-caught but predator-naïve (no previous exposure to catfish) roundtail chub Gila robusta and Sonora sucker Catostomus insignis to channel catfish and flathead catfish in a laboratory setting. Roundtail chub and Sonora sucker were included in the experiment because limited research specimens for bonytail and razorback sucker are available. These closely related but not federally protected species are also native to tributaries of the Colorado River and are good surrogates for bonytail (Kappenman et al. 2012) and razorback sucker because of similarities in morphology and behavior, especially as juveniles. Our objectives were to identify whether an innate predator avoidance response exists for these species and to assess whether these native fishes can learn to recognize noncoevolved catfishes as a threat. This information is useful in evaluating whether predator recognition training of hatchery fish could increase poststocking survival of repatriated native fishes. Methods We obtained 20 captive-reared razorback suckers (94.2 mm mean total length [TL]) from Willow Beach National Fish Hatchery, Arizona in Twenty additional captive-reared razorback sucker (107.1 mm mean TL) and 40 captive-reared bonytail chub (95.3 mm mean TL) were obtained from the Arizona Bubbling Ponds Native Conservation Facility in 2011 (Table 1; Table S1). We used a seine to capture 20 wild Sonora sucker (85.4 mm mean TL) and 20 wild roundtail chub (98.8 mm mean TL) from Fossil Creek, Arizona in 2011, in a location known to be free of nonnative fish, upstream from a man-made fish barrier. We used trammel nets to capture two flathead catfish (516 mm and 573 mm TL) and two channel catfish (479 mm and 430 mm TL) from the Verde River, Arizona. All fish were transported to the Rocky Mountain Research Station in Flagstaff, Arizona, with each species held separately in five, 568-L recirculating tanks at 20uC. All native fishes were tagged in the abdominal cavity with khz passive integrated transponder (PIT) tags and held for 10 d at a salinity of 0.3% to allow fish to recover from tagging and to remove external parasites prior to trials. Study apparatus We conducted laboratory tests in an apparatus modified from designs by Brannas et al. (1994) and Burns et al. (1997). The apparatus consisted of two 1,700-L circular tanks (1.83 m in diameter) connected to a 1 m cm Table 1. Number and sizes of bonytail Gila elegans, roundtail chub Gila robusta, razorback sucker Xyrauchen texanus, and Sonora sucker Catostomus insignis used in laboratory experiments to evaluate predator avoidance behavior in response to channel catfish Ictalurus punctatus and flathead catfish Pylodictis olivaris from 2009 to Species Number Mean total length, mm (range) Bonytail (replicate 1) (80 102) Bonytail (replicate 2) (87 118) Roundtail chub (77 118) Razorback sucker (80 105) (replicate 1) Razorback sucker (87 133) (replicate 2) Sonora sucker (84 105) clear acrylic tube (Figure 1). An air stone in each circular tank provided aeration. Native fish could move freely from one tank to the other through the connecting tube, but catfish were restricted to the side of the apparatus into which they were placed because of their large size and inability to fit through the connecting tube. We positioned two PIT tag antennas connected to portable PIT tag readers (FS2001; BiomarkH) 30 cm from each end of the connecting tube (Figure 1). Each scanner was set to scan continuously for PIT tags and to store the date and time associated with each tag detection. This allowed us to determine the direction of movement for individual native fish. Behavioral trials A single species of fish was randomly separated into two groups of 10 fish, identified by tag number, and placed into each tank. Fish were allowed to move throughout the apparatus during an overnight trial (8 12 h) with overhead lights off. We conducted trials in an enclosed room with no natural light. A single light beam, focused on the clear connecting tube, discouraged fish from remaining continuously within the connecting tube. In the morning following each trial, fish were caught from both tanks and scanned. Scanners were downloaded and fish were placed back into the subsequent trial. We used the known location of each fish at the start and end of the trial and the recorded information from the two PIT tag scanners to calculate a time budget for each fish (Text S1; Data