This article was downloaded by: [Central Michigan University]On: 14 November 2014, At: 08:37Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

North American Journal of FisheriesManagementPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/ujfm20

Comparison of White Sucker AgeEstimates from Scales, Pectoral FinRays, and OtolithsRyan M. Sylvester a & Charles R. Berry Jr. ba South Dakota State University, Department of Wildlife andFisheries Sciences , Brookings, South Dakota, 57007, USAb South Dakota Cooperative Fish and Wildlife Research Unit, U.S.Geological Survey, South Dakota State University, Department ofWildlife and Fisheries Sciences , Brookings, South Dakota, 57007,USAPublished online: 08 Jan 2011.

To cite this article: Ryan M. Sylvester & Charles R. Berry Jr. (2006) Comparison of White SuckerAge Estimates from Scales, Pectoral Fin Rays, and Otoliths, North American Journal of FisheriesManagement, 26:1, 24-31, DOI: 10.1577/M04-147.1

To link to this article: http://dx.doi.org/10.1577/M04-147.1

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the“Content”) contained in the publications on our platform. However, Taylor & Francis,our agents, and our licensors make no representations or warranties whatsoever as tothe accuracy, completeness, or suitability for any purpose of the Content. Any opinionsand views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Contentshould not be relied upon and should be independently verified with primary sourcesof information. Taylor and Francis shall not be liable for any losses, actions, claims,proceedings, demands, costs, expenses, damages, and other liabilities whatsoever orhowsoever caused arising directly or indirectly in connection with, in relation to or arisingout of the use of the Content.

This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014

Comparison of White Sucker Age Estimates from Scales,Pectoral Fin Rays, and Otoliths

RYAN M. SYLVESTER*South Dakota State University, Department of Wildlife and Fisheries Sciences,

Brookings, South Dakota 57007, USA

CHARLES R. BERRY, JR.South Dakota Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, South Dakota State

University, Department of Wildlife and Fisheries Sciences, Brookings, South Dakota 57007, USA

Abstract.—The ages of 229 white suckers Catostomus

commersonii from six drainages in the upper Missouri River

basin were estimated from scales, pectoral fin ray sections,

and lapilli otolith sections to evaluate the potential bias of age

estimates between structures. Age estimates were compared

by calculating the coefficient of variation, average percent

error, percent agreement, and percent agreement within 1 year,

as well as by constructing age bias plots. Overall, the relative

precision of age estimates from pectoral fin rays and otoliths

was higher than that of age estimates from scales and otoliths,

but neither pair differed in precision from scales and fin rays.

The relative precision of age estimates between pairs of

structures was variable both within and among drainages, and

few trends could be detected. The percent agreement between

structures ranged from 50.0% to 93.8% among drainages, but

9 of 18 pairs had agreement rates greater than 70.0%. Percent

agreement within 1 year was greater than 85.0% for all pairs

of structures in all drainages. Age estimates from scales

underestimated the age estimates from pectoral fin rays and

otoliths beyond age 3, while pectoral fin rays only slightly

underestimated ages from otoliths of fish older than age 6. We

recommend sectioned lapilli otoliths for estimating the age of

white suckers, especially if mature individuals are present in

the population and lethal collection techniques are allowed.

Pectoral fin ray sections are the best nonlethal structure for

estimating the age of white suckers but may underestimate the

ages of fish older than 5 years. Scales remain suitable for

estimating the ages of immature fish, but their use is not

recommended for mature fish. This information will allow

fisheries managers and researchers to select the most

appropriate structure for use in future age assessment studies

of white suckers and other catostomid species.

Estimating the age of fish is a common technique

used to understand fish longevity and the growth and

mortality rates of fish populations; however, obtaining

accurate age information is crucial to an accurate

understanding of these metrics (Campana 2001). Many

structures have been used to estimate age of fishes,

including scales, various fin rays, fin spines, vertebrae,

cleithra, opercles, and otoliths. Otoliths have several

advantages over scales and spines for estimating age

because otoliths are not subject to resorption and their

growth is acellular rather than by ossification (Secor et

al. 1995). Higher precision of age estimates from

otoliths has led several authors to recommended

otoliths over other structures for estimating age

(Boxrucker 1986; Sharp and Bernard 1988; Hoxmeier

et al. 2001). However, higher precision of age

estimates provides no insight into the biases or

accuracy of age estimates among or between structures.

