Factors Effecting Reproductive Potential Relative to Body Size
of Channel Catfish in three Northern Idaho Lakes.
1 | Griffin CHANNEL CATFISH REPRODUCTIVE POTENTIAL
Factors Effecting Reproductive Potential Relative to Body Size
of Channel Catfish in three Northern Idaho Lakes.Kayla M. Griffin,
Student of University of Idaho, Department of Fish and Wildlife,
University of Idaho, Moscow, Idaho
Little is known about the population dynamics of Ictalurus
punctatus, more commonly known as the channel catfish. Within
riverine environments, channel catfish have successfully
established naturally reproducing populations. Populations living
in lake environments have not however, and little is known about
the factors that negatively affect natural reproduction. The goal
of this research was to determine the effects of fish diversity,
surface area, and stocking rate on the reproductive potential as
indexed by body size in age two, three, and four year old channel
catfish within three lakes in northern Idaho. We determined that
differences in fish diversity, surface area, and stocking rates do
influence the body size and reproductive potential of channel
catfish between lakes, but do not have as great of an influence on
age classes within lakes. Future studies should investigate these
factors as well as others, to further investigate the population
dynamics of channel catfish.
The state of Idaho provides a variety of fishing opportunities
to satisfy the diversity of fishermen found within the northwest.
Though river systems seem to dominate the state, lakes and
reservoirs stocked by state agencies provide easy fishing access
for those who may not be the most experienced fishermen. These
small lakes and reservoirs, often deemed Family Fishing Waters, are
managed for the use of the public and provide many non-native sport
fish species for anglers to catch. One of the most common species
found within these reservoirs is the channel catfish (Ictalurus
punctatus). Channel catfish are generally a bottom oriented, highly
piscivorous fish native to eastern and central North America
(Fishes of Idaho 2014). Channel catfish typically reach sexual
maturity around the age of three, but sexual maturity is strongly
influenced by biotic and abiotic factors (Davis 2009). Within river
systems channel catfish have established healthy reproducing
populations, but lake populations have not and must be continually
stocked by managers to maintain population sizes. By understanding
the factors that influence reproductive potential, managers can
make informed management decisions to achieve and maintain
naturally reproducing channel catfish populations within lake
systems. Obtaining naturally reproducing populations would save
agencies money and time by reducing the amount of fish grown in
hatcheries for stocking every year. Channel catfish are a species
of management concern for many agencies because they are one of the
most heavily targeted fish species by anglers nationwide (USFW
2002). However, very little is known about the factors affecting
the population dynamics of channel catfish populations. Stocking
rates and management practices vary greatly between management
agencies and between water bodies. To stock each lake
appropriately, we must understand how channel catfish populations
are influenced by lake specific environments. The stocking rate of
a lake can greatly affect the body size of an individual. Over
stocking can lead to stunted populations and under stocking can
lead to small population sizes. The surface area of a lake can also
have an influence on the body size of an individual within a
population. The amount of habitat and nutrients available in a
small surface area lake in comparison to a large surface area lake
can vary greatly. The fish diversity found within a body of water
is another factor that influences the body size of an individual.
The amount of predator and competitor species coexisting within the
lake can have a negative or positive influence on body size. The
goal of this research was to determine the effects of fish
diversity, surface area, and stocking rate on the reproductive
potential as an index of body size in age two, three, and four year
old channel catfish within a series of lakes in northern Idaho.
This study was conducted under the assumption that body size of
channel catfish is proportional to their reproductive potential.
Based on this assumption, we hypothesized that a statistical
difference would be detected in the body sizes of individuals
within Hauser Lake, Rose Lake, and Jewel Lake due to variations in
fish diversity, surface area, and stocking rates.STUDY AREAThe
study area in the context of this study includes three lakes
currently being stocked with channel catfish in northern Idaho.
Hauser Lake, Rose Lake, and Jewel Lake were chosen due to their
observed variability in surface area, fish diversity, and stocking
rates. Hauser LakeHauser Lake is the largest of the three lakes,
with a surface area of 223 hectares, and is located about 8 miles
west of Post Falls, Idaho, near the Idaho-Washington border (Figure
1). Hauser Lake has an annual stocking rate of 23 channel catfish
per hectare. There are thirteen different species of fish within
this lake which include rainbow trout, cutthroat trout, largemouth
bass, smallmouth bass, bullhead catfish, northern pike, tiger
muskie, kokanee, crappie, yellow perch, pumpkinseed, bluegill, and
channel catfish (Table 1). Rose LakeRose Lake is located 23 miles
southeast of Coeur d Alene, Idaho and has a surface area of 122
hectares (Figure 1). It contains seven different species including
largemouth bass, crappie, bluegill, yellow perch, bullhead catfish,
pumpkinseed, and channel catfish. Rose Lake has an annual stocking
rate of 27 channel catfish per hectare (Table 1). Jewel LakeJewel
Lake is the smallest of the three lakes with a surface area of 12
hectares. It is located 19 miles southwest of Sandpoint, Idaho and
contains four different species; rainbow trout, bluegill, yellow
perch, and channel catfish (Figure 1). The annual stocking rate for
Jewel Lake is 46 channel catfish per hectare (Table 1).
