Cienega Creek Fish Surveys 2005 Gila chub status investigation

Transcription

1 Cienega Creek Fish Surveys 2005 Gila chub status investigation A cooperative project between the Bureau of Land Management (BLM) and The Arizona Game and Fish Department (AZGFD). Dean Foster, AZGFD native fish specialist Tucson Regional Office Jeff Simms, BLM fisheries biologist Tucson Field Office 1

2 Arizona Game and Fish Department Mission To conserve, enhance, and restore Arizona s diverse wildlife resources and habitats through aggressive protection and management programs, and to provide wildlife resources and safe watercraft and off-highway vehicle recreation for the enjoyment, appreciation, and use by present and future generations. The Arizona Game and Fish Department prohibits discrimination on the basis of race, color, sex, national origin, age, or disability in its programs and activities. If anyone believes they have been discriminated against in any of AGFD s programs or activities, including its employment practices, the individual may file a complaint alleging discrimination directly with AGFD Deputy Director, 2221 W. Greenway Rd., Phoenix, AZ 85023, (602) or U.S. Fish and Wildlife Service, 4040 N. Fairfax Dr., Ste. 130, Arlington, VA Persons with a disability may request a reasonable accommodation, such as a sign language interpreter, or this document in an alternative format, by contacting the AGFD Deputy Director, 2221 W. Greenway Rd., Phoenix, AZ 85023, (602) , or by calling TTY at Requests should be made as early as possible to allow sufficient time to arrange for accommodation. Suggested Citation: Foster, D.K. and Jeff Simms Cienega Creek Fish Surveys 2005 Gila Chub, Gila intermedia, Status Investigation. Final report to the U.S. Bureau of Land Management. Arizona Game and Fish Department, Field Operations Tucson, AZ. This project was jointly funded by BLM and AZGFD 2

3 Introduction Cienega Creek is one of the last places in Arizona supporting an intact native fish fauna which is uncontaminated by exotic fish. Cienega Creek drains portions of the Whetstone, Empire, and Santa Rita Mountains in S.E. Arizona and flow northwest into the Tucson Basin where its name is changed to Pantano Wash (Map 1). Pantano Wash and Tanque Verde Creek meet and form the now dry Rillito River and from here the floodwaters of Cienega Creek flow into the Santa Cruz River. Gila chub has been found in 2 separate reaches of Cienega Creek separated by 4 miles of dry stream bed (Maps 2 and 3). The upper segment is ~1.5 miles long with base flows less than 0.25 cfs. Aquatic habitats are dominated by pool and thickly vegetated marsh and willow swamp macrohabitat types with a mud substrate. The lower creek is ~2.7miles long and has a base flow that varies from 0.1 in summer to 0.5 cfs during the wither. Common aquatic habitat associations on Cienega Creek are deep, vertical walled, slit-like pools connected by narrow, swift runs surrounded by several feet of marsh on both sides. Riffles with gravel or cobble substrate are present but uncommon. Stream gradient on Cienega Creek varies but is generally about 0.5%. Aquatic habitats are bordered by Gooding willow, cottonwood, ash and other riparian trees. The broad flood plains are comprised of fine textured alluvium (silt, sand, and clay),marsh adapted plants and large stands of giant sacaton (Sporobolus wrightii) grass. Three native fish species call Cienega Creek home: Gila chub (Gila intermedia, LE), Gila topminnow (Poeciliopsis o. occidentalis, LE), and longfin dace (Agosia chrysogaster, unlisted). Fish surveys have been conducted on Cienega Creek since A visual fish count of Gila Chub (Gila intermedia) was conducted in 1990 and spot-checking of chub with electrofishing gear has been conducted from time to time over the past 15 years. Annual fish surveys have been conducted to follow Gila topminnow population trend and screening for exotic fishes (Young 1995). However, no population monitoring has been conducted for Gila chub at Cienega Creek. This species was proposed for listing in 2002 and was formally listed as endangered this year (USFWS 2005). This study represents the first real attempt to estimate the Gila chub abundance in the two separated reaches. Characterizing Habitat Methods Pool macrohabitats were delineated using the classification system in McCain et al (1989). Only those pools big enough and deep enough to set a 2-foot diameter hoop net were selected for each study reach. The following information was recorded for each pool: length, average channel width, average depth, and maximum depth. Average width was taken at a single location in the middle of a habitat when the habitat was small and uniform. If the habitat was large or banks irregular than 3 or more width measurements were taken and averaged. Average depth was estimated by taking depth measurements at ¼, ½ and ¾ the distance across the wetted width. When the banks were shear the 3 data points were divided by 3. When the banks sloped into the water gradually, the 3 data points were divided by 4 (Plats et al. 1983). Average depth was estimated in one representative location in small habitats and at 3 or more locations for large habitats. The average of multiple average depth estimates was recorded as the final average depth. Length and widths were measured by a recently calibrated HAGLOF DME 201 to the 3