Age-estimating structures such as otoliths, scales,

opercles, and pectoral fin rays have been validated in

many species, including the river redhorse Moxostomacarinatum, rainbow trout Oncorhynchus mykiss, andcommon carp Cyprinus carpio (Hutson 1999; Hining etal. 2000; Brown et al. 2004). Many of these validation

studies found that otoliths were accurate for age

estimation, but validation studies are still needed for

many species (Beamish and McFarlane 1983). Com-

parison of age estimates between structures is an

alterative technique to validation that may provide

useful information on the accuracy and bias of age-

estimating structures. Comparisons of age estimates

from various structures have been performed for many

species, including yellow perch Perca flavescens(Niewinski and Ferreri 1999), river carpsuckers

Carpiodes carpio (Braaten et al. 1999), and white

suckers Catostomus commersonii (Scidmore and Glass

1953; Ovchynnyk 1969; Quinn and Ross 1982).

Early age estimation studies of white suckers relied

on scales (Spoor 1938; Geen et al. 1966), but later

studies evaluated vertebrae, cleithra, opercles, and

pectoral fin ray sections (Scidmore and Glass 1953;

Beamish and Harvey 1969; Ovchynnyk 1969; Beamish

1973). Many of these studies agreed that scales did not

provide accurate age estimates for mature fish, and

some authors recommended the use of pectoral fin ray

sections to estimate age. Despite such recommenda-

tions, Quinn and Ross (1982) questioned the reliability

* Corresponding author: wyomingfish@yahoo.com

Received August 31, 2004; accepted July 28, 2005Published online December 19, 2005

24

North American Journal of Fisheries Management 26:24–31, 2006� Copyright by the American Fisheries Society 2006DOI: 10.1577/M04-147.1

[Management Brief]

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014

of age estimates from pectoral fin rays in fish older

than 7 years because of the lack of annulus formation

and the difficulty in interpreting fin ray sections.

Comparisons of white sucker age estimates from scales

and pectoral fin ray sections are common (Scidmore

and Glass 1953; Beamish and Harvey 1969; Beamish

1973; Barton 1980; Quinn and Ross 1982), but other

comparisons are rare. Ovchynnyk (1969) evaluated 20

structures for estimating age of white suckers and

found fewer annuli on scales than on other structures;

however, otoliths were not used in that study. Bond

(1972) compared white sucker age estimates from

scales and otoliths, saw general agreement between age

estimates, and proposed that scales were accurate up to

age 9. Otoliths (lapilli) were later determined to be

a reliable age-estimating structure for white suckers

(Thompson and Beckman 1995).

To date, no published studies have compared white

sucker age estimates from scales, pectoral fin ray

sections, and sectioned otoliths. Our objectives were

(1) to compare age estimates between three pairs of

age-estimating structures (i.e., scales versus pectoral

fin rays, scales versus otoliths, and pectoral fin rays

versus otoliths) and (2) to quantify potential biases

between pairs of age-estimating structures for white

suckers sampled in the upper Missouri River basin.

We considered age estimates from otoliths to be

accurate, because Thompson and Beckman (1995)

previously validated otoliths as a reliable estimator of

age for 2–18-year-old white suckers from Lake

Taneycomo, a coldwater reservoir in southwestern

Missouri.

Methods

White suckers were collected in August 2002 and

June and July 2003 from six drainages in the upper

Missouri River basin. Drainages included the Nowood

River drainage in north-central Wyoming; the Beaver

Creek drainage in south-central North Dakota; the Elm

River drainage on the border between North Dakota

and South Dakota; the Rock Creek and Frenchman

River drainages, located in southwestern Saskatche-

wan, Canada, and north-central Montana; and the

Sweet Grass River drainage, located in southwestern

Montana (Figure 1). Fish were collected by electro-

fishing with Smith-Root model 15-B and LR-24

backpack units (Smith-Root, Inc., Vancouver, Wash-

ington) and by seining (4.6- or 9.2-m length; 1.2-m

height; 4.88-mm mesh). The total length (mm) and

weight (g) of each fish were measured to the nearest

unit in the field. Scales (N ¼ 10–20 per fish) were

collected in the field below the dorsal fin and above the

lateral line on the left side of the fish (Beamish 1973).

The left pectoral fin was excised as close to the body as

possible (Quinn and Ross 1982). The scales and

a pectoral fin were placed in a scale envelope to dry

before further preparation. Each fish was preserved in

70% ethanol for later collection of lapilli and sagittal

otoliths.

