First Record of a Cymothoid Isopod from a Tidewater Goby and Three New Tidewater Goby Localities in Humboldt County, California

Home , Cymothoidae, Elthusa, Slender goby

CALIFORNIA FISH AND GAME EVALUATING GPS COLLAR ERROR 167 California Fish and Game 94(4):194-199 2008

First record of A cymothoid isopod FROM a tide- user, unlike the POSREC model. water goby and three new tidewater goby lo- ACKNOWLEDGMENTS calities in Humboldt County, California

Adam J. Frimodig1 and Greg H. Goldsmith This study was supported by the California Department of Fish and Game (CDFG) U.S. Fish and Wildlife Service Deer Herd Management Improvement Program, the CDFG Sierra Nevada Bighorn Arcata Fish and Wildlife Office Sheep Recovery Program, the California Deer Association, and the Department of 1655 Heindon Road Biological Sciences at Idaho State University. We thank I. Oshima for suggestions on Arcata, California 95521 improving ArcView scripts, M. C. Nicholson for his original GIS work that contributed to the BadFix extension, and A. Ellsworth for the loan of collars. This is a contribu- The tidewater goby, Eucyclogobius newberryi (Teleostei: Gobiidae), is a small tion from the Sierra Nevada Bighorn Sheep Recovery Program, and is Professional fish species restricted to brackish estuaries and lagoons along the California coastline Paper 052 from the Eastern Sierra Center for Applied Population Ecology. from Tillas Slough, Del Norte County, to Agua Hedionda, San Diego County (Swift et al. 1989). In 1994, the tidewater goby was listed as federally endangered under LITERATURE CITED the Endangered Species Act, due primarily to its disappearance from nearly 50% of its historic locations and the unstable status of remaining populations (USFWS 1994, Cain, J. W., P. R. Krausman, B. D. Jansen, and J. R. Morgart. 2005. Influence of topography and GPS fix interval on GPS collar performance. Wildlife Society Bulletin 33:926-934. 2005). Tidewater goby populations are negatively influenced by competition from D'Eon, R. G., R. Serrouya, G. Smith, and C. O. Kochanny. 2002. GPS radiotelemetry error non-native fish species, such as mosquitofish, centrarchids, striped bass, as well as and bias in mountainous terrain. Wildlife Society Bulletin 30:430-439. both the yellowfin and chameleon goby (Swift et al. 1989, USFWS 2005); predation D'Eon, R. G. 2003. Effects of a Stationary GPS Fix-rate Bias on Habitat-selection Analyses. by the introduced African clawed frog, Xenopus laevis (Lafferty and Page 1997), and Journal of Wildlife Management 67:858-863. parasitism by both the trematode, Cryptocotyle lingua (Swift et al. 1989, Swenson D'Eon, R. G., and D. Delparte. 2005. Effects of radio-collar position and orientation on GPS 1999), and microsporidian, Kabatana newberryi (McGourty et al. 2007). To date, radio-collar performance, and the implications of PDOP in data screening. Journal of Ap- no reports exist of a cymothoid isopod and tidewater goby association. plied Ecology 42:383-388. The family Cymothoidae (Crustacea, Isopoda, Cymothoidae) consists of 380 spp. DeCesare, N. J., J. R. Squires, and J. Kolbe. 2005. Effect of forest canopy on GPS-based in 42 genera worldwide (Trilles 1991; N. Bruce, New Zealand’s National Institute movement data. Wildlife Society Bulletin 33:935-941. Di Orio, A. P., R. Callas, and R. J. Schaefer. 2003. Performance of two GPS telemetry collars of Water and Atmospheric Research, personal communication). Most cymothoids under different habitat conditions. Wildlife Society Bulletin 31:372-379. occur in coastal, shallow-water environments (Bunkley-Williams and Williams Dussault, C., R. Courtois, J.-P. Ouellet, and J. Huot. 1999. Evaluation of GPS telemetry collar 1998). Cymothoids are ectoparasitic, protandrous hermaphrodites considered to performance for habitat studies in the boreal forest. Wildlife Society Bulletin 27:965- be permanent symbionts (Brusca 1981, Bunkley-Williams and Williams 1998). 972. Many cymothoids are capable of causing deleterious effects to their host by inflict- Dussault, C., R. Courtois, J.-P. Ouellet, and J. Huot. 2001. Influence of satellite geometry and ing large wounds, impairing growth rates, and occasionally killing the fish (Brusca differential correction on GPS location accuracy. Wildlife Society Bulletin 29:171-179. 1981, Bunkley-Williams and Williams 1998, Bakenhaster et al. 2006). Cymothoids Frair, J. L., S. E. Nielsen, and E. H. Merrill. 2004. Removing GPS collar bias in habitat selec- have been reported as ectosymbionts on a wide variety of host spp., mostly fishes tion studies. Journal of Applied Ecology 41:201-212. (as summarized by Bunkley-Williams 1984). However, relatively few records exist Gau, R. J., R. Mulders, L. M. Ciarniello, D. C. Heard, C. L. B. Chetkiewicz, M. Boyce, R. Munro, G. Stenhouse, B. Chruszcz, M. L. Gibeau, B. Milakovic, and K. L. Parker. 2004. that document cymothoid isopods infecting gobiid spp. (Popov 1933, Hatch 1947, Uncontrolled field performance of Televilt GPS-Simplex™ collars on grizzly bears in Legrand 1952, Brusca 1981, Nieto and Alberto 1994, Charfi-Cheikhrouha et al. 2000, western and northern Canada. Wildlife Society Bulletin 32:693–701. Ravi and Rajkumar 2007). Hatch (1947) and Brusca (1981) both reported cymothoids Hooge, P. N., and B. Eichenlaub. 1997. Animal movement extension to ArcView. Version 1.1. infecting the arrow goby, Clevelandia ios, in the eastern Pacific Ocean, but no records Alaska Biological Science Center, U.S. Geological Survey, Anchorage, Alaska, USA. have documented an association between cymothoids and the tidewater goby. Hosmer, D. W., and S. Lemeshow. 2000. Applied Logistic Regression. Second edition. John One tidewater goby, 26 mm Total Length (TL), and associated cymothoid, 4 mm Wiley & Sons, New York, New York, USA. TL, were collected on 28 August 2006 in an unnamed slough tributary to the mainstem Krausman, P. R., V. C. Bleich, J. W. Cain, T. R. Stephenson, D. W. DeYoung, P. W. McGrath, P. K. Swift, B. M. Pierce, and B. D. Jansen. 2004. Neck lesions in ungulates from collars 1AJF current address: California Department of Fish and Game, Marine Region, 619 Second incorporating satellite technology. Wildlife Society Bulletin 32:987-991. Street, Eureka, CA 95501. E-mail: [email protected]. Lawler, A. 2000. Scientists gain access to sharper GPS signal. Science 288:783. 194 166 CALIFORNIA FISH AND GAME Notes 195 remove >55% of successful fixes, yet still retain suspect locations (Fig. 3). We created the "BadFix" extension for ArcView 3.x, which evaluates the length and angular deviation of movement vectors and applies a logistic regression model. Application of BadFix reduces habitat-associated biases by screening positions regardless of fix quality. A limitation of the screening approach we employ in BadFix is the identification of some authentic movements that approximate an out-and-back pattern. When we used the BadFix extension to screen movements of a Lotek GPS4400s collar deployed on a male puma, Felis concolor, 16 of 743 (2.2%) movements were flagged as "bad" at the 95% probability level, although we had no reason to believe GPS error was involved. Instead, the return of the puma to feed at a kill site ap- proximated the out-and-back pattern the BadFix extension was designed to identify. When movements of a male bighorn sheep wearing a Televilt Telus GPS collar were screened at 95% probability, only 25 of 5150 (0.5%) of movements were identified as "bad". In both instances, a smaller sample of suspect locations were identified for further evaluation by the researcher. We believe that the screening method we present should be considered for its effectiveness at identifying potentially erroneous locations, while including more unaffected data and remaining less influenced by habitat-associated bias when compared to screening by fix quality alone.

