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NEVADA DEPARTMENT OF WILDLIFE
FISHERIES DIVISION
FIELD TRIP REPORT
DATE(S): 19 and 20 March, 2015
LOCATION(S): Lake Jacqueline, Desert Shores Lake Association, Las Vegas, Clark
County, Nevada
PURPOSE(S): Investigate reported fish die-off and associated water quality
PERSONNEL: Kevin Guadalupe
PREPARED BY: Kevin Guadalupe, Endemic Fish and Amphibian Biologist
INTRODUCTION
On the morning of 19 March representatives from Desert Shores Community Association
(DSCA) inquired about potential causes associated with fish die-offs at Lake Jacqueline. Lake
Jacqueline is an approximately 39 surface-acre north-south running elongate privately owned
lake in northeast Las Vegas maintained by the DSCA, providing aesthetic and recreational
opportunities for residents. It was reported that no incident to this extent has occurred prior in
Lake Jacqueline. Warmwater fish species typically favor 8-10 ppm of dissolved oxygen, and
sustain life adequately at levels greater than or equal to 6 ppm. Levels below 6 ppm are typically
stressful and undesirable to most warmwater fish species. The DSCA contacted the Nevada
Department of Wildlife (NDOW) for assistance in assessing temperature, dissolved oxygen, and
general lake and fishery condition at Lake Jacqueline.
METHODS and MATERIALS
Water temperature and milligrams per Liter (mg/L) of dissolved oxygen was measured at three
locations using a YSI 55 handheld meter with a 20 foot cable. The sensor probe membrane was
replaced and calibrated to 2,400 feet elevation onsite prior to data collection. Conductivity (µs),
pH, total dissolved solids (TDS) in parts per thousand (ppt) was measured at surface locations
using a handheld Oakton Test-r 35 multi-parameter meter.
Visual observations were made to inventory species occurrence, and to document the extent and
distribution of expired fishes.
On 19 March, measurements were taken at the Desert Shores Lakes Association marina dock, the
southeast corner of Lake Jacqueline (South Dock), and from a kayak in the middle of the
southeast bay (Table 1). A handheld Garmin etrex 20 recorded locations of all data measurement
locations (Figure 1). Measurements were recorded from 1511hours to 1633 hours in the
afternoon towards the peak photosynthetic period at surface levels, mid-depths, and at the bottom
relative to the depth of the survey area.
On 20 March measurements were recorded at the South Dock and Marina Dock from 0630 hours
to 0700 hours at surface, mid-depth, and at the bottom.
RESULTS
On 19 March highly saturated dissolved oxygen (>10.00 ppm) levels were measured at the
Marina Dock and South Dock (Figure 2 and 3). Temperatures ranged from 58.28°F to 60.44°F
during surveys times. Favorable oxygen and temperature measurements were measured at the
surface and mid-level measurements from a kayak in the southeast corner of the lake. A low
dissolved oxygen measurement was recorded at 8.45 feet towards the bottom, ranging from 1.372.27 mg/l of DO.
There were seven species of game fish and ornamental fish species observed expired within Lake
Jacqueline (Table 3). Introduced pet trade red ear slider turtles were also observed, but appeared
in general good health. Floating expired fish were not observed on the north side of Breakwater
Drive Road Bridge near a bubbling aerator. General appearance of expired fishes was healthy
without obvious signs of external parasites, or unhealthy looking body length to weight
measurements. The majority of expired fish were observed in the south side of Lake Jacqueline
in the 16.89 surface acres south of Breakwater Drive Road Bridge.
Temperatures and dissolved oxygen levels did not significantly differ (p >0.05) between DO
measured in the afternoon of 19 March and morning of 20 March. A drastic fluctuation in diel
(24 hour) temperature and DO was not detected at the sample locations between photosynthetic
peak in the afternoon of 19 March and the morning of 20 March.
TABLE1. Water parameter measurements recorded on a handheld YSI 55 oxygen temperature
probe at Lake Jacqueline, Desert Shores, Las Vegas NV on 19-20 March, 2015.
