Historic and Recent Age Structure and Growth of Endangered Lost River and Shortnose Suckers in Upper Klamath Lake, Oregon

Home , Age class structure, Chasmistes, Lost River sucker, Shortnose sucker

Environ Biol Fish (2010) 89:239–252 DOI 10.1007/s10641-010-9679-9

Historic and recent age structure and growth of endangered Lost River and shortnose suckers in Upper Klamath Lake, Oregon

Mark R. Terwilliger & Tamal Reece & Douglas F. Markle

Received: 28 October 2009 /Accepted: 21 June 2010 /Published online: 13 July 2010 # Springer Science+Business Media B.V. 2010

Abstract Seventy-four lapilli from Lost River suck- level. Growth in body length for both species ers captured in Upper Klamath Lake in 1970 during a appeared determinate in that growth was rapid until snag fishery on spawning adults and 192 lapilli from maturity, and then slowed over several years until adults sacrificed from 2001–2006 were examined to growth in length was nearly nonexistent; a 650– determine age and growth parameters; lapilli from 700 mm Lost River sucker could be between 14 and 165 shortnose suckers sacrificed from Upper Klamath 57 years old, while a 460 mm shortnose sucker Lake from 2001–2006 were also examined. Relative could range from 12–24 years old. In contrast, while marginal distance analyses indicated that growth growth in body length slowed for both species, body marks were annuli and formed in December–January. mass continued to increase. This growth strategy, Lost River suckers from the historic collection were which is also found in other western lake suckers, aged to 57 years, while Lost River and shortnose may allow for more energy to be utilized for suckers from the recent collection were aged to reproduction and help populations persist in spite 40 years and 24 years, respectively. Larger and older of years of limited recruitment or recruitment failure. Lost River suckers were represented in the historic collection compared to the recent collection. Uncou- Keywords Age . Growth . Upper Klamath Lake . pling of otolith length and fish length in Lost River Lost River Sucker . Shortnose sucker suckers as well as a large spread in the predicted age- at-size for shortnose suckers precluded the ability to back-calculate size-at-age. Likelihood ratio Introduction tests indicated the growth model parameters were significantly different at both the sex and collection The Lost River sucker, Deltistes luxatus, and the shortnose sucker, Chasmistes brevirostris, are large, long-lived catostomids endemic to the Upper Klamath Tamal Reece is deceased Basin of southern Oregon and northern California : : M. R. Terwilliger (*) T. Reece D. F. Markle (Moyle 2002). They are usually described as obliga- Department of Fisheries and Wildlife, tory lake-dwellers, and the primary refuge for both Oregon State University, species is Upper Klamath Lake in south-central 104 Nash Hall, Corvallis, OR 97331-3803, USA Oregon (Perkins et al. 2000a). Although historically e-mail: [email protected] abundant, both species were listed as endangered 240 Environ Biol Fish (2010) 89:239–252