Management Implications

We reiterate the recommendations of D'Eon et al. (2002) that researchers screen raw GPS data for anomalous positions that are clearly impossible, regardless of what model GPS collar is employed. Although an individual position may seem plausible, when it is immediately preceded and followed by near-parallel movements of unusually long distance over short times, the reliability of the fix should be questioned. Thus, we add the suggestion that a tool such as Animal Movement (Hooge and Eichenlaub 1997) be employed to aid in visual identification of anomalous fixes. We further recommend employing an automated screening tool such as the BadFix extension for larger data sets or when errors are common. We employed BadFix not only for triage of POSREC data, but for screening movement data from collars that now collect >10,000 locations. Researchers employing remote data download via direct radio may find automated screening useful for flagging artifacts of transmission we have experienced using VHF and UHF systems. The BadFix extension for ArcView 3.x is available for download from the World Wide Web at (http://arcscripts.esri.com/details. asp?dbid=14434) and is provided as open-source and may be freely modified. We echo the recommendations of (Moen et al. 1997, Rempel and Rodgers 1997) that researchers understand factors affecting the type and precision of GPS locations, and further suggest that sample data be obtained from the model of collar being considered. Although our request for sample data was met with the provision of data from a prototype collar that was not the same as the product we purchased, requests of other manufacturers may be handled in a forthright manner. We further recommend that GPS collar users test and evaluate results of their collars before deployment. Figure 1. Known tidewater goby population sites in the Humboldt Bay area, including three new localities (shown in circles) discovered in 2006: (1) an unnamed slough tributary to the mainstem This recommendation is only practicable for collars that allow data retrieval by the Elk River; (2) Wood Creek; and (3) McDaniel Slough. 196 CALIFORNIA FISH AND GAME EVALUATING GPS COLLAR ERROR 165

Elk River in Humboldt County, California (40º45’3"N, 124º11'16"W) (Fig. 1). Elk precision of ATS, Lotek, and Televilt Simplex and Tellus collars produced location River is the largest freshwater tributary to Humboldt Bay draining a watershed of 137 errors consistent with those reported for various conditions of terrain, canopy, and km2 in area (Manka2 2005). An extensive northern range-wide study for tidewater collar orientation using ATS, Lotek, and Telonics collars (D'Eon 2003, Di Orio et al. gobies during the summers of 2003 - 2006 in northern California did not reveal an 2003, Cain et al. 2005, D'Eon and Delparte 2005). associated cymothoid at any other site. A total of 1,818 tidewater gobies were col- In our effort to quantify the errors we suspected after recovering POSREC collected from 19 of the 76 total sites sampled from Tillas Slough, Del Norte County to lars used in 50 animal deployments, we sought and received 191 positions from Garcia River, Mendocino County during the four year study. The tidewater goby and a POSREC collar (serial no. C600-176), which had been activated at an outdoor associated cymothoid were placed in a holding container in order to observe swim- location before shipping to a customer (Q. Kermeen, Telemetry Solutions, personal ming behavior of the goby, subsequently anesthetized in tricaine methanesulfonate communication). The maximum location error from this POSREC collar was 118.4 (MS-222), transferred to 95% EtOH, and placed in the Humboldt State University m (Table 1, identified as “prototype”), and characteristic of a non-defective GPS Fish Collection (catalog number HSU 4275). The isopod was identified to the Family unit, but in sharp contrast to location errors we obtained from eight POSREC col- Cymothoidae using a dissecting microscope. The isopod was a male and/or juvenile, lars, including units with serial numbers bracketing C600-176. For example, collar which are often impossible to identify to genus or species level. The cymothoid is C600-175, used in our optimal sky-view test, showed errors >500 m in 20.7% of reported as branchial parasite based on its position covering the gills, which leads 101 fixes (Fig. 5), and collar C600-219 demonstrated errors of >1,000 m in 26.6% us to believe this specimen may belong to the genus Elthusa (N. Bruce; J-P. Trilles, of 45 fixes (all 2-D) at the indoor location. Data provided from collar C600-176 had University of Montpellier, personal communication). Hatch (1947) and Brusca been collected at 30-minute intervals, while we present data for ≥1 hour intervals, (1981) reported, mainly in California waters, Elthusa californica as a parasite to but Cain et al. (2005) reported no difference in location accuracy within this range the arrow goby, which is a close relative of the tidewater goby. A total of 66 arrow of fix intervals. Personnel at Telemetry Solutions could not explain the difference gobies were collected during the four year study from nine different sites, but none and referred us to Televilt. We sent Televilt a summary of our data and requested the were associated with a cymothoid. source of the unprecedented errors in every collar tested and an explanation for the Cymothoids have piercing-sucking mouthparts that are used for parasitic feeding normal performance of collar C600-176. Weeks later, after repeatedly requesting an and are capable of causing detrimental effects to their host (Stoskopf 1992, Bunkley- explanation, we received the response, “To make it short: It is the performance of Williams and Williams 1998, Bakenhaster et al. 2006). Both the tidewater goby the GPS receiver that is the problem” (Anders Lindgren, Televilt/TVP Positioning and cymothoid were living at the time of collection, and the goby did not display AB, personal communication). We were further informed that the problem was with, any clear visible signs of deterioration such as lesions, fin rot, or lethargic swim- “the SiRFStarI receivers, that we used in your collars,” that have “a larger spread of ming behavior. The cymothoid was lodged underneath the goby’s operculum and data,” and that collar C600-176, "most likely has a SiRFStarII GPS receiver,” and its length (over 15% of the goby’s length) caused the operculum to be considerably was, “one of our prototypes.” Mr. Lindgren asserted that after February 2003, collars stretched (Fig. 2). The cymothoid, nearly encased by the stretched operculum, was with serial numbers >425 used the newer GPS receiver. Televilt did not acknowledge situated directly above the goby’s gill arches. We believe its presence may harm that the observed performance was unacceptable and consequently refused to discuss the goby via three possible mechanisms: (1) the isopod may deform or erode the replacement of the 32 defective collars. If the statement about the serial numbers gill filaments based on its position (Sadzikowski and Wallace 1974, Brusca 1981, is accurate, some 425 POSREC-Science™ 600 collars containing the problematic Williams and Bunkley-Williams 1985, Sievers et al. 1996, Thatcher et al. 2003); (2) GPS receiver have been sold, and can be expected to also show extraordinarily large the isopod may restrict respiration from the physical blockage of the gill opening location errors. The problem is not isolated to the 600-series collars we purchased. (Segal 1987, Adlard and Lester 1995); and (3) the presence of the cymothoid may We located a user of POSREC-Science™ 300 collars who had documented the flaw, hinder the goby’s weight balance and/or swimming endurance (Sievers et al. 1996, and were also informed that over 1,000 POSREC collars were sold in the Americas Östlund-Nilsson et al. 2005). (Q. Kermeen, personal communication). This is the first reported association of a cymothoid with a tidewater goby. Other In the absence of a solution from the manufacturer, researchers are faced with a authors suggest that cymothoids often have high host and site specificity (Brusca 1981, dilemma of how to salvage flawed POSREC data. Frequent location errors of several Bunkley-Williams and Williams 1998); and small fish may be more vulnerable to kilometers render data unacceptable for all but the most course-scaled evaluation of cymothoid infestation (Adlard and Lester 1995). At least five cymothoid spp. have habitat selection or migration, thereby necessitating some type of data screening. been reported from gobiids: E. californica from the arrow goby mainly in California Screening to retain only "3-D" or "3-D+" fixes magnifies inherent bias against loca- waters (Hatch 1947, Brusca 1981), Anilocra frontalis from the two-spotted goby, tions where canopy cover, topography, or collar orientation preclude acquisition of 2Manka, P. 2005. Suspended sediment yields in tributaries of Elk River, Humboldt County, high-quality fixes (Frair et al. 2004, D'Eon and Delparte 2005). While our data indicate California. M.S. Thesis, Humboldt State University, Arcata, California. that "3-D+" fixes have a lower frequency of errors; screening for “3-D+” fixes would 164 CALIFORNIA FISH AND GAME Notes 197 fixes. To avoid overfitting and ensure broad applicability among collar programs, taxa, and study areas we chose the 2-predictor model:

Pbad =logit (-4.77487 + 0.002656 * LengthN_NP1 + 0.02860 * AngDev) A classification test at 50% probability yielded 100% concordance with 552 subjectively identified “bad” fixes and 99.1% concordance identifying 541 fixes as

Figure 2. Picture of a cymothoid isopod (Isopoda, Cymothoidae) associated with a tidewater goby. The cymothoid is situated underneath the stretched right operculum of the goby indicated by the top and bottom arrows, and directly above the gill opening indicated by the middle arrow. Gobius flavescens, the rock goby, Gobius paganellus, and the sand goby, Gobius minutus, in the Atlantic Ocean (Legrand 1952, Nieto and Alberto 1994), Cymothoa indica from the maned goby, Oxyurichthys microlepis, in the Indian Ocean (Ravi and Rajkumar 2007), Nerocila bivittata from the slender goby, Gobius geniporus, in the Mediterranean Sea (Charfi-Cheikhrouha et al. 2000), andNerocila tartakowski from the knout goby, Mesogobius batrachocephalus, in the Black Sea (Popov 1933) (J-P. Trilles, personal communication). Presently, there is a lack of sufficient range-wide tidewater goby studies to assess whether or not the cymothoid found in this study is Figure 6. POSREC GPS collar movement path, mule deer RVD210, 10 Apr 2002–21 Sep 2002, accidental or actually targets this endangered fish species. Most isopod gill parasites generated after screening all ≥2-D fixes using the BadFix ArcView extension at the 50% prob- do not greatly distort the operculum and this male cymothoid was disproportionately ability level (n=1,064 fixes remaining). large for the size of the tidewater goby host, suggesting that the isopod infestation “good,” while incorrectly classifying 5 as “bad.” Application of the logistic model may be accidental (N. Bruce, personal communication). Additionally, this is the first to 89,232 movement lines generated from all ≥2-D fixes at the 50% probability level record of tidewater gobies inhabiting Elk River. Two other new locations, Wood resulted in classification of 31,672 (36.0%) fixes as bad. Of these, 18,028 were 2-D, Creek (40º47’1"N, 124º5’57"W) and McDaniel Slough (40º51’27"N, 124º6’20"W), 6,407 "3-D," and 7,237 "3-D+." Screening with this approach greatly reduced the were also discovered during the summer of 2006. Therefore, increased sampling frequency of anomalous movements (Fig. 6). and research clearly needs to be conducted on the tidewater goby, as well as careful inspection of individuals to determine if cymothoids are associated, in order to better DISCUSSION understand and manage the population. Acknowledgments Field deployment of POSREC collars generated movement patterns unlike those The authors thank A. Scheiff for his assistance in conducting the field work. We are from any other GPS collar we have examined (e.g., Fig. 2) and showed numerous also greatly appreciative for the helpful comments provided by N. Bruce, J-P. Trilles, movements that were obviously improbable although inapparent when viewed solely as C. Chamberlain, R. Wetzer, A. Kinziger, C. Swift, and two anonymous reviewers. a swarm of points (Fig. 1). Location errors obtained from POSREC collars exceeded This work was conducted under a California Department of Fish and Game permit those of any GPS collar in our testing or reported in the literature. Evaluation of the (# 000998) and a federal subpermit (FWSAFWO-7). 198 CALIFORNIA FISH AND GAME EVALUATING GPS COLLAR ERROR 163