Location
Marina
Dock
Marina
Dock
Marina
Dock
South Dock
From Kayak
From Kayak
From Kayak
South Dock
South Dock
Marina dock
Marina dock
Marina dock
Date
Time
Depth from
surface
(ft)
3/19/2015
1511
0
15.7
60.26
106.5
10.11
3/19/2015
1513
2.5
14.9
58.82
96
10.13
3/19/2015
1520
5.2
14.9
58.82
89.7
9.06
3/19/2015
3/19/2015
3/19/2015
3/19/2015
3/20/2015
3/20/2015
3/20/2015
3/20/2015
3/20/2015
1612
1632
1628
1633
0630
0632
0656
0704
0707
0
0
4
8.45
0
2
0
2.5
5.2
15.8
15.5
14.7
14.6
14.1
14.1
13.8
13.8
13.8
60.44
59.9
58.46
58.28
57.38
57.38
56.84
56.84
56.84
103.43
109.3
82
20.1
98.5
82.8
93.3
90.2
76.1
10.28
10.9
8.55
2.27
10.16
8.56
10.17
9.78
7.84
Temp
(°C)
Temp
(°F)
% Oxygen
Saturation
DO
(mg/L)
TABLE 2. Water parameter measurements recorded on a handheld Oakton Testr 35 multiparameter probe.
Location
Marina Dock
South Dock
Marina dock
Date
pH
Conductivity (µs)
TDS (ppt)
3/19/2015
3/20/2015
3/20/2015
8.7
8.8
8.81
1960
1952
1951
1.4
1.39
1.38
TABLE 3. Encountered fish species at Lake Jacqueline, Desert Shores, Las Vegas NV on March
19-20, 2015.
Common name
Black Crappie
Bluegill
Channel Catfish
Common Carp
*Grass Carp
Koi (decorative carp)
Largemouth Bass
Genus species
sub species
Pomoxis nigromaculatus
Lepomis macrochirus
Ictalurus punctatus
Cyprinus carpio
Ctenopharyngodon idella
Cyprinus carpio
Micropterus salmoides
haematopterus
FIGURE 1. Map of water quality measurement locations at Lake Jacqueline, Desert Shores, Las
Vegas, NV on 19-20 March, 2015.
0
Dissolved Oxygen (mg/L)
4
6
8
2
10
12
0
Depth (ft)
2
4
6
8
10
Marina Dock
South Dock
From Kayak
FIGURE 2. Dissolved oxygen level measurements taken at Marina Dock, South Dock, and from a
kayak at Lake Jacqueline on 19 March, 2015 using a handheld YSI 55 meter.
50
55
Temperature (°F)
60
65
0
Depth (ft)
2
4
6
8
10
Marina Dock
South Dock
From Kayak
FIGURE 3. Water temperature level measurements taken at Marina Dock, South Dock, and from a
kayak at Lake Jacqueline on March 19, 2015 on a handheld YSI 55 meter.
DISCUSSION
A possible scenario for the cause of the fish kill at Lake Jacqueline is that it was a result of lake
turnover that occurs in warm eutrophic (nutrient rich) lakes. Typically, excess nutrients and
decomposing layers of a lake stay locked beneath due to thermal stratification. During the
spring-mixing period, oxygen and carbon dioxide levels can reach equilibrium with the
atmosphere, increasing the likelihood of lake turnover and mixing (Goldman and Horne 1994).
Eventually the difference in temperature and density between the overlying water and the
beneath is so slight that the slightest wind can mix the stratified layers, mixing the anoxic,
potentially toxic decomposing, carbon dioxide producing, and lethal nutrient rich levels with the
surface water. Decomposing leaf litter accumulated over winter months and organic materials
including dead fish can increase the biological oxygen demand (BOD) on a lake from these
lower aphotic (lightless) zones. Fish that are unable to find refuge during the time of mixing can
perish over long enough exposure. After such an event, the sediments of a eutrophic lake may
take several weeks of mixing before their oxygen debt is fully balanced and carbon dioxide
levels return to normal. As temperatures in the Las Vegas Valley increase, lake levels will again
start to stratify.