(USFWS 1988) because of ageing and declining available on adult ages of both species came from populations, apparently caused by recruitment failure opercles collected during three substantial lake-wide since the early 1970s. These population declines have fish kills (1995–1997), caused by low dissolved been linked to several factors, including: high fishing oxygen levels exacerbated by bacterial infection pressure on spawning adults (Bienz and Ziller 1987); (USFWS 2001). Data from these kills indicated that land use practices in the area, such as water most of the fish were born after closure of the sport diversions, habitat reduction, and poor water quality fishery; therefore, the age distributions were truncated associated with agricultural and timber practices compared to historic distributions, with most fish around the lake and its tributaries; hybridization; and under 10 years old (Markle and Cooperman 2002). competition with and predation by exotic species Conservative estimates placed the number of suckers (USFWS 1988). killed during these three years at 8800 fish (USFWS Historically, both species were so abundant in the 2001), a number comparable to those reported Upper Klamath Basin that adults were utilized in both annually during the snag fishery in the early 1980s a subsistence fishery by the Klamath and Modoc (Markle and Cooperman 2002). The removal of these tribes as well as in a popular sport “snag” fishery on large, old fish from the population has likely been spawning adults that began in the early 1900s and detrimental to both species. As a group, western lake peaked in the 1960s and 70s (primarily D. luxatus, suckers are characterized by 30–40+ year life spans, but also including Ch. brevirostris, and to a lesser late maturation (between ages 4–10 years), high extent the Klamath largescale sucker, C. snyderi) fecundity and iteroparity (Cooke et al. 2005). This (Markle and Cooperman 2002). Fishing effort was life history strategy ensures that reproductive output is concentrated in three primary areas: in-lake springs, allocated across many years, ensuring some repro- the Williamson River at Highway 97, and the Sprague ductive success despite periods that may be unsuitable River at Chiloquin (Fig. 1). The in-lake fisheries were for larval and juvenile survival (Leaman and Beamish located in the northwest part of the lake at Harriman 1984). Broad age distributions may also reduce Springs and at springs along the eastern shore. recruitment variability, as there may be age-related According to regional newspapers, sport fishermen differences in spawning times and locations (Lambert snagged an estimated 50 tons of suckers (approxi- 1987) which could span a wider range of environ- mately 12,500 fish) during spawning runs in the mental conditions favorable for larval survival (Ber- Williamson and Sprague Rivers during a three-week keley et al. 2004a). Removal of large adults from the period in 1966 (Markle and Cooperman 2002). spawning populations reduced the reproductive po- Golden (1969) reported entire pickup trucks loaded tential of the species, created a bottleneck that with fish as common occurrences. After several years restricted growth of the sucker populations (NRC of declining catches (NRC 2004) and elimination of 2004), and coupled with poor recruitment due to spawning groups (Andreasen 1975), the Klamath unfavorable environmental conditions, had imperiled Basin Interagency Working Group conducted surveys both sucker species. In 2005, an Independent Scien- in the mid-1980s that indicated negligible recruitment tific Review Panel (established as required by the to spawning populations (Bienz and Ziller 1987; Endangered Species Act) identified significant and Scoppettone and Vinyard 1991). Further, opercle age sharp population declines and lack of recruitment as data collected from Lost River suckers after an current applicable threats to both species (Cascade unexplained 1986 fish kill showed that no substantial Quality Solutions 2005). recruitment had occurred during the previous 18 years, The age distributions of populations are funda- with 95% of the fish aged at between 19 and 35 years mental indicators of their status. This work represents (Scoppettone and Vinyard 1991; NRC 2004); only the first study of age, growth, and longevity for seven shortnose suckers, aged four to 20 years, were populations of adult and sub-adult Lost River and collected (Scoppettone and Vinyard 1991). These data shortnose suckers based on age estimates from prompted the state of Oregon to close the sport sectioned otoliths, and contributes to the overall fishery in 1987. knowledge of both historic and recent populations. Although Lost River and shortnose suckers were The objectives of this study were to determine if these listed over 20 years ago, most of the information species could be aged using lapillar otoliths, and, if Environ Biol Fish (2010) 89:239–252 241 so, to provide information on age structure, growth, damaged or missing, the left lapillus was used. Lapilli and longevity of Lost River and shortnose sucker were embedded in epoxy resin (Spurr 1969) and a populations from Upper Klamath Lake and its 1.0 mm-thick oblique section running anterodistal- tributaries, and to compare age and growth data posteromedial that included the core was made using between historic and recent collections of Lost River a Buehler Isomet low-speed saw with a diamond- suckers. tipped wafering blade. An oblique section was necessary because the main growth axis of the lapillus projects ventrally, the core is not centrally located, Methods and the longest axis of the lapillus sits at an oblique angle relative to the head of the fish. Sections were Lapillar otoliths used in this study came from two mounted on glass slides using Crystal Bond adhesive, sources, one of which will be referred to as historic sanded with 600-grit wet/dry sandpaper to remove and the other as recent. The historic collection, made saw marks and gain proximity to the core, and by the Oregon Department of Fish and Wildlife polished on a felt pad with 0.5 μm alumina powder. (ODFW) in 1970, consisted of lapilli and biological The otolith was flipped several times during grinding data from 94 Lost River suckers sampled during a and polishing to create a thin section showing visible creel survey of the snag fishery over three days (April increments from core to edge (see Secor et al. 1992). 11, 15 and 17) at two snagging sites (on the Otolith sections were digitally photographed with a Williamson River near the Highway 97 bridge and Leica DFC320 digital camera attached to a Leitz Sprague River at Chiloquin, Fig. 1). Otoliths from 74 Biomed compound microscope, with transmitted light fish that had accompanying length and sex data were under 40× magnification. These digital images analyzed (Table 1). The recent collection was made allowed for repeated annuli counts and measurements available to us by the United States Geological for precision estimates. Ages were assigned from Survey (USGS), which collected lapilli and biological counts of growth increments that were comprised of a data from 192 Lost River suckers and 165 shortnose wide translucent and narrow opaque band, and all fish suckers during sampling in Upper Klamath Lake from were assigned a nominal birthdate of 1st January. 2001–2006 (Table 1). Capture methods used by Annuli were counted and measured to the nearest USGS included trammel netting in the northern 0.0001 μm using Image Pro Plus 6.0 (2006) software. section of Upper Klamath Lake, the lower Williamson Due to the curvature of the posterior edge of the River, and east-side spring areas as well as sampling otolith and the location of the more “centralized” the Sprague River fish ladder by trammel and dip net core, a single measuring path from core to edge would (Fig. 1); see Janney et al. (2008) for gear specifica- not be perpendicular to all annuli. Therefore, two tions and methods. Although both data sets are measurement paths were used: the first was a path assumed to be representative of the age structure of perpendicular from the core to the 4th increment, and spawning adults at the time of collection, comparison the second was shifted towards the distal edge and ran of age-class structure between the historic and recent perpendicularly from the 4th increment to the ventral samples must be done with caution. ODFW notes edge (Fig. 2). An otolith radius was determined by indicated that fishers in 1970 discarded smaller fish summing the increment widths measured along these and lost or broke tackle on larger fish (Bill Tinnis- two growth axes. wood, ODFW, pers. comm.), and no fish analyzed Within-reader precision was estimated in terms of were captured at shoreline springs. Recent otolith absolute percent error as outlined in Beamish and samples came from suckers that were somewhat longer Fournier (1981). Annuli on otoliths from all Lost in length than that of the sampled populations in 2003 River and shortnose suckers were counted three times and 2005 and somewhat smaller in length than sampled by the senior author. The median age (and increment populations in 2006. Both sample sets appear to have widths associated with that age) obtained from the some unknown size bias with the 1970 samples three reads was used in all subsequent analyses. probably more strongly biased towards larger fish. Counts and measurements were made over the course We selected the right lapillus for all analyses; of several months without information regarding fish however, in a few cases where the right lapillus was size or capture date. 242 Environ Biol Fish (2010) 89:239–252