Literature Cited Adlard, R.D., and R.J.G. Lester. 1995. The life cycle and biology of Anilocra pomacentri (Isopoda: Cymothoidae), an ectoparasitic isopod of the coral reef fish, Chromis nitida (Perciformes: Pomacentridae). Australian Journal of Zoology 43:271-281. Bakenhaster, M.D., R.S. McBride, and W.W. Price. 2006. Life history of Glossobius hemir- amphi (Isopoda: Cymothoidae): Development, reproduction, and symbiosis with its host Hemiramphus brasiliensis (Pisces: Hemiramphidae). Journal of Crustacean Biology 26:283-294. Brusca, R.C. 1981. A monograph on the Isopoda, Cymothoidae (Crustacea) of the eastern Pacific. Zoological Journal of The Linnean Society 73:117-199. Bunkley-Williams, L. 1984. Geographic distribution and early life history of Anilocra (Isopoda: Gnathiidae). Journal of Crustacean Biology 8:668-678. Bunkley-Williams, L., and E.H. Williams. 1998. Isopods associated with fishes: a synopsis and corrections. Journal of Parasitology 84:893-896. Charfi-Cheikhrouha, F., Zghidi, W., Ould Yarba, L., and J-P. Trilles. 2000. Les Cymothoidae (Isopodes parasites de poissons) des côtes tunisiennes : écologie et indices parasitologiques. Systematic Parasitology 46:146-150. Hatch, M.H. 1947. The Chelifera and Isopoda of Washington and Adjacent Regions. University of Washington, Publications in Biology 10(5):155-274. Lafferty, K.D., and C.J. Page. 1997. Predation on the endangered tidewater goby, Eucyclogo- bius newberryi, by the introduced African clawed frog, Xenopus laevis, with notes on the frog’s parasites. Copeia 3:589-592. Legrand, J.J. 1952. Contribution a l’etude experimentale et statistique de la biologie d’ Anilocra physodes L. Archives de Zoologie experimentale et generale 89:1-56. McGourty, K.R., A.P. Kinziger, G.L. Hendrickson, G.H. Goldsmith, G. Casal, and C. Azevedo. Figure 5. POSREC collar C600-175 tested under optimal sky visibility. N=101 fixes (2-D and 3-D). 3-D fixes (n=76) denoted by triangles. 2007. A new microsporidian infecting the musculature of the endangered tidewater goby (Gobiidae). Journal of Parasitology 93:655-660. Nieto, P., and L.J. Alberto. 1994. Presence of Anilocra frontalis H. Milne Edwards, 1840 positions. None of the 154 “3-D+” fixes, however, showed errors >135.8 m. The single (Isopoda, Flabellifera) on the southern Atlantic Coast of the Iberian Peninsula: spectrum POSREC collar tested under optimal sky-view conditions yielded results consistent of parasitism and parasitic relationship with Gobius paganellus Linnaeus, 1758 (Pisces, with these unprecedented errors, with 3-D location errors >1,000 m and 2-D errors Gobiidae). Crustaceana 66:67-77. >1,600 m (Fig. 5). Further, tests with the handheld Garmin III receiver and with 4 Östlund-Nilsson, S., L. Curtis, G.E. Nilsson, and A.S. Grutter. 2005. Parasitic isopod Anilocra ATS G2000 collars, at the indoor location where three POSREC collars collected 351 apogonae, a drag for the cardinal fish Cheilodipterus quinquelineatus. Marine Ecology fixes, failed to produce errors of a magnitude approaching that of POSREC collars Progress Series 287:209-216. at the same location (Table 1). Popov, A.M. 1933. Uber parasitische Isopoden von Fischen aus dem Schwarzen Meer. Zoolo- gischer Anzeiger Akademische Verlagsgesellschaft. MBH Leipzig 101:193-198. Error Screening Ravi, V., and M. Rajkumar. 2007. Effect of isopod parasite, Cymothoa indica on gobiid fish, Oxyurichthys microlepis from Parangipettai coastal waters (South-east coast of India). Journal of Environmental Biology 28(2):251-256. We subjectively identified “good” (n=1,322) and “bad” (n=1,358) positions among Sadzikowski, M.R., and D.C. Wallace. 1974. The incidence of Lironeca ovalis (Say) (Crustacea, data from POSREC collars deployed on mule deer and used 806 and 776, respective, Isopoda) and its effects on the growth of white perch, Morone americana (Gmelin), in the “good” and “bad” fixes to generate a logistic model. A random subset of 546 and Delaware River near Artificial Island. Chesapeake Science 15:163-165. 552 fixes were retained to test classification accuracy. Stepwise selection yielded Segal, E. 1987. Behaviour of juvenile Nerocila acuminata (Isopoda, Cymothoidae) during a model including three predictors, in order of entry; AngDev, the angular devia- attack, attachment and feeding on fish prey. Bulletin of Marine Science 41:351-360. tion of sequential movement vectors (V V ), LengthN_NP1, the mean length of Sievers, G., C. Lobos, R. Inostroza, and S. Ernst. 1996. The effect of the isopod parasite n, n+1 sequential movement vectors (Vn,Vn+1), and RateN_NP1, the mean rate of sequential Ceratothoa gaudichaudii on the body weight of farmed Salmo salar in southern Chile. movements (V V ). Examination of variable RateN_NP1 showed that some collars Aquaculture 143:1-6. n, n+1 Stoskopf, M.K. 1992. Fish medicine. W.B. Saunders Co., Philadelphia, Pennsylvania. were strongly influenced by variation in the time between successful GPS fixes, due to programming of uneven fix intervals, or consecutive failures of scheduled GPS 162 CALIFORNIA FISH AND GAME Notes 199 meaning that ≥5 satellites were used to solve for the position, is provided in addition Swenson, R.O. 1999. The ecology, behavior, and conservation of the tidewater goby, Eucycl- to the conventional “2-D” and “3-D”2. These “3-D+” locations comprised 44.8% ogobius newberryi. Environmental Biology of Fishes 55:99-119. of GPS fixes from animal deployments, and displayed noticeably fewer anomalous Swift, C.C., J.L. Nelson, C. Maslow, and T. Stein. 1989. Biology and distribution of the tide- fixes, though questionable locations remained (Fig. 3). A fourth category of “1-D” water goby, Eucyclogobius newberryi (Pisces: Gobiidae) of California. Contributions in Science, Natural History Museum of Los Angeles County 404:1-19. (n=1,246 or 1.4%) is what Televilt describes as a fix calculated with <3 satellites, 2 Thatcher, V.E., J.M. Souza-Conceição, and G.F. Jost. 2003. Lironeca desterroensis sp. Nov. using parameters from previous positions . We eliminated 1-D locations from our (Isopoda, Cymothoidae) from the gills of a marine fish, Cetengraulis edentulous Cuvier, analyses. of Santa Catarina Island, Brazil. Revista Basileira de Zoologia 20:251-255. Trilles, J-P. 1991. Catalogue mondial des Cymothoidae. Studia Marina, Kotor 21/22:5-288. Fixed-Location Testing of GPS Collar Precision U.S. Fish and Wildlife Service. 1994. Endangered and Threatened Wildlife and Plants: deter- mination of endangered status for the tidewater goby. Federal Register 59:5494-5498. No GPS collar showed directional bias relative to averaged 3-D positions with a U.S. Fish and Wildlife Service. 2005. Recovery Plan for the Tidewater Goby (Eucyclogobius Rockwell PLGR, Garmin GPS12XL, or GPS III at planned test locations. The 95% newberryi). U.S. Fish and Wildlife Service, Portland, Oregon. vi + 199 pp. confidence interval for each collar overlapped those of the averaged handheld GPS Williams, E.H., and L. Bunkley-Williams. 1985. Cuna insularis n. gen. and n. sp. (Isopoda: Cymothoidae) from the gill chamber of the sergeant major Abudefduf saxatilis (Linnaeus receiver. Osteichthyes) in the West Indies. Journal of Parasitology 71:209-214. POSREC collars displayed errors greater than any other collar at ≥95th percentile,

Received: 3 July 2007 Accepted: 17 September 2007

Figure 4. Error distribution (all 2-D and 3-D fixes) from fixed-location POSREC collars. Errors >2100 m (n=7) not illustrated. with location errors for combined 2-D and 3-D locations that exceeded one order of magnitude larger than for every other collar tested (Table 1). These unique errors were characterized by a bimodal error distribution with the expected log-normal distribution for errors <100 m, and a second peak at approximately 600 m (Fig. 4). This unanticipated distribution persisted among 3-D fixes after elimination of 2-D

2 Televilt/TVP Positioning AB, unpublished document, “What is fix type.txt” CALIFORNIA FISH AND GAME EVALUATING GPS COLLAR ERROR 161

REFEREE ACKNOWLEDGMENTS

The following individuals have reviewed manuscripts for California Fish and Game during 2008. The list is as complete as possible. The editors apologize for any omission and sincerely thank all those who have contributed to the quality of the journal by providing competent and timely reviews.

Averill-Murray, R. Henen, B. Muth, A. Barnes, T. Henry, F. Pearson, D. Figure 2. GPS collars deployed on a desert bighorn ewe D7 (POSREC; n=852 locations) and Sierra Nevada bighorn ewe S62 (Lotek GPS 4400s; n=1035 locations) and ram S18 (Televilt Barry, S. Israel, J. Richter, D. Simplex; n=651 locations) over the same period: 20 Mar – 8 Sep in 2004 (Posrec, Simplex) and Bolster, B. Jennings, M. Single, J. 2005 (Lotek). All fixes (2-D and 3-D) are included. Cain, J. Lafferty, K. Stephenson, T. Coulston, P. Lea, R.N. Sullivan, R. but did not eliminate them (Fig. 1). These novel patterns were present in data from Feeney, R. Locke, J. Swift, C. all POSREC collars (n=32) regardless of taxon or study area, though implausible Hanan, D. Moreno, S. Thompson, J. fixes did not become apparent until sequential positions were connected. Once movement paths were generated, however, the star-shaped patterns were prominent and uncharacteristic of paths generated using other GPS collars (Fig. 2). POSREC collar data did not provide dilution of position (DOP) information that could have enabled the screening of fix quality (D'Eon and Delparte 2005). Neither did data include the number of satellites used to obtain a fix, though a fix category of “3-D+”,