Lake Jacqueline temperature was measured as nearly uniform through the water column on 19
and 20 March, ranging from 56.84° F to 60.44 °F. Night time ambient air lows ranged from 56
to 65 °F in the Las Vegas valley during the week of 14 March through 21 March (Table4, Figure
5). This problem is compounded at night time hours when natural oxygen producing processes
(photosynthesis) drop to zero.
Although oxygen is an indicator of lake health, it is one variable among many others contributing
to a lake’s ecosystem. An anoxic zone potentially lethal to fish was detected when sampling
1.33 mg/L to 2.27 mg/L of dissolved oxygen at 8.4 feet below the surface at the South Side of
Lake Jacqueline. However, low oxygen levels alone are probably not enough to kill fishes of
different species both tolerant (carp) and moderately tolerant to low dissolved oxygen levels
(largemouth bass) within the lake at such drastic levels. Experiments with the critical low
oxygen shock level with bluegill, largemouth bass, and catfish found that these species can
survive 24 hours in dissolved oxygen levels as low as 0.75, 0.92., and 0.95 mg/L for 24 hours
when exposed in a shock test at 25 °C [77°F] (Moss and Scott 1961).
Excess nutrients in a lake bottom can be just as harmful as those that come from the surrounding
watershed. Fertilizer runoff can also increase oxygen consumptive processes and increase
biological oxygen demand.
It is unlikely a fish parasite or disease rapidly killed this many fish since it affected fish of
different species in a singular event. In general and based on general, visual observations, the
fish collected were in healthy state of length and body mass ratio. Fish examined for general
appearance and health looked healthy and did not have visible external parasites (hook worms,
trematodes, etc), gill lesions, or bacterial infections as in warmer months.
The possible scenario and causes presented are hypothetical and based on basic limnological
functions. Additional monitoring is needed to gain substantiated empirical evidence to know
exactly why fish perspired in such large quantities at Lake Jacqueline.
TABLE 4. Temperature measured in the Las Vegas Valley for the week of 15 March, 2015
through 21 March, 2015. Data was accessed through the weatherunderground.com website on
23 March, 2015.
2015
Mar
15
16
17
18
19
20
21
high
83
84
84
78
80
81
85
Temp. (°F)
avg
71
72
73
72
71
68
71
low
58
60
61
65
62
55
56
high
13
15
17
18
21
13
23
Wind (mph)
avg
6
7
8
8
8
7
11
high
18
19
22
24
28
15
29
FIGURE 5. Weekly weather history graph from 15 March, 2015 through 21 March, 2015. Graphs
were accessed through the weatherunderground.com website on 23 March, 2015.
RECOMMENDATIONS
In most situations, DO greater than 6 mg/L (or ppm) can support self sustaining populations of
recreational sport fish. Varieties of options are commercially available to regulate, mix, and
enhance the common problems facing artificial lakes in desert climates. Many of these products
are available by purchase through such companies as Pentair Aquatic Eco-Systems:
Pentairaes.com. Creating artificial oxygen rich refuges during nighttime hours could potentially
decrease the impact of lake events. In addition, monitoring equipment like those produced by
Onset can monitor seasonal and diel oxygen and temperature fluctuations for aquatic lake
management purposes.
It is recommended that the DSCA work with a private company
specializing in pond and lake management/consulting to develop appropriate measures to prevent
future fish die-offs.
LITERATURE CITED
D. D. Moss & D. C. Scott (1961) Dissolved-Oxygen Requirements of Three Species of
Fish, Transactions of the American Fisheries Society, 90:4, 377- 393,
DOI:10.1577/1548-8659(1961)90[377:DROTSO]2.0.CO;2
Goldman, Charles R., and Horne J., Alexander. 1994. Limnology. McGraw-Hill, Inc,
New York.