2010 Tule Lake Sucker Relocation Project

Transcription

1 2010 Tule Lake Sucker Relocation Project Summary Report June 1, 2010 Prepared for: The Bureau of Reclamation Klamath Basin Area Office Authors: Ian Courter Jay Vaughan Shadia Duery

2 BACKGROUND AND OBJECTIVES Dry meteorological conditions in the Klamath Basin during the 2010 water year were expected to cause significant reductions in water available for Tule Lake. Lake depths were expected to drop substantially due to evaporative loss in the summer and fall without replenishment by irrigation return flows. In anticipation of this quandary, the Bureau of Reclamation contracted with Cramer Fish Sciences (CFS) to capture and relocate as many endangered Lost River and shortnose suckers as possible prior to lake level reductions. Past studies indicated that adult suckers primarily reside in Sump 1A of Tule Lake during the period of performance for this relocation project. The effort was planned to occur in May 2010 over a two week time period. In addition to fish capture and transport, CFS catalogued the species, sex, and length of each fish being moved. We also PIT tagged fish prior to release. This report describes our effort and provides a summary of the basic biological information collected from the fish during the relocation project. METHODS We used six, 300-foot trammel nets, as defined by state and federal collection permits held by Reclamation to capture adult Lost River and shortnose suckers in Tule Lake, Sump 1A. The multi-filament trammel nets had a 12 inch mesh wall size, 1.5 inch bar inside mesh and were approximately 6 feet from the float line to the lead core bottom line. Each of two boats fished three trammel nets during the collection period (May 10-21, 2010). Both boats operated well in Tule Lake s shallow water (2-3 feet deep) and are described as follows: (1) ft. Smith-Root SR-16H aluminum electrofishing boat equipped with a 50 hp Yamaha outboard and an onboard fish holding tank with aeration system (2) ft. Thunderjet Alexis outfitted with an onboard fish holding tank and aeration system Nets were set and checked for entangled fish once every 1-2 hours. We used the information gathered during telemetry and population monitoring studies to identify the areas within Sump 1A that were most likely to hold adult suckers (Hicks et al. 1999, Beckstrand et al 2000, Hodge 2008, Hodge and Buettner 2009). Placement of nets was adjusted as necessary to maximize efficiency of capture throughout the project. All adult suckers captured were removed from the trammel nets and held temporarily in aerated holding tanks onboard each vessel. Suckers were placed in floating net-pens (Figure 1) prior to processing and transfer to land-based transport tanks. Any non-target species entangled in the nets were released at the point of capture. During fish processing, suckers were identified to species and sex, measured for fork length (mm) and implanted with a passive integrated transponder (PIT) tag near the 1

3 pelvic girdle using a large gauge needle and plunger (Figure 2). After processing, fish were moved individually, by hand to land-based transport tanks. Land-based transport was conducted using large pickup trucks equipped with fiberglass live-wells with approximately 200 gallons of capacity. Live-wells were filled with water at the USFWS Tule Lake Wildlife Refuge field office located on Hill Road. Salt and fish slime were added according to Reclamation s directions. The primary vehicle used for transport was a Ford F450 dump truck, capable of hauling two, 200-gallon tanks (Figure 3). Fish were transported to Howard Bay, located on the southwest shore of Upper Klamath Lake. A limited number of fish were transported by Reclamation biologist Torrey Tyler to other sites in the Upper Klamath Lake area. During transport, water temperature was monitored and, when necessary adjusted with ice to maintain an optimal range near 15oC, but not less than 1oC below Tule Lake temperatures to avoid temperature shock. Figure 1: Capture Figure 2: Processing Figure 3: Transport RESULTS In total, we fished net-hours over the course of 10 days (Table 1). Numbers of fish captured varied on a daily basis (Figure 4), and appeared to be dependent upon wind and temperature conditions, as well as fishing location. Lost River and shortnose suckers were oriented towards sources of flow and shoreline areas. For example, the southwest corner of the lake produced a significant numbers of fish proximate to an irrigation water return that was actively flowing. In total, 413 suckers were captured in Tule Lake and relocated to Upper Klamath Lake, yielding a catch per unit effort (CPUE) of 1.09 fish/net-hr (Table 1). Weather Conditions were extremely variable throughout the course of the relocation project, which had a substantial effect on daily capture rates. Prospecting for productive fishing sites began on May 10 and 11 when temperatures were cold, and wind and snow made fishing difficult. Capture rates remained low until the end of the day on May 11 when crews set a net in the English Channel and captured four fish within a half hour. Temperatures warmed substantially the following day (Figure 4) and winds died down. Both boats fished heavily in the English Channel on May 12 and captured 113 fish. Fishing remained productive in the Channel but steadily declined until May 18, at which point both boats began exploring sites along the southern shore. The southwest corner of the lake produced steady, moderate numbers of fish until fishing ended on May 21. Figure 5 shows average daily lake temperatures and CPUE estimates throughout the project. Field crews observed higher catch rates during warmer days, but fish distribution 2