Scales were cleaned if necessary and pressed onto

acetate slides (0.3 mm) by use of an Ann Arbor roller

press. Scales were then projected on a microfiche

projector at 103 magnification or were viewed under

a compoundmicroscope at 1003magnification by use of

transmitted light. Scale annuli were distinguished as

areas of crowding or crossing over of circuli (Spoor

1938). Regenerated scales were not used to estimate age.

Whole or proximal portions of pectoral fin rays were

set in epoxy and sectioned (0.5–0.7 mm) on the

transverse plane using an Isomet slow-speed saw

(Buehler, Lake Bluff, Illinois). Fin ray sections were

wet or dry sanded with 600-grit sandpaper if necessary.

Fin ray sections were viewed with transmitted light on

a compound microscope at 1003 magnification or

a dissecting microscope at 10–633 magnification

(Scidmore and Glass 1953). We used transmitted light

to distinguish pectoral fin ray annuli as light bands on

a dark background (Cuerrier 1951; Ovchynnyk 1969;

Beamish 1973).

FIGURE 1.—Locations of the six drainages in the upper

Missouri River basin where white suckers were collected in

August 2002 and June and July 2003 for comparisons between

age-estimating structures.

MANAGEMENT BRIEF 25

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014

Lapilli otoliths were collected, cleaned, allowed to

dry, set in epoxy, and sectioned (0.5–0.7 mm) on the

transverse plane through the focus using an Isomet

slow-speed saw (Secor et al. 1992; Thompson and

Beckman 1995). Otolith sections were wet sanded with

600-grit sandpaper if necessary. Sections were then

viewed under a dissecting microscope with a fiber optic

light source and a black background at 10–633

magnification. Annuli were identified as transparent

bands adjacent to opaque bands, and age was estimated

as the number of opaque bands. Sagittal otoliths were

used as backups if poor sections of both lapilli otoliths

occurred. Sagittal otoliths were prepared, sectioned,

and viewed by the same methods as used for lapilli

otoliths.

Fish were selected from across the entire range of

collected fish within each of the six drainages. Three

ages for each fish (N ¼ 229) were estimated (scale,

pectoral fin ray, otolith) by one experienced reader.

The relative precision between ages estimated from

scales, pectoral fin rays, and otoliths for each fish was

quantified as the average percent error (APE; Beamish

and Fournier 1981) and coefficient of variation (CV;

Chang 1982) between structures, as calculated by the

following formulas:

APE ¼ ½ð1=RÞ3XR

i

ðjXij � Xjj=XjÞ�3 100

CV ¼ ðSD=XjÞ3 100 ;

where R¼ the number of times each fish was aged; Xj¼

the average age calculated for the jth fish; and Xij¼ the

ith age determination of the jth fish. Percent agreement

was calculated as the percentage of estimated ages that

agreed between each pair of structures. The overall CV

between age estimates from scales, fin rays, and

otoliths was calculated for each age-class and structure

to assess which age-classes were responsible for most

of the variation in age estimates. Percent agreement

within 1 year was calculated as the percentage of

FIGURE 2.—Length frequency distributions of white suckers

collected from six drainages in the upper Missouri River basin

in 2002 and 2003.

FIGURE 3.—Length frequency distributions of white suckers

for which ages were estimated from scales, pectoral fin ray

sections, and sectioned lapilli otoliths. Fish were collected

from six drainages in the upper Missouri River basin in 2002

and 2003.

26 SYLVESTER AND BERRY

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014

estimated ages that were within 1 year of each other.

The mean CV and APE values with 95% confidence

intervals were used to compare precision between pairs

of structures in each of the six drainages and for the

combined samples.

Age bias plots (Campana et al. 1995) were

constructed to quantify the bias between age-estimating

structures. Linear regression was fitted to the observed

data of the mean estimated age of one structure versus

the age of another structure. The slope and intercept of

the observed regression line were compared to the

slope and intercept of a theoretical 1:1 line (indicating

complete agreement between structures) by use of

analysis of covariance (ANCOVA). The hypotheses

tested were that (1) the slope was equal to 1.0 and (2)

the intercept was equal to zero. Rejection of either or

both hypotheses (P � 0.05) was interpreted as bias

between structures. A slope that was not equal to 1.0 or

an intercept that was not equal to zero provided

evidence for age estimate bias between structures.

