Publications (WR)
Water Resources
3-1989
Red swamp crayfish ecology in Lake Mead
Suzanne E. Leavitt
University of Nevada, Las Vegas
Jennifer Stephens Haley
University of Nevada, Las Vegas
Mikell Hager
University of Nevada, Las Vegas
Donald H. Baepler
University of Nevada, Las Vegas
Nevada Department of Wildlife
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Repository Citation
Leavitt, S. E., Haley, J. S., Hager, M., Baepler, D. H., Nevada Department of Wildlife (1989). Red swamp crayfish ecology in Lake
Mead.
Available at: http://digitalscholarship.unlv.edu/water_pubs/96
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Environmental Research Center
University of Nevada, Las Vegas
Las Vegas. Nevada 89154
(702) 739-3382
BUREAU Or RECLAMATION DCNVER LIBRARY
RED SWAMP CRAYFISH ECOLOGY IN LAKE MEAD
Suzanne E. Leavitt
Jennifer Stephens Haley
Mikell Hager
Dr. Donald H. Baepler
DATE DUE
SEP 23 (1997
Lake Mead Limnological Research C
Environmental Research Center
University of Nevada-Las Vegas
In Cooperation With:
The Nevada Department of Wildlif.f
David A. Buck
John Hutchings
QAVLORO
March 1989
Final Report
PRINTED IN U S A
ACKNOWLEDGMENTS
This study was funded by the Nevada Department of Wildlife. We would like to thank
them for their support. We would especially like to thank Dave Buck and John Hutchings of the
Nevada Department of Wildlife for their cooperation and involvement in this study. In addition,
we would like to thank Michele Salas for her help in the field and with the report graphics, typing,
and editing.
11
ABSTRACT
Red swamp crayfish (Procambarus clarkii) were trapped in Flamingo Wash, an urban wash
of Las Vegas, during four periods of 1988. Life history and reproductive success were determined.
The trapped crayfish were marked and released into a study cove in Lake Mead as part of an
experimental stocking program.
Retrap data from the study cove were used to determine life
history, habitat preferences, and movement patterns of the stocked crayfish.
In addition, a
literature search was done on red swamp crayfish ecology, including food preferences, life history,
habitat preferences and fish predation.
ui
ABSTRACT
Red swamp crayfish (Procambarus clarkii) were trapped in Flamingo Wash, an urban wash
of Las Vegas, during four periods of 1988. Life history and reproductive success were determined.
The trapped crayfish were marked and released into a study cove in Lake Mead as part of an
experimental stocking program.
Retrap data from the study cove were used to determine life
history, habitat preferences, and movement patterns of the stocked crayfish.
In addition, a
literature search was done on red swamp crayfish ecology, including food preferences, life history,
habitat preferences and fish predation.
ui
Table of Contents
Page
I.
Introduction
1
A.
B.
C.
D.
E.
1
3
4
6
6
History of Fisheries in Lake Mead
Habitat Preferences
Life History of the Red Swamp Crayfish
Feeding Habits
Predation on Crayfish
II.
Description of the Study Area
IE.
Methods
10
A.
B.
C.
10
10
D.
E.
F.
IV.
7
Literature Review
Lake-wide Crayfish Population Sampling
Population Sampling and Life History Evaluation
in Flamingo Wash
Lake Mead Stocking Program
1.
Marking and Release
2.
Monitoring
Predation by Game Fish
Habitat Improvement by Vegetation Introduction
Results
A.
B.
C.
D.
E.
F.
13
14
14
16
18
18
19
Literature Review
Lake-wide Crayfish Population Sampling
Population Sampling and Life History Evaluation
in Flamingo Wash
Lake Mead Stocking Program
1.
Life History
2.
Habitat Preferences
3.
Movement Patterns
Predation by Game Fish
Habitat Improvement by Vegetation Introduction
19
19
19
22
24
24
27
45
47
V.
Conclusions
47
VI.
Literature Cited
48
IV
List of Figures and Tables
Page
8
Figure 1.
Map of Lake Mead
Figure 2.
Lake Mead water elevations (in feet) from January 1984
through December 1988
9
Locations of red swamp crayfish sampling sites monitored
between October 1986 and July 1987
11
Distribution of red swamp crayfish in Lake Mead from
trap catches (October 1986 - July 1987)
12
Figure 5.
Location of study cove
15
Figure 6.
Trapline placement in the study cove
17
Figure 7.
Percent of red swamp crayfish trapped in each sex/age class in
Flamingo Wash during four trapping periods
21
Percent of red swamp crayfish trapped in each sex/age class in
the study cove during four trapping periods
25
Number of red swamp crayfish trapped at various distances
from the Lot 1, Lot 2, and Lot 3 release sites during the
first stocking period
28
Figure 10. Number of red swamp crayfish trapped at various distances
from the Lot 1, Lot 2, and Lot 3 release sites during the
second stocking period
32
Figure 11. Number of red swamp crayfish trapped at various distances
from the Lot 1, Lot 2, and Lot 3 release sites during the
third stocking period
36
Figure 12. Number of red swamp crayfish trapped at various distances
from the Lot 1, Lot 2, and Lot 3 release sites during the
fourth stocking period
42
Table 1.
Number of red swamp crayfish recaptured after each release
23
Table 2.
Percent recaptured from previous releases
23
Table 3.
Catch per unit effort of red swamp crayfish trapped
in various habitats
26
Mean temperature (C), dissolved oxygen (DO - mg/1),
conductivity (EC - micro mho/cm) and pH from the
surface of the water to the bottom of the cove at the
study site
46
Figure 3.
Figure 4.
Figure 8.
Figure 9.
Table 4.
List of Appendices
Appendix A.
Annotated bibliography to crayfish ecology.
Appendix B.
Habitat sampled by each trap during each introduction period.
VI
I.
INTRODUCTION
A.
History of Fisheries in Lake Mead
The sport fisheries in Lake Mead are comprised mainly of largemouth bass
(Micropteris salmoides), striped bass (Morone saxatilis), and rainbow trout (Salmo
gairdnerii). Largemouth bass were introduced into the reservoir in 1935 shortly
after the completion of Hoover Dam, and threadfin shad (Dorosoma petenense)
were introduced in 1954 to expand the forage base for largemouth bass (Allan and
Roden, 1978). The largemouth bass fishery began declining in 1963 after Glen
Canyon Dam was constructed 456 km upstream. The largemouth fishery declined
even more in the late 1970's, and the population is still severely depleted. Striped
bass and rainbow trout were introduced in 1969 to augment the failing largemouth
bass fishery. Although the lake has supported a substantial fishery in the past
(Allan and Roden, 1978), current evaluations of the fishery have provided little
hope for the future. The trout fishery collapsed in 1977, and the striped bass
fishery began experiencing problems in 1978 when emaciated fish appeared in the
population. Striped bass catch decreased drastically in 1979, and the population
was comprised of small and often emaciated fish during the early 1980's (Paulson
and Baker, 1984).
The red swamp crayfish is an important food source for two prominent
game fish in Lake Mead, the largemouth bass (Micropterus salmoides) and the
striped bass (Morone saxatilis), as determined by creel census data collected by the
Nevada Department of Wildlife (NDOW). Therefore, crayfish serve not only as an
important link in the food chain of fish, but also play an important role in recycling
nutrients from the benthos upwards into the higher trophic levels.
The red swamp crayfish was first reported from lakes Mead and Mojave by
Allan and Roden (1978). Jonez and Sumner (1954) had previously reported the
introduction of Astacus sp. in the Willow Beach area of Lake Mohave by bait
releases, but these records were not documented with collections.
Two lake-wide crayfish surveys conducted in October 1986 and April 1987
indicated that population densities of P. clarkii in Lake Mead are very low. This
species has, however, become established throughout the lake and is reproductively
successful (Peck et al., 1987). These results are inconsistent with food habitat
analysis completed by Albert and Baker (1982) which indicate that crayfish are
being utilized heavily as forage during certain times of the year.
This study is the result of a contract between the Nevada Department of
Wildlife (NDOW) and the Lake Mead Limnological Research Center (LMLRC) to
evaluate the potential for stocking red swamp crayfish (Procambarus clarkii) in
Lake Mead and whether these crayfish will become reproductively successful
resulting in a broader forage base for game fish.
The objectives of this study were to:
1.
Determine the distribution and relative abundance of red swamp crayfish in
Lake Mead on a seasonal basis.
2.
Determine the breeding season, reproductive success, growth patterns, and
food preferences for red swamp crayfish in Lake Mead.
3.
Study the life history of red swamp crayfish in Las Vegas urban washes to
determine breeding season, reproductive success, and growth patterns.
4.
Analyze patterns of crayfish predation.
5.
Monitor the success of the vegetation transplant project and recommend
specific plants that might be important to crayfish based on life history and
microhabitat data collected in this study.
B.
Habitat Preferences
Red swamp crayfish inhabit temporary lentic systems in its original home
range, the lower Mississippi River Valley. Habitats are dry in the summer and
crayfish survive in burrows. In the absence of predacious fish or in the presence of
sufficient cover to protect the crayfish from predation, it establishes sustaining
populations in both permanent lentic and lotic environments.
As a result of
introductions, its range now includes both the east and west coasts of the United
States, Hawaii, Japan, Africa, Central America, and Europe (Huner and Romaire,
1978). Konikoff (1977) found that the main factors regulating natural P. clarkii
populations were the hydrologic cycle and macrophyte densities and that predation
can compound the effects of these factors in already unfavorable environments.
Penn (1956) observed that in Louisiana most individuals of P. clarkii were
found in shallow water (less than 15 inches deep) which was either clear or muddy,
permanent, static, and exposed to full sunlight. Most collections were made in
habitats with mud bottoms and aquatic vegetation.
The aquatic plants most
commonly associated with crayfish included bulrush (Scirpus sp.), cattails (Typha
sp.), smarrweed (Pofygonum sp.), rush (Juncus sp.), and spiny naiad (Najas marina).
Baker (1980) found that Procambarus was most often found in slow-moving
water that was shaded, turbid, and had an abundance of aquatic vegetation for
cover.
Crayfish are most active at night (Penn, 1943). However, observation of the
diurnal distribution of the red swamp crayfish in a clear stream in California
showed a differential use of the center (exposed) and the bank (sheltered) portions
of the stream by juveniles and adult crayfish. Juveniles were found more frequently
in the open, unsheltered parts of the stream, and adults occupied the most
sheltered areas (Beingesser, 1985).
Witzig et al. (1983) found that P. clarkii densities were highest in shallow
water and dense vegetation.
When vegetation had decomposed and was not
available as cover, crayfish showed no preference for deep or shallow areas. The
authors suggested that terrestrial vegetation decomposed more slowly than aquatic
vegetation and, therefore, served as a better source of cover and nutrients.
C.
Life History of the Red Swamp Crayfish
Many details of the red swamp crayfish life history have been studied. The
following is a summary of information on red swamp crayfish life histories in
Louisiana presented by Penn (1956).
In the winter, red swamp crayfish activity is restricted and most of the
adults of both sexes over-winter in burrows in the drying marsh and swamp floors.
Juveniles pass the winter in the water in or near the same localities, growing
slightly. In January, with the advent of the pre-spring rains, the burrowing adults
enter the water; shortly thereafter, the form U males change to form I (sexually
active).
In the spring, with increasing temperature and plant food supply, the
juveniles grow rapidly, most of them reaching sexual maturity by May. 'Some
copulation occurs in late spring but apparently many of the mature females retain
sperm stored in their annul! from the previous summer and early fall.
The first eggs are laid and carried by the females in late June and early July.
Succeeding waves of egg-laying continue through August and early September.
Most, if not all, of the year old males are in form I during the summer. Copulation
occurs frequently in July and continues through September. Females which will live
throughout the coming winter molt after their young have become free-swimming.
The year's crop of juveniles appears in increasing numbers in late July and August.
The mature population disappears at this time and apparently many of the females
burrow.
In September, most of the form I males and a few of the mature females
leave the marsh by the tens of thousands and wander overland. Most of these
crayfish fall prey to other animals; the remainder probably die since they are in
extremely poor physical condition. The remaining adult females and large form II
males burrow before the winter drought and cold sets in. The juvenile population
remains in the water over winter.
