Survival of razorback sucker stocked into the lower Colorado River

Survival of razorback sucker stocked into the lower Colorado River Trip Report 2-6: Palo Verde and Cibola Divisions 9-13 and 23-27 October 2006 Prepared by Brian R. Kesner and Joshua R. Campbell Submitted by Paul C. Marsh Arizona State University Tempe, Arizona 85287-4501 In behalf of Agreement Number 06FC300002 between Arizona State University and U.S. Bureau of Reclamation Boulder City, Nevada 89006 November 28, 2006

Summary Portions of the lower Colorado River, Palo Verde and Cibola Divisions, were surveyed 9-13, 23-27 October 2006 for presence of razorback sucker Xyrauchen texanus. The study area included the main river channel, C-5 and C-7 backwaters in Riverside County, California and the upper section of A-7, the upper and lower sections of A-10, and Hippie Hole backwaters in La Paz County, Arizona. Methods were boat electrofishing and trammel netting which resulted in contact with a total of 1,296 fish representing at least 14 species. One-hundred and five individual razorback suckers were encountered, representing 105 capture events. Sixty-four fish contained PIT tags, we implanted tags into 41 fish. A total of 105 fish was processed for gender, length and weight. Sex determinations were 48 juvenile, 11 female, 39 male, and 7 unknown. Mean total length was 37.8 cm (range 30.0 61.0 cm) and mean weight was 526 g. All live fish were released near their capture sites, there were four mortalities. Introduction Razorback suckers have been repatriated to the lower Colorado River for more than 25 years, but stocking was accelerated in the late 1990s to meet requirements of a U.S. Fish and Wildlife Service Biological Opinion of lower river operations (USFWS 1997). Monitoring was largely sporadic and incidental to sport-fish related activities until autumn 2004 when Reclamation contracted with Arizona State University to focus collection activities on these fish. The purpose of this work is to continue that assessment of survival of stocked fish by performing an intensive, opportunistic survey that targets razorback sucker in approximately 282 km of river from Parker Dam downstream to Yuma, Arizona. The intention is to collect multiple samples from the main channel and all watercraft-accessible backwaters and side channels to assess post-stocking survival, distribution, and abundance of the target species. Population abundance of razorback sucker will be estimated quantitatively using mark-recapture methods if adequate data are available. Study Area The study area included two different localities. From 9-13 Oct 2006, surveys were conducted in the main river channel and at the A-7 1 and A-10 backwaters within the U.S. 1 Backwaters in the Palo Verde and Cibola administrative divisions of the lower Colorado River are identified with an alphanumeric name designating their location: A= Arizona backwater or C= California backwater, followed by a number indicating their sequence North to South. Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 2

Bureau of Reclamation (USBR) Palo Verde Division (Fig. 1). From 23-27 Oct 2006, surveys were conducted in the main river channel, C-5 (Goose Flats), C-7 (McIntyre Park), and Hippie Hole backwater (Fig. 2) within the USBR Palo Verde and Cibola Divisions. All surveys were carried out between river mile (RM 2 ) 99 and 120 in La Paz County, Arizona and Riverside County, California. The most recent previous survey of these areas was conducted in May 2006 (Karam & Kesner 2006). Razorback suckers have routinely been stocked into A-7 backwater (RM 120), and fish to support experimental studies have been stocked into upper and lower sections of A-10 backwater (Table 1). Methods Primary sampling methods were boat electrofishing and trammel netting. Electrofishing (Smith-Root SR-18H package with GPP 7.0 pulsator) was conducted during evening and nighttime. Nominal settings were 340 volts, 11 amps, pulsed DC. Trammel nets (46 x 1.8 m x 3.8 cm mesh) were set and retrieved the same evening during the first week and set overnight during the second. Net set locations were chosen based on water depth (ideally >1.5 m) and habitat (proximal to cover but free of submerged obstacles or debris). Net sites generally were in backwaters and eddies off main channel. Sets were intentionally placed in remote, slightly inaccessible locations in attempt to minimize potential conflicts with anglers and recreational watercraft users. Nominal time for setting nets was at sunset and removal was over a range of times depending on catch. Large mesh (20.4 cm stretch) gill nets were set to evaluate large fish predator densities. Because these nets were not intended for monitoring razorback sucker, the effort is not documented in this report. All fish were identified to species when possible and counted by life stage (age-0 [youngof-year plus small bodied species such as red shiner, mosquitofish, and mollies] and age-1+ [adult]) and method of capture. When applicable, native fish were individually measured (total length [TL], in cm), scanned for wire tag (WT) and passive integrated transponder (PIT) tag, sexed (male, female, juvenile, and unknown [for fish 40 cm for which gender could not be reliably determined]), and examined for general health and condition. A PIT tag was implanted into the abdominal cavity of natives if none was 2 River miles are measured upstream from the Southerly International Boundary near San Luis, Arizona. Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 3