S1). Time in each tank was converted to proportions so that data were comparable across trials. We conducted all trials at 22uC (62). Each species was subjected to four trials conducted in the same order with trials 1 3 conducted on consecutive nights and trial 4 conducted 2 wk later (Table 2). In the first trial, we placed 10 native fish of a given species into each tank with no predators present. Fish were allowed to explore the apparatus overnight, while PIT tag scanners recorded their movements. For the second trial, we placed 1 channel catfish and 1 flathead catfish at the same time into one side of the apparatus (chosen at random) and then placed 10 native fish into each tank, with the movements of each native fish again monitored Journal of Fish and Wildlife Management December 2013 Volume 4 Issue 2 308

3 Figure 1. Photo of experimental laboratory setup used from 2009 to 2011 to evaluate predator-avoidance behaviors of bonytail Gila elegans, roundtail chub Gila robusta, razorback sucker Xyrauchen texanus, and Sonora sucker Catostomus insignis to channel catfish Ictalurus punctatus and flathead catfish Pylodictis olivaris predators using continuous-read PIT (passive integrated transponder) tag detectors. overnight. In the third trial, we used a safety pin to attach a dead native fish of the species being tested to the lower jaw of each catfish and monitored the movements of all live native fish again within the apparatus. This trial simulated the effects of a predation event. Darwish et al. (2005) demonstrated that prey learn to recognize predators through the association of adverse stimuli (visual or chemical) paired with a predator cue. This trial allowed us to produce the adverse stimuli of a predation event at a desired point in time. At the end of the trial, the dead native fish were removed from the mouth of each catfish, all tanks were drained and the water was replaced. All fish were returned to their separate 568-L recirculating tanks by species and held for 2 wk, during which time they were fed AquamaxH 600 pelleted feed once daily. In the final trial, we again tested each species within the apparatus with one channel catfish and one flathead catfish again placed in one tank (chosen at random). We applied this same series of four trials (Table 2) to each species of native fish, with the same group of 20 fish used in all trials. The same two catfish were used for each sequence of trials, but different catfish were used for each replicate. We conducted two replicates of the four trials for bonytail and razorback sucker, but we conducted only one replicate for roundtail chub and Sonora sucker. We subjected razorback sucker and Sonora sucker to an additional fifth trial at the end of the experiment, where they were again tested in the apparatus with no predators present (Table 2). This additional control trial was used to determine whether the behavior (i.e., reduced movement) that we observed for these two species in the earlier treatments was the result of the trial (presence of catfish with a dead conspecific attached) or the result of repeated handling. For each treatment, we evaluated the combined responses of chub species (two replicates of bonytail and Table 2. Order of sequential overnight trials conducted in the laboratory to evaluate the behavioral response of bonytail Gila elegans, roundtail chub Gila robusta, razorback sucker Xyrauchen texanus, and Sonora sucker Catostomus insignis to channel catfish Ictalurus punctatus and flathead catfish Pylodictis olivaris from 2009 to Trial Species used and experimental sequence 1 Native fish species only (razorback sucker, bonytail, roundtail chub, or Sonora sucker) 2 Native fish species + 1 channel catfish and 1 flathead catfish 3 Native fish species + 1 channel catfish and 1 flathead catfish, each with a dead conspecific attached 4 2 weeks after trial 3, Native fish species + 1 channel catfish and 1 flathead catfish 5 Native fish species only (razorback sucker or Sonora sucker) Journal of Fish and Wildlife Management December 2013 Volume 4 Issue 2 309