Studies of crayfish in Atchafalaya Basin, Louisiana, which contains water
year round, resulted in the highest crayfish collection in May. By June, most
crayfish were mature, and breeding occurred in the summer and fall. Youngof-the-year appeared in December, and their peak growth occurred in the spring
(O'Brien, 1977). Red swamp crayfish have the potential, however, to reproduce
during a large part of the year (Konikoff, 1977). This gives crayfish populations
better tolerance of irregular variation in habitat conditions including variable
hydrologic cycles and changing vegetation communities.
Lowery and Mendes
(1977) noted that although a portion of the red swamp crayfish population in an
African lake was found to breed throughout the year, peaks of recruitment were
found associated with rising water levels.
Measurement of crayfish production in ponds with differing hydrological
regimes (one with permanent water, one with irregular flooding events, and a pond
with controlled flooding) showed that production was 32 times higher with a
controlled flooding regime than at the other two sites (Faille, 1980).
Changes in sex and sexual state (mature or reproductive to nonreproductive) ratios of crayfish populations occur seasonally and in relation to
different nitrogen levels in ponds (Rhodes and Avault, 1987a). Huner (1983) found
that development and molting of male crayfish occurred during different times of
the year dependent on different flooding cycles. However, crayfish in all flooding
cycles showed maturation peaks in the spring.
Rhodes and Avault (1987b) found that peak egg production occurs during
October of the female's first year.
Only 17 percent of the females observed
produced a second clutch of eggs the following April. Peaks in production observed
around December are probably the result of second population of late maturing
crayfish.
D.
Feeding Habits
Penn (1956) reported that P. clarkii was observed feeding on the aquatic
vegetation including Achyranthes, Jussiacea, Pofygonum, Sagittaria, Najas, Cfiara,
Elodea, Potomogeton, and algae but not on Myriophyllum and Marsilea. Crayfish
will also feed on periphyton, detritus, gastropods, and immature benthic insects
(Lorman and Magnuson, 1978).
E.
Predation on Crayfish
Saiki and Ziebell (1976) studied the effect of recently established crayfish
populations on growth of stunted bass in an impoundment before the introduction
of shad as additional forage.
condition,
Crayfish (Orconectes causeyi) densities," bass
and food habits were evaluated over a one-year period.
Young-of-the-year crayfish appeared in the spring, and maximum adult densities
were measured in June. Bass 7.0 cm to 14.9 cm fed on crayfish in the spring, and
larger bass consumed crayfish all year.
Growth of older bass improved once
crayfish were available as forage, and condition factors for the fish also increased.
Stocking of crayfish is recommended to increase the forage base for bass in new
impoundments.
Saiki and Tash (1979) observed crayfish behavior in relation to predation by
bass in laboratory and field situations. Predation rates on crayfish were examined
in relation to density of plants as cover in plastic pools. Increased plant density
significantly decreased predation rates. Size selectivity by bass for smaller crayfish
also diminished at higher plant densities.
Huner (1983) noted that experimental ponds containing green sunfish and
crayfish (Procambarus spp.) showed significantly lower crayfish production levels
than ponds containing only crayfish.
II.
DESCRIPTION OF THE STUDY AREA
Lake Mead is located on the lower Colorado River where it forms the border
between Clark County, Nevada, and Mohave County, Arizona (Figure 1). The regional
climate is arid with an annual mean precipitation of less than 11.6 cm. The mean daily
maximum temperature for July is 40°C and the mean daily minimum temperature for
January is -1°C. Lake Mead was formed with the closure of Hoover Dam in 1935. The
lake first reached maximum operating level in 1944, has a surface area of 660 km2 and a
volume of 36 km3, and is one of the largest reservoirs in the United States. At maximum
operating level, the shoreline of Lake Mead is 885 km, with a maximum length of 183 km
and a maximum width of 28 km. It has a maximum depth of 180 meters and a mean depth
of 55 meters. The all-time maximum operating level was reached during July of 1983.
Since that time, the operating level has been successfully maintained at approximately 368
meters with annual variation of approximately four meters. In 1988, however, the lake
level dropped approximately four meters between March and September, and remained at
this low level for the rest of the year (Figure 2). Since the closure of Glen Canyon Dam in
1963 to form Lake Powell approximately 460 km upstream, most of Lake Mead has
LIBRARY
AUG 2 ! 1997
Buieau ol Reclamation
Reclamation Service Center
Lake Mead
Arizona - Nevada
Shoreline Elevation: 3 6 6 in
lilue Point bay
Roqei's Bay
00
W a t e r Barge Cove
Fish
Hatchery
Cove
Hoover Dam
Figure 1.
Map of Lake Mead.
Grand
Wash
UJ
__i
LU
Ld
1200^
1195
J
F
M
A
M
J
J
A
S
O
N
D
MONTHS
Figure 2. Lake Mead water elevations (in feet) fron January
1984 through December 1988.
become extremely oligotrophic, with measured orthophosphorus levels as low as 0.001 mg/1
(Paulson and Baker, 1984).
The dissected nature of the desert terrain flooded by Lake Mead has resulted in a
cove and point topography. Many of the coves are located at the mouths of dry washes and
receive inflows of runoff water containing nutrients and particulate organic matter during
the infrequent rains.
III.
METHODS
A.
Literature Review
A computerized abstract search was done to gather information on the red
swamp crayfish.
Approximately 200 articles were collected from numerous
scientific publications and reviewed, and those considered important to the
research were included in an annotated bibliography (Appendix A).
B.
Lake-wide Crayfish Population Sampling/Effects of Overton Arm Fertilization on
Crayfish Populations
A study to evaluate the population densities and distribution of red swamp
crayfish in Lake Mead was started in the fall of 1986 (Peck et al., 1987). It was
concluded from the lake-wide sampling (Figure 3) that red swamp crayfish were
present throughout the lake and also occurred in some drainages entering the lake
(Figure 4). Besides being widely distributed throughout the system, the population
was found to be reproductively active.
However, trap data indicated that the
population density was extremely low. A catch per trap day (CPTD) value of one
or less was common for the lake during the sampling period.
Therefore, it is
extremely difficult to study crayfish reproductive cycles, growth patterns, and
10
Muddy Arm
Virgin Bowl
Lake Meacl
Arizona - Nevada
Shoreline Elevation: 3(.Hi in
Las Vegas Wash
Hoover Dam
Figure 3.
Locations of red swamp crayfish sampling sites monitored between October 1986 and July 1987
Overton Wildlife
Management Area
Virgin River
Procambarus clarkii
LEGEND
Shoreline Elevation 366
0
5 km
in Lake Mead
Rogers Spring
Bighorn I s l a n d
Las Vegas
Bay
Hemenway
Harbor
f«cl Cnvn»
?igure
4. Distribution of red swamp crayfish in Lake Mead from trap catches (October 1986-July 1987).
habitat preferences by trapping or observation of naturally existing populations.
Consequently, the trapping effort was reduced significantly from that outlined in
the project proposal.
An extensive trapping effort did, however, take place in the Overton Arm in
October 1988 in order to investigate the effects of the Overton Fertilization Project
on crayfish populations.
In May and June 20,000 gallons of ammonium
polyphosphate were put in the Overton Arm with the use of 200 volunteer boats.
Traps were placed in the following Overton Arm areas: Mud Wash, Bark Bay, Fire
Bay, Salt Bay, Glory Hole, Lime Wash, Calico Bay, and Roger's Bay. In each area
a line comprised of 8 traps was set along the shoreline in 1-3 meter water depth in
the following habitats: mud, brush, rocks/boulders, and spiny naiad (Najas marina).
Results from this effort were compared to results gathered by previous
investigators before the May 1988 Overton Arm Fertilization.
C.
Population Sampling and Life History Evaluation in Flamingo Wash
Crayfish were trapped in Flamingo Wash four times in 1988: January,
March, July, and November. Minnow traps with 4 cm openings were baited with
chicken pieces and set at various locations in the wash. The traps were retrieved
after 24 hours. Crayfish were sexed and carapace length was measured. Habitat
conditions for each trapped area were recorded, including the presence of aquatic
vegetation or other forms of cover. Trapping continued over several days until
approximately 1,600 individuals were caught. These individuals were then used in
the stocking program.
13
D.
Lake Mead Stocking Program
1.
Marking and Release
Individuals trapped in Las Vegas Wash were placed in ice chests
and transported to the laboratory where they were marked. Three different
marks were used on each third of the trapped population. In January 1988,
marks were placed on the left-most uropod and consisted of one hole for
Lot 1, two holes for Lot 2, and a diagonal cut for Lot 3. Different uropods
were marked with this code on each of the subsequent releases; in March,
the second uropod from the left was used, in July, the third from the left
was marked, and in November 1988, the right uropod was marked. Each
marked group had an equal proportion of adults to juveniles and males to
females.
Crayfish were transported to a cove on Saddle Island in Boulder
Basin of Lake Mead (Figure 5). This cove was selected because it had a
wide range of habitats available for crayfish, including brush, mud, gravel,
rocks, emergent plants, inundated terrestrial plants, and aquatic plants.
In January, crayfish in Lot 1 were placed on a muddy bank with
inundated terrestrial shrubs within the cove.
Individuals in Lot 2 were
placed near a small cattail stand, and individuals in Lot 3 were released on a
gravel and rock embankment. As water levels receded during the year, the
habitat in Lot 1 and Lot 2 release sites changed in subsequent
introductions. In April, Lot 1 was released into a combination of inundated
terrestrial and aquatic vegetation, with aquatic vegetation becoming the
principal habitat in the last two introductions. Habitat at Lot 2's release
area remained the same until the November release,
14
when aquatic
Boulder Basin
Figure 5. Location of study cove.
15
vegetation replaced the now desiccated cattail stand. The habitat at the Lot
3 release site remained the same for all introductions.
2.
Monitoring
Two days following the transplant, a series of ten 80 m long trap
lines were established in the study cove (Figure 6). Eight standard size
crawfish traps (41.9 cm long, 22.7 cm diameter, and a 5.7 cm diameter
entrance) were used per line, and the traps were placed 10 m apart.
Chicken pieces were used as bait. After the traps were set, a diving survey
of the cove was made to map the general morphometry of the cove and the
exact placement of each of the traps within various habitat components
(plants, brush, mud, and rocks).
Appendix B describes which trap
lines/traps sampled a given habitat during the four monitoring periods.
From this information, a' catch per unit effort (CPUE) was calculated for
each habitat type represented in the study area.
CPUE is calculated by
taking the total number of crayfish caught per habitat type during a trapping
period divided by the total number of traps used in that habitat during the
same period. In addition, the crayfish movement patterns were determined
by dividing the study cove into sections according to trap distances away
from initial release sites. The distance categories used were: 0-40 m, 40-80
m, 80-120 m, 120-200 m, and 200+ m. The distances moved by crayfish
from each lot's release site were figured for each monitoring date.
Temperature, dissolved oxygen, conductivity, and pH were measured during
each of the monitoring periods.
16
Figure 6.
Trapline placeman! in- the study cove.
The trap lines were retrieved 24 hours after their placement and the
trapped crayfish were aged as adult or juvenile (carapace length less than 30
mm), sexed, and identified according to the trap they were in and their lot
number. The traps were then re-established in their permanent sites, and
crayfish were returned to the general area the trap line covered.
Traps
were set and retrieved every 24 hours for four days and then periodically
thereafter or until returns reached 10 percent of the first day's catch.
E.
Predation by Game Fish
NDOW conducted an annual creel census of the fish caught by anglers in
Lake Mead from August 1987-August 1988.
From this census, the stomach
contents of each creeled game fish (largemouth bass and striped bass ) were
analyzed and the percentage containing crayfish was determined.
F.
Habitat Improvement by Vegetation Introduction
As part of the Cover Enhancement Project funded by NDOW, 1,200 sago
pondweed tubers (Potamogeton pectinatus), an aquatic plant species, were placed in
Roger's Bay in the upper basin of Lake Mead and 1,200 tubers were placed in Fish
Hatchery Cove in the lower basin (Figure 1).
