Eel River Recovery Project P.O. Box 214 Loleta, CA 95551 707 839-4987
January 21, 2020 Mr. Jonathan Nelson Environmental Program Manager I Anadromous Fishes Conservation and Management Program Fisheries Branch CA Department of Fish and Wildlife 830 S Street Sacramento, CA 95811
Re: Eel River Recovery Project (ERRP) Revised Application for Scientific Collectors Permit (SC# 190820002)
Dear Jonathan,
We very much appreciate your reaching out via email on November 19 regarding our application for a Scientific Collectors Permit (# SC 190820002) to take large adult Sacramento pikeminnow (Ptychocheilus grandis) in a key reach of the South Fork Eel River. You stated that “the Department would like to again extend an offer of assistance to the Eel River Recovery Project in developing a study that meets the needs of scientific rigor established in Fish and Game Code Section 1002 and the California Code of Regulations Title 14 Section 650.” Toward that end, we have consulted Dr. Bret Harvey and Dr. Peter Moyle regarding the revision of our application to improve its scientific rigor. You are likely aware that these scientists are some of the foremost authorities on pikeminnow in the Eel River (Brown and Moyle 1991, 1997; Harvey and Nakamoto 1999, Harvey et al. 2002, 2004; Kinziger et al. 2014, Nakamoto and Harvey 2003, Reese and Harvey 2002, White and Harvey 2001). The revised study design is below and we are seeking feedback from California Department of Fish and Wildlife (CDFW) scientists. Also, some new scientific information has emerged about Eel River steelhead genetics that has bearing on our application. The information below corresponds sequentially with CDFW reasons for permit denial in your email (in italics).
1) The SCP application lacked a sufficient description of a statistically defensible study design that will evaluate the impacts to the population structure of Sacramento Pikeminnow and the hypothesized response of the native fish community.
After discussion of study design with Dr. Harvey, he shared a recently published paper (Christie et al. 2019) that compares the precision of results of various ecological study designs. Our original application for an SCP utilized a Before/After (BA) design, where we would simply compare the size distribution of pikeminnow before and after extraction in our entire 12-mile index reach. Christie et al. (2019) point out that utilizing a control reach for comparison with the treated reach, or a Before/After Control Impact (BACI) design, provides a much more powerful tool for judging impacts of treatments in Eel River Recovery Project Resubmission of SCP with Improved Study Design Page 1 ecological experiments. They found that the BACI designed studies performed 2.9–4.2 times better than BA studies. Therefore, ERRP is changing our study design to BACI from the previous BA design.
The index reach of the South Fork Eel River from Rattlesnake Creek to Standish Hickey State Park is 12 miles long. Instead of extracting large adult pikeminnow from the entire 12 miles, we wish to leave the upper six-mile reach from Rattlesnake Creek to Cedar Creek (R1) as a control reach, and remove pikeminnow from the lower reach that extends from Cedar Creek to Standish Hickey State Park (R2). The BACI design lends itself to statistical analysis, which was a previously stated preference by CDFW. The full citation for Christie et al. (2019) is in the reference section and we are attaching a copy of the paper with this application.
ERRP currently has four years of baseline data of high quality from volunteer dives that have included teams from the University of California Berkeley, the U.S. Bureau of Land Management Arcata office, professional fisheries scientists and seasoned volunteers from seven years of previous ERRP dives, including for fall Chinook. There is some variability between R1 and R2 in terms of the number of pikeminnow supported annually (Table 1). The distribution of all size classes of pikeminnow greater than 4 inches in R1 versus R2 from 2016-2019 can be viewed as Figure 1. The proportion of larger pikeminnow greater than 12 inches in R1 and R2 from 2016 to 2019 varied more, with larger fish almost always more numerous in R2 (Figure 2), which is why R2 will be the treated reach and R1 will serve as the control reach.
To reiterate from our SCP application, ERRP intends to continue trend monitoring for as long as our SCP extends to judge the impacts of large adult pikeminnow removal. If our SCP allows us to remove large pikeminnow in 2020, then the data collected in late June or early July 2021 for the 12-mile reach from Rattlesnake Creek to Standish Hickey State Park will be our first results. Dr. Harvey has volunteered to assist with the T-test we will be running to compare before and after data, similar to Taylor et al. (2006). We hope that our three-year SCP will be extended in 2023 and that we can continue this exercise for ten years, which is the life span of Sacramento pikeminnow.