Types of potential bias include reader bias, systematic

bias (i.e., not recognizing the first annulus in fin rays,

causing age estimates to be low by 1 year), true bias

between structures, or a combination of all three types

of bias. We considered ages estimated from otoliths to

be accurate based on the validation of otolith age

estimates by Thompson and Beckman (1995); howev-

er, no known-age fish were used in this study.

Results

Ages were estimated for 229 white suckers across

the entire length range of fish collected in each of the

six drainages (Figures 2, 3). Most white sucker

populations were dominated by shorter length-groups

(,25 cm), but longer groups (.30 cm) were collected

in the Nowood River, Rock Creek, and Frenchman

River drainages. Most fish were less than 6 years of age

based on scales, but fish older than 6 years were

present based on sections of pectoral fin rays and

sectioned otoliths (Table 1). Age differentials for pairs

of structures generally increased with age; the

maximum estimated age difference was 5 years

between a scale and otolith and 3 years between

a pectoral fin ray and otolith (Table 1; Figure 4).

Overall, the relative precision (i.e., CV and APE) of

ages estimated from pectoral fin ray sections and

sectioned otoliths was higher than the precision of ages

estimated from scales and otoliths; neither pair differed

from scales and pectoral fin rays in terms of precision

(Table 2). The relative precision of age estimates

among pairs of structures was not different within each

of the six drainages, but the relative precision of age

estimates between scales and pectoral fin rays was

different among several drainages (Table 2). Pectoral

fin ray and otolith age estimates had the highest percent

agreement (78.6%) for the combined sample and had

the highest percent agreement within 1 year (97.8%).

Percent agreement between structures ranged from

50.0% to 93.8% among drainages, but the percent

agreement for 9 of the 18 pair–drainage combinations

was greater than 70.0% (Table 2). Percent agreement

within 1 year between structures was greater than

85.0% in all six drainages; agreement within 1 year

TABLE 1.—Age frequency of white suckers collected from six drainages throughout the upper Missouri River basin in 2002

and 2003 and subjected to age estimation based on scales, pectoral fin rays, and lapilli otoliths.

Age

Drainage Fish N Structure 0 1 2 3 4 5 6 7 8 9 10 11

Overall 229 Scale 28 64 59 50 14 11 3 0 0 0 0 0Pectoral 26 59 60 43 18 11 8 1 1 2 0 0Otolith 21 72 58 41 13 12 5 2 3 1 0 1

Nowood River 56 Scale 7 22 11 4 6 5 1 0 0 0 0 0Pectoral 7 21 11 3 5 4 3 0 0 2 0 0Otolith 6 22 11 5 1 6 2 0 1 1 0 1

Beaver Creek 16 Scale 2 0 5 7 2 0 0 0 0 0 0 0Pectoral 2 0 5 6 3 0 0 0 0 0 0 0Otolith 2 2 5 6 1 0 0 0 0 0 0 0

Elm River 16 Scale 8 1 3 4 0 0 0 0 0 0 0 0Pectoral 8 1 4 3 0 0 0 0 0 0 0 0Otolith 8 3 5 0 0 0 0 0 0 0 0 0

Rock Creek 54 Scale 6 11 18 15 1 2 1 0 0 0 0 0Pectoral 2 10 21 15 1 3 2 0 0 0 0 0Otolith 0 13 21 14 2 2 2 0 0 0 0 0

Frenchman River 57 Scale 3 14 14 17 5 3 1 0 0 0 0 0Pectoral 3 11 12 14 8 4 3 1 1 0 0 0Otolith 1 12 13 14 8 4 1 2 2 0 0 0

Sweet Grass River 30 Scale 2 16 8 3 0 1 0 0 0 0 0 0Pectoral 4 16 7 2 1 0 0 0 0 0 0 0Otolith 4 20 3 2 1 0 0 0 0 0 0 0

MANAGEMENT BRIEF 27

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014

exceeded 90.0% for 16 of the 18 pair–drainage

combinations (Table 2).

Overall, the ages estimated from scales, pectoral fin

rays, and otoliths were the same for ages 0–3,

indicating good precision between structures for

immature fish. Scales began to underestimate ages

from pectoral fin ray sections and sectioned otoliths at

age 4, whereas pectoral fin ray sections began to

underestimate ages from otoliths at about age 6 (Figure

4). Bias in age estimates was present between scales

and pectoral fin ray sections, scales and otoliths, and

pectoral fin rays and otoliths, but most of this bias was

due to older individuals in a few drainages (Table 3;

Figure 4). With the exception of young fish (i.e., ,age

2), the precision of age estimates generally decreased

as the estimated age of fish increased (Figures 4, 5).