Fig. 1 Map of Upper Kla- math Lake and adjoining Agency Lake, Oregon, showing Oregon Depart- ment of Fish and Wildlife and U.S. Geological Survey sampling locations for Lost River and shortnose suckers Williamson River

Sprague River Agency Lake Chiloquin Dam fish ladder

Highway 97 bridge

Williamson River weir

Harriman Springs Eastern shoreline springs

Upper Klamath Lake

N Klamath Falls

0 5 kilometers

In his review of age validation methods, Campana (2001) recommended that two procedures be followed Table 1 Numbers of Lost River suckers (LRS) and shortnose when it was not possible to determine absolute age: suckers (SNS) by sex aged in this study collected in 1970 by determination of age at first increment formation and Oregon Department of Fish and Wildlife (Historic) and from verification of increment periodicity across the entire 2001–2006 by the U.S. Geological Survey (Recent). Five LRS and 1 SNS from the recent collection had no accompanying age range of interest. To validate the age of first capture date and were excluded from this table increment formation, we measured the distance from core to leading edge in lapilli from randomly selected Year Historic-LRS Recent-LRS Recent-SNS October-caught age-0 Lost River suckers and short- ♂♀Unk. ♂♀Unk. ♂♀Unk. nose suckers (20 of each species), and assumed that otolith radius in these suckers approximated that of 1- 1970 44 29 1 year-old fish. Comparisons of similar measurements 2001 1 0 0 1 0 0 were then made to 20 adults from each species. In 2002 38 30 4 15 31 6 order to validate the periodicity of growth increment 2003 8 26 0 22 30 3 formation, we separated both species into two groups 2004 0 2 0 3 1 0 (younger, faster growing individuals and older, slower 2005 14 19 0 8 1 0 growing individuals) based upon length-at-age curves 2006 23 22 0 24 19 0 (see below), determined the relative marginal distance Environ Biol Fish (2010) 89:239–252 243

observed length at hatch. We used a mean observed length-at-hatch of 10 mm for Lost River suckers and 8 mm for shortnose suckers as determined by Hoff et al. (1997). Likelihood ratio tests were used to compare von Bertalanffy parameter estimates between collections and sexes of Lost River suckers and between sexes for shortnose suckers (Kimura 1980;Cerrato1990; Haddon 2001).