Table 1. ERRP pikeminnow data for South Fork Eel River from 2016-2019.
Year R1 R2 Total Y2016 349 1067 1416 Y2017 399 774 1173 Y2018 807 662 1469 Y2019 263 351 614
2) Spearfishing is a lethal method and the Department concludes there is associated risk of lethal take of a CESA Candidate Species Summer Steelhead. In addition, the Department informed you prior to submitting the application that spearfishing was not a supported methodology for this project. The Department proposed alternative methods of take that would be considered for this activity including, hook and line, electrofishing, trapping, and netting.
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ERRP SF Eel Total Pikeminnow by Reach 2016-2019 1600
1400
1200
1000
800
600
400
200
0 Y2016 Y2017 Y2018 Y2019
R1 R2
Figure 1. Total number of pikeminnow over 4 inches in length from Rattlesnake Creek to Cedar Creek (R1) and Cedar Creek to Standish Hickey State Park (R2) from ERRP dives 2016-2019.
Location of Large Pikeminnow in SF Eel Index Reaches 2016-2019 600
500
400
300
200
100
0 Y2016 Y2017 Y2018 Y2019
R1 R2
Figure 2. Total number of pikeminnow over 12 inches in length from Rattlesnake Creek to Cedar Creek (R1) and Cedar Creek to Standish Hickey State Park (R2) from ERRP dives 2016-2019.
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In a presentation at Humboldt State University on December 4, 2019, Samantha Kannry shared her findings on Eel River basin-wide genetic analysis of 1600 steelhead juvenile tissue samples. She confirmed via email (1/20/20) that she did not find any summer steelhead alleles in South Fork Eel River samples, which “means it is very unlikely that there are any there.” Therefore, the Department’s concern that we might accidentally kill an adult summer steelhead is moot.
Your concern about incidental take of non-target species is unwarranted in that ERRP has the ability to draw from an elite corps of divers from the Humboldt Skindivers Association that can use scuba gear. These highly experienced divers are extremely unlikely to harvest any species other than pikeminnow. HSA members are assisting ERRP with recruitment of divers, training, and with creating a dive team extraction plan. Reconnaissance scuba dives will take place before extraction of large adults to practice species identification and to study how adult pikeminnow react to a team of scuba divers, including capturing video imagery with Go Pro cameras.
While the original SCP called for use of Hawaiian slings, HSA members recommend the use of pole spears. These present less risk in terms of divers potentially spearing each other, which was previously a major concern for ERRP. Dr. Harvey highly recommends the use of block nets above and below pools and said that pikeminnow may leap over nets when agitated, so extraction teams need to be ready for such contingencies. CDFW wardens and biologists are welcome to oversee harvest activities.
In our experience, hook and line methods for capture of the numbers of large adult pikeminnow needed for this study are not effective, and smaller, less piscivorous pikeminnow are often first to be caught. Furthermore, once one pikeminnow is hooked, it releases a pheromone that makes other pikeminnow less likely to bite. Work by Stillwater Sciences for the Wiyot Tribe in 2019 showed that baited traps are effective for capturing pikeminnow (Figure 3), but only smaller size classes (Abel Brumo, personal communication).
Electrofishing would be ineffective and have potential undesirable side effects. Large adult pikeminnow in our 12-mile index reach are concentrated in just four pools greater than 25 feet deep that would be inaccessible to any electrofishing craft. In addition, electrofishing has a maximum depth effectiveness of about 10 feet, leaving any fish swimming deeper than that undisturbed. Also, electrofishing could have detrimental effect on native Sacramento suckers. The depth of the pools would also confound use of nets to capture large adult pikeminnow.
Again, selective removal of large adult pikeminnow in these settings can only be carried out using scuba and spears, in conjunction with block nets at the top and bottom of the pool.
3) The issue of compensatory predation by smaller Sacramento pikeminnow, and other predatory animals, not targeted by spearfishing may have unintended consequences.
