2007 SOUTHEASTERN NATURALIST 6(3):479–490
Life -history Aspects of Hypentelium etowanum (Alabama Hog
Sucker) (Actinopterygii: Catostomidae) in Northern Georgia
Christopher T. O’Kelley1 and Steven L. Powers1,*
Abstract - Life-history aspects of Hypentelium etowanum (Alabama Hog Sucker)
were investigated from 12 monthly collections in Shoal and Moore creeks (Etowah
River Drainage) in Cherokee County, GA. Specimens were collected primarily from
riffles, runs, and flowing pools, and examined for age, growth, food habits, and
reproductive cycle. Chironomidae composed the bulk of the diet, with consumption
lowest in winter and peaking in spring. Spawning appeared to occur in spring with
493–2717 ripe eggs ranging from 1.5 to 2.8 mm in diameter present in specimens
collected in March, April, and May. Sexual maturity appeared to occur by 3 years of
age, with a maximum lifespan of greater than 4 years. The largest specimen collected
was a female 190 mm standard length and 132 g total weight.
Introduction
Hypentelium etowanum (Alabama Hog Sucker) was described by
David Starr Jordan in 1877 from specimens collected in the Etowah River
near Rome, GA (Gilbert 1998) and is sister to the widespread H.
nigricans (LeSueur) (Northern Hog Sucker) (Berendzen et al. 2003, Harris
et al. 2002). Hypentelium etowanum is relatively common in small to
large streams throughout the Mobile and upper Chattahoochee River
drainages of northern Georgia, Alabama, and eastern Mississippi. It is
distinguished from other catostomids within most of its range by dark
oblique bars across the dorsum; bright orange pectoral, pelvic, and anal
fins; horizontal pale stripes along the scale rows; flattened interorbital
region; and highly protrusible mouth with papillose lips (Boschung and
Mayden 2004). In spite of the wide range and conspicuous nature of H.
etowanum, little is known of its biology. Information regarding reproduction
is restricted to the collection of a nuptial female by Burr (1979)
during late spring in a fast-flowing trough of the Chattahoochee River at
19 ºC water temperature. Etnier and Starnes (1993) reported that lengthfrequency
data suggested H. etowanum have a maximum age of at least 5
years. The primary purpose of this study is to elucidate some of the
aspects of the life history of H. etowanum.
Study Area
The study area encompassed Shoal and Moore creeks upstream of their
confluence (34.3240°N, 84.5636°W), near Waleska in Cherokee County,
1Department of Biology, Reinhardt College, Waleska, GA 30183-2981. *Corresponding
author - SLP@reinhardt.edu.
480 Southeastern Naturalist Vol. 6, No. 3
GA (Fig. 1). Shoal Creek is a typical upland fourth-order tributary of the
Etowah River. Near the mouth of Moore Creek, Shoal Creek is between 5.3
and 9.8 m wide and less than 1.5 m deep at normal flows. Substrate is
primarily gravel to cobble with sporadic bedrock in riffles, gravel to sand in
runs, and sand and silt in pools. At its mouth, Moore Creek is a second-order
stream between 3.1 and 6.4 m wide and less than 1.0 m deep at normal flows.
Substrate is similar to that of Shoal Creek. Most H. etowanum collected
during this study were taken from run and flowing-pool habitats. Upstream
of their confluence, both watersheds are mostly forested with moderate
agricultural use and sparse residential development. Water temperatures
during collections ranged from 5 °C in December and January to 26 °C in
July. Species richness of fishes within the study reach is relatively high, with
34 species representing nine different families collected during this study
(Table 1). Of these, only Lepomis auritus and Perca flavescens appear to be
nonindigenous (Boschung and Mayden 2004).
Figure 1. Map of Hypentelium etowanum (Alabama Hog Sucker) study area in Shoal
and Moore creeks upstream of their confluence (34.3240°N, 84.5636°W), near
Waleska in Cherokee County, GA.
2007 C.T. O'Kelley and S.L. Powers 481
Methods
Hypentelium etowanum and associated species were collected over a
one-year period spanning from August 2004 to July 2005 by monthly sampling
during daylight hours near the end of each month using a 3.3 m x 1.3 m
Table 1. Fishes collected from Moore and Shoal creeks within study area between August 2004
and July 2005.