Figure 3. POSREC GPS collar movement path, mule deer RVD210, 10 Apr 2002–21 Sep 2002, 200 generated from 3-D and better fixes (n=1344). Crosses denote "3-D+" fixes (n=840). 160 CALIFORNIA FISH AND GAME CALIFORNIA FISH AND GAME California Fish and Game 94(4):200-207 2008 in Bishop (hereafter “indoor" location), for a total of 663 positions collected under INDEX TO VOLUME 94 (2008) GPS receiving conditions ranging from optimal to marginal. Additional fixed-collar position data were collected from Lotek 4400s (n=2; 2 and 12 days), Televilt Simplex AUTHORS (n=3; 6-119 days), and Televilt Tellus (n=3; 5-14 days) collars in 2003-2006 under similar conditions (Table 1). In an effort to replicate conditions at the indoor location Anderson, Scott D., Benjamin H. Becker, and Sarah G. Allen: Observations and where most fixed-location POSREC GPS collar data were collected, we activated Prey of White Sharks, Carcharodon carcharias, at Point Reyes National Seashore: four ATS model GPS2000 GPS collars at the same interior location for 16 days. We 1982 – 2004, 33 – 44 further employed a Garmin III Plus handheld GPS receiver to collect fixes over a Bailey, Tracy: see Berry, Keith, and Bailey 24-day period (median frequency of fixes=48.5 min) to explore the possibility that Becker, Benjamin H.: see Anderson, Becker, and Allen this indoor location could cause a marked increase in GPS location error. Berry, Kristin H., Kevin Keith, and Tracy Bailey: Status of the Desert Tortoise in Red Rock Canyon State Park, 98 - 118 Error Screening Berry, Kristin H.: see Keith, Berry, and Weigand Bleich, Vernon C.: see Villepique, Bleich, Pierce, Stephenson, Botta, and Bowyer We explored metrics to identify suspect out-and-back movements among GPS Borchert, Mark, Frank, W. Davis, and Jason Kreitler: Carnivore Use of an Avocado collar data from animal deployments to separate pseudo-movements resulting from Orchard in Southern California likely artifacts in the data from actual animal movements. We wrote scripts in Botta, Randall A.: see Villepique, Bleich, Pierce, Stephenson, Botta, and Bowyer ArcView to calculate angular deviation (Zar 1999), mean length and mean rate of Bowyer, R. Terry: see Villepique, Bleich, Pierce, Stephenson, Botta, and Bowyer sequential movement vectors (Vn,Vn+1), and the standard deviation of mean length Carretta, James V.: see Lowry, Carretta, and Forney and mean rate, relative to prior and subsequent movement vectors. We also used a Clark, Howard O. and Mary C. Orland: comparison of Two Camera Trap Systems DEM to derive slope and aspect for each GPS location. Movement vectors >500 for Detection of American Martin on a Winter Landscape, 53 – 59 m in length followed by vectors with azimuths of near 180 degree opposition were Croteau, Joe and Brett Furnas: Aerial Implementation Monitoring of Green Tree subjectively identified as “bad” when we judged the GPS fix improbable because Retention in Clearcuts on Northern California Private Timberlands, 169 - 179 of intervening topography, distance from other fixes, or unusually high speed of the Davis, Frank Wl: see Borchert, Davis, and Kreitler implied movement. Movement vectors that appeared valid were subjectively identi- Forney, Karen A.: see Lowry, Carretta, and Forney fied as “good”. We used SPSS 11.0 for Mac OS X (SPSS Inc., Chicago, Illinois) to Frimodig, Adam J. and Greg H. Goldsmith: First Record of a Cymothoid Isopod generate a logistic regression model of the probability a GPS position was flawed, from a Tidewater Goby and Three New Tidewater Goby Localities in Humboldt based upon the characteristics we judged were likely to indicate an erroneous location County, California, 194 - 199 (Hosmer and Lemeshow 2000). Logistic regression is applied as a tool to differentiate Furnas, Brett: see Croteau and Furnas characteristics of uncontrolled data gathered from animal deployments, where the true Goldsmith, Greg H.: see Frimodig and Goldsmith locations and movements are unknowable. Forward stepwise selection was employed Goldsmith, Greg: see McGourty, Kinziger, and Goldsmith on variables derived from ArcView, with P=0.15 for entry and P=0.20 for removal. Gunderson, Donald R.: see Shaw and Gunderson We developed an ArcView 3.x extension incorporating the metrics calculated above Harvey, James T.: see Laird and Harvey to generate a logistic probability for each position in an animal movement path. Henkel, Laird A. and James T. Harvey: Abundance and Distribution of Marine Jones, Rick L., Floyd W. Weckerly, and Dale R. McCullough: Influence of Age and Sex RESULTS on Dressed-Whole Body Weight Relationships in Black-Tailed Deer, 137 - 142 Keith, Kevin, Kristin H. Berry, and James F. Weigand: When Desert Tortoises are Field Deployment of POSREC Collars Rare: Testing a New Protocol for Assessing Status, 75 - 97 Keith, Kevin: see Berry, Keith, and Bailey POSREC collar deployed on mule deer and bighorn sheep yielded a total of 89,283 Kinziger, Andrew: see McGourty, Kinziger, and Goldsmith positions, and produced star-shaped patterns when sequential fixes were connected Kogut, Nina J.: Overbite Clam, Corbula amurensis, Defecated Alive by White Stur- (Fig. 1). Sequential vectors showed thousands of improbable out-and-back move- geon, Acipenser transmontanus, 143 - 149 ments of up to 16 km (one-way), sometimes traversing 3,500 m mountains in winter, Kreitler, Jason: see Borchert, Davis, and Kreitler and returning to nearly the starting location ≤6 hours later. Elimination of 2-D fixes Linstrand, Len, III: A New Elevation Record for Shasta Salamander, Hydromantes (n=24,097 or 27.0%) reduced the magnitude and frequency of suspect movements, 201 202 CALIFORNIA FISH AND GAME EVALUATING GPS COLLAR ERROR 159

shastae, in Northern California, 119 - 121 Lowry, Mark S., James V. Carretta, and Karen A. Forney: Pacific Harbor Seal census in California during May - July 2002 and 2004, 180 - 193 Mammals in Nearshore Waters of Monterey Bay, California, 1 – 17 Martinez, Juana Lopez: see Rodriquez-Romero, Palacios-Salgado, and Martinez 34.1 118.4 17.1 260.6 100% 1486.3 1165.1 465.6 55.5 37.2 Matchett, Elliott L. and James S Sedinger: A Change in Waterfowl Species in the 486.3 338.4 72.7

Honey Lake Valley, California, 44 – 52

McCullough, Dale R.: see Jones, Weckerly, and McCullough 28.1 82.8 ___ 142.1 99% 1429.9 904.7 ______McGourty, Katie, Andrew Kinziger, and Greg Goldsmith: Spawning Time, Fecundity, 107.9 240.7 ___

Habitat Utilization, and Parasites of a Northern California Population of Tidewater Goby, Encyclogobius newberryi, 18 – 32 20.8 17.4 15.8 67.6 95% 852.6 53.0 61.3 36.1 33.4 Orland, Mary C.: see Clark and Orland 42.8 41.1 20.0

Palacios-Salgado, Deivis S.: see Rodriquez-Romero, Palacios-Salgado, and Marti-

nez 8.1 6.5 3.8 12.5 3-D fixes 50% 15.2 5.9 19.4 7.4 7.8 Pierce, Becky M.: see Villepique, Bleich, Pierce, Stephenson, Botta, and Bowyer 8.3 10.1 5.5 Rodriguez-Romero, Jesus, Deivis S. Palacios-Salgado, and Juana Lopez Martinez:

First Records of the Firnged Sculpin, Icelinus fimbriatus,(Scorpaeniformes: Cot- 291 147 87 195 n 117 215 38 82 28 tidae), Off the West Coast of Baja California, Mexico, 150 - 153 660 388 94

Sedinger, James S.: see Matchett and Sedinger Shaw, Franklin R. and Donald R. Gunderson: Notes on the Life History traits of the 317.4 118.4 127.3 260.6 100% 3352.9 2139.5 465.6 172.7 167.3 Rosethorn Rockfish, Sebastes helvomaculatus, 123 - 136 486.3 338.4 117.2

Stephenson, Thomas R.: see Villepique, Bleich, Pierce, Stephenson, Botta, and

Bowyer 81.4 50.2 44.0 138.5 99% 2565.5 1681.5 ___ 171.5 ___ Villepique, Jeffrey, T., Vernon C. Bleich, Becky M. Pierce, Thomas R. Stephenson, 161.7 240.8 ___

Randall A. Botta, and R. Terry Bowyer: Evaluating GPS Collar Error: A Critical Evaluation of Telebilt Posrec-Science Collars and a Method for Screening Loca- 36.8 21.0 20.1 68.6 95% 1735.4 951.9 58.5 39.0 82.2 tion Data, 155 - 168 65.5 64.4 24.0

Weckerly, Floyd W.: see Jones, Weckerly, and McCullough

Weigand, James F.: see Keith, Berry, and Weigand 8.3 8.7 6.9 8.3 12.1 All 2-D and 3-D fixes 50% 470.4 20.0 8.0 10.5 9.3 11.1 5.5

SUBJECT 100 249 208 312 868 n 81

66 351 953 939 98

b b d e, f d, f d, f

Abundance: and Distribution of Marine Mammals in Nearshore Waters of Monterey c c c Bay, California, 1 – 17 g g Age: Influence of, and Sex on Dressed-Whole Body Weight Relationships in Black- Outdoor 191 Location Outdoor Indoor Indoor Outdoor Outdoor Indoor Outdoor Tailed Deer, 137 – 142 Indoor Outdoor Indoor Outdoor Camera Trap Systems: Comparison of Two, for Detection of American Marten on a

Winter Landscape, 53 – 59

location errors (m) for eight GPS collar models and one handheld unit with exceptional denoted by bold type. h a

Census, Pacific Harbor Seal: In California during May – July 2002 and 2004, 180

– 193 Deer, Black-Tailed: Influence of Age and Sex on Dressed-Whole Body Weight Re- Year 2000 Year G2000 III Plus GPS2000 GPS4400s Posrec Posrec Simplex Simplex Tellus Tellus Prototype

lationships in, 137 – 142

Desert Tortoise: New Protocol: When Rare, for Assessing Status, 75 – 97 Planned test locations (ATS, Lotek) and unplanned tests at dropped collar locations (n=385 of 939 fixes; Lotek), vicinity of Seward, Alaska. locations (n=385 of 939 fixes; Lotek), vicinity Seward, Lotek) and unplanned tests at dropped collar Planned test locations (ATS, Pre-deployment tests on truck dashboard, Bishop, CA. Pre-deployment test in windowsill, Bishop, CA. Data from POSREC prototype collar (see discussion). Percentile errors are also referred to as CEP (circular error probable). Percentile errors are also referred to as CEP Interior of wood-framed building, Bishop, CA. (n=101 fixes) Planned test in optimal sky view area, Bishop, CA

Unplanned tests at deer mortality locations and outside the homes of biologists, vicinities Bishop and San Ysidro, CA. Unplanned tests at deer mortality locations and outside the homes of biologists, vicinities Bishop San GPS Model ATS Garmin Lotek Televilt Table 1. Percentile Table a b c d e f g h 158 CALIFORNIA FISH AND GAME INDEX TO VOLUME 94 203

Desert Tortoise: Status of, in Red Rock Canyon State Park, 98 – 118 Distribution: Abundance and, of Marine Mammals in the Nearshore Waters of Monterey Bay, California 1 – 17 Fecundity: Spawning Time, Habitat Utilization, and Parasites of a Northern California Population of Tidewater Goby, Encyclogobius newberryi, 18 – 32 Goby, Tidewater: First Record of a Cymothoid Isopod from a, and Three New Locali- ties for in Humboldt County, California, 194 – 199 Green Tree Retention: Aerial Implementation Monitoring of, in Clearcuts on Northern California Private Timberlands, 169 – 179 Habitat Utilization: Spawning Time, Fecundity, and Parasites of a Northern California Population of Tidewater Goby, Encyclogobius newberryi, 18 – 32 Isopod, Cymothoid: First Record of a, From a Tidewater Goby and Three New Tide- water Goby Localities in Humboldt County, California, 194 – 199 Life History Traits: of the Rosethorn Rockfish, Sebastes helvomaculatus, 123 – Figure 1. All point locations (left) and movement path (right) generated from POSREC GPS col- 136 lar deployed on mule deer RVD210, 10 Apr 2002–21 Sep 2002; all fixes (2-D and 3-D; n=1895). Marten, American: Comparison of Two Camera Trap Systems for Detection of, on "3-D" and "3-D+" fixes (n=1344) denoted by triangles. a Winter Landscape, 53 – 59 of an independent measure of the true location, this is a measure of precision rather Mexico, Baja California: First Records or the Fringed Sculpin, Icelinus fimbriatus, than accuracy per se. We did, however, test for bias using the average of 100 3-D (Scorpaeniformes:Cottidae) Off the West Coast of, 150 – 153 locations collected with a Rockwell PLGR (Rockwell Collins, Cedar Rapids, Iowa.), Monterey Bay, California: Abundance and Distribution of Marine Mammals in Garmin GPS12XL, or GPS III (Garmin, Inc., Lenexa, Kanas.) receiver at each planned Neashore Waters of, 1 – 17 test location. Additional collar data were requested from Telemetry Solutions, at the Orchard, Avocado: Carnivore Use of, in Southern California, 61 – 74 time the distributor of Televilt products in the Americas. Parasites: Spawning Time, Fecundity, Habitat Utilization and, of a Northern California We conducted tests of ATS 2000 model year (n=8) and Lotek GPS 2000 (n=7) Population of Tidewater Goby, Encyclogobius newberryi, 18 – 32 collars in the vicinity of Seward, Alaska (60°06’N, 149°27’W) from 6 May 2000, (4 Point Reyes National Seashore: Observations and Prey of White Sharks at,: 1982 – days after selective availability was disabled; Lawler 2000) through 11 August 2000, 2004, 33 – 44 at a total of 22 planned test sites and 2 dropped-collar sites. Most planned sites (78%) Private timberlands: Aerial Implementation Monitoring of Gree Tree Retention in were located under closed-canopy (e.g., Alnus crispa or Picea sitchensis), as were Clearcuts on Northern California, 169 – 179 two dropped collars. Locations were distributed over a range of slopes and aspects. Rockfish, Rosethorn: Notes of the Life History Traits of, 123 – 136 Collars were oriented upright at approximately 0.5 m height; however, 30% of test Salamander, Shasta: A New Elevation Record for, 119 – 121 collars were disturbed by black bears, Ursus americanus, during the 1-20 day trials, Sculpin, Fringed: First Records of the, Off the West Coast of Baja California, Mexico, resulting in horizontal or downward orientation of the GPS antenna. We pooled the 150 – 153 953 (ATS) and 939 (Lotek GPS 2000) GPS positions by manufacturer. These data Sex: Influence of Age and, on Dressed-Whole Body Weight Relationships in Black- represent a range of worst-case conditions of canopy cover, topography, and collar Tailed Deer, 137 – 142 orientation in a steeply sloped, high-latitude environment. Sturgeon, White: Overbite Clamm, Corbula amurensis,Defecated Alive by, 143 One POSREC collar was tested in an area of optimal sky view at 1-m height in – 149 sagebrush, Artemesia tridentata, habitat in Bishop, California (37°22’N, 118°24’W) Tidewater Goby: Spawning Time, Fecundity, Habitat Utilization, and Parasites of a for 14 days. We augmented planned collar testing with retrospective analyses of in- Northern California Population of, 18 – 32 stances where immobile GPS collars provided additional and unplanned data useful Waterfowl Species Composition: A Change in, in the Honey Lake Valley, California, for determining the extent of location errors. Position data from fixed collars were 44 – 52 obtained from POSREC collars that continued to acquire fixes while on deceased mule White Sharks: Observations and Prey of, at Point Reyes National Seashore, 1982 – deer (n=2 collars) for 12 and 22 days prior to recovery. Data also were obtained from 2004, 33 – 43 POSREC collars outside the homes of two biologists (n=2; 4 and 92 days), and from three collars active for 13-201 days on shelves inside a 1-floor wood-framed building 204 CALIFORNIA FISH AND GAME EVALUATING GPS COLLAR ERROR 157