Results

Lapilli from 266 Lost River suckers (360–790 mm FL) and 165 shortnose suckers (280–550 mm FL) were examined. Of the Lost River sucker otoliths analyzed, 131 were from females ranging from 387– 785 mm FL and 129 were from males ranging from 360–734 mm FL. Six Lost River sucker otoliths had either sex or length data missing. Further analysis of length-at-age (see below) showed that the length data for the 360 mm male Lost River sucker may have had numbers transposed because the data fell approxi- mately six standard deviations from fitted models; this sucker data was therefore excluded from further Fig. 2 Oblique section of a lapillus from a 13-year-old Lost River sucker captured in Upper Klamath Lake, Oregon, showing length-at-age analyses. We found significant differ- the two paths used for annuli counts and measurements ences in fork lengths between historic and recent collections of Lost River suckers (Kolmogorov- Smirnov, p=0.00; Fig. 3) with recently collected Lost (RMD), the ratio of the distance from the last growth River suckers being smaller on average than historic mark to the edge to the distance separating the last collections. Of the shortnose sucker otoliths, 82 were two marks (see Panfili and Morales-Nin 2002), and from females ranging from 283 to 550 mm FL and 74 plotted the mean RMD by month. Lost River and were from males ranging from 280 to 474 mm FL. shortnose suckers classified as “younger” had fewer Data on length or sex was missing from nine short- than 12 and 11 growth marks, respectively, on their nose sucker otoliths. Fork lengths of shortnose lapilli. This semi-direct validation technique allowed us suckers were significantly less than those of Lost to pool otolith measurements into two age categories River suckers collected over the same time period and accounted for the reduction in growth with age. (Kolmogorov-Smirnov, p=0.00; Fig. 3). To investigate the relationship between otolith size Otolith sections displayed well-formed alternating and fish size, we ran general linear models using opaque and translucent zones that were easily counted Statgraphics Centurion statistical software (Statpoint, and measured. An average percent error of 1.9% for Inc. 2005) that included sex, fork length, and age as Lost River suckers and 4.0% for shortnose suckers factors. Lost River and shortnose sucker growth were was estimated, indicating relatively high within-reader modeled using a two-parameter modification of the von precision (see Campana 2001). Oblique sections Bertalanffygrowthcurveinwhichthesizeatbirthisfixed revealed that otolith structure consisted of an opaque (Fabens 1965; Neer et al. 2005; Campana et al. 2009): core surrounded by a wide opaque area whose outer Kt edge demarcated the first annulus. The translucent L ¼ L1 ðL1 L Þe ; t 0 and opaque zones for the following 3–4 annuli were where Lt = predicted length at age t (in years); L∞ = relatively wide and easy to distinguish, and successive theoretical asymptotic length; K = rate constant; L0 = annuli were relatively narrow and pronounced. 244 Environ Biol Fish (2010) 89:239–252

18 15 mark formation, indicating that growth marks were 12 annuli and could be used to age both species. 9 LRS-Historic The oldest Lost River sucker aged in this study was a 6 3 57 year old male (673 mm FL) from the historic col- 0 lection, while the two oldest Lost River suckers from the 3 6 recent collection were a 40 year old female (708 mm FL) 9 and a 40 year old male of unknown length. The age LRS-Recent 12 distribution of Lost River suckers from the recent 15 18 collection was significantly younger than that of the historic collection (Kolmogorov-Smirnov, p<0.01; 250 300 350 400 450 500 550 600 650 700 750 800 850 Fig. 5). The oldest shortnose sucker, from the recent

Frequency 18 collection, was a 24 year old female (505 mm FL). Recently collected shortnose suckers were also relative- 15 ly younger when compared to recently collected Lost 12 River suckers (Kolmogorov-Smirnov, p<0.01; Fig. 5). SNS-Recent 9

6 1 LRS 3 0.9 0 0.8 3 3 1 0.7 2 2 5

250 300 350 400 450 500 550 600 650 700 750 800 850 61 0.6 65 8 1 Fork length (mm) 41 10 0.5 56 RMD 0.4 1 Fig. 3 Length frequency distributions of Lost River suckers 1 (LRS) and shortnose suckers (SNS) captured in Upper Klamath 0.3 1 Lake, Oregon, and aged in this study. LRS-Historic refers to 0.2 young suckers collected by Oregon Department of Fish and Wildlife in 0.1 old 1970; LRS-Recent and SNS-Recent refer to suckers collected 0 by the U.S. Geological Survey from 2001–2006 162 3 4 5 7 8 9 10 11 12