4 nearest 0.1-foot (3 cm). Depths were measured using a surveyor s rod to the nearest 0.1 foot (3 cm). Fish sampling All fish were collected using identical, single-throat hoop nets that were 2-feet in diameter, strung with 3/16-inch mesh, and were supported by three hoops. All hoop nets had been treated at the factory with a green dip to increase durability. 2 PVC poles with attached stretch cords were fitted to each net to ensure that they remained open and fishing when in the water. The hoop net traps were baited using perforated containers filled with Purina Aquamax Carnivore pellets. Traps were set so that a portion of the net was always above water to reduce the likelihood of mud turtle by-catch mortalities. The preferred hoop net set was horizontal but when shorelines were shear then the nets were fished vertically. Before the sampling began it was decided that the number of hoop nets needed to adequately sample a given pool would be based on one net for every thirty feet of pool. Pools were then randomly selected for sampling until our supply of 22 hoop nets were exhausted. The lower reach was sampled on October and the upper reach was sampled on October Fish were collected, identified, and counted the following day and then the nets were reset following refreshment of the bait. In addition the Gila chub were measured and anal fin-clipped on the first day. Fish were returned to the same pool from which they were collected. This process was repeated on the second day with the exception that this time to verify recaptures the chub were put into acrylic viewing containers and inspected for the presence of a clipped anal fin. A simple Lincoln-Peterson index for estimating populations of closed systems was used to estimate the abundance of catchable Gila chub in both the upper and lower reaches of BLM managed Cienega Creek. The formula is N=MC/R, where N = Population abundance estimator, M = number of individuals originally marked, C = number of individuals collected on day 2, and R = number of day two individuals with marks (# of recaptures). The Peterson estimator assumes that losses and additions due to emigration, immigration, mortality, and recruitment are zero. Results 79 lower reach pools greater than 2 feet deep were recorded and measured. The total surface area of these 79 pools was 79,423 ft 2 (table 1). The UTM locations for the lower reach pools is given in table 2 and can be found on Map #2 by cross-referencing with the GPS waypoint number. 15 of the pools were selected for the fish sampling and are shown in red. The surface area of the 15 pools was 19,301 ft 2 and represented 24% of the available pool habitat. 33 upper reach pools greater than 2 feet deep were recorded and measured. The total surface area of these 33 pools was 36,258 ft 2 (table 3). The UTM locations for the lower reach pools is given in table 4 and can be seen on Map #3 by cross-referencing with the GPS waypoint number. 12 of the pools were selected for the fish sampling and are shown in red. The surface area of the 12 pools was 13,631 ft 2 and represented 37.5% of the available pool habitat. Surveys captured 375 fish and 17 turtles in the upper each and 1078 fish and 20 turtles in the lower reach (table 5). 215 of the 375 fish caught in the upper reach were chub, compared to 451 of 1078 in the lower reach. 203 longfin dace were captured in the lower reach whereas no dace 4

