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22001177 SOUTHEASTERN NATURALIST 1V6o(3l.) :1363,1 N–3o4. 23
Relative Abundance, Growth, and Mortality of the White
Catfish, Ameiurus catus L., in the St. Marys River
Peter C. Sakaris1,*, Timothy F. Bonvechio2, and Bryant R. Bowen2
Abstract - Declines in Ameiurus catus (White Catfish) abundance throughout much of their
native range have been attributed to the rapid colonization of invasive Ictalurus furcatus
(Blue Catfish) and Pylodictis olivaris (Flathead Catfish). Because of the potential for imperilment
throughout a majority of its native range, we examined the White Catfish population
in the St. Marys River, GA, one of the few locations where the catfish assemblage is still
native. White Catfish (n = 1244) dominated the ictalurid assemblage, making up 79% of
the catfish caught in the St. Marys River. Overall, length of White Catfish varied from 89
to 486 mm TL, with the majority of fish between 220 and 260 mm. Ages of White Catfish
varied from 1 to 11 years but was dominated by the 2012 year class (age 3). We estimated a
von Bertalannfy growth model for the population (L∞ = 486 mm TL, K = 0.246, t0 = -0.290).
Catch-curve analysis indicated that White Catfish had a 45% annual survival rate in 2015.
This White Catfish population assessment will provide biologists with baseline parameters
to aid in future management and conservation of this declining native species.
Introduction
Ameiurus catus (L.) (White Catfish) is a freshwater bullhead catfish species that
is native to Atlantic Coastal drainages extending from New York to Florida and west
to the Apalachicola basin in Florida, Georgia, and Alabama (Boschung and Mayden
2004). White Catfish are omnivores with diets consisting of various insects (e.g.,
midges, scuds, and mayflies), fish, detritus, and pondweed (Boschung and Mayden
2004, Crumpton 2000). White Catfish inhabit low-velocity, mud-bottomed pools,
open channels, and backwaters of small to large rivers, and also occur in tidal waters
with salinities up to 5 ppt (Boschung and Mayden 2004). The White Catfish
has been widely introduced in systems outside of its native distribution, throughout
the United States and on other continents (Britton and Davies 2006, US Geological
Survey 2017).
Life-history data are very limited for the White Catfish, particularly for populations
in the species’ native range. Schwartz and Jachowski (1965) used vertebrae
to age White Catfish, documenting ages up to 12 years for specimens from the
Patuxent River, MD, and up to 14 years in a Maryland millpond population. Hughes
and Carlson (1986) used pectoral spines to estimate the ages of White Catfish from
the Hudson River Estuary, NY, with the majority of fish between 4 and 7 years old
(max age = 8 yrs). In a follow-up study, White Catfish with ages up to 14 years were
documented in the Hudson River Estuary population (Jordan et al. 2004). Crumpton
1Georgia Gwinnett College, School of Science and Technology-Biology, Lawrenceville, GA
30043. 2Georgia Department of Natural Resources, Wildlife Resources Division, PO Box
2089, Waycross, GA 31502-2089. *Corresponding author - psakaris@ggc.edu.
Manuscript Editor: Benjamin Keck
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(1999) also used pectoral spines to age White Catfish from the Clermont Chain
of Lakes, FL, with ages of fish varying from 2 to 7 years. Unfortunately, pectoral
spines may underestimate the ages of older catfish (Barada et al. 2011, Maceina and
Sammons 2006, Nash and Irwin 1999), and otoliths typically provide more accurate
and precise age estimates than pectoral spines for some ictalurid species (Barada
et al. 2011, Buckmeier et al. 2002, Khan et al. 2013, Maceina and Sammons 2006,
Maceina et al. 2007). Keller (2011) used lapillar otoliths to estimate ages of White
Catfish in the Delaware River Estuary and documented fish up to 1 4 years old.
Rapid declines in population abundances of small-bodied native catfishes along
the Atlantic Coastal Plain have occurred quickly following the introduction of large
nonnative piscivorous catfish. Invasive Ictalurus furcatus (Valenciennes in Cuvier
and Valenciennes) (Blue Catfish) and Pylodictis olivaris (Rafinesque) (Flathead
Catfish) have been implicated in these population declines (Bonvechio et al. 2009,
Brown et al. 2005, Guier et al. 1984, Homer and Jennings 2011, Kaeser et al. 2011,
Kwak et al. 2006, Moser and Roberts 1999, Sakaris et al. 2006, Thomas 1995).