A strong relationship between the size of pikeminnow and their prey limits the potential for “compensatory” predation by small pikeminnow when larger fish are removed (Nakamoto and Harvey 2003). There are also no robust data showing a negative relation between the abundance of large pikeminnow and intermediate-sized pikeminnow. Like the intended consequence of improving conditions for native salmonids in one of the most important reaches for their populations in the Eel River, any unintended consequences will be measurable.
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Figure 3. Pikeminnow in baited trap deployed by Stillwater Sciences and Wiyot Tribe in summer 2019. Photo provided by Emmanuel Cyr and the Wiyot Tribe.
In a recent radio interview on KMUD News (Wednesday, December 4) regarding the pikeminnow issue, CDFW Public Information Officer Peter Tira stated that the Department would be open to:
“Work with the applicant on a new permit application or to modify the existing proposal, so we hope that this is just the beginning of the story, not the end of the story. We welcome another application from this group and look forward to getting one on the books that we can move forward with.”
We are hopeful that the information submitted above and attached will be sufficient for the reconsideration of our SCP. If CDFW is receptive, we would be happy to also refile our SCP on-line through the Department’s web portal. We are pleased that CDFW is open to a partnership to manage pikeminnow in the Eel River and to further our scientific understanding of this species and how the aquatic community responds to management activities.
Sincerely,
Patrick Higgins, ERRP Managing Director [email protected]
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References
Brown, L.R., and P.B. Moyle. 1991. Changes in habitat and microhabitat within an assemblage of stream fishes in response to predation by Sacramento squawfish (Ptychocheilus grandis). Canadian Journal of Fisheries and Aquatic Sciences 48(5): 849-856.
Brown, L.R. and P.B. Moyle. 1997. Invading species in the Eel River, California: successes, failures, and relationships with resident species. Environmental Biology of Fishes. Vol. 49, p 271-291.
Brumo, Abel. Personal Communication. Email re: Wiyot / Stillwater SF Eel River pikeminnow study updates. 12/3/19.
Christie, A.P., T. Amano, P.A. Martin, G.E. Shackleford, B.I. Simmons, and W.J. Sutherland. 2019. Simple study designs in ecology produce inaccurate estimates of biodiversity responses. Journal of Applied Ecology, 2019;00:1–13. DOI: 10.1111/1365-2664.13499.
Harvey, B. C., and R. J. Nakamoto. 1999. Diel and seasonal movements by adult Sacramento pikeminnow (Ptychocheilus grandis) in the Eel River, north-western California. Ecology of Freshwater Fish 8: 209–215.
Harvey, B. C., J. L. White and R. J. Nakamoto. 2002. Habitat relationships and larval drift of native and nonindigenous fishes in neighboring tributaries of a coastal California river. Transactions of the American Fisheries Society 131:159-170.
Harvey, B. C., J. L. White and R. J. Nakamoto. 2004. An emergent multiple predator effect may enhance biotic resistance in a stream fish assemblage. Ecology 85: 127-133.
Kannry, Samantha. Personal Communication. Email re: Steelhead Genetics Results? 1/20/20.
Kinziger, A. P., R. J. Nakamoto, and B. C. Harvey. 2014. Local-scale invasion pathways and small founder numbers in introduced Sacramento pikeminnow (Ptychocheilus grandis). Conservation Genetics 15(1): 1-9. doi: 10.1007/s10592-013-0516-5.
Nakamoto, R.J. and B.C. Harvey. 2003. Spatial, Seasonal, and Size-Dependent Variation in the Diet of Sacramento Pikeminnow in the Eel River, Northwestern California. California Fish and Game Bulletin 89 (1): 30-45 2003.
Reese, C.D. and B.C. Harvey. 2002. Temperature-Dependent Interactions between Juvenile Steelhead and Sacramento Pikeminnow in Laboratory Streams. Transactions of the American Fisheries Society. Volume 131, Issue 4, 2002.
Taylor, B.W., A.S. Flecker, and R.O. Hall Jr. 2006. Loss of Harvested Fish Species Disrupts Carbon Flow in Diverse Tropical River. Science, Vol. 313, August 11, 2006. P 833-837.
White, J.L. and B.C. Harvey. 2001. Effects of an introduced piscivorous fish on native benthic fishes in a coastal river. Freshwater Biology (2001) 46, 987-995.
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