Scientific name Common name
Petromyzontidae
Ichthyomyzon gagei Hubbs and Trautman Southern Brook Lamprey
Clupeidae
Dorosoma cepedianum (Lesueur) Gizzard Shad
Cyprinidae
Campostoma oligolepis Hubbs and Green Largescale Stoneroller
Cyprinella callistia (Jordan) Alabama Shiner
Cyprinella trichroistia (Jordan and Gilbert) Tricolor Shiner
Cyprinella venusta Girard Blacktail Shiner
Luxilus chrysocephalus Rafinesque Striped Shiner
Notemigonus crysoleucas (Mitchill) Golden Shiner
Notropis chrosomus (Jordan) Rainbow Shiner
Notropis stilbius (Jordan) Silverstripe Shiner
Notropis xaenocephalus (Jordan) Coosa Shiner
Phenacobius catostomus Jordan Riffle Minnow
Semotilus atromaculatus (Mitchill) Creek Chub
Catostomidae
Hypentelium etowanum (Jordan) Alabama Hog Sucker
Moxostoma duquesnei (Lesueur) Black Redhorse
Moxostoma erythrurum (Rafinesque) Golden Redhorse
Ictaluridae
Ameiurus melas (Rafinesque) Black Bullhead
Noturus leptacanthus Jordan Speckled Madtom
Fundulidae
Fundulus stellifer (Jordan) Southern Studfish
Cottidae
Cottus bairdii Girard Mottled Sculpin
Cottus carolinae (Gill) Banded Sculpin
Centrarchidae
Lepomis auritus (Linnaeus) Redbreast Sunfish
Lepomis cyanellus Rafinesque Green Sunfish
Lepomis macrochirus Rafinesque Bluegill
Micropterus coosae Hubbs and Bailey Redeye Bass
Micropterus punctulatus (Rafinesque) Spotted Bass
Pomoxis annularis Rafinesque White Crappie
Pomoxis nigromaculatus (Lesueur) Black Crappie
Percidae
Etheostoma scotti Bauer, Etnier, and Burkhead Cherokee Darter
Etheostoma stigmaeum (Jordan) Speckled Darter
Perca flavescens (Mitchill) Yellow Perch
Percina kathae Thompson Mobile Logperch
Percina nigrofasciata (Agassiz) Blackbanded Darter
Percina palmaris (Bailey) Bronze Darter
482 Southeastern Naturalist Vol. 6, No. 3
seine and a Smith-Root Model 24 backpack electrofisher. A total of 184 H.
etowanum was collected, preserved in 10% formalin, rinsed with water, and
transferred into 70% EtOH for long-term storage. Specimens were
accessioned into the University of Alabama Ichthyological Collection
(UAIC 14729-14740). Observations for spawning behavior of H. etowanum
were attempted by snorkeling and bank observation during March, April,
May, and June, but no spawning activity was observed.
Standard length (SL) of each specimen was measured using digital calipers
and recorded in mm. Specimens were blotted dry, and total weight (TW),
eviscerated weight (EW), and gonad weight (GW) were measured using a
digital analytical balance and recorded to the nearest 0.001 g. Standard length
and EW were plotted against month to provide length- and weight-frequency
distributions to illuminate age and growth information. Pearson product
moment correlation coefficients were calculated, and regressions by least
sum of squares were performed for SL with EW and SL with the natural log
of EW. Sexual size dimorphism was tested using a two-sample t-test. According
to Raney and Lachner (1946), H. nigricans from New York form
annuli on scales in the spring. Generally following Raney and Lachner
(1946), scales (n = 3) were removed from the dorsolateral region of specimens
collected in April and the two largest specimens collected during this
study (185 and 190 mm SL) and examined for corroboration of length- and
weight-frequency distributions. While aging fishes using scales may be
imperfect, it provides another line of evidence in age and growth studies and
in conjunction with length- and weight-frequency distributions, provides a
clearer picture of fish biology (see Summerfelt and Hall 1987). Specimens
less than 12 months of age were counted as age 0+, specimens 12–23 months
were counted as age 1+, specimens, 24–35 months were counted as age 2+,
specimens 36–47 months were counted as 3+, specimens greater than 47
months were counted as 4+. Proportion of total specimens collected represented
by each age class was calculated to approximate the age-class makeup
of the population studied. Gonadosomatic index (GSI) was calculated for all
specimens by dividing GW by EW. One-way analysis of variance was
performed to detect differences in mean GSI from different months. In gravid
females, ova were enumerated, and diameters of five representative ova were
measured to the nearest 0.01 mm. The anterior third of the gastrointestinal
track was dissected, and its contents were removed and weighed using a
digital analytical balance and recorded to the nearest 0.001 g. One-way
analysis of variance was performed to detect differences in mean weight of
stomach contents from different months. Pearson product moment correlation
coefficients (r) were calculated, and regressions by least sum of squares
were performed for EW and weight of stomach contents, EW and variety of
stomach contents, and EW and proportion of stomach contents as
Chironomidae larvae to investigate influence of size on feeding. Food items
were identified to the lowest practical taxon following Thorp and Covich
(1991) and Merritt and Cummins (1996) and enumerated. Due to mastication
by pharyngeal teeth, most stomach contents were not identifiable below
2007 C.T. O'Kelley and S.L. Powers 483
family, order, or sometimes class. All statistical analyses were executed
using Data Desk 6.0 (Data Description, Inc., Ithaca, NY) with alpha for all
tests equal to 0.05. Standard deviation is abbreviated as SD.