SCIENTIFIC NAMES METHODS

Anas platyrhynchos, 44 Our methodology emanated in response to conspicuous problems with data ob- Artemisia tridentata, 45 tained from deployment of POSREC GPS collars and our need to quantify apparent Martes pennanti, 53 location errors. Data were compiled from a variety of sources including planned Merluccius productus, 152 tests, pre-deployment testing, opportunistic data collected from collars deployed in Abies magnifica, 170 the field that became stationary after collar loss or animal mortality, and from collars Acamptopappus sphaerocephalus, 101 tested during past research. Our methods were not intended to generate data suitable Acer macrophyllum, 119 for side-by-side comparisons of accuracy among GPS collar models, but instead to Acipenser transmontanus, 143 present a representative range of location error from GPS collars, including those Alnus crispa, 158 of three models from Televilt currently absent in the literature, for comparison with Alnus tenuifolia, 170 POSREC collars. Ambrosia dumosa, 78, 101 Anas acuta, 44 Field Deployment of POSREC Collars Anas clypeata, 44 Anas strepera, 44 We deployed POSREC 600-series store-on-board collars on mule deer (Kraus- Anilocra frontalis, 196 man et al. 2004) beginning in March 2002 in Round Valley, California (37°25’N, Arctostaphylos viscida, 120 118°37’W), at the base of the Sierra Nevada, as part of long-term study of predator- Argentian aialis, 152 prey interactions (Pierce et al. 2000, Pierce et al. 2004). Additional collars were Artemesia tridentata, 158 similarly deployed on mule deer in the San Ysidro mountains, California (33°13’N, Aythya affinis, 44 116°30’W). Eleven collars were re-deployed during 2002-2005 when collars were Balaenoptera musculus, 37 recovered after animal mortality or after recapture and subsequent refurbishment Bassia hypsopifolia, 45 of collars. Seven collars were re-deployed on bighorn sheep inhabiting the White Blephariopoda occidentalis, 11 Mountains (37°25’N, 118°14’W) and Sierra Nevada (36°32’N, 118°11’W) in 2004. Bromus sp., 113 Resultant field data included locations from a total of 50 animal deployments of 32 Bromus tectorum, 45 POSREC 600-series store-on-board GPS collars. All collars were programmed by Callorhinus ursinus, 33 the manufacturer to attempt GPS fixes at intervals of 1-6 hours. We shipped collars Calocedrus decurrens, 119, 170 to the former distributor, Telemetry Solutions (Walnut Creek, California) or, after Canis latrans, 61, 80 5 May 2005, directly to Televilt for download, and data were returned as e-mail at- Carcharodon carcharias, 33 tachments. We imported data into ArcView 3.3 (Environmental Systems Research Carex spp., 19 Institute, Redlands, California) and used the Animal Movement extension (Hooge Ceanothus integerrimus, 120 and Eichenlaub 1997) to connect sequential GPS positions. Data were projected Cephlorhynchus hectori, 14 into UTM coordinates and retained the WGS 1984 datum. We overlaid movement Cetorhinus maximus, 34 paths on a shaded relief map generated from a digital elevation model (DEM) with Chrysothamnus spp., 45 30 m resolution. Visual examination of locations was employed to identify suspect Clevlandia ios, 169 movements exhibiting an acutely angled out-and-back pattern (Fig. 1). Clupea pallasi, 39 Coleogyne ramosissima, 78 Fixed-Location Testing of GPS Collar Precision Corbula amurenisi, 143 Corbula fluminea, 144 Data from fixed locations were assembled from a combination of planned test Corvus corax, 113 sites, ad hoc tests where drop-off mechanisms released collars from study animals or Cryptocotyle lingua, 169 where animals died, and ad hoc locations of collars activated before deployment or Cyanocitta stelleri, 56 after recovery. We used the mean of 3-D fixes from collars as the reference location Cymothoa indica, 197 (Dussault et al. 2001) and calculated error distance from this centroid. In the absence 156 CALIFORNIA FISH AND GAME INDEX TO VOLUME 94 205 mountain ranges from 2002 to 2005. Evaluation of data from those deployments Dedelphia virginiana, 61 showed numerous implausible movements, which lead us to question the accu- Dendroica coronata, 176 racy of POSREC GPS collars. Because of the questionable data encountered, Dryocopus pileatus, 176 we tested the precision of Televilt POSREC-Science™ 600 collars under several Elthusa californica, 196 conditions: 1) an area of optimal sky visibility; 2) ad hoc test locations where Elthusa, 196 collars remained attached to deceased mule deer prior to recovery of the collar; Elytrigia elongate, 45 and 3) ad hoc test locations inside a 1-floor, wood-framed building, or outside the Emerita analoga, 11 homes of two biologists, for a total of 663 GPS positions. Unprecedented errors Empidonax oberholseri, 176 in excess of 2 km occurred in 2% of fixes, whereas 12% of fixes were >1 km and Encyclogobius newberryi, 18, 169 53% > 100 m from the true location. Comparisons among six additional GPS Engraulis mordax, 11, 40 collar models from three manufacturers showed POSREC collars to be unique Enhydra lutris, 1 in their lack of precision. Because viewing point data alone may belie the pres- Eriogonum fasciculatum, 78 ence of flawed GPS fixes, we urge researchers using GPS collars, particularly Erodium cicutarium, 113 Televilt POSREC collars, to evaluate patterns of movement to ensure that data Eschrichtus robustus 2, 37 are not affected by sampling artifacts. We developed a method for screening Eumetopias jubatus, 181 GPS collar data and provide an ArcView extension useful for removing erroneous Felis concolor, 69, 166 fixes. We suggest researchers contemplating purchases of GPS collars obtain Glaucomys sabrinus, 56 test data from the individual collars they will deploy, to ensure that real-world Gobius flavescens, 197 precision meets study objectives. Gobius geniporus, 197 Gobous pagwnellus, 197 INTRODUCTION Gopherus agassizii, 75, 98 Grayia spinosa, 78 Studies of GPS accuracy have evaluated effects of canopy and terrain (Rempel et Gulo gulo, 53 al. 1995, Dussault et al. 1999, D'Eon et al. 2002, Di Orio et al. 2003, Cain et al. 2005, Hippoglossina stomata, 152 DeCesare et al. 2005) as well as collar orientation (Moen et al. 1996, D'Eon and Delparte Hydromantes shastae, 119 2005). These studies elucidated external influences on location accuracy, and have Hymenoclea, salsola, 101 important implications for the interpretation of data from GPS collars (D'Eon 2003, Icelinus cavifrons, 150 Frair et al. 2004). These comparisons of accuracy in commercially available GPS Icelinus fimbriatus, 150 collars, however, have been limited to collars made by Advanced Telemetry Systems Icelinus quadriseriatus, 150 (ATS; Isanti, Minnesota), Lotek Wireless (Newmarket, Ontario), and Telonics, Inc. Icelinus tenius, 150 (Mesa, Arizona). Frair et al. (2004) and Gau et al. (2004) provided data on respective Juglans californica, 63 fix rates and reliability of Televilt GPS-Simplex™ collars, but did not assess accuracy Juncus balticus, 45 or precision. This work documents the unprecedented magnitude of location errors Juniperus occidentalis, 78 inherent in widely deployed Televilt POSREC-Science™ GPS collars. Kabatana newberryi, 169 Evaluation of GPS collar error was not a planned objective of our studies, but Kabatana newberryi, 30 when extraordinarily improbable position data were detected after deploying collars Kathetostoma averruncus, 152 on study animals, we sought data from collars at fixed locations to verify the pres- Lamna ditropis, 34 ence of errors. To this end, we combined controlled testing with opportunistic data Larrea tridentata, 78, 101 from fixed locations identified retrospectively from a database of GPS collar fixes, Lepidopus fitchi, 152 yielding data from several GPS collar models under a range of satellite visibility Lithocarpus densiflorus echinoides, 120 conditions and illuminating the prevalence of heretofore unprecedented errors. We Loligo opalescens, 11 also provide a method that is broadly applicable to screening GPS collar data for Lycium andersonii, 78 patterns characteristic of flawed locations. Lynx rufus, 57, 61 Lyopsetta exilis, 152 206 CALIFORNIA FISH AND GAME CALIFORNIA FISH AND GAME California Fish and Game 94(4):155-168 2008