5 were captured in the swampy upper reach. The lower reach of Cienega Creek maintained flowing water whereas the upper reach did not maintain flow. A surprising result from the study was the large numbers of Gila topminnow captured in the hoop nets. 160 Gila topminnows were captured in the upper reach and 424 topminnows were captured in the lower reach. 334 chub were marked and released during day one in the lower reach and 32 were recaptured the next day, thus recapture rates were about 10% (table 5). The Peterson index estimated total catchable chub abundance in the lower reach at 4810 chub. In the upper reach only 1 of 122 marked chub was recaptured and so the Peterson index could not be used due to a lack of recaptures. However, if we assume that hoop nets captured similar proportions of the total catchable populations in both reaches, then we can draw inferences on the upper chub population based upon the lower population. In the lower reach the Peterson estimate suggests that the twoday sampling effort captured 38.6% of the catchable chub in the sampled pools. So if we assume that 38.6% of the catchable chub in the upper sampled pools were captured (215 fish, see table 5) then we can estimate the Gila chub abundance for the entire upper reach at 1481 chub. Adding these two estimates gives a total abundance estimate of 6291 chub. There was substantial variability in catch rates for the three species of fish between pools within a reach. In the lower reach Gila chub and longfin dace were captured throughout while Gila topminnow were common in the lower end but not captured above pool 41 (figure 1). Gila chub dominated the catch in the upper reach, while Gila topminnows were much less commonly encountered and longfin dace were absent from the upper reach (figure 1). The largest Gila chub were found in the lower reach and reached 151 mm TL while the largest chub captured in the upper reach was 112 mm. Examination of the length frequency histogram (figure 2) suggests at least two distinct cohorts in the lower reach with average sizes of mm and mm plus additional large adults as well. The trend in the upper reach is more pyramidal in shape with no discernible size breakpoint between cohorts and a lack of large adults. Gila chub average 50mm to 90mm in length in the upper reach with no discernible trend toward either larger or smaller fish within the reach (figure 3). In contrast, Gila chub in the lower reach averaged 38mm to 100mm in length with the smallest average sized fish being found in the furthest downstream pools. This downstream reach dried completely in early summer 2005 and rewetted prior to these surveys during Fall Catch per unit effort was highly variable between pools and nets within a pool (figure 4.) Gila chub and longfin dace catch rates ranged from 0 to about 25 fish for a 12-hour overnight set. Gila topminnow catch rates ranged from 0 to as many as 30 fish for a 12-hour overnight set. Turtle captures averaged 1 to 3 per pool. Discussion Still needs to be written -Differences in fish communities between upper and lower reaches are the result of habitat differences lower section more stream-like and upper section more swamp-like 5

6 - Chub appear to be doing well despite of recent losses via disease (fungus?) -Argument for using the Peterson estimator--- The pools in Cienega Creek at this time were either not connected or poorly connected via shallow flow so immigration and emigration assumptions were probably met. It is unknown if mortality following the first netting period occurred, but no mortalities of released fish were seen during the surveys. - data suggests that chub spawning/recruitment occurs throughout the summer (evidence - YOY observed in October in combination with one inch fish from springtime spawn). Literature Cited McCain M., Fuller D., Decker L., and K. Overton Stream Habitat Classification and inventory procedures for northern California. Fish Habitat Relations Program, U.S. Forest Service, Eureka CA Platts, W.S., Megahan W.F. and G. W. Minshall Methods for evaluating stream, riparian and biotic conditions. U.S. Forest Service, General Technical Report INT-138. Young, K.L., and M.A. Lopez Fall Fish count summary Technical Report 81. Nongame and Endangered Wildlife Program. Arizona Game and Fish Department, Phoenix, AZ. U.S. Fish and Wildlife Service Endangered and threatened wildlife and plants: Listing Gila chub as endangered with critical habitat: final rule. Fed Reg. 70 (211): Acknowledgements The authors would like to thank the following volunteers and fellow employees for their assistance in the field: insert BLM folks here and Jason West (BLM), Erica Sontz, Andrew Schultz, Dr. Scott Bonar (UofA), TNC 6

7 Map 1. Permanent pools in upper Cienega Creek are shown as blue dots. The cluster towards the bottom of the page is the upper reach as this stream flows north through the project area. 7

8 Map 2. Permanent pools in the lower reach of Cienega Creek are shown as blue dots. Pool numbers can be determined by cross-referencing with the waypoint numbers in table 2. 8

9 Map 3. Permanent pools in the upper reach of Cienega Creek are shown as blue dots. Pool numbers can be determined by cross-referencing with the waypoint numbers in table 4. 9