Tubers were wrapped in cheesecloth bags and weighted with gravel. These
bags were evenly distributed throughout the coves from the side of a boat to depths
of between 2 and 15 meters. These introduction sites were monitored periodically
for plant growth, percent cover, and fish use.
Terrestrial and emergent vegetation species were also planted in the spring
of 1988. 154 rooted woody plants and 344 direct woody cuttings were introduced at
Bluepoint Cove in the upper basin in April and May 1988 (Figure 1). 241 rooted
woody plants, 181 woody cuttings, and approximately 242 emergent plants were
18
introduced at Fish Hatchery Cove in April and May. Approximately 242 emergent
plants were introduced at Roger's Bay in May 1988. In total, approximately 1,400
terrestrial and emergent plants were introduced in April and May. Species planted
include: seepwillow baccharis (Baccharis glutinosa), willows (Salix gooddingii and 5.
exigua),
narrowleaf cattail (Typha angustifolia), and bulrush (Scirpus robustus).
Sites were monitored bimonthly for survival and establishment of introduced
plants.
IV.
RESULTS AND DISCUSSION
A.
Literature Review
Appendix A contains an annotated bibliography of crayfish life histories,
habitat requirements, effects and types of predation, and general crayfish ecology.
B.
Lake-wide Crayfish Population Sampling
Trapping after the Overton Arm Fertilization Project resulted in a zero
CPTD; the CPTD for the same area during the 1986 trapping effort was 0.05.
Based on these results, it does not appear that the fertilization project had an effect
on crayfish population densities in the Overton Arm. Therefore, it is concluded
that the fertilization project did not have an effect on the benthic invertebrates or
crayfish densities.
C.
Population Sampling and Life History Evaluation in Flamingo Wash
Areas of Flamingo Wash, a natural drainage of the Las Vegas Valley, were
sampled four times during 1988. Life history and population dynamics of the red
swamp crayfish were determined. From these data, the highest crayfish densities
were found in areas with a mud or silt bottom, some rocks, and extensive growth of
cattails. Water depths ranged from 15 cm to 2 m, and there was a constant source
19
of slow moving water. Adult females represented approximately 44 percent of the
total numbers caught for all the sampling dates except November-December when
there was a 10 percent increase in the proportion of adult females (Figure 7).
Adult females represented the dominant sex/age class for the 1988 sampling. In
the April-May and July-August sampling periods, adult form I males represented 45
percent of the trapped crayfish, with 25 percent and 37 percent in the
January-February and November-December periods.
Adult form II (sexually
inactive) males represented less than 10 percent of the trapped crayfish for all four
sampling periods. In the January-February period, approximately 12 percent of
trapped crayfish were represented by juvenile males and females, with their
percentages decreasing to 1 percent in the November-December sampling period.
The ratio of juvenile males to females was 1:1 during the sampling periods.
It appears that there were no significant seasonal variations in the
percentages of adult form II males and adult females; only the adult form I males
and juveniles exhibited seasonal variations. Typically, the frequency of form II
males increases in the winter when reproduction ceases and sexually active males
(form I) molt into form IPs (Penn 1956). However, there was a decrease in the
occurrence of form II males during the winter in Flamingo Wash.
This
inconsistency is either the result of reduced trapability of form IPs due to their
susceptibility to predation, or a die-off of form Ps from low reproduction. The
juveniles caught in January-February represent the release of over-wintered
juveniles. These crayfish then matured and became adults by late spring/early
summer. An additional increase in the number of juveniles should have occurred in
July-August following the peak egg laying in June; this increase was not picked up
in our sampling because of their reduced trapability in the summer due to
increased predation. In conclusion, it appears that the life history of red swamp
20
100-,
ESS Adult Female
CZ1 Adult Male 1
tZ) Adult Male 2
CD Juvenile Male
•I Juvenile Female
1
90 -j
8070-
-£ 600)
o
50i-_
0)
CL
40-
3020-
s
^
_^
r^
\
^
s
\
\
10-
X
n
X
R[ 1
Jan - Feb
^
X
X
X
X
^ X
X
X
X
X
^ X
X
X
X
Rn.
April - May
\
^ X
Y
s
\
X
X
\
X
X
FL_
July — Aug
X
FL_
Nov - Dec
Rgure 7. Percent of red swamp crayfish trapped in each sex/age
class in Flamingo Wash during four trapping periods.
21
crayfish in Flamingo Wash is similar to the life history patterns reported in the
literature.
D.
Lake Mead Stocking Program
During each introduction, 1,600 marked crayfish were released into three
areas of the study cove. An estimate of the native population in the study cove, life
history trends of the crayfish in Lake Mead, habitat preferences, and movement
patterns were determined from the subsequent monitoring. A total of 145 crayfish
were recaptured for the January-February release, 661 for April-May release, 376
for July-August, and 575 for November-December releases (Table 1).
Using
Peterson's mark-recapture equation,
Marked sample
_
M sample + U sample
M total
M total + U total
the native population of the study cove was estimated to be 65 individuals. The
estimated number of native crayfish corresponds to a CPTD of 0.13 which
compares to the outer Las Vegas Bay CPTD value of 0.10 calculated during the
1987 lake-wide sampling (Peck etal, 1987).
In addition to low recapture numbers for each release, there was also a low
percentage of hold-overs from previous releases. Only 6.2 percent of the crayfish
stocked during the January-February release (Introduction 1) were recaptured
during the April-May monitoring, with none being caught in the July-August or
November-December periods. The April-May release had 2.9 percent held over
into July-August, and only 0.3 percent of the July-August crayfish were recaptured
during the November-December monitoring (Table 2). Low returns from previous
releases are probably due to movement of crayfish out of the trap range. Also, it is
possible that some of the crayfish died due to stress stemming from the
introductions, predation, or natural causes.
22
Table 1:
Number of red swamp crayfish recaptured after each release. Trapping continued
until success was 10 percent of initial catch.
Trapping Dates
January-February
April-May
145
July-August
661
376
November-December
575
Table 2: Percent recapture from previous releases.
Trap Dates
Jan-Feb
April-May
July-Aug
April-May
6.2%
N/A
N/A
July-Aug
0
2.9%
N/A
Nov-Dec
0
0
0.3%
23
1.
Life History
Percentages of adult females and form I males in the study cove
were slightly different from those in the Flamingo Wash; however, they
followed the same patterns over time (Figure 8).
There were a lower
precentage of form II males in April-May and July-August than the other
stocking periods.
period.
The peak juvenile occurrence was in the July-August
The life history trends exhibited by the red swamp crayfish in
Flamingo Wash appear to parallel the trends exhibited in the study cove.
2.
Habitat Preferences
The most preferred habitat was emergent vegetation represented by
a small stand of cattails (Typha angustifolia).
A CPUE value of 20.0 was
calculated for January-February (Introduction 1) release and 62.0 and 25.0
for the April-May (Introduction 2) and July-August (Introduction 3)
releases (Table 3). By the fourth introduction (November-December), the
cattail stand was desiccated, due to receding lake levels, and not available to
the crayfish.
The next most preferred habitat was inundated terrestrial
shrubs represented by a small stand of seepwillow baccharis (Baccharis
glutinosd) in another area of the cove.
This habitat was only available
during the first two introductions, with CPUE values of 2.5 and 14.0
respectively.
Submerged aquatic vegetation was the third major habitat
selected by red swamp crayfish, with sago pondweed (Potamogeton
pectinatus) occurring in the April-May and July-August releases and spiny
naiad (Najas marina) in the November-December release. Their calculated
CPUE values were 12.75 and 6.83 for sago pondweed and 18.43 for spiny
naiad.
24
100-|
"
90 "I
QQ j
\
70-£
ES Adult Female
Cn Adult Male 1
CZ] Adult Male 2
i Juvenile Male
•i Juvenile Female
60-
(U
\
(U
S
\s
o 50-
a. 4030-
—
n.
s9 x
X
\
^
\
S
^
Rn.
Jan — Feb
I
^
X
X
s X
s
s X
s x n ——
April — May
X
X
X
X
X
X
X
X
$
I
s x
^N
X
x
s x
2010-
5
*
X
nfll
July — Aug
x
Y
PL. '
Nov — Dec
Rgure 8. Percent of red swamp crayfish trapped in each sex/age
class in the study cove during four trapping periods.
25
Table 3:
Catch per unit effort of red swamp crayfish trapped in various habitats. POPE =
sago pondweed (Potamogeton pectinatus} NAMA = spiny naiad (Najas marina).
Habitat
Jan-Feb
Cattails
20.00
62.00
Inundated
Terrestrial
Shrubs
02.50
14.00
Submerged
Aquatic
Vegetation
April-May
July-Aug
Nov-Dec
25.00
12.75
(POPE)
06.83
(POPE)
18.43
(NAMA)
05.58
Rocks
01.82
06.98
04.40
Brush
01.00
03.50
03.00
Gravel/Sand
00.82
03.41
01.64
01.29
Mud
00.41
02.07
01.27
01.22
26
Of the remaining habitat types sampled, rocks had CPUE values for
four introductions of 1.82, 6.98, 4.40, and 5.58, respectively. Brush was
available in the first three introductions with CPUE's of 1.0, 3.5, and 3.0.
CPUE's in gravel/sand were 0.82, 3.41, 1.64, and 1.29. Mud was the least
preferred habitat with a CPUE of 0.41 for January-February, 2.07 for
April-May, and 1.27 and 1.22 for the last two introductions, respectively.
The forms of vegetation selected by red swamp crayfish as preferred
habitats offer a source of cover and food to the crayfish. By living at the
bases of cattails and inundated terrestrials and within the dense mats
formed by aquatic vegetation, the crayfish are better able to avoid predation
by fish. In addition, the plant material provides an accessible food source
for the resident crayfish. When vegetation is not available, rocks and brush
are the next preferred habitats. However, they only provide a limited form
of cover, and they also provide substrate for periphyton as a food source
during certain seasons. Gravel/sand combinations and mud were the least
preferred habitat because they offer virtually no cover or food sources to
the crayfish.
3.
Movement Patterns
In addition to life history and habitat preferences of the stocked
crayfish, the general movement patterns were also determined from the
monitoring.
During each of the introductions, there appeared to be a
steady movement of crayfish out of the cove and into the surrounding areas.
Figure 9 shows movements of crayfish released from the lot 1, 2, and 3
release sites for the January-February introduction. Crayfish released at
the lot 3 location exhibited the most movement throughout the monitoring
27
CD
?J
Number of crayfish trapped
Nrrber of crayfish trapped
I
ro
01
ro
V
0
I-
o
r
J
1
\
Q
1 _
00
8
^
o
o
o
T
8
8
8
b
I
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o
1
4
o
4
8 S
8
Number of crayfish trapped
8
5
1
NuT6sr of crayfish trapped
03
03
1
o
CO
o
03
03
o
ro
8
\
\
50\
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1
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8
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|
i
1
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• i
NLmber of crayfish frcpped
5... .8
Number of crayfish trapped
03
03
CO
ro
ro
03
figure y.
Number or red swamp craynsn trapped at various distances trom the Lot 1,
Lot 2, and Lot 3 release sites during the first stocking period
(January 26, 1989). (Continued)
Lot 2
01-28-88
01-29-88
70
70
60
50
I 50
50
.-6
1
f. *°
8
•a *>
4O
JO
| 20
20
10
0
0-40
4O-80
80-120 120-200
20O+
0-4O
4O-aD
02-02-88
8O-120 12O-200
20O+
02-03-88
70 r
/u
tSSSSSs!
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60-
SO
lillO 1
$
£ 40
1
%
•*.
1
1
20
10
20
10
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0
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4O-60
80-120 120-200
200+
1
1
0-40
4O-80
02-12-88
^
„
1
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1
80-120 120-200
1
200+
02-25-88
/U
70
cssssss
ESSSSS9
kilro 1
tx)
60 r "" '
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• " •"" •
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i
r
10
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80-120 120-200
i
0
1
1
1
1
200+
Ostcnce moved from htroobcticn site
(meters)
Distance movea from htrodjction site
(meters)
29
1
O
OJ
\
8
S
S 8 8
Number of crayfish trcpped
CO
CO
ro
2-3-
3 i;
2
f
CD 3
O
^
i\
r
\
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I
1
1
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B
|
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S S 8
Number of croyfish trcpped
8
Number of crayfish trapped
co
CO
O
CJ
rn
CO
0
(O
0
(0
V_
1)
I
?.