1 SNS Checks were noted within the first four annuli, but 0.9 0.8 their irregular spacing and contrast made them 0.7 2 19 19 7 relatively easy to distinguish from annular marks, 2 0.6 34 which exhibited higher contrast and could be fol- 1 0.5 28 1

RMD 37 2 lowed along the ventral surface (reference Fig. 2). 0.4 2 When we compared the age at first annulus formation 0.3 2 8 between young-of-the-year and adult suckers, we saw 0.2 young no significant differences in mean lapillar radius at age- 0.1 old 1 for either lifestage (t-test; p=0.11 and 0.32 for Lost 0 River and shortnose suckers, respectively), corroborat- 16211345 78910 12 ing our determination of the first annulus. When we CAPTURE MONTH validated periodicity of growth mark formation Fig. 4 Mean relative marginal distances (RMD) and associated (Fig. 4), trends were similar for both age groups of standard errors plotted by month for young and old Lost River both species, with relatively low RMD values occur- suckers (LRS) and shortnose suckers (SNS). Numbers above ring early in the calendar year and relatively large and below each point represent sample size. Lost River suckers RMD values occurring late in the year. Although lake from historic and recent collections were combined for the analysis. No suckers were captured in Upper Klamath Lake in ice-over prevented sampling in December and January, either collection in January or December; Lost River suckers the data were consistent with single, winter growth were also not collected in June Environ Biol Fish (2010) 89:239–252 245

30 respectively; Table 2; Fig. 6): a 400 mm fish could LRS-Historic 20 have the same otolith length as a 700 mm fish. The 10 relationship between otolith length and fish length for 0 shortnose suckers was also strong (ANOVA, p<0.01) and exhibited a larger effect size than that for Lost 10 LRS-Recent 20 River suckers (Fig. 6). Sex was not a statistically significant factor in the shortnose sucker model 30 (ANOVA, p=0.2583, Table 2) and was dropped. A 40 much stronger positive relationship existed for both 50 species between otolith length and fish age (ANOVA, 0 102030405060 p<0.0001; Fig. 7). Sex and fork length were

30 significant in the Lost River sucker model (Table 2; Frequency ANOVA, p=0.0023 and 0.0006 for sex and fork 25 length, respectively), but sex was not significant in 20 the shortnose sucker model (ANOVA, p=0.2583 and SNS-Recent 0.00 for sex and fork length, respectively). 15 Likelihood ratio tests indicated that growth model 10 parameters were significantly different between collections and sexes for Lost River suckers and between 5 sexes for shortnose suckers (Table 3), so data were 0 not combined. Female Lost River suckers exhibited 0 102030405060 higher L∞ values and lower growth coefficient values than males in both historic and recent collections Age (years) (Table 4). Growth in body length of male and female Fig. 5 Age distributions of Lost River suckers (LRS) and Lost River suckers from the historic sample was shortnose suckers (SNS) captured in Upper Klamath Lake, relatively rapid until maturity (age 7–9), slowed for Oregon, and aged in this study. LRS-Historic refers to suckers several years post-maturity, and essentially ceased collected by Oregon Department of Fish and Wildlife in 1970; over the remaining 40 years of life (Fig. 8). Although LRS-Recent and SNS-Recent refer to suckers collected by the U.S. Geological Survey from 2001–2006. the age structure was truncated compared to the historic sample, Lost River suckers from the more A strong relationship but trivial effect (small slope) recent collection exhibited similar traits in growth existed between otolith length and fish length for Lost over the first 16 years of life, with growth in body River suckers (ANOVA, p<0.01) when sex and age length essentially ceasing over the last few years of were accounted for in a general linear model life. In contrast, body mass continued to increase with (ANOVA, p=0.0023 and 0.0000 for sex and age, age up to about age 30 in both sexes (Terwilliger,