More specifically, population declines of several Ameiurus spp. (bullhead catfishes)
have been documented in the past several decades (Cailteux and Dobbins 2005,
Dobbins et al. 2012, Guier et al. 1984, Homer and Jennings 2011, Thomas 1995).
For example, Homer and Jennings (2011) reported a relatively immediate, negative
influence of introduced Blue Catfish in the Oconee River system, GA, as native
White Catfish abundances declined with concurrent growth and expansion of the
Blue Catfish population.
Few White Catfish populations remain unaltered by rapidly expanding invasive
catfishes along the Atlantic Coastal Plain. In addition, White Catfish populations
that continue to dominate the ictalurid community are rare and include populations
that reside in the St. Johns River in Florida (Jay Holder, Florida Fish and Wildlife
Conservation Commission, DeLeon Springs, FL, pers. comm.), the Ogeechee River
(Tim Barrett, Georgia Department of Natural Resources [GADNR], Richmond Hill,
GA, pers. comm.) and the St. Marys River of Georgia (current study), the Delaware
River Estuary (Keller 2011), and the New, Newport, and White Oak rivers in North
Carolina (Davis and McCoy 1965, Rachels and Ricks 2016). Considering the long
history of persistently expanding Flathead Catfish populations (i.e., since the 1950s;
Quinn 1987) and more recently the establishment and growth of Blue Catfish populations
in the southeastern Georgia rivers (Bonvechio et al. 2012), the introduction
of these nonnative predators and their further expansion throughout coastal plain
river systems may ultimately occur. Therefore, assessment of native catfish populations
before invasions would inform management decisions, providing managers
with baseline population data that may be used to evaluate and monitor effects of
a future invader. In the event of an invasion, managers may decide to institute an
invasive species removal program to minimize the effects of the nonnative predator
on native fauna in the system (Bonvechio et al. 2011a, b). Accordingly, we aimed
to assess a native catfish assemblage, not currently affected by an invasive species,
in the St. Marys River, GA. Our specific objectives were to estimate the relative
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abundances of all catfishes present in river, as well as describe the age, growth, and
mortality of the most abundant species, the White Catfish.
Field-Site Description
The headwaters of the St. Marys River originate in the Okefenokee swamp in
Charlton County, GA. It flows southward, eastward for a short stretch, northward,
and then eastward again forming the Florida–Georgia State border. The St. Marys
River watershed is located in Georgia and Florida and drains ~3367 km2, with
~1981 km2 of drainage in Georgia (GADNR EPD 2002). The St. Marys River runs
for 230 km before it empties into the Atlantic Ocean near the city of St. Marys,
south of Cumberland Island (GADNR EPD 2002). Although 52 species of fish (17
families) reside in the St. Marys basin, fish populations are limited in productivity
by acidic waters, low alkalinity, and large fluctuations in river flows (GADNR EPD
2002). Historical discharge of the St. Marys has fluctuated widely from 22 to 4520
m3/s with a mean annual discharge of 779 m3/s (US Geological Survey, MacClenney,
FL, gauge). We chose 6 fixed standardized sampling locations, with the upper
most sampling station upstream of the Traders Hill boat ramp located at river kilometer
89 (30°45'23"N, 82°01'07"W) and the lowest station occurring downstream
of the Camp Pickney boat ramp at approximately river kilometer 31 (30°46'44"N,
82°47'19"W).