4 Figure 2. Proportion of time that chubs (bonytail Gila elegans two replicates, and roundtail chub Gila robusta one replicate) spent on each side of the experimental apparatus in four sequential overnight laboratory trials conducted from 2009 to The filled-in circles are the means of three replicates and the error bars represent 6 1 standard error. The fish in these trials had no prior exposure to catfish Ictalurus punctatus and Pylodictis olivaris predators. one replicate of roundtail chub) and the combined response of the sucker species (two replicates of razorback sucker and one replicate of Sonora sucker). In our view, similarities in the morphology and behavior of these closely related species as juveniles makes it appropriate to combine them together for analysis. For each treatment, we evaluated the mean proportion of time (61 SE) spent on either side of the experimental apparatus. For suckers, we also report the mean number of tag detections (61SE) as an index of movement before, during, and after exposure to the simulated predation event. Results Native fish moved freely through the tube connecting the two tanks, with individual fish moving between tanks Figure 3. Proportion of time that suckers (razorback sucker Xyrauchen texanus two replicates, and Sonora sucker Catostomus insignis one replicate) spent on each side of the experimental apparatus in four sequential overnight laboratory trials conducted from 2009 to The filled-in circles are the means of three replicates and the error bars represent 6 1 standard error. The fish in these trials had no prior exposure to catfish Ictalurus punctatus and Pylodictis olivaris predators. Journal of Fish and Wildlife Management December 2013 Volume 4 Issue 2 310

5 Figure 4. Movement of the sucker species (razorback sucker Xyrauchen texanus two replicates, and Sonora sucker Catostomus insignis one replicate) within the experimental apparatus as measured by mean number of PIT (passive integrated transponder) tag detections occurring during five sequential overnight laboratory trials conducted from 2009 to The filled-in circles are the means of three replicates and the error bars represent 6 1 standard error. All fish in these trials had no prior exposure to catfish Ictalurus punctatus and Pylodictis olivaris predators. up to 96 times within a given night. In trial 1, neither chubs nor suckers appeared to spend more time in one tank or the other when no predators were present (Figures 2 and 3). Chub species With only catfish present on one side of the apparatus (trial 2), the chub species spent a greater proportion of time on average in the tank containing catfish (70%) than in the tank without catfish (29%, SE = 5.14; Figure 2). When catfish and dead conspecifics were present (trial 3), this behavior switched, with chub species spending more time in the tank that did not have catfish (65%) than in the tank with catfish present (35%, SE = 0.58; Figure 2). Two weeks later (trial 4), chubs again did not appear to differ in the amount of time spent in either the presence (58%) or absence of catfish (42%, SE = 7.05; Figure 2). Sucker species With only catfish present on one side of the apparatus (trial 2), the sucker species did not appear to differ in the amount of time spent in either tank (50% and 49%, SE = 6.3; Figure 3). When catfish with dead conspecifics were present (trial 3), the sucker species spent significantly more time in the tank containing catfish with dead conspecifics (69.7%) than in the tank with no catfish (30%, SE = 12.5; Figure 3). Two weeks after dead conspecifics were removed (trial 4), the sucker species again did not appear to differ in the amount of time spent in either tank (51% and 49%, SE = 3.2; Figure 3). Analysis of tag detections indicated that when catfish with dead conspecifics were present (trial 3), the suckers restricted their movements to near zero (Figure 4). For the sucker species (n = 3), tag detections decreased from an average of 31 detections in trial 2 to an average of 5 in trial 3, after exposure to catfish with a dead conspecific. This reduced movement continued 14 d after exposure to catfish with dead conspecifics, with a mean of 10 tag detections in trial 4 (Figure 4). Two razorback sucker and one Sonora sucker were consumed by catfish during trial 4, conducted 14 d after exposure to catfish with dead conspecifics. This was the only predation that occurred during our study. Discussion Our study suggests that the chub, and sucker species we tested do not inherently recognize channel catfish or flathead catfish as a predatory threat, yet can rapidly (within 12 h) learn and change their behavior in response to the sight or scent of a dead conspecific in conjunction with a novel