10 Cienega Creek Narrows Crossing (above Fresno Cyn Confluence) to Cold Spring Waterfall (Above Mattie Cyn Confluence) 11/02/05 and 11/09/05 True No. Sheet No habitat type length ft² width ft² Area ft² mean depth max depth overstory % comments 1 1 Pool _ Pool _ Pool Pool Pool Pool Pool Pool Pool _ Pool Pool Pool Pool Pool Pool Glide? 0 too shallow Pool Pool Pool Pool Pool Pool Pool bottoms SA,GR,SI Pool above falls below Pump Canyon Pool filamentous algae Pool Pool lots of topminnow visible 27 27b Pool Pool gravel/sand bottoms can be overlain with silt 29 28b Pool Pool Pool b Pool Pool b Pool Pool Pool Pool Pump Canyon pool, cobble substrate Pool b Pool silt substrate Pool pure mud substrate, at Pump Canyon, lots of topminnow Pool Pool Pool sycamore sapling 12R , acc Pool Pool Pool Pool Pool Pool a Pool b Pool Pool true 46, coati tree habitat GPS NAD Pool Pool lots of topminnow visible, longfin abundant as well, bedrock controls visible in deepest pools Pool Pool b Pool bedrock substrate 58 50c Pool stream gauge Pool Pool Pool gravel/sand substrate Pool gravel/sand substrate Pool Pool ? 65 56a Pool b Pool Pool Pool Pool no frogs, no mexican gartersnakes observed from? Pool Pool Pool Pool Pool No Pool Found Pool Pool Pool Pool Pool Fishing Spider = Genus Dolomedes Total Area Table 1. Pool habitat data collected in the lower reach. 10

11 Cienega Creek lower reach - from above The Narrows to above Fresno Gap Random Sample Pool # GPS Waypoint # nets req'd NAD27 Easting Northing Fish seen? Notes Date Local-Time x R Sep-05 11: R Sep-05 11: R Sep-05 11:54 x R Sep-05 11: R Sep-05 12:00 x R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12:10 x R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12:19 x R Sep-05 12:22 x R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12:28 x R Falls 22-Sep-05 12: R Falls 22-Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12: R Sep-05 12:46 x R Sep-05 12:48 x R Sep-05 12: R Pump Canyon dam pool 22-Sep-05 12: R Sep-05 12:56 x R Sep-05 13: R Sep-05 13: R Sep-05 13:04 x R Sep-05 13: R Sep-05 13: R Sep-05 13: R Sep-05 13: R Sep-05 13: R Sep-05 13: R Sep-05 13: R Sep-05 13: R Sep-05 13: R gage 22-Sep-05 13: R Sep-05 13:29 x R Honey Hole 22-Sep-05 13: R Sep-05 13: R Sep-05 13: R Honey Hole 22-Sep-05 13: R Sep-05 13: R Sep-05 13: R Sep-05 13: R Sep-05 13: R Fresno Gap 22-Sep-05 13: R Oct R Oct-05 x R Oct R Oct R Oct-05 x R Oct R Oct R Oct R Oct-05 x R Oct-05 Table 2. Pool location data for the lower reach. 11

12 Box Well (downstream of Gardner Cyn) to Head Waters 10/20/05 and 10/21/05 True No. Sheet No habitat type length ft² width ft² Area ft² mean depth max depth overstory % comments Area 1 1 Pool stagnant, fungus, willows 2 2 Pool stagnant, fungus, 3 3 Pool flowing, no fungus 4 4 Pool Pool stagnant with diatom scum 6 6 Pool open sunny, very clear, back swimmers 7 7 Pool Pool Gardner Canyon 9 9 Pool Pool cottonwood site, no topminnow, 100's Gila chub, 100s notonectids Pool big juniper, chub, no topminnow Pool R , topminnow Pool R , Pool Pool R , Pool fall fish count pool FC0316, Brads taking photos, pondweed=potomagetan Pool FC Pool Pool Pool Pool floating algae Pool Pool Trace Pool old road crossing Pool covered with duckweed Pool Pool sunny Pool shaded Pool a Pool b Pool c Pool d Pool Total Area Table 3. Pool habitat data collected in the upper reach. 12