Methods
Field sampling
We conducted catfish sampling using low-amperage, pulsed DC electrofishing
(200–1000 volts at 18 pulses per sec. and >1 amp of output) dur ing daylight hours
in a downstream direction from a 5.1-m aluminum jon boat. We used Smith-Root©
electrofishing backpack shock boxes, following sampling procedures described
in previous research studies conducted by GADNR (Bonvechio et al. 2011, 2016;
Thomas 1995). A chase boat was also deployed in an effort to increase capture efficiency
(Cunningham 2004, Daugherty and Sutton 2005). Sampling occurred over
3 field days between 28 July and 5 August 2015 when water temperatures exceeded
27 °C and water levels were well within the banks of the river. We sampled each
transect (n = 6) for 1 hr to calculate a relative index of abundance (fish/hr). All catfish
were measured to the nearest mm (total length [TL]) and weighed to the nearest
0.1 g. We obtained a White Catfish age analysis subsample (n = 184) using 5 fish per
1-cm group up to 350 mm TL and all fish >350 mm TL. Retained fish were place on
ice and returned to the lab for measurements, determination of sex, and extraction
of lapilli otoliths (Long and Stewart 2010).
Aging methods
We lightly browned otoliths from the collected fish on a hotplate to improve the
clarity of annuli (i.e., annular growth rings; Buckmeier et al. 2002). Otoliths were
then embedded in a clear epoxy resin and sectioned along a transverse plane with a
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high-precision, low-speed diamond sectioning saw (Preciso, Model CL-40). Each
otolith was sectioned only once at the core, and then glued with Crystal Bond in a
position perpendicular to the plane of a microscope slide (Buckmeier et al. 2002).
If necessary, we polished otolith sections with ultra-fine (1500-grit) sandpaper to
further enhance the clarity of annuli. Otolith sections were viewed under a dissecting
microscope, illuminated with a fiber optic light source. Similar to Steuk and Schnitzler
(2011), 2 independent experienced readers estimated the age of each fish, and
differences in age between readers were reconciled by a third experienced reader.
Data analyses
We constructed an age–length key from the aged fish and extrapolated to the
entire sample (Ricker 1975). The instantaneous (Z) and total (A) rates of annual
mortality were estimated for age-2 and older fish using weighted catch-curve regression
in the Fishery Analysis and Modeling Simulator Software (FAMS; Slipke
and Maceina 2014, Smith et al. 2012). We also fit a von Bertalanffy growth model
(Ricker 1975) for the White Catfish population using FAMS. Mean total length at
age was used to compute the growth curve, and growth was not extrapolated past
the maximum age obtained in the sample (age 11). Sexes were combined for all
mortality and growth estimates. All models were considered significant at α = 0.05.
Results
Abundance and assemblage
White catfish (n = 1244) dominated the ictalurid community, making up 79% of
the catfish assemblage, followed by Ictalurus punctatus (Rafinesque) (Channel Catfish;
n = 282 [18%]), Ameiurus natalis (Lesueur) (Yellow Bullhead; n = 42 [2.7%]),
and Ameiurus nebulosus (Lesueur) (Brown Bullhead; n = 5 [0.3%]). Mean CPE for
White Catfish was 209.2 fish/hr (SE = 12.0), followed by Channel Catfish at 47.4
fish/hr (8.7), Yellow Bullhead at 7.1 fish/hr (4.8,) and Brown Bullhead at 0.8 fish/
hr (0.2).
White Catfish population characteristics
White Catfish total lengths varied from 89 to 486 mm, with the majority of fish
between 220 and 260 mm and a mean length of 249 mm (Fig. 1). Mean relative
weight was 86, with lower condition observed among larger fish, especially above
30 cm (Fig. 1). Of the 184 fish collected for age estimation, 67 were females and
72 were males. Forty-five fish were deemed immature, and we could not determine
their sex. As a result, the sex ratio for the age sample did not significantly deviate
from 1:1 (χ2 = 0.18, P = 0.67). Fecundity estimates were not calculated for females
due to the majority of ovaries already appearing spent.
Age, growth, and survival
Only 1 otolith section was considered unreadable and was removed from the
age sample. Initial reader agreement between the 2 readers was 73.8% (135/183).
Of the 48 disagreements, 40 only differed by 1 year (40/48 [83%]). The majority of
disagreements were resolved by the third reader, resulting in final ages estimated for
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2017 Vol. 16, No. 3
97.8% of the sample (179/183). Ages of White Catfish varied from 1 to 11 years, but
was dominated by a 2012 year class (age 3; Fig. 2). We computed a von Bertalanffy
growth model (L∞ = 486 mm TL, K = 0.246, t0 = -0.290) for the population (r2 = 0.94,
Figure 1. Double axis length–frequency distributions (2-cm bins; shaded bars) and mean
relative weights (Wr; solid diamonds) of White Catfish collected from the St. Marys River,
GA, in 2015.