Discussion

Prior to this study, we assumed that otoliths would

provide more accurate age estimates than scales or

sections of pectoral fin rays because they had been

indirectly validated (Thompson and Beckman 1995).

After comparing age estimates of the three structures,

we conclude that otoliths may be more accurate for

estimating white sucker age than either scales or

pectoral fin ray sections, as these latter structures

underestimated ages from otoliths. The precision of

ages for individual fish affected differences in precision

between pairs of structures within each drainage.

Young fish that had an age discrepancy of 1 year

between structures had a higher CV and APE than did

older fish with a discrepancy of 1 year because the

relative error was larger. This led to large confidence

intervals for precision metrics for individual pairs of

structures and few differences within or among drain-

ages. The combined sample in our study supports

observations and concerns that were reached by

previous authors regarding the use of scales and

pectoral fin ray sections to estimate the age of mature

white suckers (Beamish and Harvey 1969; Ovchynnyk

1969; Beamish 1973; Quinn and Ross 1982) and

further strengthens support for the use of otoliths to

estimate age.

Scale irregularities, false checks, and false annuli on

scales and fin ray sections were difficult to distinguish

from true annuli and may have contributed to errors in

estimated age (Beamish and Harvey 1969). Scale and

pectoral fin ray sections were often assigned the same

age in some drainages, but both often overestimated the

age from the otolith section; this result suggests the

presence of false annuli or checks on the scales and

pectoral fin ray sections (Beamish and Harvey 1969;

Beamish 1973). These potential false annuli occurred

on individual fish, but the overall trend was the

underestimation of otolith ages by scales and pectoral

fin rays. Despite some age discrepancies, the overall

mean age estimates from all three structures were

equivalent for ages 0–3, indicating that all three

structures may be suitable for estimating the age of

younger fish. Ages estimated from scales underesti-

mated ages from pectoral fin rays and otoliths beyond

age 3, which is similar to findings in other studies that

have reported bias of scales versus pectoral fin rays at

about age 5 (Beamish and Harvey 1969; Beamish

1973; Quinn and Ross 1982). Pectoral fin ray sections

yielded precise ages relative to ages estimated from

otoliths up to age 7, although slight underestimation

occurred in some older fish. If scales or pectoral fin ray

sections are used instead of otoliths to estimate white

sucker age, their potential errors, biases, and limitations

FIGURE 4.—Age bias plots of white suckers collected from

six drainages in the upper Missouri River basin in 2002 and

2003 and subjected to age estimation based on scales, pectoral

fin ray sections, and otoliths. In each panel, the error bars

represent the 95% confidence intervals, the dotted line

indicates the theoretical 1:1 agreement line of age estimates

between structures, and the solid line is the observed

regression line. An asterisk next to an observed slope or

intercept denotes a significant difference from the slope or

intercept of the theoretical 1:1 agreement line and thus

indicates bias between the structures.

28 SYLVESTER AND BERRY

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014

must be taken into consideration. Differences in age

estimates between structures can have impacts on

population metrics such as growth estimates (Braaten

et al. 1999) and population metrics derived from age

frequencies (e.g., annual mortality and survival rates).

Annuli distinctness and formation on scales varied

among drainages. All drainages had individual fish

with regenerated scales and irregularities. White sucker

populations in the Frenchman River and Rock Creek

drainages grew more slowly than more southerly

populations; scale annuli from these fish were often

indistinct, circuli often did not cross over, and scales

were generally difficult to interpret. These character-

istics have been observed in other slow-growing white

sucker populations (Dence 1948; Geen et al. 1966) and

may have resulted in the lower precision of age

estimates in these drainages.

Pectoral fin ray sections were easy to read, but the

thickness of the section often had to be adjusted for

individual fish. Poor differential light transparency

obscured the annuli if the section was too thick,

whereas too much light transparency made the annuli

TABLE 2.—Comparison of precision and agreement metrics between pairs of age-estimating structures collected from white

suckers in 2002 and 2003 in the upper Missouri River basin (N¼ number of fish, CV¼ coefficient of variation, APE¼ average

percent error, %¼ percent agreement, and 1 year¼ percent agreement within 1 year). Values for CV and APE are means, with

95% confidence intervals in parentheses.