Table 2 ANOVA table summarizing results Model Source Sum of Squares DF Mean Square F-Ratio P-Value of fitting a general linear statistical model relating LRS-OL Sex 137608.0 2 68804.1 6.22 0.0023 Lost River sucker (LRS) FL 132140.0 1 132140.0 11.94 0.0006 and shortnose sucker (SNS) Age 1.95 × 107 1 1.95 × 107 1760.80 0.0000 otolith length (OL) to pre- 6 dictive factors of sex, fork Residual 2.83 × 10 256 11069.1 length (FL), and age. Total (corrected) 3.88 × 107 260 DF = degrees of freedom SNS-OL Sex 15246.7 2 7623.36 1.37 0.2583 FL 94436.3 1 94436.3 16.92 0.0001 Age 3.03 × 106 1 3.03 × 106 542.12 0.0000 Residual 865209.0 155 5582.0 Total (corrected) 1.38 × 107 159 246 Environ Biol Fish (2010) 89:239–252

4000 a LRS from 1913 to 1962 (Fig. 11), with two relatively strong p<0.0001, coefficient = 0.40 year classes (1948 and 1949) accounting for 28% of 3000 the sample. The Lost River sucker birthyear distribution from the recent collection was truncated compared 2000 to the historic sample, and was represented by 21 year classes ranging from 1963 to 1999 (Fig. 11), with two 1000 relatively strong year classes (1990 and 1991) account-

*controlled for sex and age ing for 55% of the sample. Shortnose suckers from the 0 recent collection were represented by 15 year classes

250 300 350 400 450 500 550 600 650 700 750 800 850 ranging from 1979 to 2000 (Fig. 11), with two periods of relatively strong year classes: 1990–1991, which 4000 b SNS accounted for 35% of the sample, and 1998, which p<0.0001, coefficient = 0.92 Otolith length (µm) accounted for nearly 20% of the sample. 3000

2000 Discussion

1000 This study represents the first attempt at ageing adult *controlled for age and sub-adult Lost River and shortnose suckers using 0 otoliths. High precision estimates and the results of

250 300 350 400 450 500 550 600 650 700 750 800 850 RMD analyses support the use of lapilli for ageing Fork length (mm) adults and sub-adults of both species. Previous attempts Fig. 6 Scatterplots of otolith length on fork length for (a) Lost River suckers (LRS) and (b) shortnose suckers (SNS). LRS from historic and recent collections were combined for the 4000 analyses a

3000 unpubl. data). Male and female Lost River suckers achieved 50% of L∞ by age 6 and 75% between ages 2000 10 and 11 (Fig. 8). Longevities of Lost River suckers from both collections were similar between sexes. 1000 Male and female shortnose sucker growth in body LRS

µm) length was relatively rapid until age 5 before slowing 0 over the next six years and essentially ceasing for 0 102030405060 ages greater than 11 years (Fig. 9). This reduction in growth rate occurred at an age coinciding with the 4000 b onset of maturity for this species. Male and female Otolith length ( shortnose suckers achieved 50% of L∞ by age 3 and 3000 75% between ages 5 and 6 (Fig. 9). Female shortnose suckers exhibited greater longevity than males (24 years 2000 and 19 years for females and males, respectively), and like Lost River suckers, exhibited higher L∞ values and 1000 lower growth coefficient values than males (Table 4). SNS Rarefaction of both historic and recent samples 0 (Fig. 10) showed that the recent sample was repre- 0 102030405060 sented by fewer year-classes of Lost River suckers Age (years) than the historic sample, and curves showed no evidence Fig. 7 Scatterplots of otolith length on age for (a) Lost River of crossing. Lost River suckers from the historic suckers (LRS) and (b) shortnose suckers (SNS). LRS from collection were represented by 27 year classes ranging historic and recent collections were combined for the analyses Environ Biol Fish (2010) 89:239–252 247

Table 3 Likelihood ratio χ 2 tests comparing von Berta- Comparison Hypothesis Linear constraints RSS r df P lanffy parameter estimates between historic (h) and LRS: Historic vs. Recent HΩ none 660294.10 recent (r) collections of Lost Hω1 L∞h=L∞r 661632.97 0.5226 1 0.470 River suckers (LRS), and Hω K =K 664014.33 1.4495 1 0.229 between male (1) and fe- 2 h r male (2) Lost River and Hω3 L∞h=L∞r 702908.24 16.13558 2 0.000 shortnose suckers (SNS) Kh=Kr from each collection LRS Historic: male vs. female HΩ none 128375.96

Hω1 L∞1=L∞2 162547.99 17.2287 1 0.083

Hω2 K1=K2 133761.06 2.9997 1 0.000

Hω3 L∞1=L∞2 176447.72 23.2185 2 0.000 K1=K2 LRS Recent: male vs. female HΩ none 441228.67