I
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8
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Number of crayfish trapped
]
•
j
i
Number of croyfish trcpped
.
CD
CD
(O
0
i-«
1
8
03
co
ro
1
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=
i
8
period, with no crayfish from this group being trapped on the last date. The
majority of these crayfish were trapped between 80 and 200+ m from the
release site. Crayfish released at the lot 2 location appeared to have the
least amount of movement, with the majority of crayfish trapped in the 0-40
m range. Movement from the lot 1 location also appeared to be minimal.
Lot 1 and 2 crayfish were released into areas with terrestrial or emergent
vegetation, which may explain the slower movement out of these areas.
Crayfish from lot 3 were released on a gravel and rock embankment which
provided little food or cover to the crayfish. This presumably explains the
greater amount of movement from this area.
During the April-May release, lot 3 crayfish exhibited the same
movement trends as in the first release, with the majority of crayfish caught
between 80 and 200+ m (Figure 10). Crayfish released at the lot 2 location
were mainly caught in the 0-40 m range except on the last date when they
were found in the 80-120 m and 200+ m areas.
Crayfish from lot 2
appeared to have the same movement trends in the April-May release as in
the January-February release. Lot 1 crayfish showed greater movement in
the April-May release than in the January-February release, with crayfish
being caught in the 80-120 m and 200+ m areas on the last date. This is
probably due to receding water levels which reduced the amount of
inundated terrestrial vegetation available to the crayfish during the second
introduction.
In addition,
some crayfish released during the first
introduction in lot 1 and 3's locations were re-caught in all of the distance
ranges during the April-May monitoring. However, first introduction lot 2
crayfish were found only in 0-80 meters from the release site.
31
OJ
NJ
o
5
8
iS
S
B
Number of crayfish trapped
Number of crayfish trcpped
8
03
T
03
I
3
6 8
03
CB
6
«
03
02
03
8
•
8
o
8
o
en
5
Number of crayfish trapped
a s a 8 a
timber of crayfish
o
Ol
I
*
Number of crayfish trapped
8
Number of crayfish trapped
10
OJ
5
S
8
8 8 S 8
Number of crayfish trcpped
ti
Number of crayfish trqpped
8
ro
o
01
I
CD
TCD
ro
I
3
8
o
i
o
i
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o
Number of crayfish trapped
o
|!I
Number of crayfish trapped
CD
ca
O
02
03
CD
8
S 8
8
iS
S
S
CD
CD
o
m
o
en
1
II
Number of crayfish trapped
8
Number of crayfish trapped
figure J.O.
iNumuej. OL leu swamp cj.dyj.ibJi Liappeu di_ Vdixous uxsLdiiceb iioin cut; J-.OL x,
Lot 2, and Lot 3 release sites during the second stocking period
(April 30, 1988).
(Continued)
Lot 3
05-02-88
05-03-88
70
60
50
20
10
0
0-4O
4O-80
80-120 120-200
20O+
0-4O
4O-80
80-120 120-200
05-06-88
05-04-88
.-5
20O+
70
70:
60
60!
50
50
4O
X 40
g
30
20
20
10
10
0
0-4O
4O-BO
SO-120 120-200
200+
0-40
40-BO
80-120 120-200
200+
05-26-88
05-12-88
70
70
60
60
50
*
40
40
^o
g
-5 »
20
20
10
10
0
0-4O
4O-80
80-120 120-200
20O+
D'etnce moved from htrtxLictcn site
I
0-4O
T
4O-80
I
8O-120 120-200
200+
Distance movod fran niroduction site
(meters)
(meters)
34
Crayfish released in lot 3's location in July-August again exhibited
the most movement, with the majority of the crayfish being caught in the
200+ m area (Figure 11).
Lot 1 crayfish appeared to move out of the
release site at a slower rate than in the previous two introductions; however,
by the last monitoring date no crayfish from lot 1 were trapped. During
July-August, a stand of sago pondweed was present in the lot 1 release site
which may explain the slower outward movement, whereas the cattail stand
in lot 2's site was gradually becoming desiccated due to receding water
levels. This prompted more movement from lot 2 crayfish than had been
exhibited in the first two releases. Second introduction crayfish were also
caught during the July-August monitoring, with lot 1 and 2 crayfish caught
from 0-120 meters away from their release sites, whereas lot 3 crayfish were
found only in the 120-200 m range. Crayfish from lot 1 and 2 sites seem to
stay in the release area longer than lot 3 crayfish which tended to move out
of the study cove.
Figure 12 shows movements of crayfish released at lots 1, 2, and 3
for the November-December introduction. Crayfish released at lot 1's site
exhibited a minimal outward movement, with the majority remaining in the
0-40 m area. Lot 2 and 3 crayfish appeared to move steadily out of the
release sites, with crayfish caught only in the 40-120 m and 200+ m areas
for lot 2, and from 80-200+ meters for lot 3 on the last monitoring date.
During the November-December release, lot 1's area had a dense bed of
spiny naiad which offered ample cover for the crayfish, whereas lot 2 had a
few scattered patches of spiny naiad and lot 3's area was comprised of
gravel and rock. Apparently, neither area provided enough cover to hold
the released crayfish in the area. However, lot 3 crayfish were the only ones
35
Figure 11.
Number ot red swamp craynsn trapped at various distances rrom tne L,ot x,
Lot 2, and Lot 3 release sites during the third stocking period
(July 14, 1988).
Lot 1
07-16-88
07-17-88
70 —
mi^m
30
'
'"
htTD 2
T)
f
''
| 50-
;5 40
-5
"S,
30
$
3
20 i
i
4O
§
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o
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1
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0
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SO-120 120-200
1CXH-
SSBI
SB
i
0-4O
i
-iO-80
SO-120 120-200
200+
D'stoxc moved trcm niroducticn site
(meters)
Oistance moved from ntrtxtictjon site
Imetersl
07-18-88
07-19-88
70
70
60
hlro 3
60
50
I
40
^-o
ssar
ggB
r
htro 3
5°
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8
30
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20
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I 20
10
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4O-BO
i
80-120 120-200
0-»O
200+
40-flO
80-120 120-200
200+
Dstance moved from ntnxtictcn ste
(meters)
Distance mowed from ntrodicticn site
(meters)
36
Figure 11.
Number of red swamp crayrish trapped at various distances trom the Lot 1,
Lot 2, and Lot 3 release sites during the third stocking period
(July 15, 1988).
(Continued)
Lot 1
07-20-88
07-28-88
70
HBOI
00
60
50
-s
40
!
1
DO
•ft
40
1
30
1
i
20
30
20
10
10
0
u
0-40
4O-80
8O-120 120-200
litna 3
^
200+
i
0-4O
4O-SO
08-11-88
70
60
X
40
30
20
10
I
0--4O
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l
80-120 120-200
l
200+
mcMsd hun ntrodjcticn stto
(meters)
Oistnce moved frcm ntrodjction site
(meters)
0
]
i
I
40-80
T
T
80-120 120-200
200+
O'etnce moved fiun htnoduction ste
(meters)
37
OJ
00
Number of crayfish trapped
Number of crayfish Iropped
CO
03
CD
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CB
03
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iff
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20-
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6
8
8
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Number of crayfish trapped
IS
of crayfish trcpped
8
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Number of crayfish tapped
8
Number of crayfish trapped
CO
CO
O
CD
I
03
CO
<s
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o
8
£
8
8
IS 6
8
Number of acyfish trapped
8
Number of crayfish trapped
CD
I
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03
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(•0
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Number of crayfish trapped
c5
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Number of crayfish trapped
o
co
g
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I
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CD
03
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8
Number of crayfish trapped
1
I
CO
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03
03
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f\
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Number of crayfish trapped
CD
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e
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rt
H-
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3 ft
cu
£0
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Nunnber of crayfish trapped
Number of crayfish trapped
S3
O
"^
O
Ui
§
T
o
o
6
8
6 8
8
is
£
8
Number of crayfish trapped
8
Nurrber of crayfish trapped
i
T
CD
CD
5r+1
ro
o
C
fD
3
rt
HD
VI
h1- o
riyure xz.
iMumoer o i rea swainp eraynsn trapped ac various distances rrom tne Lot 1,
Lot 2, and Lot 3 release sites during the fourth stocking oeriod
(November 15, 1982).
Lot 1
11-17-88
11-19-88
70p
TO
J
40 '
b
'o
| 20
10
0
4O-flO
80-120 120-200
200+
0-40
4O-60
11-20-88
BO-120 120-200
200+
11-29-88
70 r
70
60
60
40
I
30
^
10
10
0
0
0-4O
4O-80
80-120
12O-200
0-40
200+
4O-80
Dctunce
O'sbnce moved from htroductbn ste
(meters)
12-13-88
70
B3SSB?;fq
r>tro 4-
60
50
£
40 ...
o
»
........
-
20
10
gBSu-—
0-40
4O-flO
r^-^-^"" '•
80-120 120-200
200+
D'stcnce movea from ntroctiction ste
(meters)
42
80-120 120-200
200+
frxum puxxkjctcn site
i meters)
O
O
T
D
O
i
o
O
Number of crayfish trapped
O
O
CO
!-
o
o
Njrtier of crayfish trapped
Number of crayfish trapped
f*.
o
03
03
CD
I
fO
03
03
I
(0
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Number of crayfish trapped
o
y
Number of crayfish trapped
i
i
s 8 -a s 8
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—
i
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u>
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o
03
03
co
CD
03
3
o
ft
a
(D BJ
H 3
0
ngure i/.
Numoer or rea swamp crayrisn trapped at various distances rrom tne Lot 1,
Lot 2, and Lot 3 release sites during the fourth stocking period
(November 15, 1982).
(Continued)
Lot 3
11-17-88
11-19-88
70
/o
60
60
BBH
htro 3
50
.•6
-
.-6
40i
-
-
-._
hire 4
40
30
20j
b-pr •
i* 1
10
n iHi
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10
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i
i
80-120 120-200
0
200+
1
0-4O
4O-flO
11-20-88
itif'•'*•
20O+
11-29-88
70
70
60
60
I 50
50
I
40
8
[
80-120 120-200
«>
X
20
101
0
4O-BO
Dstoncc
80-120 120-200
200+
0-40
fru 1 1 intrtxijctian site
(meters)
40-flO
80-120
120-200
200+
O'stnoe mc*«d from ntrxxbcticn ste
(meters)
12-13-88
70
60
50
40
30
20
10
0-40
4O-60
80-120 120-200
200+
Distance m&ad frcm ntroduction site
(meters)
44
caught from the July-August release. They were found 120-200+ meters
away from their release site.
In conclusion, the crayfish in lot 3 showed more movement than in
lots 1 and 2. This was probably due to an inadequate source of cover in the
lot 3 release location.
In addition, it is possible that the habitat and food sources in the
study coves were inadequate to handle the number of crayfish released
during each introduction, thereby contributing to the outward movement
patterns exhibited by the released crayfish.
From limnological data
collected in the cove (Table 4), there were no signs of water quality
problems (other than low productivity) which might have also caused the
outward movement.
E.
Predation by Game Fish
Wilde and Paulson (1989) found that in Lake Mead, the major component
of striped bass diets during the spring of 1981 and 1982 were red swamp crayfish.
However, the incidence of crayfish in game fish stomachs from August 1987 to
August 1988 was extremely low. Of 975 striped bass stomachs analyzed, only 10
contained red swamp crayfish remains. Ninety-six largemouth bass stomachs were
also analyzed for this period, and again only 10 contained crayfish remains. Even
though recent stomach analysis indicates that red swamp crayfish are a minor
component in the Lake Mead game fish diets, it is well documented in the
literature that crayfish are utilized by bass as food.
F.