Scale and pectoral fin ray Scale and otolith Pectoral fin ray and otolith

Drainage N CV APE % 1 year CV APE % 1 year CV APE % 1 year

Overall 229 12.6 8.9 71.6 94.8 17.9 12.7 63.8 94.3 9.9 7.0 78.6 97.8(3.7) (2.6) (4.5) (3.2) (3.5) (2.5)

Nowood River 56 4.8 3.4 80.4 94.6 13.5 9.6 71.4 92.9 11.4 8.1 76.8 94.6(2.9) (2.1) (8.8) (6.3) (8.7) (6.1)

Beaver Creek 16 1.3 0.9 93.8 100.0 10.7 7.6 68.8 100.0 12.0 8.5 62.5 100.0(2.7) (1.9) (9.4) (6.6) (9.3) (6.6)

Elm River 16 7.7 5.4 81.3 100.0 18.9 13.3 50.0 100.0 11.2 7.9 68.8 100.0(9.0) (6.4) (11.0) (7.8) (9.6) (6.8)

Rock Creek 54 19.5 13.8 66.7 96.3 23.1 16.3 66.7 98.1 8.0 5.6 87.0 100.0(10.5) (7.4) (12.2) (8.6) (7.6) (5.4)

Frenchman River 57 17.5 12.4 54.4 87.7 17.9 12.7 54.4 86.0 11.2 7.9 75.4 96.5(7.6) (5.4) (7.6) (5.4) (7.6) (5.4)

Sweet Grass River 30 14.0 9.9 80.0 100.0 20.3 14.4 66.7 100.0 6.3 4.4 86.7 100.0(13.8) (9.8) (14.2) (10.1) (6.1) (4.3)

TABLE 3.—Summary of ANCOVA comparisons between the theoretical and observed slopes and intercepts of age bias plots

for three age-estimating structures collected from white suckers in the upper Missouri River basin in 2002 and 2003.

Pair of structures Metric df Statistic P-value

Scale age versus pectoral fin age Model 3 F ¼ 949.17 ,0.0001Error 19Pectoral fin 1 F ¼ 1,646.92 ,0.0001Pectoral fin 3 treatment 1 F ¼ 103.77 ,0.0001Slope t ¼ �10.19 ,0.0001Intercept t ¼ 2.86 0.0099

Scale age versus otolith age Model 3 F ¼ 624.56 ,0.0001Error 20Otolith 1 F ¼ 1,249.68 ,0.0001Otolith 3 treatment 1 F ¼ 128.40 ,0.0001Slope t ¼ �11.33 ,0.0001Intercept t ¼ 3.34 0.0033

Pectoral fin age versus otolith age Model 3 F ¼ 720.63 ,0.0001Error 20Otolith 1 F ¼ 1,919.20 ,0.0001Otolith 3 treatment 1 F ¼ 13.93 0.0013Slope t ¼ �8.73 0.0013Intercept t ¼ 1.50 0.1484

MANAGEMENT BRIEF 29

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014

indistinguishable if the section was too thin (Scidmore

and Glass 1953). The center of the fin ray may have

obscured the first annulus, and crowding of annuli in

distal portions of fin ray sections may have occurred in

older fish, perhaps leading to errors in the estimated

age (Quinn and Ross 1982; Pehna et al. 2004).

Sections of lapilli otoliths were easy to interpret,

although some crowding of distal annuli occurred in

fish older than 6 years (Thompson and Beckman

1995). Sections of otoliths must contain the nucleus

and may result in age estimation error if this

requirement is not met (DeVries and Frie 1996). It is

possible that the timing of fish collection may have

affected recognition of annuli on otoliths because of

differences in timing of annulus formation (Beckman

and Wilson 1995). Thompson and Beckman (1995)

reported that about 5% of white suckers in Lake

Taneycomo, Missouri, had an annulus at the marginal

edge in June, but the percentage increased to nearly

80% in August. White suckers used for age estimation

in our study were collected in August 2002 (i.e., the

Nowood River, Beaver Creek, and Elm River drain-

ages) and June and July 2003 (i.e., Rock Creek,

Frenchman River, and Sweet Grass River drainages).