catfish predator (Figures 2 4). When alarm cues from the skin of an injured conspecific were paired with the visual and or chemical cues of a predator, it elicited a response in all of the native species we tested, although these behaviors varied by species. The ability to detect chemical alarm signals in damaged skin of an injured conspecific and infer the presence of a predator is well-established in fish and commonly known as Schreckstoff (Mathuru et al. 2012). The chub species appeared to swim away from the threat, whereas the suckers reduced overall movement (Figures 2 and 3). These types of behaviors, known as releaser-induced recognition learning, have been reviewed in other fish species and include increased group cohesion, increased use of shelter, decreased activity, or rapid escape response to avoid areas where alarm cues have been detected (reviewed in Chivers and Smith 1998). Observations of all of the native species during our tests indicate they initially moved to positions underneath the catfish, as if they were trying to hide under them, and may have perceived the catfish as cover. Mueller et al. (2007) also reported razorback sucker reared in hatcheries to be predator-naïve and seek cover under flathead catfish in an experimental setting. Chinook salmon Oncorhynchus tshawytscha also do not exhibit an innate predator avoidance response to the Journal of Fish and Wildlife Management December 2013 Volume 4 Issue 2 311

6 odor of introduced smallmouth bass Micropterus dolomieu, but did respond to the odor of native northern pikeminnow Ptychocheilus oregonensis (Kuehne and Olden 2012); this indicates that prey naiveté may play an important role in predation vulnerability of native fishes to introduced predators. Chub that experienced a dead conspecific in conjunction with a catfish predator in our trials responded by swimming away from the threat (Figure 2). Two weeks after trial 4, however, the chub species did not differ in the amount of time spent either in the presence or absence of catfish (Figure 2). This may indicate that, for the chub species, the initial predator avoidance response did not persist, and the chub again did not perceive the catfish as a threat or perceived them only as cover. Little movement of the sucker species occurred during tests when catfish with dead suckers were present (Figure 3). Suckers would either not move at all during the test or swim from the side of the apparatus that was free of catfish to the side with the catfish and then remain motionless for the remainder of the test period. For this reason, our time-budget approach for data analysis (Figure 3) did not yield very useful information for the sucker species. We evaluated the raw number of PIT tag detections as an index of movement in addition to evaluating the time spent on each side of the apparatus for the sucker species (Figure 4). This additional method of analysis for the sucker species enabled us to quantify the reduced movement exhibited by the suckers in response to a dead conspecific and a predator. June sucker Chasmistes liorus demonstrate a similar response (i.e., increased time spent motionless) when exposed to the odor of predatory largemouth bass Micropterus salmoides in laboratory tests (Kraft 2009). Reduced activity in response to a threat may be beneficial for avoiding detection by predators, especially for benthic fishes in low-visibility environments. In laboratory experiments, larval razorback suckers were shown to be susceptible to predation by Colorado pikeminnow Ptychocheilus lucius and green sunfish Lepomis cyanellus in clear water, but were able to avoid predation as turbidity increased (Johnson and Hines 1999). Our tests included groups of fish because predatoravoidance training in a hatchery setting would only be logistically feasible with large groups of fish. Additional research may be needed to determine whether antipredator behaviors of a single individual are similar to those exhibited by fish in groups. Antipredator behaviors exhibited by fish in groups may also not confer survival advantages if numbers of fish in the wild are so low that native fish are often solitary. Additional experiments are warranted for roundtail chub and Sonora sucker because only one replicate was obtained for each of these species. In our experiments, the reduced movement of the sucker species after exposure to a dead conspecific