Evaluation of Plant Introductions
Unpredicted low lake levels in 1988 resulted in the loss of many terrestrial
plants. Seepwillow baccharis, however, had the highest survival rates. Aquatic
plant tubers had 100 percent germination success and provided 70 percent cover for
45
Table 4:
Mean water column temperature (C), dissolved oxygen (DO-mg-1), conductivity
(EC-micro mho/cm) and pH in the study cove.
Date/Time
Temp.
DO
Cond.
pH
1-28-88/1305
12.12
09.52
815
8.14
2-25-88/1215
12.23
10.52
816
8.21
5-12-88/1310
19.07
10.63
865
8.42
8-11-88/1250
27.98
10.21
867
8.54
46
fish by July 1988 (Haley et al., 1989).
From the literature and the results of the introduction monitoring, it is
apparent that vegetation plays a key role in habitat preferences of red swamp
crayfish. Therefore, plant introduction into areas with crayfish would be beneficial
to the population.
V.
CONCLUSIONS
A.
The current red swamp crayfish population density in Lake Mead is extremely low;
however, they occur throughout the lake.
B.
The life history of red swamp crayfish in Lake Mead and in Las Vegas urban
washes is similar to that reported in the literature.
C.
The population density of red swamp crayfish in Las Vegas urban washes is, in
general, high. This is probably due to optimal environmental conditions including
adequate habitat and food, a constant source of water, and no predation.
D.
Food preferences of the red swamp crayfish were reported by Penn in 1956. P.
clarkii was observed feeding on the aquatic vegetation, including Achyranthes,
Jussiacea, Potygonum, Sagittaria, Najas, Chara, Elodea, Potomogeton, and algae, but
not on Myriophyllum and Marsilea. Crayfish will also feed on periphyton, detritus,
gastropods, and immature benthic insects (Lorman and Magnuson, 1978).
E.
Based on the habitat preferences demonstrated by stocked crayfish, emergent
vegetation, including cattails and aquatic vegetation (sago pondweed and spiny
naiad), are important to red swamp crayfish on Lake Mead.
F.
This study indicates that stocked crayfish move away from a release site if
preferred habitat is not available. Consequently, a vegetative cover enhancement
project would provide habitat for stocked crayfish and help to maintain population
levels in localized areas to facilitate breeding.
G.
Stocking crayfish in Lake Mead is relatively simple. However, the introduced
populations do not become widely established and, therefore, do not provide
sufficient forage to augment the shad population.
47
VI.
LITERATURE CITED
Allan, R.C. and B.C. Roden. 1978. Fish of Lake Mead and Lake Mojave. Base fisheries data,
Boulder Canyon to Davis Dam. Nevada Dept. of Wildlife. 105 pp.
Albert, E., and J.R. Baker. 1982. Food habits of sub-adult striped bass (Morone saxatilis) in
Lake Mead, 1981-1982. Nevada Dept. of Wildlife. 13 pp.
Baker, R.K. 1980. Distribution and abundance of three introduced crayfish species in the
northern Sacramento Valley. M.A. Thesis. California State University. 40 pp.
Beingesser, K.R., and N.H. Copp. 1985. Differential diurnal distribution of Procambarus clarkii
(Girard) juveniles and adults and possible adaptive value of color differences between
them (Decapoda, Astacidea). Crustaceana, 49(2)7:164-172.
Haley, J.S., L.K. Croft, S.E. Leavitt, L.J. Paulson, and D.H. Baepler. 1989. Introduction and
Enhancement of Vegetative Cover at Lake Mead. Lake Mead Limnological Research
Center, submitted to Nevada Dept. of Wildlife. 85 pp.
Huner, J.V. 1983. Crawfish, Procambarus spp., production from summer flooded experimental
ponds used to culture prawns, Macrobrachium resenbergii, and/or channel catfish,
Ictaluruspunctatus, in south Louisiana. Freshwater Crayfish 5:379-390.
Huner, J.V., and R.P. Romaire. 1978. Size at maturity as a means of comparing populations of
Procambarus clarkii (Girard) (Crustacea, Decapada) from different habitats.
Freshwater Crayfish 4:53-64.
Jonez, A., and R.C. Sumner. 1954. Lake Mead and Mohave investigations. Nevada Fish and
Game Commission Final Report. D-J Project F-l-R, 186 pp, unpublished.
Konikoff, M. 1977. Study of the life history and ecology of the red swamp crawfish,
Procambarus clarkii, in the lower Atchafalaya Basin floodway. Final Report. U.S. Fish
and Wildl. Serv., Univ. of Southwestern Louisiana. 81 pp.
Lorman, J.G., and J.J. Magnuson. 1978. The role of crayfishes in aquatic ecosystems. Fisheries
3(6):8-10.
Lowery, R.S., and A.J. Mendes. 1977. Procambarus clarkii in Lake Naivasha, Kenya, and its
effects on established and potential fisheries. Aquaculture 11:111-121.
O'Brien, T.P. 1977. Crawfishes of the Atchafalaya Basin, Louisiana, with emphasis on those
species of commercial importance. Master's thesis. Louisiana State University. 77 pp.
Paille, R.F. 1980. Production of three populations of red swamp crawfish, Procambarus clarkii,
in southeast Louisiana. Unpublished. Master's thesis. Louisiana State University. 40
pp.
Paulson, L.J., and J.R. Baker. 1983. The effects of limited food availability on the striped bass
fishery in Lake Mead in Aquatic Resources Management of the Colorado River Ecosystem.
pp. 551-561. Ann Arbor Scientific Pub.
48
Peck, S.K., W.L. Pratt, I.E. Pollard, L.J. Paulson, and D.H. Baepler. 1987. Benthic
Invertebrates and Crayfish of Lake Mead. Lake Mead Limnological Research Center,
submitted to Nevada Department of Wildlife. 84 pp.
Penn, G.H. 1943. A study of the life history of the Louisiana red-crawfish, Cambarus clarkii
Girard. Ecology 24(1): 1-18.
Penn, G.H. 1956. The genus Procambarus in Louisiana (Decapoda, Astacidae).
Rhodes, R.J., and J.W. Avault, Jr. 1987a. Changing sexual-state relationships of a population
of red swamp crawfish Procambarus clarkii. NOAA Tech. Rep. NMFS. 0(47):51-52.
Rhodes, R.J., and J.W. Avault, Jr. 1987b. A note on recruitment cycles for the red swamp
crayfish Procambarus clarkii. NOAA Tech. Rep. NMFS. 0(47):53-54.
Saiki, M.K., and J.C. Tash. 1979. Use of cover and dispersal by crayfish to reduce predation by
largemouth bass. J. Ariz. Acad. Sci. 11:99-104.
Saiki, M.K., and C.D. Ziebell. 1976. Some trophic relationships of the largemouth bass
Micropterus salmoides (Laiepide) in a southwestern impoundment. J. Ariz. Acad. Sci.
11:99-104.
Wilde, G.R., and L.J. Paulson. 1989. Food habits of subadult striped bass in Lake Mead,
Arizona-Nevada. The Southwestern Naturalist. 34(1).
Witzig, J.F., J.W. Avault, Jr., and J.V. Huner. 1983. Crawfish, Procambarus clarkii, growth and
dispersal in a small south Louisiana pond planted with rice, Oryza sativa. Freshwater
Crayfish 5:331-343.
49
Appendix A
ANNOTATED BIBLIOGRAPHY TO CRAYFISH ECOLOGY
Abrahamsson, S. 1973. Methods for restoration of crayfish waters in Europe--the development of
an industry for production of young Pacifastacus leniusculus DANA pp.204-210 in Freshwater
Crayfish (S. Abrahamsson, ed). Studentlitterautur. Lund, Sweden.
Pacifastacus leniusculus was introduced to Sweden after a plague destroyed the native Astacus
astacus. Over 1/2 million juvenile Pacifastacus leniusculus were raised in hatcheries and
released into Swedish lakes. Juveniles stocked in early spring were reproducing within a year.
After one year, 59 percent of juvenile introductions were successful as compared to 30 percent
success rates with adult crayfish introductions. One year after a release of 1,000 juveniles in
each of two ponds, recapture rates were 21 percent and 33 percent in spite of high numbers of
fish predators. Abrahamsson recommended the quantity of introduced crayfish should not be
too low because low densities will reduce the chance of mating. Introductions should be
repeated for some years to ensure the optimum development of the crayfish populations.
Adeboye, Duro. "The Crayfish Condition Factor: A Tool In Crayfish Research." Freshwater
Crayfish Abstract 5.
A "crayfish constant, K" and a "crayfish condition factor, F" were calculated for 147 specimens
of Procambarus astacus astacus. It was found that the "crayfish constant" was constant for all
sizes and sexes in different molting cycle stages. The "condition factor" was designed to
facilitate comparative physiological studies of various crayfish species from different
laboratories. The ratio of body weight to the products of linear measurements were used to
calculate the "crayfish constant."
K=
Body Weight
Total Length X Carapace Length X Carapace Width
The unit for K is gm/cm3. The "condition factor" was derived from the product of K and the
assigned numerical value of the moulting cycle stage.
F= K X Moulting Stage
The unit for F is gm stage/cm3.
Avault, J. W. 1973. "Crayfish Farming in the United States." Freshwater Crayfish 1:240.
There are currently three types of ponds being used for crayfish farming: rice field, wooded,
and open ponds. The ponds are flooded, a practice which provides the crayfish with food and
cover sources (inundated vegetation). Crayfish diets consist mainly of plant material, small
organisms, and periphyton. Rice fields and open ponds appear to be the most effective, due to
an ample food supply available to the crayfish and do not exhibit an oxygen depletion or low
pH~unlike the wooded ponds. Crayfish farming has steadily been increasing because they are
an excellent food source for game fish.
A-2
Baker, R. K. 1980. Distribution and abundance of three introduced crayfish species in the
northern Sacramento Valley. M.A. Thesis. California State University. 40 pp.
The distribution, relative abundance, and habitat of the crayfish Pacifasticus leniusculus,
Procambarus clarldi, and Orconectes virilis are presented as examined in areas associated with
the Sacramento River in California. Several physical habitat characteristics were measured and
correlated, including the nature of the water course, vegetation, cover, and substrate, as well as
dissolved oxygen and temperature. Distinct patterns of habitat segregation were found between
species. Due to the method of collecting crayfish (by hand from under rocks), information on
P. clarldi is mainly presented for generally sub-optimal habitat types.
Beingesser, K. R., and N. H. Copp. 1985. Differential diurnal distribution of Procambarus clarldi
(Girard) juveniles and adults and possible adaptive value of color differences between them
(Decapoda, Astacidea). Crustaceana, 49(2)7:164-172
Diurnal distribution of Procambarus clarldi was observed in a clear stream in California.
Differential use of the center (exposed) and the bank (sheltered) portions of the stream by
juveniles and adults was found. Juveniles (<60mm total length, mottled green and brown in
color) were found more frequently in the open, unsheltered parts of the stream. Adults (darker
coloration-red) occupied the most sheltered areas most frequently. The lighter color of
juveniles may render them less susceptible to diurnal predators.
Black, J.B., and J.V. Huner. Breeding your own crayfish stock. (No references-miscellaneous
paper.
This is a summary of Procambarus clarldi life cycle under laboratory conditions at 23-26°C.
Chlorinated tapwater was used (hardness must be 50 ppm calcium at minimum). Crayfish were
fed alligator weed (altemanthera), Elerdea or rotted, soaked hardwood leaves, and dried
catfood. Males were in breeding form 8-9 months of the year. Females produced eggs 2-3
times a year. Young matured at about 7.5 cm in 6-8 weeks and were ready to breed within
about 4 months.
Brinck, P. 1977. Developing crayfish populations. Freshwater Crayfish 3:211-228.
A summary of crayfish (Pacifastacus leniusculus) introductions conducted over seven years in
Europe is presented. Rationale for stocking strategies and follow-up studies is included. The
success of establishing populations increased as the stocking frequency increased. However, the
author noted that determination of reproduction in the lake can be tricky when stocking has
been repeated.