The precision estimates and bias between structures

in this study were comparable to those determined in

other studies (Welch et al. 1993; Soupir et al. 1997;

Beckman 2002; Ihde and Chittenden 2002), some of

which recommended otoliths as the preferred age-

estimating structure for a variety of species. Age

validation with the use of known-age fish is still

needed for the white sucker, as recommended by

Beamish and McFarlane (1983). This study is the first

to compare age estimates from scales, pectoral fin ray

sections, and sectioned otoliths in the white sucker.

Sectioned lapilli otoliths are recommended for the best

white sucker age estimates due to underestimation of

age estimates from scales and pectoral fin ray sections.

If nonlethal techniques for estimating age are required,

pectoral fin ray sections provide closer age estimates

for mature fish than do scales in comparison to otolith

age estimates, but pectoral fin ray sections may still

underestimate the age of fish older than age 5. The

precision and bias information in this study will be

useful to fisheries professionals in assessing age of

white suckers and other catostomids in the future.

Acknowledgments

We would like to thank the Gap Analysis Project

Office of the U.S. Geological Survey for funding. S.

Freeling, S. Wall, D. Hourigan, V. Wassink, and R.

Jensen provided assistance with fieldwork and sample

preparation. Additional thanks are extended to B.

Graeb, J. Duehr, C. Hoagstrom, and several anony-

mous reviewers for providing helpful comments on this

manuscript.

References

Barton, B. A. 1980. Spawning migrations, age and growth,

and summer feeding of white and longnose suckers in an

irrigation reservoir. Canadian Field-Naturalist 94:300–

304.

Beamish, R. J. 1973. Determination of age and growth of

populations of the white sucker (Catostomus commerso-ni) exhibiting a wide range in size at maturity. Journal of

the Fisheries Research Board of Canada 30:607–616.

Beamish, R. J., and D. A. Fournier. 1981. A method for

comparing the precision of a set of age determinations.

Canadian Journal of Fisheries and Aquatic Sciences

38:982–983.

Beamish, R. J., and H. H. Harvey. 1969. Age determination in

the white sucker. Journal of the Fisheries Research Board

of Canada 26:633–638.

Beamish, R. J., and G. A. McFarlane. 1983. The forgotten

requirement for age validation in fisheries biology.

Transactions of the American Fisheries Society

112:735–743.

Beckman, D. W. 2002. Comparison of aging methods and

validation of otolith ages for the rainbow darter,

Etheostoma caeruleum. Copeia 2002:830–835.

Beckman, D. W., and C. A. Wilson. 1995. Seasonal timing of

opaque zone formation in fish otoliths. Pages 27–43 in D.H. Secor, J. M. Dean, and S. E. Campana, editors. Recent

FIGURE 5.—Mean overall coefficients of variation (CV [%];

see text for computation) of age estimates by age-group and

structure for white suckers (N ¼ 229) collected in the upper

Missouri River basin in 2002 and 2003 and subjected to age

estimation based on scales, pectoral fin ray sections, and

otoliths. Error bars represent the SEs.

30 SYLVESTER AND BERRY

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014

developments in fish otolith research. University of

South Carolina Press, Columbia.

Bond, W. A. 1972. Spawning migration, age, growth, and

food habits of the white sucker, Catostomus commersoni(Lacepede), in the Bigoray River, Alberta. Master’s

thesis. University of Alberta, Edmonton.

Boxrucker, J. 1986. A comparison of the otolith and scale

methods for aging white crappies in Oklahoma. North

American Journal of Fisheries Management 6:122–125.

Braaten, P. J., M. R. Doeringsfeld, and C. S. Guy. 1999.

Comparison of age and growth estimates for river

carpsuckers using scales and dorsal fin ray sections.

North American Journal of Fisheries Management

19:786–792.

Brown, P. L., C. Green, K. P. Sivakumaran, D. Stoessel, and

A. Giles. 2004. Validating otolith annuli for annual age

determination of common carp. Transactions of the

American Fisheries Society 133:190–196.

Campana, S. E. 2001. Accuracy, precision, and quality control

in age determination, including a review of the use and

abuse of age validation methods. Journal of Fish Biology

59:197–242.

Campana, S. E., M. C. Annand, and J. I. McMillan. 1995.

Graphical and statistical methods for determining the

consistency of age determinations. Transactions of the

American Fisheries Society 124:131–138.

Chang, W. Y. B. 1982. A statistical method for evaluating the

reproducibility of age determination. Canadian Journal of

Fisheries and Aquatic Sciences 39:1208–1210.

Cuerrier, J. P. 1951. The use of pectoral fin rays for

determining age of sturgeon and other species of fish.