continued even when dead conspecifics were no longer present (Figure 4). It was during these same two trials that two razorback suckers and a Sonora sucker were consumed by catfish during trial 4. Unfortunately, we were unable to determine whether the reduced movement observed during these trials was the result of the predation event that occurred during those trials or fish remembering the previous trial. In either case, the response of the suckers appeared to be a reduction in movement. The catfish used in our experiments typically would not eat for several days after being captured and moved into the test tank. The predation that occurred during trial 4 of our experiment suggests the catfish were becoming accustomed to being in captivity and being repeatedly moved. Other fish species have demonstrated the ability to remember a novel predator as a threat. Juvenile rainbow trout Oncorhynchus mykiss exhibit antipredator behaviors for d postconditioning (Brown and Smith 1998; Mirza and Chivers 2000). Fathead minnow Pimephales promelas also showed an antipredator response for 2 mo after a conditioning event (Chivers and Smith 1994). June sucker displayed antipredator behaviors for 2 d following a conditioning event but did not show any response after 10 d (Kraft 2009). Animals are predisposed to respond in specific ways to threats (Griffin et al. 2000). In some cases, the natural response to a novel threat may not appear to be adaptive. The ability of prey to show appropriate and effective antipredator responses once predators are detected may be equally, if not more, important than detecting the threat (Rehage et al. 2009). The natural behavior of the sucker species during our tests (e.g., remaining motionless on the bottom) would likely be very effective for avoiding native predators such as Colorado pikeminnow in the turbid Colorado River. This behavior, however, may not be adaptive for avoiding catfish, which are benthic and possess highly specialized sensory organs for locating prey in low-visibility environments. Restriction of movement to avoid detection by predators is not unique to sucker species. Green sunfish increase time spent motionless in response to chemical alarm signals (Brown and Brennan 2000), and rainbow trout have been shown to reduce activity and spend more time motionless in the presence of injured conspecifics and northern pike Esox lucius (Brown and Smith 1998). Conditioning animals to recognize predators in controlled settings demonstrates that learning can occur very quickly with only one or two exposures (Griffin et al. 2000), but repeated learning events may be needed for some species. Fathead minnow in the laboratory recognized a novel predator after a single exposure to an alarm cue paired with a predator (Mathis et al. 1996; Ferrari et al. 2005). Juvenile walleye Sander vitreus also learned to associate predation risk with odor of northern pike after a single simultaneous encounter with pike odor and chemical alarm cues (Wisenden et al. 2004). Training native fish to recognize introduced predators could be used as a management tool to reduce predation mortality of native fish reared in hatcheries that are stocked into natural systems. This tool, like other management strategies such as increasing the size of stocked native fish or acclimating native fish to natural environments prior to release, warrants further evalua- Journal of Fish and Wildlife Management December 2013 Volume 4 Issue 2 312

7 tion. Effects of antipredator conditioning on postrelease survival are unknown, but our results suggest that some native fish can be conditioned to recognize novel predators at least for a short period of time. Effectiveness of training fish to avoid introduced predators may depend on whether or not the species being conditioned naturally possesses an antipredator behavior that is appropriate. The chub species in our tests appear to possess an appropriate predator avoidance response (i.e., swimming away from the threat) to catfish and may benefit from catfish recognition training. The sucker species, however, may not gain a survival benefit from training to recognize catfish predators because their natural response to catfish (i.e., remaining motionless) may make them more vulnerable to predation. Supplemental Material Please note: The Journal of Fish and Wildlife Management is not responsible for the content or functionality