4 was patchy and wind was often a confounding factor. For example, low capture rates on May 10, 11, and 18 corresponded with windy weather conditions. In addition to the English Channel and SW Corner, we fished throughout the NW Corner and the Doughnut Hole (a large circular area encompassing the south-central portion of the lake), sites that had been highlighted as potential holding areas for suckers by previous studies. These sites produced very few fish, approximately 2-4% of our total capture. Throughout the project, nets were periodically set in these areas to monitor for fish that could have been dispersed by boat activity in the English Channel and SW Corner. Figure 6 provides a map of the areas fished and qualitative descriptions of the numbers of captures. GPS coordinates for our highest producing net-setting locations are also provided. Species, length and sex information was collected on all 413 fish. Lost River suckers were evenly split with only slightly more males than females, while shortnose suckers were comprised of about 15% more females than males (Table 2). Lost River suckers were significantly larger averaging 580 mm in fork length ( Figure 7) compared to shortnose suckers, which averaged 470 mm in length (Figure 8). Relocation of captured suckers occurred daily following data collection and PIT tagging. Transport tank water temperatures ranged between 7.8oC and 17.2oC. There were two days when transport tank temperatures were allowed to exceed 15oC (May 13 and 14). Higher temperatures were allowed because some fish were responding poorly to the 15 oc tank water, which was at times almost 3oC colder than the lake temperature. Following this observation, measures were taken to reduce the temperature differential between lake water and tank water. A moderate amount of cooling was applied when temperatures surpassed 15oC, but we also sought to maintain tank temperatures within 1oC of lake temperatures (Table 3). We observed no instantaneous mortality due to capture and hauling; however, we did observe 3.4% delayed mortality. Fourteen dead fish were collected at the primary release site, Howard Bay on May 17 by CFS crew members and staff from USGS. Mortalities were proportional to abundances captured and relocated. Seven of the mortalities occurred on May 12, five occurred on May 13, one occurred on May 14, and one occurred on May 17. The Howard Bay release site was monitored throughout the remainder of the project and no additional carcasses were collected. In addition to Lost River and shortnose suckers, we incidentally captured four other fish species listed in order of abundance: Tui Chub, Sacramento Perch, Blue Chub and Brown Bullhead (Figure 9). Bycatch estimates should be regarded as approximations. 3

5 Table 1. Summary of fishing effort and daily captures during the Tule Lake sucker relocation project. One net-hour is equal to one 300 ft trammel net fished for one hour. Date Fishing Time (hrs) Nethrs Total Catch CPUE (fish/hr) CPUE (fish/nethr) 5/10/2010 5/11/2010 5/12/2010 5/13/2010 5/14/2010 5/17/2010 5/18/2010 5/19/2010 5/20/2010 5/21/2010 Totals Total Catch May 21 May 20 May 19 May 18 May 17 May 14 May 13 May 12 May 11 May 10 0 Figure 4. Daily capture of Lost River and shortnose suckers over the course of the 10-day Tule Lake sucker relocation project. 4