Results
Age and growth
The smallest specimen collected was a female 34.58 mm SL and 0.942 g
TW taken in December. The largest specimen collected was a female 190
mm SL and 132 g TW taken in September. The August collection was the
earliest capture of young-of the-year specimens, which ranged from 42.03 to
58.95 mm SL (mean = 44.1, SD = 2.75). Scales from the largest specimens
(185–190 mm SL) examined contained four annuli each, while the smallest
specimens examined (43.08–59.23 mm SL) each contained a single annulus
located at the edge of the scale. The ratio of females to males collected was
1.75:1, and no sexual size dimorphism was detected, with mean SL for
females and males 74.6 and 74.9 mm respectively (p = 0.94). Standard
length increased with age in months (R2 = 90.6%, p < 0.001). The natural log
of EW and SL had a higher correlation (r = 0.974) than EW and SL (r =
0.924) indicating a curvilinear relationship with the natural log of EW
increasing with SL (R2 = 95.8%, p < 0.001). Mean SL and EW by month are
presented in Table 2 and Figures 1 and 2. Of the 184 specimens collected,
48.4% were age 0+, 33.2% were age 1+, 13.0% were age 2+, 4.4% were age
3+, and 1.1% were age 4+.
Figure 2. Standard length in mm ± one standard deviation by age in months for
Hypentelium etowanum (Alabama Hog Sucker) collected from Moore and Shoal
creeks between August 2004 and July 2005.
484 Southeastern Naturalist Vol. 6, No. 3
Diet
Diptera were most prevalent within H. etowanum stomachs, making up
90.6% of all food items. Chironomidae larvae made up 88.8% of all food
items and were contained in stomachs from every month. The remainder of
the Diptera were unidentifiable pupae or adults. Other food items are listed
in Table 3. Of all stomachs examined, 35.9% were empty. Weight of stomach
contents was not uniform across all months (F = 3.29, p < 0.001), with
overall feeding peaking in April. The greatest variety of food items (n = 14)
and mean weight (0.032 g, SD = 0.061) of stomach contents was also highest
in April. Feeding appeared to be lowest during the winter months of December–
February, as indicated by small numbers of items per stomach and high
frequency of empty stomachs (Table 3). All stomachs from individuals
Table 2. Age in months, standard lengths (SL) in mm and eviscerated weights (EW) in g of
Hypentelium etowanum from Moore and Shoal creeks by age in months from August 2004 to
July 2005.