Figure 2. Age–frequency distribution for the White Catfish population sampled from the St.
Marys River, GA, in Summer 2015.
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P < 0.01; Fig. 3), with White Catfish reaching mean total lengths of 270, 383, and 437
mm at ages 3, 6, and 9, respectively. Catch-curve analysis indicated that White Catfish
exhibited a 45% annual survival rate (Z = - 0.80, P < 0.01; Fig. 4).
Figure 3. Von Bertalanffy growth curve for White Catfish from the St. Marys River, GA
(diamond symbol = mean total length from age sample; open symbol = predicted length
from growth model).
Figure 4. Weighted catch-curve regression based on number at-age-data for White Catfish
collected during electrofishing on the St. Marys River in summer 2015 (n = 1244).
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Discussion
Nonnative Flathead Catfish and Blue Catfish have rapidly expanded throughout
several Atlantic Coastal drainages in the Southeast, leading to a decline in
native species (Bonvechio et al. 2009, Brown et al. 2005, Grabowski et al. 2004,
Grist 2002, Homer and Jennings 2011, Kwak et al. 2006, Sakaris et al. 2006,
Thomas 1995). Several native bullhead species have been affected in the Southeast
by nonnative introductions. The rapid expansion of the Flathead Catfish in the
Appalachicola River, FL, has been implicated as a significant factor to declines in
the native Ameiurus serracanthus (Yerger and Relyea) (Spotted Bullhead; Cailteux
and Dobbins 2005). In the Chesapeake Bay region, substantial declines in the native
White Catfish have coincided with rapid range expansions of Blue Catfish
(Schloesser et al. 2011). More recently, Homer and Jennings (2011) reported a
relatively immediate decline in native White Catfish with a concurrent increase in
the Blue Catfish population in Lake Oconee, GA. In the St. Marys River, we documented
a highly abundant White Catfish population that continues to dominate the
catfish assemblage, showing resiliency and remarkable longevity in this system
(maximum age = 11) despite a 55% annual mortality rate. No nonnative catfish
were found in the St. Marys River during this study. With the close proximity of the
St. Marys River to other systems that are currently influenced by invasive predators
(e.g., Satilla River; Bonvechio et al. 2009, 2012), biologists should closely monitor
the St. Mary’s native catfish assemblage to detect any early signs of an invasion.
Early detection, rapid response, and removal of potential invaders is vital to protecting
and sustaining native fish assemblages.
Although White Catfish can reach maximum lengths around or exceeding 500
mm TL, our longest individual measured 486 mm TL, which was shorter than a
534-mm fish that was recently found in the White Oak River, NC (Rachels and
Ricks 2016). Keller (2011) observed a specimen measuring 520 mm TL from
the Delaware River Estuary area. The majority of White Catfish collected from the
Hudson River Estuary were less than 500 mm TL (Hughes and Carlson 1986, Jordan
et al. 2004). White Catfish grew reasonably fast in the St. Marys River, with
growth rates exceeding those observed in the Hudson River Estuary population
(213–233 mm TL at age 3 and 339–349 mm TL at age 6; Hughes and Carlson 1986,
Jordan et al. 2004), the Patuxent River population (185 mm TL at age 3 and 266
mm TL at age 6; Schwartz and Jachowski 1965), and the Delaware River Estuary
population (216 mm TL at age 3 and 309 mm TL at age 6; Keller 2011). The faster
growth observed in our population could simply be attributed to a longer growing
season in the southern extent of their native distribution. Growth of White Catfish
in the St. Marys River was intermediate to growth rates of fish observed in the
Clermont Chain of Lakes and St. John’s River, FL (Crumpton 2000).