6 May 21 May 20 May 19 May 18 May 17 May 14 6 May May 12 8 May Mean Daily Lake Temperature (c) 18 May 10 CPUE (fish/net-hr) 3.5 Figure 5. Daily estimates of CPUE and corresponding averaged daily Tule Lake water temperatures. 5

7 Figure 6. Map of Tule Lake with color coded regions depicting the level of fishing success in each area. GPS coordinates are provided for our most productive net-setting locations. 6

8 Table 2. Number of Lost River (LRS) and shortnose (SNS) male and female suckers captured in Tule Lake. UNK=unknown Species LRS SNS UNK Sex F M UNK F M UNK UNK Number Captured Frequency Fork Length (mm) Figure 7. Length frequency distribution of Lost River suckers captured during the Tule Lake sucker relocation project. 7

9 50 Frequency Fork Length (mm) Figure 8. Length frequency distribution of shortnose suckers captured during the Tule Lake sucker relocation project. Table 3. Daily Tule Lake water temperatures at the time of fish processing and transport tank temperatures. Truck transport times are also provided. Date 5/10/2010 5/11/2010 5/12/2010 5/13/2010 5/14/2010 5/17/2010 5/18/2010 5/19/2010 5/20/2010 5/20/2010 5/21/2010 Water Temperature Transfer Times Tule Transport Departure Arrival Lake Tank :15 19: :00 19: :15 18: :45 17: :00 18: :00 14: :30 15: :00 15: :55 16: :00 13:00 8

10 Brown Bullhead (n= 103) Blue Chub (n= 162) Tui Chub (n= 1082) Sacramento Perch (n= 230) Figure 9. Approximate numbers of the four bycatch species captured during the Tule Lake sucker relocation project. DISCUSSION There are an unknown number of Lost River and shortnose suckers in Tule Lake. Previous estimates have ranged between a few hundred and a few thousand fish (Scoppetone and Buettner 1995; Hodge and Buettner 2009). Utilizing even the most liberal estimate, it appears that we captured and relocated a significant portion of the Tule Lake sucker population during our two-week effort. Fish distribution was patchy and we found congregations of fish along the southern shoreline and high densities in the English Channel. Future sucker capture efforts in Tule Lake, particularly those that take place in the spring, should consider targeting areas where water flow or seepage is occurring. Coordination with local water management entities and irrigators would be valuable. It may be possible to attract suckers to water control structures and thereby increase rates of capture. Through this effort we demonstrated that a significant portion of the sucker population in Tule Lake could be captured through conventional netting techniques. This finding suggests that, if necessary, application of novel fish tagging technologies could enable accurate population estimates. 9

11 References Beckstrand, J., D.M. Mauser, D. Thomson, and L.A. Hicks Ecology of shortnose and Lost River suckers in Tule Lake National Wildlife Refuge, California, Progress report #2, February December, p. Hicks, L.A., D.M. Mauser, J. Beckstrand, and D. Thomson Ecology of shortnose and Lost River suckers in Tule Lake National Wildlife Refuge, California, Progress Report, April November p. Hodge, J Sucker population monitoring in Tule Lake and Lower Lost River, Oregon and California. Unpublished report. U.S. Fish and Wildlife Service, Klamath Falls Fish and Wildlife Office, Oregon. Hodge, J. and M. Buettner Sucker population monitoring in Tule Lake and Lower Lost River, Unpublished report. U.S. Fish and Wildlife Service, Klamath Falls Fish and Wildlife Office, Oregon. Scoppettone, G. G., and M. E. Buettner Information on population dynamics and life history of shortnose suckers (Chasmistes brevirostris) and Lost River suckers (Deltistes luxatus) in Tule and Clear Lakes. U.S. Geological Survey, Reno Field Station, Reno, Nevada. 79pp. 10