Age N Mean SL SD Mean EW SD
3 4 44.10 2.75 1.35 0.26
4 8 47.75 4.90 1.83 0.48
5 9 48.57 6.70 2.09 0.90
6 9 42.96 3.95 1.53 0.40
7 12 43.50 7.40 1.46 0.80
8 10 48.45 7.33 1.95 0.86
9 10 45.47 7.53 1.71 0.82
10 14 46.92 5.58 1.80 0.59
11 13 51.66 6.93 2.38 0.94
12 8 71.48 6.24 6.09 1.40
13 24 75.98 9.65 7.52 2.63
14 9 74.14 8.36 6.99 2.71
15 1 58.95 - 2.93 -
17 3 91.01 7.59 12.25 3.02
18 3 88.56 11.18 12.59 6.45
20 3 101.5 18.65 16.91 6.93
21 3 95.76 20.37 15.10 8.51
22 4 100.62 9.55 18.34 7.07
23 3 104.17 13.14 18.71 4.89
24 5 119.75 3.83 30.01 3.22
25 1 130.84 - 38.32 -
26 3 123.02 9.03 29.08 5.28
27 2 123.93 5.58 30.28 4.54
28 4 126.12 10.54 32.98 6.70
29 3 125.67 11.99 29.47 8.04
30 2 125.45 4.67 31.86 2.75
34 1 135.39 - 36.57 -
35 3 139.11 2.83 47.72 5.63
36 2 141.06 0.76 50.13 1.34
37 2 149.67 8.71 59.89 11.81
38 2 146.11 7.57 53.05 8.41
42 1 145.07 - 50.11 -
47 1 185 - 91.27 -
52 2 187.50 3.54 104.45 14.92
2007 C.T. O'Kelley and S.L. Powers 485
Table 3. Stomach contents of Hypentelium etowanum from Moore and Shoal creeks by month from August 2004 to July 2005.
Month
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total % of total
# of stomachs 13 13 19 20 15 27 14 8 14 15 14 12 184
Detritus 1 1 10 6 6 2 7 1 34 1.14
Nematoda 5 5 0.17
Mollusca
Corbicula 1 1 0.03
Annelida
Oligochaeta 2 2 0.07
Hirudinae 1 7 14 22 0.74
Arachnida
Hydrachnida 4 1 6 3 3 15 32 1.07
Crustacea
Branchiopoda 1 33 8 5 4 31 15 10 107 3.59
Insecta
Unidentified parts 2 5 6 6 2 1 4 5 2 33 1.11
Ephemeroptera 3 3 1 1 1 1 10 0.34
Plecoptera 23 23 0.77
Coleoptera 1 1 1 3 0.10
Hymenoptera 1 1 0.03
Trichoptera 4 3 1 8 0.27
Diptera
Chironomidae larvae 4 2 556 770 717 47 187 64 111 45 140 3 2646 88.79
Unidentified pupae 2 21 8 7 1 1 40 1.34
Unidentified adults 6 2 2 3 13 0.44
Number empty 7 12 1 2 2 16 5 2 8 11 66
Total items 6 4 615 858 744 79 211 70 164 69 157 3 2980
Items/stomach 0.462 0.308 32.37 42.9 49.6 2.926 15.07 8.75 11.71 4.6 11.21 0.25
% empty 53.85 92.31 5.263 10 13.33 59.26 35.71 0 0 13.3 57.14 91.7
486 Southeastern Naturalist Vol. 6, No. 3
collected during winter contained less than four food items, and the contents
of only a single stomach were great enough to register on the balance
(0.002 g). The correlation between EW and weight of stomach contents (r =
0.337) was significant (p < 0.001), but had a low R2 of 11.4%. The correlation
between EW and variety of stomach contents was low (r = 0.114) and
not significant (R2 = 1.3%, p = 0.229). The proportion of stomach contents as
Chironomidae larvae was inversely correlated with EW (r = -0.276) and
significant (p = 0.004), but had a low R2 of 7.6%.
Reproduction
Individual GSI peaked in spring, with values greater than 0.1 only in
specimens from March and April. The highest GSI for a single individual
was 0.1423 in a female 185 mm SL from April (Fig. 3). Mean GSI did not
differ significantly among months (F = 1.69, p = 0.079). The two months
with the highest mean GSI were April (0.0169, SD = 0.0320) and September
(0.0174, SD = 0.0193). June, July, and August had low mean GSI values of
0.0047 (SD = 0.0029), 0.0039 (SD = 0.0022), and 0.0043 (SD = 0.0051),
respectively. The lowest mean GSI for a month was from December (0.0015,
SD = 0.0022). Mature eggs were present only in specimens collected in
March, April, and May, and ranged from 1.5 to 2.8 mm in diameter. Ova
ranged between 493 and 2717 (mean = 1475.5, SD = 932.28) in number in a
single mature female. The smallest female examined with mature ova was 24
months in age (124.5 mm SL, 34.53 g EW) and the smallest male with
mature testes was 22 months in age (114.4 mm SL, 28.45 g EW).
Figure 3. Eviscerated weight in g ± one standard deviation by age in months for
Hypentelium etowanum (Alabama Hog Sucker) collected from Moore and Shoal
creeks between August 2004 and July 2005.