Despite their reasonably fast growth, White Catfish (>200 mm TL) exhibited
somewhat poor body condition in the St. Marys River. Typically, fish with relative
weights between 95 and 105 are considered to be in good condition (Pope and
Cruse 2007). Similar to Rachels and Ricks’ (2016) observations of White Catfish
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from brackish rivers in North Carolina, salinity variation could be influencing
White Catfish condition due to the increased energetic demand of osmoregulation
and anabolism (Lagler et al. 1962, Pauly 1979). In addition, we conducted sampling
soon after the spawning period, which begins in late May or early June (Boschung
and Mayden 2004). Adult fish were likely replenishing energy reserves at the time
of sampling, while smaller, immature fish maintained good body condition.
Our annual mortality estimate (55%) for White catfish is quite similar to estimates
reported for other bullhead catfishes. Ameiurus brunneus Jordan (Snail
Bullhead) exhibited annual mortality rates of 60.2% (2007) and 56.1% (2010) in
Nickajack Creek, a tributary of the Chattahoochee River, GA (Sakaris et al. 2011).
Annual mortality can be as high as 79% for bullhead catfish (Ameiurus melas
(Rafinesque) [Black Bullhead]; Mork et al. 2009). Sakaris et al. (2011) reported
that Snail Bullhead were very abundant, with CPUE’s up to 205.2 fish/hr, and
suggested that mortality was density-dependent in Nickajack Creek. A similar
effect of population density on mortality may be occurring for White Catfish in
the St. Marys River. Although our mortality rate may have been slightly overestimated
due to the presence of a strong (age 3) recruitment class, we contend that
higher mortality was more of a consequence of high population density in the
system. Mean CPUE for White Catfish in the St. Marys River (209.2 fish/hr) was
substantially higher than the CPUE reported for White Catfish in the White Oak
River, NC (63.1 fish/hr; Rachels and Ricks 2016). Like White Catfish in the St.
Marys, the White Catfish population in the White Oak River, NC, is not currently
believed to be influenced by an invasive piscivore. The White Catfish catch rates
in the St. Marys are much higher than electrofishing catch rates of White Catfish
on the Satilla River (T.F. Bonvechio, unpubl. data), where Flathead catfish have
been present since the mid 1990s. In the Satilla River, White Catfish CPUE from
2007 to 2015 has averaged only 16.7 fish/hr over the 9-yr time series. Despite the
findings above, life-history and general population data for bullhead catfishes are
still very limited in the literature, and more research on the dynamics of bullhead
catfish populations is needed.
Age, growth, and life-history parameters of White Catfish are presented in this
study and should aid management and future conservation of this species. Nevertheless,
a comprehensive study of White Catfish populations across the species’
distribution is needed to properly develop species management recommendations.
Although the mechanisms as to why White Catfish and other native bullhead catfish
suffer drastic declines in abundance when invasive predators become established
in a system is unknown (Homer and Jennings 2011), future studies on unaffected
native populations are needed and should be pursued whenever po ssible.
Acknowledgments
We thank J. Biagi, J. Bythwood, B. Deener, D. Harrison, T. Litts, B. McGhin, L. Meeks,
J. Mitchell, J. Perry, S. Robinson, C. Sexton, M. Thomas, A. Trocheck, and E. Zmarzly for
their help with support, and or field and lab work. This research was funded by the Georgia
Gwinnett College and the GADNR.
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Literature Cited
Barada, T.J., A.J. Blank, and M.A. Pegg. 2011. Bias, precision, and processing time of
otoliths and pectoral spines used for age estimation of Channel Catfish. Pp. 723–731, In
P.H. Michaletz and V.H. Travnicheck (Eds.). Conservation, Ecology, and Management
of Catfish: The Second International Symposium. American Fisheries Society, Symposium
77, Bethesda, MD.
Bonvechio, T.F., D. Harrison, and B. Deener. 2009. Population changes of sportfish following
Flathead Catfish introduction in the Satilla River, Georgia. Proceedings of the
Annual Conference of the Southeastern Association of Fish and Wildlife Agencies
63:133–139.
Bonvechio, T.F., M.S. Allen, D. Gwinn, and J.S. Mitchell. 2011a. Impacts of electrofishinginduced
exploitation on Flathead Catfish, Pylodictis olivaris, population metrics in the
Satilla River, Georgia. Pp. 395–408, In P.H. Michaletz and V.H. Travnichek (Eds.). Conservation,
Ecology, and Management of Catfish: The Second International Symposium.