Brown, D.J., and J.M. Brewis. 1978. A critical look at trapping as a method of sampling a
population of Austropotambius pallipes (Lereboullet) in a mark and recapture study.
Freshwater Crayfish 4:159-164.
This study compares results from trapping to hand capture of crayfish. Population estimates
were made by mark recapture using both collection methods. Although both methods exhibited
some bias, trapping showed the greatest amount, underestimating population size three-fold.
Some alternatives are discussed, including alternation of sampling methods when using mark
A-3
recapture to estimate crayfish population size.
Chien, Y., and J.W. Avault, Jr. 1983. Effects of flooding dates and type of disposal of rice straw on
the initial survival and growth of caged juvenile crayfish, Procambarus clarkii, in ponds.
Freshwater Crayfish 5:344-350.
Caged crayfish were placed in ponds flooded in September or October with three different
types of rice straw sewage. Crayfish were fed a pelleted ration, so that differences in growth
were independent of food. Dissolved oxygen and temperature was monitored in all treatments.
Higher DO and temperatures enhanced growth but resulted in lower survival. Growth of
juvenile crayfish (14.5 mm carapace) averaged 8.7-9.3 mm over the 4-week study period.
Chien, Y.H., and J.W. Avault, Jr. 1983. Effects of flooding dates and disposals of rice straw on
crayfish, Procambarus clarkii (Girard), culture on rice fields. Aquaculture 31:339-359.
Population dynamics and production of crayfish cultured in ponds in Louisiana was followed to
assess the effect of early (September) and late (October) flooding dates in conjunction with
three methods of rice straw (food source) disposals. Growth of periphyton in the ponds was
monitored during the study, as well as physical conditions. The discussion of this study
highlights the interrelationships of factors such as temperature, dissolved oxygen, structure
(cover), and food type on survival, growth, and density of crayfish in a situation with relatively
high densities.
Clark, D.F., and J.W. Avault, Jr. 1975. Effects of feeding, fertilization, and vegetation on
production of red swamp crayfish, Procambarus clarkii. Freshwater Crayfish 2:125-138.
This study evaluates the growth and survival of juvenile crayfish stocked in metal pools during
summer and winter. The effect of 2 feed types, plantings of smartweed (Potygonum) and
alligator weed (altemanthera philoxeroides), addition of fertilizer, and control (no feed added)
on production was examined. Survival of crayfish was similar in all treatments. Growth and
production was highest in feed treatments: average weight crayfish 21-22g. Average growth
and production occurred on both the plant species; and when fertilizer only was added to the
pools, the average weight of the crayfish was 13 g. Crayfish apparently are able to survive on
phytoplankton.
Collins, N.C., H.H. Harvey, AJ. Tierney, and D.W. Dunham. 1983. Influence of predator density
on trapability of crayfish in Ontario Lakes. Can. J. Fish. Aquat. Sci. 40:1820-1828.
Density and trapability of crayfish populations were measured in several Ontario lakes. Trap
results were compared to counts made by SCUBA divers to evaluate crayfish density. Density
of predatious fish species was also measured for each lake. Trap results did not always
accurately reflect crayfish densities. In some lakes with higher fish densities, crayfish densities
were higher than reflected by trap returns. Therefore, high predator density not only decreased
crayfish abundance in some lakes, but in other lakes affected trapability of crayfish. Laboratory
observations of crayfish from lakes which differed in predator abundance confirmed that a
behavioral change resulted in lower trap catches. Crayfish from a lake with high bass densities
were less active than crayfish from a lake without bass.
A-4
Dye, L., and P. Jones. 1975. The influence of density and invertebrate predation on the survival of
young-of-the-year Orconectes virilis. pp. 529-538 in Freshwater Crayfish 2 (J. W. Avault, Jr.,
editor). Louisiana State University Division of Continuing Education. Baton Rouge, LA.
The effects of density and invertebrate predation on juvenile Orconectes virilis was examined in
two small Michigan lakes in 1973. Survival of young-of-the-year crayfish in field enclosures at
densities of 10.8/m2, 43/m2, and 172/m2 with no predators was significantly higher in the
10.8/m2 enclosure. There was no significant difference in survival of crayfish in 43/m2 and
172/m2 densities. Three invertebrate predators, Aeshnids, Notonectids, and Aeshnids
significantly reduced crayfish populations with 4-6 mm carapace lengths but not with 6-10 mm
carapace lengths. Predation by adult crayfish and Notonectids was not significant on either size
of crayfish.
Fitzpatrick, J.F., Jr. 1977. The statistical relationships of different techniques of measurements in
a crayfish species. Freshwater Crayfish 3:471-479 (O.V. Lindquist, editor). University of
Kuopio, Finland.
This study examined three methods of carapace measurement: standard carapace length,
postorbital carapace length, and maximum carapace length. Standard carapace length and
maximum carapace length were better for statistical analysis than postorbital carapace
measurements. The ratios of each type of carapace length to areola length (an important
taxonomic ratio) were determined and did not correlate as well as unsealed carapace length
data. Thus, either standard carapace length or maximum carapace length is the best method for
measuring crayfish length.
Furst, M. 1977. Introduction of Pacifastacus leniusculus (Dana) into Sweden: Methods, results
and management. Freshwater Crayfish 3:229-247.
A summary of procedures and considerations made during the initial introduction of crayfish
from the United States to Sweden. Both adult and juvenile crayfish were stocked in various
numbers and follow-up trapping was done to evaluate success in different areas. Adults tended
to move large distances after transplant (up to 600 M). If adult crayfish were held in cages for
four days, they appeared to "imprint" on the area and showed less movement (maximum
distance 25 M). However, stocking lakes with adults was stated to be the most effective and
least expensive method.
Hazlett, B.A., and D. Rittschof. 1985. Variation in rate of growth in the crayfish Orconectes virilis.
J. Crust. Biol. 5(2):341-346.
Growth of individual adult crayfish (Orconectes virilis) living in a Michigan stream was followed
by mark-recapture. 1,021 individuals were followed for a summer. Thirty-six crayfish were
measured one year later. Growth per molt was quite variable, ranging from 0-9 mm per molt.
Crayfish molted as many as three times during the summer. The growth rate of crayfish in this
stream is higher than other populations. Unlike other populations, crayfish in this study
frequently burrow. It is hypothesized that the higher growth rate may result from the burrowing
behavior, since this lowers the effective density as well as providing crayfish with roots as an
additional food source.
A-5
Huner, J.V. 1975. Observations on the life histories of recreationaily important crawfishes in
temporary habitats.
Crayfish (Procambarus clarkii and P. a. acutus) were sampled monthly with dip nets and traps
for a full year. Sampling was done in shallow (.15-.30 m) drainage ditches in southern
Louisiana, which contained Altemanthera philoxeroides, Pofygonum, and grasses. Juvenile (less
than 30 mm total length) crayfish numbers peaked in August and January for P. clarkii. Form I
(mature) males showed two peaks, in August and in April. This data illustrates that P. clarkii is
capable of multiple generations in habitats where drought conditions do not prevent them from
reproducing during early summer. Information is also presented on minimum time required
for crayfish to mature, sizes at maturity, and success of a limited mark-recapture study.
Huner, J.V., and J.W. Avault, Jr. 1976. Sequential pond flooding: A prospective management
technique for extended production of bait-size crawfish. Trans Am Fish Soc. 105(5):637-642.
Ponds in Louisiana were stocked in May, drained in June, and reflooded the first of September,
October, or November. From the middle of November, crayfish were sampled by the use of dip
nets and traps biweekly through May, measured, sexed, and released. Maturity of males was
also recorded, molt stage was determined, and crayfish over 4.5 cm were marked. Life history
differed between flooding dates. Early maturation (October) occurred in ponds flooded in
September and October but not in November. All ponds exhibited maturation peaks in spring.
Higher proportion of premolt (molt within two weeks) crayfish were caught in dip nets than in
traps. Densities of non-juvenile crayfish were estimated at 9.4-11.7 per square meter. Regular
harvesting of crayfish populations is recommended to enhance growth, especially when
densities are high and food potentially limiting.
Huner, J.V. 1977. Introductions of the Louisiana Red Swamp Crayfish, Procambarus clarkii
(Girard); an Update. Freshwater Crayfish 3:193-202.
Procambarus clarkii occurs naturally in the south-central United States and parts of northern
Mexico. However, it has been successfully introduced into California, Nevada, Hawaii, Japan,
parts of Africa, and Central America. This species is adapted to temporary, 'lentic
environments and can produce two generations annually, which has helped its establishment in
new areas. P. clarkii is proving to be a serious problem in some introduced areas, due to its
damage of irrigation levies and young plant shoots. In areas where crayfish are harvested for
commercial and fishery uses, the populations are kept in check, and a problem has not
occurred.
Huner, J.V., and R.P. Romaire. 1978. Size at maturity as a means of comparing populations of
Procambarus clarkii (Girard) (Crustacea, Decapada) from different habitats. Freshwater
Crayfish 4:53-64.
Size frequency distributions of mature (Form I) male crayfish are presented for temporary
(ditch and pond) and permanent (basin/lake) water habitats. Differences in factors such as
food availability, water quality, predation levels, and harvesting frequency on the population
dynamics of crayfish in these habitats are discussed. Size at maturity (ranging from 54-134 mm
total length) was smallest for males in roadside ditches, intermediate in most ponds, and largest
A-6
in optimal basin (lake/floodway) areas. Life history of Procambarus clarkii is reviewed in
relation to data on size and variation in size of mature males due to various habitat
characteristics.
Huner, J.V. 1983. Crawfish, Procambarus spp., production from summer flooded experimental
ponds used to culture prawns, Macrobrachium rosenbergii, and/or channel catfish, Ictalurus
punctatus, in southern Louisiana. Freshwater Crayfish 5:379-390.
In contrast to the traditional practice of draining crayfish ponds during the summer months,
production of crayfish in ponds flooded during the summer was examined. In addition, the
polyculture of crayfish with fish and prawns was examined. Crayfish did complete their lifecycle
even though ponds were not drained during the summer. However, production of crayfish was
lower. Control ponds (ponds with only crayfish) were not included, so effects of flooding dates
and species interactions cannot be differentiated. However, ponds containing green sunfish
(known predator of juvenile crayfish) showed significantly lower production levels.
Jaspers, E.J.M. 1969. Environmental conditions in burrows and ponds of the red swamp crawfish,
Procambarus clarkii (Girard), near Baton Rouge, Louisiana. Master's thesis. Louisiana State
University. 47 pp.
A comparison was made of a number of factors measured in crayfish irregular flooding events
and a pond with regular, controlled flooding. Annual production was 32 times higher for the
site with controlled flooding than for the other two sites. A number of environmental
parameters were measured at each site and found to be similar between sites. Therefore,
several aspects related to the hydrologic regime may account for the difference in production by
crayfish. Correlation of crayfish densities to physical-chemical parameters is also included.
The highest number of crayfish was sampled in May. By June, most of the crayfish were
mature. Breeding occurred in summer and fall. Young-of-year appeared in December, and
peak growth occurred in the spring. The single generation exhibited by Procambarus clarkii in
this study appears to be related to a low-water period lasting from August to October.
Konikoff, M. 1977. Study of the life history and ecology of the red swamp crawfish, Procambarus
clarkii, in the lower Atchafalaya Basin floodway. Final Report. U.S. Fish and Wildl.- Serv.,
Univ. of Southwestern Louisiana. 81 pp.
This is a 15 month study of crayfish from six different areas, including swamp and lake habitats
in southern Louisiana. Description of Life .history includes relative abundance, timing of
reproduction (from field collections and examination of gonads), and growth rates. Differences
in habitats were noted and environmental conditions were monitored. Crayfish were sampled
by several methods, including examination of burrows, night lighting, and a mark recapture
study to document crayfish movements. Examination of stomach contents was also done.
Although large differences occurred between habitats, crayfish generally reproduced in late
summer to fall. However, results in this study illustrated this species has the potential to
reproduce during a large part of the year. This variability and the non-synchrony of the life
cycle allows them better tolerance of irregular variation in habitat conditions. The main factors
noted regulating natural populations were the hydrological cycle and macrophyte densities.