13 Cienega Creek upper reach - from below Gardner to about 1.2 miles above Random Sample Pool # GPS Waypoint # nets req'd NAD27 Easting Northing Fish seen? Notes Date Local-Time R no 20-Oct-05 11:53 X R no 20-Oct-05 12: R ? 20-Oct-05 12: R ? 2 pools surveyed and combined 20-Oct-05 12: R ? 20-Oct-05 12: R ? 20-Oct-05 13:37 X R ? 20-Oct-05 14: R ? 20-Oct-05 14:11 X R yes 20-Oct-05 14:40 X R yes 20-Oct-05 14: R yes 21-Oct-05 10:36 X R yes 21-Oct-05 10:40 X R no 21-Oct-05 11:05 X R no 21-Oct-05 11: R yes 21-Oct-05 11: R yes 21-Oct-05 11: R ? 21-Oct-05 11:37 X R no 21-Oct-05 11: R yes 21-Oct-05 11:59 X R yes 21-Oct-05 12: R yes 21-Oct-05 12:24 X R yes 21-Oct-05 12: R ? 21-Oct-05 12:46 X R ? 21-Oct-05 12: R ? 21-Oct-05 13: R no 21-Oct-05 13:08 X R no 21-Oct-05 13: R no 21-Oct-05 13:20 30 N/A 1 Fall Fish Count Site Table 4. Pool location data for the upper reach. 13

14 Cienega Creek - Upper Reach Hoop Net totals Totals - day 1 Total Chub Species # caught # marked Caught (2 days) GIIN AGCH 0 Total longfin dace POOC 35 Caught (2 days) turtles 11 0 Total topminnow Totals day 2 Caught (2 days) Species # caught # new # re-captured 160 GIIN Total Turtles AGCH 0 Caught (2 days) POOC Turtles 6 Peterson 1481 chub based on lower reach Peterson estimator suggesting that 2 day catch represents 38.5% of catchables and 13,631 ft2 of 36,258 ft2 of available pool habitat was sampled Cienega Creek - Lower Reach Hoop Net totals Totals - day 1 Total Chub Species # caught # marked Caught (2 days) GIIN AGCH 133 Total longfin dace POOC 336 Caught (2 days) turtles Total topminnow Totals day 2 Caught (2 days) Species # caught # new # re-captured 424 GIIN Total Turtles AGCH 70 Caught (2 days) POOC Turtles 10 Peterson 4810 chub 19,301 ft2 of 79,423 ft2 of pool habitat was sampled Table 5. Collection totals and Gila chub population estimates for both Cienega Creek reaches based on two trapping sessions and a single mark-recapture event. 14

15 # of individuals captured # of individuals captured Total Catch - upper reach, days GIIN POOC Turtles Pool # (stream flow from right to left) Total Catch - lower reach, day AGCH GIIN POOC Turtles Pool # (stream flow from right to left) Figure 1. Gila chub, longfin dace, Gila topminnow, and mud turtles were captured throughout the lower reach. Longfin dace were not captured in the upper reach. 15

16 Occurrence Frequency (%) Occurrence Frequency (%) Gila chub length frequency - lower reach Length Groups (mm) Gila chub length frequency - upper reach Length Groups (mm) Figure 2. Gila chub consist of at least two discernible year classes in the lower reach. Year class designations in the upper reach were not discernible. 16

17 Chub Length (mm) Chub Length (mm) Gila Chub length data - upper reach Average Min Max Pool # (stream flow is right to left) Gila Chub length data - lower reach Average Min Max Pool # (stream flow is right to left) Figure 3. These graphs describe the average size of Gila chub collected from each pool. Lower reach pools 1-12 were dry earlier this summer, have refilled, and are now inhabited by small fish. 17

18 Average fish captures/12 hours Average fish captures/12 hours Average CPUE - upper reach, day GIIN POOC Turtles Pool # (stream flow from right to left) Average CPUE - lower reach, day AGCH GIIN POOC Turtles Pool # (stream flow from right to left) Figure 4. Error bars of 1 standard deviation are included to describe the variability among nets within a pool. Some pools were sampled with just one net and therefore lack error bars. 18

19 Appendix 1. Lower reach data Net soak period Day 1 Pool # Net # Date set pulled hours Species # caught # marked length (mm) notes /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN 40 19

20 1 1 10/7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN 52 20

21 1 1 10/7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: GIIN /7/ :42 9: POOC /7/ :42 9: AGCH /7/ :42 9: turtle /7/ :42 10: GIIN one mort /7/ :42 10: GIIN /7/ :42 10: GIIN /7/ :42 10: GIIN /7/ :42 10: GIIN /7/ :42 10: POOC /7/ :42 11: GIIN /7/ :42 11: GIIN /7/ :42 11: GIIN /7/ :42 11: POOC /7/ :42 11: Turtle /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN 32 21