American Fisheries Society Symposium 77, Bethesda, MD.
Bonvechio, T.F., C.A. Jennings, and D.R. Harrison. 2011b. Diet and population metrics
of the introduced Blue Catfish, Ictalurus furcatus, population on the Altamaha River,
Georgia. Proceeding of the Annual Conference of the Southeastern Association of Fish
and Wildlife Agencies 65:112–118.
Bonvechio, T.F., B.R. Bowen, J.S. Mitchell, and J. Bythwood. 2012. Non-indigenous range
expansion of the Blue Catfish (Ictalurus furcatus) in the Satilla River, Georgia. Southeastern
Naturalist 11(2):355–358.
Bonvechio, T.F., J.E. Marsik, and C.W. Bussells. 2016. Population dynamics of introduced
Flathead Catfish in two Atlantic coastal plain rivers under differing management strategies.
Journal of the Southeastern Association of Fish and Wildlife Agencies 3:128–135.
Boschung, H.T., and R.L. Mayden. 2004. Fishes of Alabama. Smithsonian Books, Washington
DC.
Brown, J.J., J. Perillo, T.J. Kwak, and R.J. Horowitz. 2005. Implications of Pylodictis
olivaris (Flathead Catfish) introduction in the Delaware and Susquehanna drainages.
Northeastern Naturalist 12:373–384.
Britton, J.R., and G.D. Davies. 2006. First record of the White Catfish, Ameiurus catus, in
Great Britain. Journal of Fish Biology 69:1236–1238.
Buckmeier, D.L., E.R. Irwin, R.K. Betsill, and J.A. Prentice. 2002. Validity of otoliths and
pectoral spines for estimating ages of Channel Catfish. North American Journal of Fisheries
Management 22:934–942.
Cailteux, R.L., and D.A. Dobbins. 2005. Population status and distribution of Spotted
Bullhead, Ameirus serracanthus, in north Florida rivers. Florida Scientist 68:122–129.
Crumpton, J.E. 2000. Relative abundance, age, growth, and food habits of Channel and
White Catfish from the Clermont Chain of Lakes. Pp. 115–119, In E.R. Irwin, W.A.
Hubert, C. . Rabeini, H. Schramm, and T. Coon (Eds.). Catfish 2000: Proceedings of
the International Ictalurid. American Fisheries Society Symposium 24, Bethesda, MD.
Cunningham, K.K. 2004. Efficacy of a chase boat for electrofishing Flathead Catfish in three
Oklahoma reservoirs. North American Journal of Fisheries Management 24:1427–1430.
Daugherty D.J., and T.M. Sutton. 2005. Use of a chase boat for increasing electrofishing
efficiency for Flathead Catfish in lotic systems. North American Journal of Fisheries
Management 25:1528–1532.
Davis, J.R., and E.G. McCoy. 1965. Survey and classification of the New–White Oak–Newport
Rivers and tributaries, North Carolina. North Carolina Wildlife Resources Commission,
Federal Aid in Sport Fish Restoration, Project F-14, Final Report, Rale igh, NC.
Southeastern Naturalist
P.C. Sakaris, T.F. Bonvechio, and B.R. Bowen
2017 Vol. 16, No. 3
340
Dobbins, D.A., R.L. Cailteux, S.R. Midway, and E.H. Leone. 2012. Long-term impacts of
introduced Flathead Catfish on native ictalurids in a north Florida, USA, river. Fisheries
Management and Ecology 19:434–440.
Georgia Department of Natural Resources Environmental Protection Division (GADNR
EPD). 2002. Saint Marys River Basin Management Plan 2002. Avialable online at
https://epd.georgia.gov/st-marys-river-basin-management-plan. Accessed August 2017.
Grist, J.D. 2002. Analysis of Blue Catfish population in a southeastern reservoir, Lake Norman,
North Carolina. Master’s Thesis. Virginia Polytechnic Institute and State University.
Blacksburg, VA.
Grabowski, T.B., J.J. Isely, and R.R. Weller. 2004. Age and growth of Flathead Catfish,
Pylodictis olivaris Rafinesque, in the Altamaha River system, Georgia. Journal of Freshwater
Ecology 19:411–417.