Predation levels can compound the effects of these factors in already unfavorable situations.
A-7
Lowery, R.S., and A.J. Mendes. 1977. Procambarus clarkii in Lake Naivasha, Kenya, and its
effects on established and potential fisheries. Aquaculture, 11:111-121.
The reproduction and distribution of crayfish in an African lake was examined four years after
introduction. The population reproduced successfully and its distribution expanded. Although
a portion of the population was found to breed throughout the year, peaks of recruitment were
found associated with rising water levels.
Unfortunately, little information on other
physical/chemical parameters is presented. However, females in berry were reported from
open water as well as from burrows. Mark recapture was used to estimate densities and
provided limited movement data. Observations show that plant populations have declined in
areas where crayfish are abundant. Crayfish have become an important food base for black
bass (Micropterus salmoides) in this lake, but may also negatively impact certain aspects of the
fisheries operations.
Mason, J.C. 1979. Effects of temperature, photoperiod, substrate, and shelter, growth, and
biomass accumulation on juvenile 82, P.J. Laurent, editor. Institut National de la Recherche
Agronomique, Thoron-les-Bains, France.
The objectives of this study were 1) to evaluate the relative importance of temperature and
photoperiod in determining growth and survival of stage two Pacifastacus leniusculus in
intensive culture; and 2) to evaluate substrate, shelter, light, and diet on growth and survival
rates in intensive culture. The best growth rates were seen with high temperature and short
photoperiod, with temperature being the predominating influence. Survival was inversely
related to growth, high temperature, and short photoperiod. Average growth rate, biomass, and
survival were not affected by diet. Survival and biomass were significantly affected by substrate.
In a comparison of high density (260 crayfish/m2) vs. low density (130 crayfish/m2) and
substrate, mortality was density-dependent on bare floor but density-independent with pebbled
floor. Burrow use was density-dependent and increased the probability of survival.
Melancon, E., Jr., and J. Avault, Jr. 1977. Oxygen tolerance of juvenile Red Swamp Crayfish,
Procambarus clarkii (Girard). Freshwater Crayfish 3:371-380.
LC50 values for acute dissolved oxygen depletion were determined for two size classes of
juvenile crayfish (total lengths of 9-12 mm and 31-35 mm). The LC50 value for 96 hours of
newly released 9-12 mm juveniles ranged from 0.75-1.10 ppm oxygen. The LC50 value for 96
hours for 31-35 mm juveniles was 0.49 ppm oxygen. Crayfish in the 31-35 mm size class that
were molting had higher mortality rates than intermolting juveniles.
O'Brien, T.P. 1977. Crawfishes of the Atchafalaya Basin, Louisiana, with emphasis on those
species of commercial importance. Master's thesis. Louisiana State University. 77 pp.
This is a study of the life history of several species of crayfish, including Procambarus clarkii
collected from a basin which contains water year-round and yields a large number of crayfish
commercially.
Correlation of crayfish densities to physical-chemical parameters is also
included. The highest number of crayfish was sampled in May. By June, most of the crayfish
were mature. Breeding occurred in summer and fall. Young-of-year appeared in December,
and peak growth occurred in the spring. The single generation exhibited by Procambarus clarkii
in this study appears to be related to a low-water period, lasting from August to October.
A-8
Faille, R.F. 1980. Production of three populations of red swamp crawfish, Procambarus clarkii, in
southeast Louisiana. Unpublished. Master's thesis. Louisiana State University. 40 pp.
Production of crayfish populations was measured from three areas exhibiting different
hydrological regimes: one with permanent water, an area with irregular flooding events, and a
pond with several methods, including examination of burrows, nightlighting, and a
mark-recapture study to document crayfish movements. Examination of stomach contents was
also done. Although large differences in abundances occurred between habitats, crayfish
generally reproduced in late summer to fall. However, results in this study illustrate that this
species has the potential to reproduce during a large part of the year. This variability and the
non-synchrony of the life cycle allows them better tolerance of irregular variation in habitat
conditions. The main factors noted regulating natural populations were the hydrological cycle
and macrophyte densities. Predation levels can compound the effects of these factors in
already unfavorable situations.
Paille, R.F. 1980. Production of three populations of red swamp crawfish, Procambarus clarkii, in
southeast Louisiana. Unpublished. Master's thesis. Louisiana State University. 40 pp.
Production of crayfish populations was measured from three areas exhibiting different
hydrological regimes: one with permanent water, an area with irregular flooding events, and a
pond with regular controlled flooding. Annual production was 32 times higher for the site with
controlled flooding than for the other two sites. A number of environmental parameters were
measured at each site and found to be similar between sites. Therefore, several aspects related
to the hydrologic regime may account for the difference in production by crayfish. Differences
between sites in food availability, predation rates, flushing rates, and the effect of irregular
changes of water levels on reproduction itself were considered as possible factors. Of these, it
was concluded that predation may be the most critical factor limiting crayfish population.
Payne, J.F. 1978. Aspects of the life histories of selected species of North American crayfishes.
Fisheries Vol. 3, No. 6, pg. 5-8.
Female crayfish secrete a translucent mucilaginous sac where the eggs and sperm are mixed and
where fertilization eventually occurs. The sac wall begins to harden and cements the eggs to
pleopods. This occurs mainly during late summer and early fall in Procambrius clarkii. Egg
development is dependent on temperature, photoperiod, water circulation, and hormonal
balances within the female. It is not unusual if 40 percent of the eggs fail to hatch due to
infertility, damage resulting in a fungal attack, and the failure of the eggs to attach to the
pleopods. The hatched crayfish remain attached to the female's pleopods during the first and
second instars, which lasts approximately 19 days. Third instar crayfish venture from the female
for short periods of time. P. clarkii females produce a brooding phermone which allows a
chemical communication to exist between the female and juveniles. Maturation rates are highly
variable and are dependent on availability of food, water quality, and temperature. If
conditions are right, P. clarkii juveniles may reach adult size within two to three months, and
two generations may be produced within a single year.
Penn, G.H. 1956. The genus Procambarus in Louisiana (Decapoda,Astacidae).
A summary of life history and ecology based on data from taxonomic collections and early life
history studies of Procambarus clarkii in Louisiana are presented. A single generation life cycle
A-9
is described. Also included is a list of associated plant species and records of plants P. clarkii
has been observed feeding on.
Pollard, I.E., S.M. Melancon, and L.S. Bakey. 1983. Importance of bottomland hardwoods to
crawfish and fish in the Henderson Lake area, Atchafalaya Basin, Louisiana. Wetlands, 3:1-25.
Distribution and abundance of several fish species, young-of-year largemouth bass, crawfish,
and zooplankton were in areas including and associated with flooded woodlands in Louisiana.
In addition, several physical/chemical parameters were monitored; stomach contents of
young-of-year largemouth bass were examined; and a mark-recapture study to estimate
crawfish abundance was done. The highest concentrations of crawfish were found associated
with the edge of floodwaters, probably resulting from increased availability of food. However,
greater concentrations of crawfish burrows were found closer to permanent water.
Young-of-year crawfish were observed to be important in the diets of adult largemouth bass.
Price, J.O., and J.F. Payne. 1979. Multiple summer molts in adult Orconectes neglectus
chaenodactylus Williams. Freshwater Crayfish 4:93-104.
A mark-recapture study was used to determine molting cycle, growth rate, and the population
size class composition of Orconectes neglectus chaenodactylus in Arkansas. Over 752 animals
were marked on the carapace or abdomen using a heated dissection probe. The article
illustrates the numbering system. The mean minimum size for adult males and females was
13.5 mm (carapace length). Females molted approximately two weeks after release of young
and then 2 to 3 times during the summer. Males molted from Form I to Form II during April
and May, then molted twice in the summer, remaining in Form II. The males then molted to
Form I in late October and November. Adult crayfish did not molt during winter. Population
size class composition of reproductive size crayfish was dominated by two-year-olds in the
spring. As the average life span of this species is 2.5 years, by fall many of the adults died,
leaving the sub-adult age/size class predominating the population.
Rhodes, R.J., and J.W. Avault, Jr. 1987. Changing sexual-state relationships of a population of
Red Swamp crawfish Procambarus clarkii. NOAA Tech Rep NMFS. 0(47): 51-52.
Changes in sex and sexual state (mature or reproductive to non-reproductive) ratios of crayfish
populations were found to occur seasonally and in relation to different nitrogen levels in ponds.
External determination of mature (inseminated) females and mature-form males is described.
The changes in these ratios are discussed in relation to crayfish population dynamics as a
predictive tool for evaluating crayfish growth and reproductive responses to different
conditions.
Rhodes, R.J., and J.W. Avault, Jr. 1987. A note on recruitment cycles for the Red Swamp
Crawfish Procambarus clarkii. NOAA Tech Rep NMFS. O(47):53-54.
Oviposition by Procambarus clarkii was examined over an eight-month period in the laboratory
for comparison with field observations of recruitment. Females which layed eggs were followed
to determine their ability to produce a second clutch. Peak egg production occurred during
October of the first year with 56 percent of the females releasing eggs. Only 17 percent of the
A-10
females produced a second clutch of eggs the following April. G mortality and deformity due to
molting was noted in females which had oviposited once. Production peaks in October and
April agree with field recruitment. It was concluded that a third peak observed in field
populations during December must result from a second population of crayfish which mature
later.
Romaire, R.P., and V.A. Pfizter. 1983. Effects of trap density and diel harvesting frequency on
catch of crawfish. N. Am. J. of Fish. Manage. 3:419-424.
The relationship of trap density and frequency of harvest to catch of crayfish was examined in
commercial crayfish ponds. Crayfish catch increased with higher densities of traps. The
optimal frequency of harvest was achieved with two six-hour (diurnal) sets and one twelve-hour
(nocturnal) set. Although increased trap effort yielded greater numbers of crayfish in this
study, when crayfish densities were high, this relationship may be dependent on densities of
crayfish as well as other factors.
Saiki, M.K., and C.D. Ziebell. 1976. Some trophic relationships of the largemouth bass
Micropterus salmordes (Laiepide) in a southwestern impoundment. J. Ariz. Acad. Sci.
11:99-104.
This study evaluated the effect of recently-established crayfish populations on growth of stunted
bass in an impoundment before the introduction of shad as additional forage. Crayfish
(Orconectes causeyi) densities, bass condition, and food habits were evaluated over a one-year
period. The macrophyte Myriophyllum exalbescens grew abundantly along the shore and served
as crayfish forage. Young-of-year crayfish appeared in the spring, and maximum adult densities
were measured in June. Bass from 7.0 cm to 14.9 cm fed on crayfish in the spring, and larger
bass consumed crayfish all year. Growth of older (stunted) bass improved once crayfish were
available as forage, and condition factor of fish also increased by the end of the study. Since
shad had not been introduced yet, it was concluded that crayfish alone could improve growth of
largemouth bass. Stocking of crayfish is suggested to improve forage bases for bass in new
impoundments.
Saiki, M.K., and J.C. Tash. 1979. Use of cover and dispersal by crayfish to reduce predation by
largemouth bass. J. Ariz. Acad. Sci. 11:99-104.
Observation of crayfish behavior in relation to predation by bass was done in lab and field
situations. Predation rate on crayfish was examined in relation to density of plants as cover in
plastic pools. Increased plant densities significantly decreased predation rates. Size selectivity
by bass for smaller crayfish also diminished at higher plant densities. Trapping of crayfish in a
southwestern lake which contained water milfoil [primary cover for crayfish] and largemouth
bass was conducted to examine seasonal distribution of crayfish. Greater numbers of crayfish
were found in vegetated areas. However, crayfish dispersed throughout the lake when plants
died back. Therefore, multiple behavioral interactions may be responsible for achieving
balanced population levels with this particular food web.
Sheppard, M.F. 1974. Growth patterns, sex ratio, and relative abundance of crayfishes in Alligator
Bayou, Louisiana. Master's thesis. Louisiana State University. 54 pp.