Hω1 L∞1=L∞2 459212.58 7.3907 1 0.007

Hω2 K1=K2 449732.07 3.5314 1 0.060

Hω3 L∞1=L∞2 483846.38 17.0578 2 0.000 K1=K2 SNS: male vs. female HΩ none 118090.52

Hω1 L∞1=L∞2 131884.85 17.2045 1 0.000

Hω2 K1=K2 119328.45 1.6268 1 0.202

Hω3 L∞1=L∞2 146075.12 33.1765 2 0.000 K1=K2 at ageing these species included the use of scales and and Berry (2006), who determined that the lapillus was opercular bones (Scoppettone 1988); however, scales the preferred hard part for ageing populations of white are notorious for underestimating age in long-lived sucker, Catostomus commersonii;further,Thompson species, and ages from opercula may also underestimate and Beckman (1995) used edge analysis to determine true age. Researchers (Scoppettone 1988; Peterson et al. that marks on lapilli were annular for that species. Belk 1999) have described the presence of hidden annuli on (1998) also reported unvalidated ages from June sucker catostomid opercular bones due to fenestrated rein- (Chasmistes liorus)lapilli. forcement bone immediately ventral to the hyoman- The maximum age of Lost River suckers aged in dibular socket, the number of which was a function of this study was 57 years, which is 14 years older the age and shape of the opercle. In contrast, lapilli for than the previously published maximum age for the these species are easily prepared for reading, growth species, and came from a relatively small sample. marks are annular, and checks are relatively easy to Previous ageing of Lost River suckers was per- distinguish from true annuli. Further support for using formed by Scoppettone (1988) and by Coleman et lapilli to age catostomids was supplied by Sylvester al. (1988), who examined opercles from fish collect-

Table 4 Calculated von Bertalanffy parameters for male and 2001–2006 by the U.S. Geological Survey (Recent), and for female Lost River suckers (LRS) collected in 1970 by the male and female shortnose suckers (SNS) from recent collec- Oregon Department of Fish and Wildlife (Historic) and from tions. Jackknifed standard errors are in parentheses

Parameter Historic Recent

LRS ♂ LRS ♀ LRS ♂ LRS ♀ SNS ♂ SNS ♀

L∞ 663.16 (10.41) 742.44 (19.73) 608.42 (23.50) 700.58 (22.82) 424.50 (6.18) 464.32 (7.07) K 0.169 (0.020) 0.133 (0.028) 0.179 (0.028) 0.130 (0.013) 0.266 (0.013) 0.237 (0.015) n 44 29 84 101 74 82 248 Environ Biol Fish (2010) 89:239–252

800 a Historic 700 27 600 24 500 21 400 Recent Historic 18 300 Females 15 200 Males 12 100 Year Classes 9 0 0 102030405060 6 3 800 b Fork length (mm) 0 700 81624324048566472 600 Specimens 500 Fig. 10 Rarefaction curves (solid lines) and 95% confidence 400 Recent intervals (dashed lines) for Lost River suckers from historic and 300 recent collections Females 200 Males 100 0 0 102030405060 Age (years) 50 LRS-Historic LRS-Recent Fig. 8 Two-parameter von Bertalanffy growth curves for Lost 40 River suckers for varying combinations of sex and collection: (a) female (solid line) and male (dashed line) Lost River 30 suckers from the historic collection; (b) female (solid line) and male (dashed line) Lost River suckers from the recent collection 20 ed during the 1986 fish kill in Upper Klamath Lake. 10 Both authors determined a maximum age of 43 years, but decomposition precluded accurate length meas- 0 urements and/or sex determinations on many fish so 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 length-at-age could not be determined. This age difference between historic Lost River suckers aged 50 SNS-Recent Percent of sample of Percent 40 600 30 500

)

400 20

300 10

200 Females 0

Fork length (mm Males 100 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 0 0 5 10 15 20 25 30 Year class Age (years) Fig. 11 Age distribution (by year class) of Lost River suckers Fig. 9 Two-parameter von Bertalanffy growth curves for from the historic (LRS-Historic) and recent (LRS-Recent) female (solid line) and male (dashed line) shortnose suckers collections and shortnose suckers from the recent (SNS-Recent) from the recent collection collections