present, and all fish were released near the site of capture. Voucher specimens up to a total of 10 individuals per non-native species 3 were fixed in 10% formaldehyde prior to rinsing and preservation in 70% ethanol, and deposited into the ASU Collection of Fishes. Exceptional individuals and others exhibiting key characteristics or other features were photographed to provide a permanent record. Results and Discussion Electrofishing and netting combined yielded a total of 1,296 fish representing at least 14 species (Table 2). Largemouth bass Micropterus salmoides accounted for 28.9% of the total catch and was the most abundant variety overall, followed by bluegill sunfish Lepomis macrochirus ( 24.2%), redear sunfish Lepomis microlophus (8.7%), razorback sucker Xyrauchen texanus (7.9%), common carp Cyprinus carpio (7.1%), threadfin shad Dorosoma petenense (5%), Lepomis sp. (juvenile sunfishes that could not reliably be assigned to species, 3.1%), redbelly tilapia Tilapia zillii (2.7%), striped bass Morone saxatilis (2.5%), channel catfish Ictalurus punctatus (2.3%), blue tilapia Oreochromis aureus (2.1%), flathead catfish Pylodictis olivaris (1.9%) and smallmouth bass Micropterus dolomieu (1.4%). Other species each contributed less than 1% to the total catch. One-hundred and five individual razorback suckers representing 105 capture events were distributed over the study backwaters as follows: 33 fish in the upper section of A- 10, 62 fish in the lower section of A-10, five fish in the upper section of A-7, two fish in C- 5, and three in Hippie Hole. Electrofishing and trammel netting encountered 59 and 44 fish, respectively. Gill netting resulted in the incidental catch of one razorback, and another razorback was found floating unassociated with any net set (released alive but in poor condition). A total of 105 fish were processed for gender, length and weight. Sex determinations were 48 juvenile, 11 female, 39 male, and 7 unknown. Mean total length was 37.8 cm (range 30.0 61.0 cm) and mean weight was 526 g (range 214 1,206 g). However, two large razorbacks (>60 cm) were not weighed. Sixty-four fish contained PIT tags and we implanted PIT tags into forty-one fish. Hatchery implanted wire tags 4 3 This represents the total number of vouchers for the entire study period. 4 All razorback suckers stocked to the lower Colorado River downstream from Parker Dam are marked with a wire tag, and with few exceptions, wire tags were inserted into the left-dorsal musculature. After February 4, 2005, fish stocked into A-10 backwater were wire-tagged in the right caudal peduncle. See Table 1 for recent stocking and marking data. Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 4

were detected in 79 fish. PIT tagged fish were at large for 25 to 304 days between release and capture, and had apparent growth rates of -0.54 to 0.68 mm/day (Table 3). Electrofishing: A total of 13,828 sec real time (230.5 min) of boat electrofishing resulted in contact with 776 fish representing at least 13 species (Table 2). Catch rate was 56 fish per 1000 sec. Largemouth bass was most abundant (41.2%), followed by bluegill sunfish, threadfin shad, razorback sucker (7.6%), common carp, Lepomis sp. (juvenile sunfishes that could not reliably be assigned to species), redear sunfish, striped bass, warmouth sunfish, and red belly tilapia. Other species each comprised less than 1% of the electrofishing catch. Trammel Netting: A total of 35 trammel net sets resulted in contact with 520 fish representing at least 12 species (Table 2). Catch averaged 14 fish per net and ranged from 0 to 51; CPUE was 1.3 fish per net-hr. Bluegill sunfish was the most abundant species (39.4%), followed by redear sunfish, largemouth bass, razorback sucker, common carp, redbelly tilapia, blue tilapia, channel catfish, flathead catfish, and striped bass. Other species each comprised less than 1% of the total trammel net catch. Average trammel netting depth was about 2.7 m, and overall average net set was 11.3 hrs (overnight and short-term combined). No razorback suckers captured in May were recaptured during the October sampling within the same backwater. Therefore, no estimates of population size are available. Problems and Solutions Attempts to keep the electrofisher s generator running the evening of October 24 were unsuccessful, therefore no electrofishing was conducted that evening. The generator continued to be troublesome, although electrofishing was conducted all other evenings. Our local Kohler dealer remedied the issue upon returning from the field. Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 5