METHODSLength and weight data were collected from channel catfish
sampled with hoop nets in Hauser Lake, Rose Lake, and Jewel Lake in
northern Idaho during 2011 and 2012. Using calcified structures
taken from each fish, ages were assigned to all fish sampled using
standardized fisheries aging techniques (Inland Fisheries
Management 2010). The number of different species contained within
each lake and surface area values were obtained through Idaho Fish
and Game records available online (IDFG 2014). All three lakes were
characterized by their surface area, fish diversity, and annual
stocking rate. Differences between average body size for age
classes two, three, and four were compared among all three lakes
using 95% confidence intervals. These intervals were obtained
through program R and were compared for overlap. Overlapping
intervals were considered an indication of a non-significant
difference between variables.ResultsHauser Lake contains the
highest fish diversity, the largest surface area, and the lowest
stocking rate of all three lakes. Rose Lake sits in the middle for
all three categories and Jewel Lake contains the lowest fish
diversity, the smallest surface area, and the highest stocking rate
(Table 1). Confidence intervals were compared across lakes for each
age class. Age 2 channel catfish confidence intervals showed
overlap between Hauser Lake and Jewel Lake. The lower 95%
confidence interval value was 283.72 for Hauser Lake. The upper 95%
confidence interval value was 285.45 for Jewel Lake (Figure 2).
These were the only overlapping intervals observed within the data.
No overlap was observed in age 3 individuals in Hauser Lake, Jewel
Lake, or Rose Lake (Figure 3). Age 4 individuals also showed no
overlap in 95% confidence intervals between all three lakes (Figure
4). Overlapping confidence intervals suggest that there is no
statistical difference between age 2 individuals found within
Hauser Lake and Jewel Lake. However, the non-overlapping 95%
confidence intervals observed between age 2 individuals in Rose
Lake and age 3 and age 4 individuals in all three lakes, suggests
that there is a statistical difference in body size between lakes
for those age classes.Confidence intervals were also compared
across all three ages within each lake. In Hauser Lake, overlap was
observed between age 3 and age 4 confidence intervals. Age 2
individuals showed no overlap with age 3 and age 4 confidence
interval values (Figure 5). Rose Lake also showed overlap between
age 3 and age 4 individuals, but no overlap in age 2 individuals
(Figure 6). Jewel Lake showed overlap in all three age classes
(Figure 7). These results suggest that there is no statistical
difference in body size for age 3 and age 4 individuals in Hauser
Lake and Rose Lake, and for all age classes in Jewel Lake.
Discussion The statistical differences observed across all lakes
can be explained by the variation in fish diversity, surface area,
and stocking rates between the three lakes. The populations within
one lake are subject to different environmental and biotic factors
than those individuals within another lake environment. Body sizes
are therefore more likely to be statistically different due to
differing environmental factors. The lack of statistical
differences between age classes within lakes can also be explained
by the variation in fish diversity, surface area, and stocking
rates. Age classes within one lake are subject to the same
environmental factors as the next age class and are therefore less
likely to be statistically different due to similar environmental
factors. Increased fish diversity within lakes provides predator
species with multiple prey options and provides different food
sources for adult channel catfish. The large spines of channel
catfish will often discourage predators such as largemouth bass
from consuming them and instead select for relatively spineless
prey like bluegill (Sismour et al. 2013). Higher species diversity
may therefore decrease predation on channel catfish once they
achieve a larger body size. An abundance of different species can
also mean more viable food sources for channel catfish. With a
number of species competing for similar food resources, channel
catfish growth may be reduced. As fish grow to larger sizes
however, many species shift their diets and select new food
sources. This is a common trait in channel catfish and large adult
catfish will begin to consume larger insects and other fish species
(Bailey and Harrison Jr. 1948). When food sources are abundant the
amount of competition between channel catfish and other species
decreases. This is because channel catfish utilize a much more
diverse array of food resources in comparison to other omnivorous
species like bluegill and yellow perch. Large surface areas provide
fish with more potential habitats for spawning and predatory
refuge. Channel catfish are cavity spawners and often need
depressions under logs or banks to build adequate nesting sites.
Lakes with large surface areas could provide higher quality
spawning habitats and increase the success of natural spawning. In
smaller lakes, like Rose Lake or Jewel Lake, natural spawning
success could be increased by providing artificial spawning
cavities for fish. Artificial spawning cavities placed in areas
with protective cover would decrease predation on eggs and improve
the success of natural spawning within lakes (Moy and Stickney
2011). Stocking rates can also greatly impact the growth and
success of channel catfish populations. Highly productive lakes
stocked with appropriate fish densities will maximize the growth of
channel catfish to produce satisfactory fisheries (Michaletz 2008).