of any supplemental material. Queries should be directed to the corresponding author for the article. Reference S1. Kraft SA Native prey versus nonnative predators: a role for behavior in endangered species conservation. Master s thesis. Logan: Utah State University. Found at DOI: / JFWM-084.S1 (896 KB PDF). Reference S2. Marsh PC, Pacey CA Immiscibility of native and non-native fishes. Pages in Spring CL, Leon S, editors. Proceedings of two symposia. Restoring native fish to the lower Colorado River: interactions of native and non-native fishes July 1999, Las Vegas, Nevada. Restoring natural function within a modified riverine environment: the lower Colorado River, 8 9 July 1998, Las Vegas, Nevada. Albuquerque, New Mexico: U.S. Fish and Wildlife Service, Southwestern Region. Found at DOI: / JFWM-084.S2; also available at Symp_Marsh&Pacey.pdf (27 KB pdf). Reference S3. Mueller GA Ecology of bonytail and razorback sucker and the role of off-channel habitats in their recovery: U.S. Geological Survey Scientific Investigations Report Found at DOI: / JFWM-084.S3; also available at /21534.pdf (9017 KB PDF). Reference S4. Mueller GA, Marsh PC Lost, a desert river and its native fishes: a historical perspective of the lower Colorado River. Denver: U.S. Government Printing Office Information and Technology Report USGS/DRD/ITR Found at DOI: / JFWM-084.S4; also available at /10026.pdf (3339 KB PDF). Reference S5. Mueller GA, J Carpenter, R Krapfel, Figiel C Preliminary testing of the role of exercise and predator recognition for bonytail and razorback sucker: U.S. Geological Survey Open File Report Found at DOI: / JFWM-084.S5; also available at /22056.pdf (1056 KB PDF). Reference S6. [USFWS] United States Fish and Wildlife Service. 2002a. Bonytail (Gila elegans) recovery goals: amendment and supplement to the bonytail chub recovery plan. Denver: U.S. Fish and Wildlife Service, Mountain-Prairie Region 6. Found at DOI: / JFWM-084.S6; also available at pdf (1443 KB PDF). Reference S7. [USFWS] United States Fish and Wildlife Service. 2002b. Razorback sucker (Xyrauchen texanus) recovery goals: amendment and supplement to the razorback sucker recovery plan. Denver: U.S. Fish and Wildlife Service, Mountain-Prairie Region 6. Found at DOI: / JFWM-084.S7; also available at backsucker.pdf (1542 KB PDF). Table S1. Sizes of all bonytail Gila elegans, roundtail chub Gila robusta, razorback sucker Xyrauchen texanus, and Sonora sucker Catostomus insignis used in laboratory experiments to evaluate predator avoidance behavior in response to channel catfish Ictalurus punctatus and flathead catfish Pylodictis olivaris from 2009 to Found at DOI: / JFWM-084.S8 (18 KB DOC). Text S1. Readme file describing the steps used in postprocessing passive integrated transponder (PIT) tag scanner downloads to evaluate native fish movement in response to channel catfish Ictalurus punctatus and flathead catfish Pylodictis olivaris within our laboratory apparatus from 2009 to Found at DOI: / JFWM-084.S9 (14 KB DOC). Data S1. Sample of archived data containing the raw passive integrated transponder (PIT) tag scanner downloads and postprocessing steps conducted for bonytail chub, Gila elegans, replicate 1 used in laboratory experiments to evaluate predator avoidance behavior in response to channel catfish Ictalurus punctatus and flathead catfish Pylodictis olivaris from 2009 to Found at DOI: / JFWM-084.S10 (5580 KB XLS). Acknowledgments We thank T. Hunt, S. Rogers, and C. Nelson for assistance with collecting fish and performing these studies. We thank Willow Beach National Fish Hatchery for providing research specimens and the Rocky Mountain Research Station in Flagstaff, Arizona for providing facilities to hold fish. W. Matter and C. Paukert provided valuable comments on earlier drafts of this manuscript. The Journal of Fish and Wildlife Management December 2013 Volume 4 Issue 2 313

8 journal Subject Editor and two anonymous reviewers also provided significant constructive comments that have improved this manuscript. This work was conducted under Federal Endangered Species permit number TE Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. References Alvarez D, Nicieza AG Predator avoidance behaviour in wild and hatchery-reared brown trout: the role of experience and domestication. Journal of Fish Biology 63: Brannas E, Lundqvist H, Prentice E, Schmitz M, Brannas K, Wiklund BS Use of the passive integrated transponder (PIT) in a fish identification and monitoring-system for fish behavioral-studies. Transactions of the American Fisheries Society 123: Brown C, Day RL The future of stock enhancements: lessons for hatchery practice from conservation biology. Fish and Fisheries 3: Brown GE, Brennan S Chemical alarm signals in juvenile green sunfish (Lepomis cyanellus, centrarchidae). 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Albuquerque, New Mexico: U.S. Fish and Wildlife Service, Southwestern Region. (see Supplemental Material, Reference S2, also available at Symp_Marsh&Pacey.pdf (August 2013). Mathis A, Chivers DP, Smith RJF Cultural transmission of predator recognition in fishes: intraspecific and interspecific learning. Animal Behaviour 51: Mathuru AS, Kibat C, Cheong WF, Shui G, Wenk MR, Freidrich RW, Jesuthansan S Chondroitin fragments are odorants that trigger fear behavior in fish. Current Biology 22: McLean IG, Schmitt NT, Jarman PJ, Duncan C, Wynne CDL Learning for life: training marsupials to recognize introduced predators. Behaviour 137: Minckley WL, Douglas ME Discovery and extinction of western fishes: a blink of the eye in geologic time. Pages 7 17 in Minckley WL, Deacon JE, editors. Battle against extinction: native fish management in the American West. Tucson: University of Arizona Press. Minckley WL, Marsh PC Inland fishes of the greater southwest: chronicle of a vanishing biota. 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9 plan for native fishes of the Lower Colorado River. Bioscience 53: Mirza RS, Chivers DP Predator-recognition training enhances survival of brook trout: evidence from laboratory and field-enclosure studies. Canadian Journal of Zoology-Revue Canadienne De Zoologie 78: Mueller GA Predatory fish removal and native fish recovery in the Colorado River mainstem: what have we learned? Fisheries 30: Mueller GA Ecology of bonytail and razorback sucker and the role of off-channel habitats in their recovery: U.S. Geological Survey Scientific Investigations Report (see Supplemental Material, Reference S3, S3); also available at Products/Publications/21534/21534.pdf (August 2013). Mueller GA, Carpenter J, Krapfel R, Figiel C Preliminary testing of the role of exercise and predator recognition for bonytail and razorback sucker: U.S. Geological Survey Open File Report (see Supplemental Material, Reference S5, / JFWM-084.S5); also available at pdf (August 2013). Mueller GA, Marsh PC Lost, a desert river and its native fishes: a historical perspective of the lower Colorado River. Denver: U.S. Government Printing Office. Information and Technology Report USGS/DRD/ ITR (see Supplemental Material, Reference S4, also available at /10026.pdf (August 2013). Myers RA, Levin SA, Lande R, James FC, Murdoch WW, Paine RT Hatcheries and endangered salmon. Science 303:1980. Olla BL, Davis MW The role of learning and stress in predator avoidance of hatchery reared coho salmon (Oncorhynchus kisutch) juveniles. Aquaculture 76: Rehage JS, Dunlop KL, Loftus WF Antipredator responses by native mosquitofish to non-native ciclids: an examination of the role of prey naiveté. Ethology115: Schooley JD, Marsh PC Stocking of endangered razorback suckers in the lower Colorado River basin over three decades: North American Journal of Fisheries Management 27: [USFWS] United States Fish and Wildlife Service. 2002a. Bonytail (Gila elegans) recovery goals: amendment and supplement to the bonytail chub recovery plan. Denver: U.S. Fish and Wildlife Service, Mountain-Prairie Region 6 (see Supplemental Material, Reference S6, dx.doi.org/ / jfwm-084.s6); also available at Bonytail.pdf (August 2013). [USFWS] United States Fish and Wildlife Service. 2002b. Razorback sucker (Xyrauchen texanus) recovery goals: amendment and supplement to the razorback sucker recovery plan. Denver: U.S. Fish and Wildlife Service, Mountain-Prairie Region 6 (see Supplemental Material, Reference S7, JFWM-084.S7); also available at southwest/sjrip/pdf/doc_recovery_goals_razorback_ sucker_2002.pdf (August 2013). Wisenden BD, Klitzke J, Nelson R, Friedl D, Jacobson PC Predator-recognition training of hatchery-reared walleye (Stizostedion vitreum) and a field test of a training method using yellow perch (Perca flavescens). Canadian Journal of Fisheries and Aquatic Sciences 61: Journal of Fish and Wildlife Management December 2013 Volume 4 Issue 2 315