Literature Cited Kesner, B. R. and A. P. Karam. 2006. Survival of razorback sucker stocked into the lower Colorado River. Trip Report 2-3: Palo Verde Division 2-11 May 2006. U.S. Bureau of Reclamation Agreement Number 06FC300002, Boulder City, Nevada. Arizona State University, Tempe. 11 pages. USBR. 1976. Lower Colorado River Maps: Colorado River-front Work and Levee System, Arizona - California. USBR. Boulder City, NV. USBR. 1990. Colorado River floodway maps. USBR, Boulder City, NV. USFWS. 1997. Final Biological and Conference Opinion on lower Colorado River operations and maintenance - Lake Mead to Southerly International boundary. U.S. Fish and Wildlife Service, Albuquerque NM. 196 pages. Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 6

Figure 1. Study area backwaters, lower Colorado River, Palo Verde Division, October 9-13 and 23-27, 2006. Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 7

Figure 2. Study area backwaters, lower Colorado River, Cibola Division, October 9-13 and 23-27, 2006 Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 8

Table 1. Summary of razorback sucker stocking records for the lower Colorado River downstream from Parker Dam, July 22, 2004 through September 30, 2006. Wire tag (WT) locations are left dorsal musculature (L Dorsal), right caudal peduncle (RCP), and above left pectoral fin (L Pectoral). Date Number of fish stocked Mean TL (mm) Tag type(s) WT location Stocking site 7/22/2004 2,567 305 WT L Dorsal A-7U Backwater 11/4/2004 2,024 327 WT L Dorsal A-7U Backwater 11/4/2004 598 366 PIT, WT L Dorsal A-7U Backwater 12/7/2004 213 343 PIT, WT L Dorsal A-7U Backwater 12/7/2004 1,822 343 WT L Dorsal A-7U Backwater 2/4/2005 70 352 PIT, WT, Radio RCP A-10U Backwater 2/4/2005 69 348 PIT, WT, Radio L Dorsal A-7U Backwater 2/4/2005 619 352 WT RCP A-10U Backwater 2/4/2005 620 348 WT L Dorsal A-7U Backwater 4/21/2005 44 378 PIT, WT RCP A-10U Backwater 4/21/2005 44 391 PIT, WT L Dorsal A-7U Backwater 4/21/2005 321 391 WT L Dorsal A-7U Backwater 4/21/2005 320 378 WT RCP A-10U Backwater 9/22/2005 969 NA WT L Dorsal A-7U Backwater 9/22/2005 120 372 PIT, WT L Dorsal A-7U Backwater 9/23/2005 988 NA WT RCP A-10U Backwater 9/23/2005 120 376 PIT, WT RCP A-10U Backwater 1/21/2006 692 NA WT L Dorsal A-7U Backwater 1/21/2006 99 375 PIT, WT L Dorsal A-7U Backwater 1/21/2006 690 NA WT RCP A-10U Backwater 1/21/2006 100 365 PIT, WT RCP A-10U Backwater 3/31/2006 753 NA WT L Dorsal A-7U Backwater 3/31/2006 98 335 PIT, WT L Dorsal A-7U Backwater 3/31/2006 765 NA WT RCP A-10U Backwater 3/31/2006 100 335 PIT, WT RCP A-10U Backwater 4/20/2006 1416 NA WT RCP A-10L Backwater 4/20/2006 9/14/2006 200 2,352 349 350 PIT, WT PIT, WT RCP L Pectoral A-10L Backwater A-10L Backwater Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 9

Table 2. Numbers of fish captured by electrofishing and trammel netting, total number caught, and proportion of total catch. USBR Palo Verde and Cibola divisions, lower Colorado River, October 9-13 and 23-27, 2006. Age Pct Species 0/1 Efish trammel total catch of total Cyprinus carpio 1 59 33 92 7.1% Dorosoma petenense 0 65 65 5.0% Ictalurus punctatus 1 8 22 30 2.3% Lepomis gulosus 0 1 1 0.1% Lepomis gulosus 1 20 4 24 1.9% Lepomis macrochirus 1 108 205 313 24.2% Lepomis microlophus 0 2 2 0.2% Lepomis microlophus 1 33 78 111 8.6% Lepomis sp. 0 40 40 3.1% Micropterus dolomieu 1 18 18 1.4% Micropterus salmoides 0 22 22 1.7% Micropterus salmoides 1 298 55 353 27.2% Morone saxatilis 0 1 1 0.1% Morone saxatilis 1 20 11 31 2.4% Oreochromis aureus 1 5 22 27 2.1% Pomoxis nigromaculatus 1 1 1 0.1% Pylodictis olivaris 1 5 20 25 1.9% Tilapia sp. 1 2 2 0.2% Tilapia zillii 0 1 1 0.1% Tilapia zillii 1 11 23 34 2.6% Xyrauchen texanus 1 59 44 103 5 7.9% Sum 776 520 1,296 100% 5 Two razorback suckers encountered incidentally were excluded from this table (see text). Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 10