2007 C.T. O'Kelley and S.L. Powers 487
Discussion
Age and growth
Hypentelium etowanum appear to grow rapidly in April as indicated
by length and weight increases at approximately 12, 24, and 36 months of
age (Figs. 2 and 3). Scales examined for this study also suggest annuli
form during spring, but due to the mild winters in Georgia, they may not
be as well defined as those observed in H. nigricans by Raney and
Lachner (1946). The largest H. etowanum examined (185–190 mm SL) all
had four annuli indicating, along with length and weight frequencies, at
least four or five different age classes in our samples. This is largely
consistent with the hypothesis of Etnier and Starnes (1993) that
Hypentelium etowanum live to five years or more as no specimens examined
during this study approached the maximum recorded size of 254 mm
SL for the species (Boschung and Mayden 2004). The low proportion of
age 3+ and 4+ specimens suggests that very few individuals survive to
the maximum age, as is typical of most fishes (Matthews 1998). However,
the low number of older specimens collected may be due in part to
the difficulty collecting larger specimens using a 3.3 m x 1.3 m seine and
a backpack electrofisher.
Diet
Increased feeding during the spring also appears to coincide with increased
energetic requirements associated with gamete production and
Figure 4. Maximum Gonadosomatic Index of Hypentelium etowanum (Alabama
Hog Sucker) from Moore and Shoal creeks by month from August 2004 to July
2005 (1 = January, 2 = February, etc.).
488 Southeastern Naturalist Vol. 6, No. 3
spawning. The prevalence of Chironomidae in stomachs may indicate selective
feeding by H. etowanum, but may also be explained by the extremely
high density that chironomids (> 20,000 individuals/m2) often reach in the
substrate of sandy runs and flowing pools (Benke et al. 1984), which appear
to be among the more regularly inhabited microhabitats for H. etowanum.
The inferior mouth placement in H. etowanum suggests that feeding would
most likely occur at or near the substrate as is typical of most Catostomidae
(Matthews 1998). The weak correlations between EW and weight of stomach
contents, and EW and proportion of diet as Chironomidae may suggest
that feeding of H. etowanum increases slightly and shifts away from
Chironomidae as individuals get larger. However, these correlations do
appear to be weak, and there is no evidence of a shift in variety of stomach
contents throughout the life of H. etowanum. Thus, it would seem that any
changes in diet associated with size are not dramatic.
Reproduction
The inability to detect differences in monthly mean GSI is likely due to
the high proportion of juveniles collected during this study. Highest individual
GSI values during spring months indicate spawning most likely
occurs in late April to May (Fig. 4). While mean GSI for females was
highest in September, no large (> 1.5 mm) mature ova were present in any
specimens collected in the fall. All ova from summer, fall, and winter
months were latent or maturing (see Heins and Machado 1993). The restriction
of large (> 1.5 mm) mature ova to specimens collected in March,
April, and May suggest a single spring spawning season despite the highest
mean GSI from fall months. Tubercles also first appeared in age-two
specimes from February, peaked in April, and were completely absent by
July. This pattern of tubercle development is consistent with observations
by Etnier and Starnes (1993) and Boschung and Mayden (2004). Burr
(1979) observed spawning of H. etowanum in the upper Chattahoochee
River on 10 and 11 June 1976 in water 19 °C. The water temperature of the
April, May and June collections for this study were 15 °C, 16 °C, and 25
°C, respectively. This appears largely consistent with the findings of Burr
(1979) suggesting spawning occurs mostly likely from late April to early
June as water temperature approaches 20 °C. No spawning activity was
observed, but most specimens collected for this study were from habitats
similar to that described by Burr (1979). Examinations of gonads, length
and mass frequency, and scale circuli indicated that sexual maturity occurs
by three years of age, as mature gonads were observed only in specimens at
two years of age or greater.
Comparison to other species of Hypentelium
The biology of H. etowanum is similar to that of the two other species of
Hypentelium and appears to be intermediate between the others in many lifehistory
aspects. Hypentelium etowanum shares a similar lifespan with H.
2007 C.T. O'Kelley and S.L. Powers 489
roanokense Raney and Lachner (Roanoke Hog Sucker) despite the much
smaller maximum size (100 mm SL) of the latter (Jenkins and Burkhead
1994). The largest of the three species ( 495 mm SL), H. nigricans appears
to be much more long-lived than the others, reaching a maximum age of 11
years (Raney and Lachner 1946). Our data from H. etowanum are largely
consistent with the findings of Raney and Lachner (1946) that rapid growth
occurs in H. nigricans during spring as evidenced by the formation of annuli
near the edge of scales from mid April to late May.