Guier C.R., L.E. Nichols, and R.T. Rachels. 1984. Biological investigation of Flathead
Catfish in the Cape Fear River. Proceedings of the Annual Conference Southeastern Association
of Fish and Wildlife Agencies 35:607–621.
Homer, M.D., and C.A. Jennings. 2011. Historical catch, age structure, sizes, and relative
growth for an introduced population of Blue Catfish in Lake Oconee, Georgia. Pp.
383–394, In P.H. Michaletz and V.H. Travnichek (Eds.). Conservation, Ecology, and
Management of Catfish: The Second International Symposium. American Fisheries
Society, Bethesda, MD.
Hughes, M.J., and D.M. Carlson. 1986. White Catfish growth and life history in the Hudson
River Estuary, New York. Journal of Freshwater Ecology 3:407–418.
Jordan, S.M., R.M. Neumann, and E.T. Schultz. 2004. Distribution, habitat use, and condition
of a native and an introduced catfish species in the Hudson River Estuary. Journal
of Freshwater Ecology 19:59–67.
Kaeser A.J., T.F. Bonvechio, D. Harrison, and R.R. Weller. 2011. Population dynamics of
introduced Flathead Catfish in rivers of southern Georgia. Pp. 405–422, In P.H. Michaletz
and V.H. Travnichek (Eds.). Conservation, Ecology, and Management of Catfish:
The Second International Symposium. American Fisheries Society, Bethesda, MD.
Keller, D.H. 2011. Population characteristics of White Catfish and Channel Catfish in the
Delaware River Estuary. Pp. 423–436, In P.H. Michaletz and V.H. Travnichek (Eds.).
Conservation, Ecology, and Management of Catfish: The Second International Symposium.
American Fisheries Society, Bethesda, MD.
Khan, S., M.A. Khan, and K. Miyan. 2013. Evaluation of ageing precision from different
structures of three threatened freshwater fish species, Clarias batrachus, Heteropneustes
fossilis, and Wallago attu. Folia Zoologica 62:103–109.
Kwak T.J., W.E. Pine III, and D.S. Waters. 2006. Age, growth, and mortality of introduced
Flathead Catfish in Atlantic rivers and a review of other populations. North American
Journal of Fisheries Management 26:73–87.
Lagler, K.F., J.E. Bardach, and R.R. Miller. 1962. Ichthyology. John Wiley and Sons, New
York, NY.
Long, J.M., and D.R. Stewart. 2010. Verification of otolith identity used by fisheries
scientists for aging Channel Catfish. Transactions of the American Fisheries Society
139:1775–1779.
Maceina, M.J., and S.M. Sammons. 2006. An evaluation of different structures to age freshwater
fish from a northeastern US river. Fisheries Management and Ecology 13:237–242.
Maceina, M.J., J. Boxrucker, D.L. Buckmeier, R.S. Gangl, D.O. Lucchesi, D.A. Isermann,
J.R. Jackson, and P.J. Martinez. 2007. Current status and review of freshwater-fish aging
procedures used by state and provincial fisheries agencies with recommendations for
future directions. Fisheries 32:329–340.
Southeastern Naturalist
341
P.C. Sakaris, T.F. Bonvechio, and B.R. Bowen
2017 Vol. 16, No. 3
Mork M.D., S.M. Bisping, J.R. Fischer, and M.C. Quist. 2009. Population characteristics of
Black Bullhead (Ameiurus melas) in Iowa natural lakes. Journal of Freshwater Ecology
24(4):635–644
Moser M.L., and S.B Roberts. 1999. Effects of nonindigenous ictalurids and recreational
electrofishing on the ictalurid community of the Cape Fear River drainage, North Carolina.
Pp. 479–485,In E.R. Irwin, W.A. Hubert, C.F. Rabeini, H. Schramm, and T. Coon
(Eds.). Catfish 2000: Proceedings of the International Ictalurid Symposium. American
Fisheries Society Symposium 24, Bethesda, MD.