Canadian Fish-Culturist 11:10–18.

Dence, W. A. 1948. Life history, ecology, and habits of the

dwarf sucker, Catostomus commersonii utawana (Math-

er), at the Huntington Wildlife Station. Roosevelt

Wildlife Bulletin 8:81–150.

DeVries, D. R., and R. V. Frie. 1996. Determination of age

and growth. Pages 483–512 in B. R. Murphy and D. W.

Willis, editors. Fisheries techniques, 2nd edition. Amer-

ican Fisheries Society, Bethesda, Maryland.

Geen, G. H., T. G. Northcote, G. F. Hartman, and C. C.

Lindsey. 1966. Life histories of two species of

catostomid fishes in Sixteenmile Lake, British Columbia,

with particular reference to inlet stream spawning.

Journal of the Fisheries Research Board of Canada

23:1761–1788.

Hining, K. J., J. L. West, M. A. Kulp, and A. D. Neubauer.

2000. Validation of scales and otoliths for estimating age

of rainbow trout from southern Appalachian streams.

North American Journal of Fisheries Management

20:978–985.

Hoxmeier, R. J. H., D. D. Aday, and D. H. Wahl. 2001.

Factors influencing precision of age estimation from

scales and otoliths of bluegills in Illinois reservoirs.

North American Journal of Fisheries Management

21:374–380.

Hutson, C. A. 1999. Aging validation, growth, and compar-

ison of four age estimators of the river redhorse

(Moxostoma carinatum). Master’s thesis. Southwest

Missouri State University, Springfield.

Ihde, T. F., and Chittenden E Jr.. 2002. Comparison of

calcified structures for aging spotted seatrout. Trans-

actions of the American Fisheries Society 131:634–642.

Niewinski, B. C., and C. P. Ferreri. 1999. A comparison of

three structures for estimating the age of yellow perch.

North American Journal of Fisheries Management

19:872–877.

Ovchynnyk, M. M. 1969. On age determination with scales

and bones of the white sucker, Catostomus commersoni(Lacepede). Zoologischer Anzeiger 175:325–345.

Pehna, J. M. F., L. A. F. Mateus, and Petrere P Jr.. 2004. A

procedure to improve confidence in identification of the

first annulus in fin spines of fishes. Fisheries Manage-

ment and Ecology 11:135–137.

Quinn, S. P., and M. R. Ross. 1982. Annulus formation by

white suckers and the reliability of pectoral fin rays for

ageing them. North American Journal of Fisheries

Management 2:204–208.

Scidmore, W. J., and A. W. Glass. 1953. Use of pectoral fin

rays to determine age of the white sucker. Progressive

Fish-Culturist 15:114–115.

Secor, D. H., J. M. Dean, and E. H. Laban. 1992. Otolith

removal and preparation for microstructural examination.

Pages 19–57 in D. K. Stevenson and S. E. Campana,

editors. Otolith microstructure and analysis. Canadian

Special Publication of Fisheries and Aquatic Sciences

117.

Secor, D. H., J. M. Dean, and S. E. Campana. 1995. Recent

developments in fish otolith research. University of

South Carolina Press, Columbia.

Sharp, D., and D. R. Bernard. 1988. Precision of estimated

ages of lake trout from five calcified structures. North

American Journal of Fisheries Management 8:367–372.

Soupir, C. A., B. B. Blackwell, and M. L. Brown. 1997.

Relative precision among calcified structures for white

bass age and growth assessment. Journal of Freshwater

Ecology 12:531–538.

Spoor, W. A. 1938. Age and growth of the sucker,

Catostomus commersoni (Lacepede), in Muskellunge

Lake, Vilas County, Wisconsin. Transactions of the

Wisconsin Academy of Science 31:457–505.

Thompson, K. R., and D. W. Beckman. 1995. Validation of

age estimates from white sucker otoliths. Transactions of

the American Fisheries Society 124:637–639.

Welch, T. J., M. J. Van Den Avyle, R. K. Betsill, and E. M.

Driebe. 1993. Precision and relative accuracy of striped

bass age estimates from otoliths, scales, and anal fin rays

and spines. North American Journal of Fisheries

Management 13:616–620.

MANAGEMENT BRIEF 31

Dow

nloa

ded

by [

Cen

tral

Mic

higa

n U

nive

rsity

] at

08:

37 1

4 N

ovem

ber

2014