Macoma balthica, 145 Martes americana, 53 Martes pennanti, 176 EVALUATING GPS COLLAR ERROR: A CRITICAL EVALU- Megaptera novaeangliae, 37 ATION OF TELEVILT POSREC-SCIENCE™ COLLARS AND Mephitis m. macoura, 62 A METHOD FOR SCREENING LOCATION DATA Mephitis mephitis, 61 Mesogobius batrachocephalus, 197 JEFFREY T. VILLEPIQUE1 Mirounga angustirostris, 33, 181 Sierra Nevada Bighorn Sheep Recovery Program Monolene asaedai, 152 California Department of Fish and Game Mycoplasma agassizii, 80, 101 407 West Line St. Mycoplasum testudineum, 101 Bishop, CA 93514 Nerocila bivittata, 197 VERNON C. BLEICH Nerocila tartakowski, 197 Sierra Nevada Bighorn Sheep Recovery Program Octopus rubescens, 11 California Department of Fish and Game Odocoileus hemionus, 155 407 West Line St. Odocoileus virginianus, 137 Bishop, CA 93514 Ophiodon galeoides, 152 Ovis canadensis, 155 BECKY M. PIERCE Oxyurichthys microlepis, 197 Sierra Nevada Bighorn Sheep Recovery Program Panthera onca, 62 California Department of Fish and Game Parus gambeli, 176 407 West Line St. Bishop, CA 93514 Persea americana, 62 Phoca vitulina, 1, 33 THOMAS R. STEPHENSON Phoco vitulina richardsi, 180 Sierra Nevada Bighorn Sheep Recovery Program Phocoena phocoena, 1 California Department of Fish and Game Physeter macrocephalus, 37 407 West Line St. Picea sitchensis, 158 Bishop, CA 93514 Pinus contorta, 54 Pinus jeffreyi, 54, 170 RANDALL A. BOTTA Pinus lambertiana, 119, 170 California Department of Fish and Game 4949 Viewridge Dr. Pinus monophylla, 78 San Diego, CA 92123 Pinus ponderosa, 119, 170 Piranga ludoviciana, 176 R. TERRY BOWYER Pleuronichthys guttulatus, 152 Department of Biological Sciences Pleuronichthys verticalis, 152 Idaho State University Poecile gambeli, 57 Pocatello, ID 83209 Populus balsamifera, 170 Populus tremuloides, 170 Wildlife telemetry collars incorporating Global Positioning System (GPS) Procyon lotor, 61 units are thought to provide accurate locations when the GPS receiver obtains an Pseudotsuga menziesii, 54, 119, 170 adequate sky view. We deployed 32 POSREC-Science™ 600 series 12-channel Quercus agrifolia, 63 GPS collars (Televilt/TVP Positioning AB, Lindesberg, Sweden) on mule deer, Quercus chrysolepis, 119 Odocoileus hemionus, and bighorn sheep, Ovis canadensis, in three California Quercus kelloggii, 119 1 Quercus vacciniifolia, 120 Current address: California Department of Fish and Game, P.O. Box 3222, Big Bear City, CA 92314. email: [email protected] 155 INDEX TO VOLUME 94 207

Raja inorata, 152 Ribes roezlii, 120 Ruppia maritima, 19 Sarcobatus vermiculatus, 45 Sardinops sagax, 40 Schismus sp., 113 Scirpus acutus, 45 Scirpus maritimus, 45 Scirpus spp., 19 Sciurus, griseus, 61 Scorpaena guttata, 152 Sebastes elongatus, 126 Sebastes exsul, 152 Sebastes helvomaculatus, 123 Sebastes semicinctus, 152 Senna armata, 101 Sialia mexicana, 176 Sistichlis elongate, 45 Sousa chinensis, 14 Strix occidentalis caurina, 171 Susicyon thous, 62 Synodus lucioceps, 152 Taxidea taxus, 69 Toxicodendron diversilobum, 120 Turdus migratorius, 176 Tursiops truncates, 5 Typha latifolia, 45 Umbellularia californica, 119 Urocyon cinereoargenteus, 61 Ursus americanus, 61, 158 Vulpes macrotis, 80, 102 Vulpes necator, 176 Xenopus laevis, 169 Xylorhiza tortifolia, 78 Yucca brevifolia, 78, 103 Zalophus californianus, 1, 33, 181 Zaniolepis frenata, 152

OSP 09 112252 CONTENTS

ARTICLES

Evaluating GPS Collar Error: A Critical Evaluation of Televilt Posrec-Science™ Collars and a Method for Screening Location Data ...... Jeffrey T. Villepique, Vernon C. Bleich, Becky M. Pierce, Thomas R. Stephenson, Randall A. Botta, and R. Terry Bowyer 155

Aerial Implementation Monitoring of Green Tree Retention in Clearcuts on Northern California Private Timberlands...... Joe Croteau and Brett Furnas 169

Pacific Harbor Seal Census in Californian during May – July 2002 and 2004………Mark S. Lowry, James V. Carretta, and Karin A. Forney 180

NOTES

First record of a cymothoid isopod from a tidewater goby and three new tidewater goby localities in Humboldt County, California...... Adam J. Frimodig, and Greg H. Goldsmith 194

REFEREE ACKNOWLEDGMENTS...... 200

INDEX TO VOLUME 94...... 201