Nash, M.K., and E.R. Irwin. 1999. Use of otoliths versus pectoral spines for aging adult
Flathead Catfish. Pp. 309–316, In E.R. Irwin, W.A. Hubert, C.F. Rabeini, H. Schramm,
and T. Coon (Eds.). Catfish 2000: Proceedings of the International Ictalurid Symposium.
American Fisheries Society Symposium 24, Bethesda, MD.
Pauly, D. 1979. Gill size and temperature as governing factors in fish growth: A generalization
of von Bertalanffy’s growth formula. Ph.D. Dissertation. Berichte aus dem Institut
Fur Meereskunde an der Universitat Kiel, Kiel, Germany.
Pope, K.L., and C.J. Kruse. 2007. Condition. Pp. 423–471, In C.S. Guy and M.L. Brown
(Eds.). Analysis and Interpretation of Freshwater Fisheries Data. American Fisheries
Society, Bethesda, MD.
Quinn, S.P. 1987. Stomach contents of Flathead Catfish in the Flint River, Georgia. Proceedings
of the Annual Conference of the Southeastern Association of Fish and Wildlife
Agencies 41:85–92.
Rachels, K.T., and B.R. Ricks. 2016. Characteristics of recreationally important fish populations
of the White Oak River. North Carolina Wildlife Resources Commission, Federal
Aid in Sport Fish Restoration, Project F-108, Final Report. Ral eigh, NC.
Ricker, W.E. 1975. Computation and interpretation of biological statistics of fish populations.
Fisheries Research Board of Canada Bulletin 191. Ottawa, ON, Canada.
Sakaris, P.C., E.R. Irwin, J.C. Jolley, and D. Harrison. 2006. Comparison of native and in -
troduced Flathead Catfish populations in Alabama and Georgia: Growth, mortality, and
management. North American Journal of Fisheries Management 26:867–874.
Sakaris, P.C., D. Smith, E. Davis, and B.E. Macham. 2011. Assessment of the Snail Bullhead
catfish population in Nickajack Creek, Georgia. Pp. 313–323, In P.H. Michaletz
and V.H. Travnichek (Eds.). Conservation, Ecology, and Management of Catfish: The
Second International Symposium. American Fisheries Society, Bethesda, MD.
Schloesser, R.W., M.C. Fabrizio, R.L. Latour, G.C. Garman, B. Greenlee, M. Groves, and
J. Gartland. 2011. Ecological role of Blue Catfish in Cheseapeake Bay communities
and implications for management. Pp. 369–382, In P.H. Michaletz and V.H. Travnichek
(Eds.). Conservation, Ecology, and Management of Catfish: The Second International
Symposium. American Fisheries Society, Bethesda, MD.
Schwartz, F.J., and R. Jachowski. 1965. The age, growth, and length–weight relationship
of the Patuxent River, Maryland ictalurid White Catfish, Ictalurus catus. Chesapeake
Science 6(4):226–229.
Slipke, J.W., and M.J. Maceina. 2014. Fishery analysis and modeling simulator (FAMS).
Version 1.64. American Fisheries Society, Bethesda, MD.
Smith M.W., A.Y. Then, C. Wor, G. Ralph, K.H. Pollock, and J.M. Hoenig. 2012. Recommendations
for catch-curve analysis. North American Journal of Fisheries Management
32(5):956–967.
Southeastern Naturalist
P.C. Sakaris, T.F. Bonvechio, and B.R. Bowen
2017 Vol. 16, No. 3
342
Steuck, M.J., and C.C. Schnitzler. 2011. Age and growth of Flathead Catfish from Pools
12 and 13 of the Upper Mississippi River. Pp. 699–712, In P.H. Michaletz and V.H.
Travnichek (Eds.). Conservation, Ecology, and Management of Catfish: The Second
International Symposium. American Fisheries Society, Bethesda, MD.
Thomas, M.E. 1995. Monitoring the effects of introduced Flathead Catfish on sport fish
populations in the Altamaha River, Georgia. Proceedings of the Annual Conference of
the Southeast Association of Fish and Wildlife Agencies 47:531–538.
US Geological Survey. 2017. Ameiurus catus. Nonindigenous Aquatic Species Program.
Available online at https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=729. Accessed
8 October 2016.