250 Environ Biol Fish (2010) 89:239–252

This growth pattern is similar to other western lake Perkins et al. 2000b), and may produce more fit eggs suckers, including the cui-ui (Ch. cujus), June sucker and larvae which might better survive to recruit to the (Ch. liorus), and razorback sucker (Xyrauchen texanus). adult population (Hislop 1988;Berkeleyetal.2004a). Scoppettone (1988) showed that cui-ui from Pyramid The long-lived, iteroparous life history strategy seen in Lake, Nevada, exhibited rapid growth to age 10 these species makes them susceptible to overexploita- followed by little to no growth in body length over the tion, and the snag fishery reduced the number of old subsequent 32 years of the species’ life span. Belk spawners and subsequently lowered per capita egg (1998) aged only 10 June suckers from Utah Lake, production (Markle and Cooperman 2002). After listing, Utah, and noted a 24-year age difference in fish that populations of both species exhibited a transition from were essentially the same length. The rapid increase in older, larger individuals to primarily smaller, recruit- body length to maturation, followed by growth in body sized individuals by the late 1990s indicating recruit- mass rather than length over a long reproductive ment into the spawning populations (Janney et al. lifespan, allows for more energy to be utilized for 2008). Unfortunately, the fish kills of the mid-90s reproduction and helps western lake sucker populations coincided with the time when the strong year classes to persist in spite of years of limited recruitment or from the early 1990s would have been expected to recruitment failure (Belk 1998;Berkeleyetal.2004a). begin spawning (Markle and Cooperman 2002), and the Data for Lost River suckers reinforces this point. percentage of recruit-sized suckers in spawning runs has Although there are strong limitations based on essen- steadily declined over the decade since (Janney et al. tially two non-random snapshot samples, each data set 2008). In fact, it has been estimated that spawning had only one relatively strong recruitment period, populations of both species were reduced between 80– between 1–2 decades prior to the sample (Fig. 10). 90% from 1995 to 1998 (USFWS 2002;NRC2004). Ageing studies on cui-ui (Scoppettone 1988) and Although, as a group, western lakesuckers are charac- razorback sucker (McCarthy and Minckley 1987)have terized by 30–40 year lifespans, a recent demographic also demonstrated persisting populations despite 18-year analysis of Klamath sucker spawning populations from and 30-year droughts in recruitment for those species. 1995–2006 revealed low annual survival probabilities Age distributions by year class of Lost River and and average reproductive lifespans of only 8 years for shortnose suckers aged in this study (Fig. 11) indicate Lost River suckers and 3.6 years for shortnose suckers correspondence of renewed recruitment with closure (Janney et al. 2008). Lethal research take for ageing of the sport fishery in 1987. Although age samples structures may need to be recognized as a cause for were haphazard and the 1970 samples could not have concern and non-lethal alternatives explored. detected them, none of the available age data provide evidence of Lost River sucker recruitment from 1968 Acknowledgements We are grateful to Eric Janney and Scott to 1988. The 1986 fish kill data showed 95% were Vanderkooi, U.S. Geological Society, Klamath Falls field office, born before 1967 (Scoppettone and Vinyard 1991). In for providing recent otoliths for this study. Authorizations for contrast, the 1995–1997 fish kill data showed almost recent collections were under Federal permit TE007907 and Oregon State permits OR2001-010, OR2002-022, OR2003-1033, all were born after 1987 (Markle and Cooperman OR2004-1793, OR2005-2538, and OR2006-3241. Ariel Muldoon 2002; NRC 2004). Assuming different fish kills do (OSU) provided statistical assistance and Bill Tinniswood, Oregon not have differential size bias, both data sets should Department of Fish and Wildlife, shared creel notes from the snag have detected production from 1968 to 1988. Those fishery. Steve Campana provided insights on the validation technique and growth modeling. Finally, we wish to acknowledge decades of low recruitment, to be expected in a long- the work of our late student and coauthor, Tamal Reece, whose lived species, were coincident with and may have meticulous work enhanced this study and whose untimely death been exacerbated by the fishery. cut short his future contributions. Although we aged no historic shortnose suckers, the age distribution of the recently captured shortnose suckers mirrors that of Lost River suckers, with few fish References born prior to closure of the fishery. The larger, older spawners that were typically targeted in the snag fishery Andreasen JK (1975) Systematics and status of the family are known to produce more gametes than smaller, Catostomidae in southern Oregon. Dissertation, Oregon younger suckers (Buettner and Scoppettone 1990; State University Environ Biol Fish (2010) 89:239–252 251

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