Life histories of six species of crayfish, including Procambarus clarkii, were studied in a swampy
A-ll
area subjected to periodic flooding in southern Louisiana. Crayfish were sampled by dip
netting and seining monthly over a two-year period. Size, frequency, distribution, and resulting
growth patterns of 2,068 P. clarkii sampled during the study are presented. There appears to be
one generation per year, young first appearing as early as September, slow growth occurring
during the winter, increasing in April to June until the majority of the population was adult size.
It was also observed that Procambarus spp. readily moved into the inundated floodplains during
high water, allowing access to additional food sources.
Somers, K.M., and D.P.M. Stechey. 1986. Variable trapability of crayfish associated with bait
type, water temperature, and lunar phase. Am. Midi. Nat. 116(l):36-44.
Comparison of trap results with SCUBA collections of Orconectes virilis and Cambarus bartoni
in an Ontario oligotrophic lake was done during October. The effects of four bait types
(chicken, pork liver, fish, and dry dog food), water temperature, and lunar phase on number
and size of crayfish caught was assessed. The mean carapace length of crayfish taken in traps
was larger than crayfish caught by divers. The sex ratio was biased toward males for trap
catches, but was essentially 1:1 for SCUBA results. Although the number of crayfish caught by
each bait type was not different, the size of crayfish was largest for traps with chicken,
decreasing for liver, fish, and then dog food. Low temperatures were shown to reduce
trapability, and the lunar phase (or cloudiness) may also affect size of crayfish catch. Several
combinations of interactions between these factors and variation in habitat were also evaluated.
Sommer, T.R., and C.R. Goldman. 1983. The Crayfish Procambarus clarkii from California rice
fields: Ecology, problems, and potential for harvest. Freshwater Crayfish 5:418-428.
The life history and distribution of P. clarkii in California is presented in conjunction with a
survey of its effects on the rice industry. This species may inhabit two-thirds of the State of
California, and appears to have a negative impact on a majority of the rice growing operations.
The timing of flooding rice fields is shifted from Louisiana studies and often results in a shorter
growing season. Crayfish are reported to begin reproduction in April when fields are reflooded,
and young are produced continuously through the summer. Fields are drained starting in late
August, and crayfish must often rely on burrows for survival through the winter, as many fields
are left dry until spring.
Sommer, T.R. 1984. The biological response of the crayfish Procambarus clarkii to transplantation
into California rice fields. Aquaculture, 41:373-384.
Established populations of crayfish resulting from range extension in Southern California were
studied over a two-year period. Comprehensive life history data was collected to evaluate
physical conditions, reproduction, growth, density, and biomass of crayfish. Generally, timing of
life cycle events for crayfish in California were similar to crayfish in Louisiana. However,
differences in the hydrological cycle resulted in a shift in periods of activity, decreased juvenile
growth rates and biomass, and lower densities of adults. In spite of suboptimal conditions,
these populations may be reaching harvestable levels.
Stein, R.A., and J.J. Magnuson. 1976. Behavioral response of crayfish to a fish predator. Ecology,
Vol. 57 No. 4, pp. 751-761.
The smaller the crayfish, the more vulnerable it is to fish predation; therefore, they tend to alter
A-12
their behavior more dramatically than larger, adult crayfish. Walking, climbing, and feeding
were supressed in small crayfish by the presence of a predator; however, burrowing and chelae
display were increased in all size groups of crayfish. Adult males were less affected by the
presence of a predator than adult females. This is due to the males' larger chelae which offer
more protection. Smaller crayfish will also select substrates offering the greatest protection
against fish predation.
Taub, S.H. 1972. Exploitation of crayfish by largemouth bass in a small Ohio pond. Progressive
Fish Culture 34(l):55-58.
A pond with an established population of the burrowing crayfish (Cambarus diogenes) was
stocked with largemouth bass fingerlings to assess the population dynamics of these two species
in association. Crayfish densities, bass growth and food habits, and observations of plant
growth were measured over a two-year period. Initial growth of fish was good but slowed
during the second year. Incidence of crayfish in bass stomachs remained high (>40%) in spite
of a severe reduction in crayfish densities. Observations of plants showed that macrophyte
biomass and diversity increased as the crayfish population was reduced. Therefore, predation
by fish on crayfish populations can be very effective and result in major biological shifts in
community structure.
Weingartner, D.L.
1982. A field-tested internal tag for crayfish (Decapoda,
Crustaceana, 43 (2): 181-188.
Astacidae).
Crayfish tagging should: 1) not disrupt behavior, growth or longevity; 2) survive molting and
the lifecycle of the crayfish; 3) be applicable to all life stages; 4) provide individual recognition;
and 5) provide recognition without dissection. A new method of hypodermically injecting
color-coded fishing line (3.5 mm long) for large crayfish (carapace length) 17.5 mm, or sewing
thread (1.5 mm long) for smaller crayfish parallel to the midline of the abdomen near the fifth
sternite, was found to be superior to conventional tagging methods.
Wiernicki, C. 1984. Assimilation efficiency by Procambarus clarfdi fed Elodea (Egera densa) and
its products of decomposition. Aquaculture, 36: 203-215.
The ability of four size classes of crayfish to assimilate two sizes of Elodea fragments was
examined in a compartmentalized tank. Comparison was also made between different ages (0,
15, 33, and 45 days) of plant material to evaluate the importance of microorganisms in diet. A
carbon 14 radiotracer was used to differentiate plant material from microorganisms in the diets
of crayfish. Aging improved assimilation efficiency, and microorganisms were especially
important for smaller sizes of crayfish due to their enhanced ability to handle smaller fragments
than adults.
Witzig, J.F., J.W. Avult, Jr., and J.V. Huner. 1983. Crawfish, Procambarus clarkii, growth and
dispersal in a small south Louisiana pond planted with rice, Oryza sativa. Freshwater Crayfish
5:331-343.
Crayfish growth and distribution in a culture pond was examined after flooding with regard to
water depth, vegetation density, pond area, and time after flooding. Unharvested rice Oryza
sativa, served as cover and the major food source. Crayfish densities were higher in shallow
water (0.6 to 0.8 m), dense vegetation ( > 646 g/m, dry wt.), and center areas. No preference for
A-13
deep or shallow areas was seen approximately 200 days after flooding when vegetation had
decomposed in both areas. With decreasing nutrient resources, crayfish biomass decreased.
Supplemental high protein feed was recommended to sustain crayfish growth. The author notes
that terrestrial vegetation decomposes slower than aquatic vegetation and would serve as a
better supplement.
A-14
Appendix B
Appendix B. Habitat sampled by each trap during each introduction period. Aquatic plants =
POPE (Potamogeton pectinatus) and NAMA (Najas Marina), terrestrial plant = BAGL (Baccharis
glutinosa), emergent plant = cattails.
Trap
Intro 1
Intro 2
Intro 3
Intro 4
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
Rock
Gravel
Gravel
Gravel
Gravel
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
Rock
Gravel
Mud
Mud
Mud
Mud
Mud
Mud
Rock
Gravel
Mud
Mud
Mud
Mud
Mud
Mud
Rock
Gravel
Mud
Mud
Mud
Mud
Mud
Mud
Rock
Gravel
Mud
NAMA
Mud
Mud
Mud
Mud
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
Rock
Rock
Mud
Rock
Rock
Rock
Rock
Rock
Rock
Rock
POPE
Rock
Rock
Rock
Rock
Rock
Rock
POPE
POPE
Rock
Rock
Rock
Rock
Rock
Rock
NAMA
NAMA
NAMA
Rock
Gravel '
Gravel
NAMA
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
Rock
Mud
Mud
Rock
Rock
Rock
Rock
Rock
Rock
POPE
Rock
Rock
Rock
Rock
Rock
Rock
Rock
POPE
POPE
Rock
Rock
Rock
Rock
Rock
Rock
NAMA
NAMA
Rock
Rock
Rock
Rock
Gravel
(Continued)
B-2
Appendix B. (Continued) Aquatic plants = POPE (Potamogeton pectinatus) and NAMA (Najas
Marina), terrestrial plant = BAGL (Baccharis glutinosa), emergent plant = cattails.
Trap
Intro 1
Intro 2
Intro 3
Intro 4
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
Rock
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
Mud
Mud
Mud
Mud
Mud
Rock
Rock
Rock
POPE
Mud
Mud
Mud
Mud
Brush
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
7-1
7-2
7-3
7-4
7-5
7-6
7-7
7-8
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock
Rock '
Rock
8-1
8-2
8-3
8-4
8-5
8-6
8-7
8-8
BAGL
BAGL
Mud
Mud
Mud
Mud
Mud
Mud
BAGL
POPE
POPE
POPE
Mud
Mud
Mud
Mud
POPE
Mud
Mud
Mud
Mud
Mud
Mud
Mud
NAMA
NAMA
Mud
Mud
Mud
Mud
Mud
Mud
Continued
B-3
Appendix B. (Continued) Aquatic plants = POPE (Potamogeton pectinatus) and NAMA (Najas
Marina), terrestrial plant = BAGL (Baccharis glutinosa), emergent plant = cattails (cont.).
Trap
Intro 1
Intro 2
Intro 3
Intro 4
9-1
9-2
9-3
9-4
9-5
9-6
9-7
9-8
Cattails
Mud
Mud
Mud
Mud
Mud
Mud
Mud
Cattails
POPE
Mud
Mud
Mud
Mud
Mud
Mud
Cattails
Mud
Mud
Mud
Mud
Mud
Mud
Mud
NAMA
NAMA
Mud
Mud
Mud
Mud
Mud
Mud
10-1
10-2
10-3
10-4
10-5
10-6
10-7
10-8
Rock
Rock
Mud
Mud
Mud
Mud
Mud
Rock
Rock
Rock
Mud
Mud
Mud
Mud
Mud
Mud
Rock
Mud
Mud
Mud
Mud
Mud
Rock
Rock
Rock
Rock
Mud
Mud
Mud
Rock
Rock
Rock
11-1
11-2
11-3
11-4
11-5
11-6
11-7
11-8
Trapline
Established
on 2/1/89
Rock
Gravel
Gravel
Rock
Mud
Mud
Brush
Brush
Rock
Rock
Gravel
Gravel
Rock
Mud
Brush
Brush
Rock
Gravel
POPE
Rock
Mud
Brush
Brush
POPE
Rock
Gravel
Gravel
Gravel
Mud
Mud
Rock
Rock
12-1
12-2
12-3
12-4
12-5
12-6
12-7
12-8
Trapline
Established
on 2/1/89
Rock
Rock
Gravel
Gravel
Gravel
Mud
Mud
Mud
Rock
Rock
Gravel
Gravel
Gravel
POPE
Mud
Mud
Rock
Gravel
Gravel
POPE
POPE
POPE
POPE
POPE
Rock
Gravel
Gravel
Gravel
Mud
NAMA
,NAMA
NAMA
(Continued)
B-4
Appendix B. (Concluded) Aquatic plants = POPE (Potamogeton pectinatus) and NAMA (Najas
Marina), terrestrial plant = BAGL (Baccharis glutinosa), emergent plant = cattails (cont.).
Trap
Intro 1
Intro 2
Intro 3
Intro 4
13-1
13-2
13-3
13-4
13-5
13-6
13-6
13-8
Trapline
Established
on 2/1/89
Rock
Rock
Gravel
Gravel
Gravel
Brush
Gravel
Gravel
Trapline
Established
on 5/2/89
Rock
Rock
Gravel
Gravel
Rock
Brush
Gravel
Rock
Rock
Rock
Gravel
Gravel
Gravel
Brush
Rock
Rock
Rock
Rock
Gravel
Gravel
Gravel
Rock
Gravel
Gravel
14-1
14-2
14-3
14-4
14-5
14-6
14-7
14-8
Trapline
Established
on 2/1 1/89
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
Rock
Trapline
Established
on 5/2/89
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
Rock
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
Rock
Gravel
Gravel
Gravel
Rock
Rock
Rock
Rock
Rock
15-1
15-2
15-3
15-4
15-5
15-6
15-7
15-8
Trapline
Established
on 2/1 1/89
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Trapline
Established
on 5/2/89
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
Rock
Gravel
Gravel
Gravel
Gravel
Gravel
Gravel
Rock
Rock
B-5