Table 3. Individual growth data for razorbacks recaptured during trip 2-6: October 9-13 and 23-27, 2006. Total length (TL) is in millimeters. TL growth is the difference between tagging and capture TL, and TL daily growth is TL growth divided by days at large. Recapture Days TL daily date at large Sex Tagging TL Capture TL TL change growth 10/09/2006 25 Juvenile 330 337 7 0.28 10/09/2006 25 Male 360 370 10 0.4 10/09/2006 25 Juvenile 315 322 7 0.28 10/12/2006 28 Juvenile 305 300-5 -0.18 10/09/2006 25 Juvenile 375 385 10 0.4 10/12/2006 28 Juvenile 325 330 5 0.18 10/09/2006 25 Juvenile 355 348-7 -0.28 10/12/2006 28 Juvenile 355 355 0 0 10/12/2006 28 Juvenile 340 345 5 0.18 10/12/2006 28 Male 355 360 5 0.18 10/12/2006 28 Juvenile 330 322-8 -0.29 10/12/2006 28 Juvenile 335 340 5 0.18 10/12/2006 28 Male 370 375 5 0.18 10/12/2006 28 Juvenile 365 365 0 0 10/10/2006 193 Juvenile 350 447 97 0.5 10/12/2006 28 Male 350 350 0 0 10/12/2006 28 Juvenile 310 310 0 0 10/12/2006 175 Unknown 355 405 50 0.29 10/12/2006 175 Juvenile 345 385 40 0.23 10/25/2006 147 Female 595 610 15 0.1 10/09/2006 304 Unknown 327 410 83 0.27 10/12/2006 28 Juvenile 350 353 3 0.11 10/09/2006 25 Juvenile 325 337 12 0.48 10/12/2006 28 Juvenile 305 315 10 0.36 10/12/2006 28 Juvenile 340 345 5 0.18 10/12/2006 28 Male 335 330-5 -0.18 10/12/2006 28 Juvenile 335 340 5 0.18 10/12/2006 28 Juvenile 335 320-15 -0.54 10/12/2006 28 Juvenile 330 330 0 0 10/12/2006 28 Juvenile 330 325-5 -0.18 10/12/2006 28 Juvenile 375 390 15 0.54 10/12/2006 28 Juvenile 310 315 5 0.18 10/12/2006 28 Unknown 400 405 5 0.18 10/12/2006 28 Male 395 395 0 0 10/12/2006 28 Male 335 335 0 0 10/12/2006 28 Juvenile 350 360 10 0.36 10/12/2006 28 Juvenile 320 312-8 -0.29 Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 11

Table 3. continued. Recapture Days TL daily date at large Sex Tagging TL Capture TL TL growth growth 10/12/2006 28 Male 330 323-7 -0.25 10/12/2006 28 Male 355 345-10 -0.36 10/12/2006 28 Juvenile 395 395 0 0 10/12/2006 28 Male 320 310-10 -0.36 10/25/2006 41 Juvenile 325 335 10 0.24 10/09/2006 25 Juvenile 360 377 17 0.68 10/09/2006 25 Male 380 385 5 0.2 10/12/2006 28 Juvenile 340 342 2 0.07 10/12/2006 28 Juvenile 395 395 0 0 10/12/2006 28 Male 325 330 5 0.18 10/12/2006 28 Juvenile 350 345-5 -0.18 10/12/2006 28 Juvenile 315 315 0 0 10/12/2006 28 Juvenile 335 327-8 -0.29 10/12/2006 28 Male 360 364 4 0.14 10/12/2006 28 Male 335 327-8 -0.29 10/12/2006 28 Male 360 360 0 0 10/12/2006 28 Juvenile 340 335-5 -0.18 10/12/2006 28 Juvenile 320 323 3 0.11 10/12/2006 28 Juvenile 320 315-5 -0.18 10/12/2006 28 Male 390 395 5 0.18 10/12/2006 28 Male 370 365-5 -0.18 10/12/2006 28 Juvenile 360 366 6 0.21 10/09/2006 25 Juvenile 325 327 2 0.08 10/12/2006 28 Juvenile 340 340 0 0 10/12/2006 28 Juvenile 350 350 0 0 10/12/2006 28 Juvenile 355 347-8 -0.29 10/12/2006 28 Male 375 370-5 -0.18 Avg: (64fish) 41 349 354 5 0.06 Trip Report 2-6: Palo Verde and Cibola Division, October 9-13 and 23-27, 2006 12