Managers should fully understand the population dynamics and
productivity of each lake to appropriately stock channel catfish.
The factors affecting channel catfish growth are not only
ecologically beneficial to management agencies but are also
economically beneficial. By striving to achieve naturally
reproducing populations for anglers to utilize, fishing license
dollars could increase as catfish populations grow and with less
need for stocking, agencies will spend less money on hatchery
raised fish. In turn this will decrease costs to management
agencies and increase money from fishing license sales as channel
catfish fisheries improve. To achieve healthy, naturally
reproducing populations of channel catfish within lake
environments, managers must fully understand the ecology and
population dynamics of the lake before making management decisions.
Studies like ours can reveal important information about biotic
relationships within lake environments and future studies should
investigate these factors further. Due to limitations in our data
collection process, depth data could not be obtained for this
study. However, future studies should utilize factors such as
depth, daily average temperature, and proportional size
distribution to better understand relationships affecting channel
catfish growth.
APPENDIXFigure 1 a) Map image of Hauser Lake located about 8
miles west of Post Falls, Idaho, near the Idaho-Washington border.
b) Map image of Rose Lake located 23 miles south east of Coeur d
Alene, Idaho. c) Map image of Jewel Lake located southwest of
Sandpoint, Idaho.
Figure 2 Upper and lower confidence intervals centered on the
mean confidence interval for age two channel catfish in Hauser
Lake, Jewel Lake, and Rose Lake. The dashed lines are provided to
easily see areas of overlap.
Figure 3 Upper and lower confidence intervals centered on the
mean confidence interval for age three channel catfish in Hauser
Lake, Jewel Lake, and Rose Lake. The dashed lines are provided to
easily see areas of overlap.
Figure 4 Upper and lower confidence intervals centered on the
mean confidence interval for age four channel catfish in Hauser
Lake, Jewel Lake, and Rose Lake. The dashed lines are provided to
easily see areas of overlap.
Figure 5 Upper and lower confidence intervals centered on the
mean confidence interval for age two, age three, and age four
channel catfish within Hauser Lake. The dashed lines are provided
to easily see areas of overlap.
Figure 6 Upper and lower confidence intervals centered on the
mean confidence interval for age two, age three, and age four
channel catfish within Rose Lake. The dashed lines are provided to
easily see areas of overlap.
Figure 7 Upper and lower confidence intervals centered on the
mean confidence interval for age two, age three, and age four
channel catfish within Jewel Lake. The dashed lines are provided to
easily see areas of overlap.
Table 1 Surface area (ha), stocking rate (fish/ha), and total
number of species (including Ictalurus punctatus) for Hauser Lake,
Rose Lake, and Jewel Lake in northern Idaho.LakeSurface
areaStocking rate# of species
Hauser2232313
Rose122277
Jewel12464
REFERENCESAmerican Fisheries Society Idaho Chapter. 2014. Fishes
of Idaho. . Accessed 5 Nov 2014. Bailey, Reeve M. and Harry M.
Harrison Jr. 1948. Food Habits of the Southern Channel Catfish
(Ictalurus Lacustris Punctatus) in the Des Moines River, Iowa.
Trasactions of the American Fisheries Society 75: 110-138.Davis,
Kenneth B. 2009. Age at puberty of channel catfish, Ictalurus
punctatus, controlled by thermoperiod. Aquaculture 292:
244-247.Hubert, W. A., and M. C. Quist, editors. 2010. Inland
fisheries management in North America, 3rd edition. American
Fisheries Society, Bethesda, Maryland. Idaho Fish and Game [IDFG].
2014. Fish Stocking Information. Idaho Fish and Game. . Accessed 5
Nov 2014.Michaletz, Paul H. 2006. Prey resource use by bluegill and
channel catfish in small impoundments. Fisheries Management and
Ecology 13: 347-354.Michaletz, Paul H. 2008. Variable Responses of
Channel Catfish Populations to Stocking Rate: Density-Dependent and
Lake Productivity Effects. North American Journal of Fisheries
Management 29: 177-188. Moy, Philip B. and Robert R. Stickney.
1987. Suspended Spawning Cans for Channel Catfish in Surface-Mine
Lake. The Progressive Fish-Culturist 49: 76-77. Sismour, Edward N.,
Shelley C. Nellis, Scott H. Newton, D'arcy Mays, and Michael L.
Fine. 2013. An Experimental Study of Consumption of Channel Catfish
Ictalurus punctatus by Largemouth Bass Micropterus salmoides when
Alternative Prey Are Available. Copeia 2013(2):277-283.U.S. Fish
and Wildlife Service and Bureau of the Census [USFW]. 2002. 2001
national survey of fishing, hunting, and wildlife-associated
recreation Washington, D.C.: U.S. Government Printing Office.