The diet of Hy. etowanum appears similar to that of H. nigricans and
H. roanokense, as all appear to feed mostly on Chironomidae larvae
living in the substrata of streams. Jenkins and Burkhead (1994) also suggested
that a slight dietary shift away from aquatic insect larvae may
occur in older H. nigricans similar to that suggested by the weak negative
correlation between EW and proportion of stomach contents as
Chironomidae found in this study.
All three Hypentelium species appear to reach sexual maturity at about
three years of age with males sometimes maturing a year earlier in H.
nigricans and two years earlier in H. roanokense. We did not detect a
difference in age at maturity between males and females for H. etowanum.
All three species appear to spawn in similar habitats during the spring
months as water temperature approaches 20 °C.
Acknowledgments
We thank D.M. Jolly, C.K. Ray, and J.J. McLaughlin for assistance with field
and lab work. We thank J.M. Scott, B.R. Kuhajda, and M.C. Bennett for suggestions
and assistance regarding analyses and manuscript preparation. Fishes were
collected under Georgia Scientific Collecting Permit number 16494 issued to S.L.
Powers. This study was conducted as an undergraduate independent research
project by C.T. O’Kellley.
Literature Cited
Benke, A.C., T.C. Van Arsdall, Jr., D.M. Gillespie, and F.K. Parrish. 1984. Invertebrate
productivity in a subtropical blackwater river: The importance of habitat
and life history. Ecological Monographs 54(1):25–63.
Berendzen, P.B., A.M. Simons, and R.M. Wood. 2003. Phylogeography of the
Northern Hogsucker, Hypentelium nigricans (Teleostei: Cypriniformes): Genetic
evidence for the existence of the ancient Teays River. Journal of Biogeography
30:1139–1152.
Boschung, H.T., and R.L. Mayden. 2004. Fishes of Alabama. Smithsonian Institution
Press, Washington, DC. 736 pp.
Burr, B.M. 1979. Observations on spawning and breeding coloration of Moxostoma
lachneri in Chattahoochee River, Georgia. Georgia Journal of Science 37(3–
4):205–207.
Etnier, D.A., and W.C. Starnes. 1993. The Fishes of Tennessee. University of
Tennessee Press, Knoxville, TN. 681 pp.
490 Southeastern Naturalist Vol. 6, No. 3
Gilbert, C.R. 1998. Type Catalogue of the Recent and Fossil North American
Freshwater Fishes: Families Cyprinidae, Catostomidae, Ictaluridae,
Centrarchidae, and Elassomatidae. Florida Museum of Natural History Special
Publication No. 1. Gainesville. 284 pp.
Harris, P.M., R.L. Mayden, H.S. Espinosa Perez, and F. Garcia de Leon. 2002.
Phylogenetic relationships of Moxostoma and Scartomyzon suckers
(Catostomidae) based on mitochondrial cytochrome b sequence data. Journal of
Fish Biology 61:1433–1452.
Heins, D.C., and M.D. Machado. 1993. Spawning season, clutch characteristics,
sexual dimorphism, and sex ratio in the Redfin Darter Etheostoma whipplei.
American Midland Naturalist 129(1):161–171.
Jenkins, R.J., and N.M. Burkhead. 1994. Freshwater Fishes of Virginia. American
Fisheries Society. Bethesda, MD. 1079 pp.
Matthews, W.J. 1998. Patterns in Freshwater Fish Ecology. Kluwer Academic Publishers.
Norwell, MA. 756 pp.
Merritt, R.W., and K.W. Cummins. 1996. An Introduction to the Aquatic Insects
of North America. Third Edition. Kendall/Hunt Publishing Co., Dubuque, IA.
862 pp.
Raney, E.C., and E.A. Lachner. 1946. Age, growth, and habits of the hogsucker,
Hypentelium nigricans (LeSueur), in New York. American Midland Naturalist
36(1):76–86.
Summerfelt, R.C., and G.E. Hall (Eds.). 1987. Age and Growth of Fish. Iowa State
University Press. Ames, IA. 544 pp.
Thorp, J.H., and A.P. Covich. 1991. Ecology and Classification of North American
Freshwater Invertebrates. Academic Press, Inc. San Diego, CA. 911 pp.