22 6 4 10/7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: POOC /7/ :03 11: GIIN mort /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: GIIN /7/ :03 11: POOC /7/ :03 11: AGCH /7/ :03 11: AGCH /7/ :03 11: POOC /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN 46 22

23 /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: GIIN /7/ :15 11: POOC /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: GIIN /7/ :15 12: AGCH /7/ :15 12: POOC /7/ :28 12: GIIN

24 /7/ :28 12: GIIN /7/ :28 12: GIIN /7/ :28 12: turtles /7/ :28 12: GIIN /7/ :28 12: GIIN /7/ :28 12: GIIN /7/ :28 12: GIIN /7/ :28 12: GIIN /7/ :28 12: POOC /7/ :28 12: turtles /7/ :42 12: GIIN /7/ :42 12: GIIN /7/ :42 12: GIIN /7/ :42 12: GIIN /7/ :42 12: POOC /7/ :42 12: AGCH /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: GIIN /7/ :56 13: POOC /7/ :56 13: Turtle /7/ :56 13: AGCH /7/ :01 13: GIIN

25 /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: GIIN /7/ :01 13: AGCH /7/ :26 13: GIIN /7/ :26 13: GIIN /7/ :26 13: POOC /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: POOC /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN 46 25

26 /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: GIIN /7/ :33 14: POOC /7/ :33 14: AGCH 37 ~60% adults /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN 81 26

27 /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: GIIN /7/ :54 15: AGCH 52 27

28 /7/ :25 16: GIIN /7/ :25 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: AGCH /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :30 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN 82 28

29 /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: GIIN /7/ :35 16: AGCH /7/ :54 17: GIIN /7/ :54 17: GIIN 137 slight orange fin bases /7/ :54 17: turtles 3 one mort, accid. Net soak period Day 2 Pool # Net # Date set pulled hours Species # caught # new # re-captured length (mm) notes /8/2005 9:43 9: AGCH 1 1 adult /8/ :52 9: GIIN /8/ :05 9: GIIN juv. 4, adult /8/ :22 10: GIIN /8/ :22 10: POOC /8/ :22 10: Turtle /8/ :22 10: Scud /8/ :34 10: GIIN /8/ :34 10: POOC /8/ :34 10: Turtle /8/ :34 10: AGCH /8/ :49 10: GIIN orange fin bases /8/ :49 10: POOC /8/ :49 10: AGCH /8/ :57 10: GIIN /8/ :57 10: Turtle /8/ :09 10: GIIN /8/ :09 10: POOC 1 29

30 /8/ :34 11: GIIN /8/ :44 10: GIIN /8/ :44 10: POOC /8/ :54 12: GIIN /8/ :54 12: AGCH /8/ :54 12: POOC /8/ :15 12: GIIN /8/ :15 12: POOC /8/ :15 12: AGCH /8/ :35 12: GIIN /8/ :35 12: AGCH /8/ :35 12: POOC /8/ :58 13: AGCH /8/ :08 13: GIIN /8/ :19 13: GIIN /8/ :19 13: AGCH /8/ :08 13: /8/ :17 14: GIIN /8/ :17 14: POOC /8/ :45 14: GIIN /8/ :45 14: Turtle /8/ :50 14: GIIN /8/ :08 14: GIIN 2 2 I chub mort /8/ :08 14: Turtle /8/ :08 14: POOC 3 30

31 Appendix 2. Upper reach data Net soak period Day Pool # Net # Date set pulled hours Species # caught # marked length (mm) notes /27/ :55 10: /27/ :20 10: GIIN /27/ :20 10: GIIN /27/ :20 10: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: POOC 1 mort /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN 50 31

32 /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: GIIN /27/ :40 11: RACH 1 bullfrog - dispatched /27/ :47 12: GIIN /27/ :47 12: turtles /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN 78 32

33 /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :47 12: GIIN /27/ :05 11: GIIN /27/ :05 11: GIIN /27/ :05 11: GIIN /27/ :05 11: GIIN /27/ :05 11: POOC /27/ :05 11: turtles /27/ :05 11: GIIN /27/ :05 11: /27/ :05 11: /27/ :05 11: /27/ :05 11: